Category Archives: Issue 45 (December 2017)

Welcome to Issue 45, December 2017!

In the last issue I mentioned that I was in correspondence with the DVLA concerning my request for details of past owners of my PB. The correspondence has ‘snowballed’ a bit because the DVLA has come back, praying in aid of our old friend, The Data Protection Act. I have written to my Member of Parliament suggesting a possible solution (if the DVLA really want to be helpful) and that’s where the matter currently rests. I’ll produce an update for the next issue.

The ’spammers’ have been at it again. Steve Wallace and John Morley have been in touch to report unwelcome contacts. It is extremely difficult to stop these people, so vigilance is the order of the day. You can always contact me if you are in any doubt.

Our Totally T-Type 2 Tours have been really well supported, ever since the first one, The Tour of Rutland, which was organised in 2013. Our 2018 Tour of The Cotswolds, which is based at the Wyck Hill House Hotel & Spa in Stow-on-the-Wold is already fully booked. It’s most heartening to get such endorsement but I know that there are some regular attenders who haven’t booked and will therefore be disappointed. From experience of running these Tours there are inevitably last- minute cancellations so I am keeping a reserve list for those who wish to express an interest.

Not wishing to let the grass grow under our feet, we have already booked the hotel for our 2019 Tour of mid-Wales. The dates are 23/24/25 August 2019 and the venue is The Metropole Hotel & Spa in Llandrindod Wells. As this is a Bank Holiday weekend (the hotel was fully booked in the weeks either side of these dates) we have been offered a special deal of half the normal tariff for those wishing to stay over on the Monday night (to avoid the traffic).

At this rate we’ll soon be in the 2020s and, of course, the centenary of the M.G. marque is looming large. There has been much debate as to whether this important anniversary should be celebrated in 2023 or 2024. On behalf of The MG ‘T’ Society Limited I am firmly of the view that it should be 2023.

In the publication The Story of the M.G. Sports written in late 1927 (published early in 1928) and issued by Managing Director, Cecil Kimber to Morris Garages salesmen, the first line of the Introduction reads When the M.G. Sports Cars were first introduced in 1923….

The 1923 date refers to the order by Kimber for six two-seater bodies from Charles Raworth of Oxford which Cec Cousins, who was responsible for building the cars, regarded as the first Morris Garages products that may be considered M.G.s.

It seems to me that these two primary sources cannot be disputed by those who advocate the celebration of the marque in 1924.

Issue 44 was the first to be printed by our new printers, Cambrian Printers. When these were being prepared for dispatch to printed copy subscribers, they were found to be inside the 100gm weight step, but only just. To be on the safe side I affixed sufficient postage to cover the next weight step, but it grieved me to overpay Royal Mail. So, for this issue, I will pay at the 100gm weight step and if this results in anybody being incorrectly surcharged, will they please let me know.

Later in this issue we have reproduced the TD and TF wiring diagrams in colour. We have John Dutton (a previous Treasurer of the MG Car Club) to thank for this. John has also sent me the TA, TB and TC (both versions) diagrams in colour and these will appear in the next two issues.

It occurs to me that we could arrange for these diagrams to be printed in enlarged (A3) size. At the time of writing I don’t know what the unit cost would be, but I can’t think it would be over-expensive. Perhaps those who are interested could let me know via the website contact form, please?

Issue 44 contained an article by Neil Wallace about rolling road tests on his TF1500. We were hoping for an update for this issue, but Neil has not been able to provide one for the following reason:

I am still experimenting with different advance curve settings, and as I use the car much less in the winter months (it’ll be off the road for a month or two whilst I get the seats re-connolised) I regret it might be the spring 2018 before I can write something useful to the readers. Sorry, but I won’t forget my commitment. 

All I can say at this stage is that I am on my second curve setting, and the performance so far is impressive – especially accelerating up steep hills with two up in the car.

TA0252, the prototype TA (CJO 617) has turned up as a ‘barn find’ and is in the ownership of Angie and Andy King. It was in previous ownership for 54 years in Herefordshire and was last on the road in March 1967. The TA owner used to grasstrack a Rudge 500 single cylinder motor bike carried on a trailer to meetings behind the TA up until the mid-sixties. Regrettably, not enough space for a picture, but one will be included in the next issue.

Just sufficient space to say we will be attending the International MG & Triumph Spares Day at Stoneleigh on Sunday 11^th February. As usual we will be in Hall 1 on a shared stand with ‘TA Brian’.

JOHN JAMES

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DISCLAIMER BY THE EDITOR

Totally T-Type 2

is produced totally on a voluntary basis and is available on the website www.ttypes.org on a totally FREE basis. Its primary purpose is to help T-Type owners through articles of a technical nature and point them in the direction of recommended service and spares suppliers. Articles are published in good faith but I cannot accept responsibility or legal liability and in respect of contents, liability is expressly disclaimed.

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The clock in my TC has never run for more than a few hours, even though it has been returned to a well-respected instrument restorer a number of times. Come to think of it, I’m not sure that I’ve seen many TCs with a reliable clock. It’s not surprising really as the clock always had a reputation for poor reliability. For this reason, many people may have already incorrectly attributed it, like everything else in the car that has wires attached and is unreliable, to the ‘Prince of Darkness’, Joseph Lucas. However, on this occasion they’d be wrong, the TC clock was actually made by Smiths Motor Accessories Ltd.

The Smiths ‘Pin’ clock first appeared in 1938 and was intended to replace their 8-day hand-wound clockwork car clock as fitted to the TA. Their pin clock is a hybrid of 17^th Century clock technology, which uses a balance wheel and spring to measure time, and an electromagnet to provide its driving force. The clock appeared in many guises with different faces, cases and setting stems, but the basic ‘engine’ was common to all. It quickly dominated the car clock market and was still being fitted as the car clock of choice well into the 1960s, including to marques far more prestigious than MG, including by Jaguar, Alvis, Bristol and Rolls Royce/Bentley.

It is an ingenious design and has refinements such as jewelled bearings for the balance staff, but the cause of the unreliability and hence the clock’s poor reputation, are the contacts that apply power to the electromagnet each time the balance wheel rotates. The balance wheel oscillates back and forth five times a second, so over 3 million times every week. Or put another way, if my clock had run continuously since my car was built in 1947 the balance wheel would by now have oscillated an incredible 11 billion times! The problem is that each time the contacts apply power to the electromagnet a minute part of the contact material is vaporised by the tiny arc produced as the contacts open. The result is that the contacts wear quickly and soon the clock only shows the correct time twice a day.

Now Clocks 4 Classics have devised a simple repair kit that will get your clock going again for far less than the price of a tank of fuel. Their repair kit consists of a tiny printed circuit board (Photo 1) containing a processor (bottom centre) that drives the electromagnet in place of the contacts. The kit is not a quartz crystal conversion. Instead the balance wheel and spring are retained and continue to be used to measure time.

Fitting the repair kit is not difficult and requires no soldering. There are versions for positive earth and negative earth cars. It does however mean stripping the clock down to its component parts, including removing the hands and dial. Clocks 4 Classics have videos on their website (www.clocks4classics.com) which firstly tell you how to determine if your clock is suitable for repair and then provide an overview of exactly what is involved in fitting the kit. There are also detailed fitting instructions to download. If the idea of dismantling your clock doesn’t appeal Clocks 4 Classics will fit the kit for you.

Photo 1 – The circuit board showing the controller (bottom centre).

The first step is to remove the clock from the car (Photo 2) and then remove the four screws that attach the base and setting stem (Photo 3).

Above: Photo 2 – The clock as removed from the Rev Counter ready to be modified. Below: Photo 3 -The clock with back and setting stem removed.

For this part of the repair, and to use later during reassembly, it is a good idea to make a simple holder to protect the hands and dial when working on the clock face down. The next step is to remove the two brass hexagonal spacers that hold the coil and then remove the coil assembly (Photo 4) by snipping the wires, leaving them as long as possible.

Photo 4 – The coil removed ready to remove the input terminal for modification.

Next, the balance wheel and support can be removed by unscrewing the remaining two brass spacers. Supplied in the kit is a sticker which fits to the underside of the balance wheel to register its rotational position. Next, the tag which is connected to the battery supply can be removed. The tag has to be modified but this is not a difficult operation. The remaining gears on the back side of the clock can be left in place. On the front of the clock the hands and dial can then be removed (Photo 5).

Photo 5 – Front of the clock with hands and dial removed.

With the clock now largely disassembled, the parts can be cleaned and the pivots lubricated if necessary before fitting the printed circuit board and beginning re-assembly.

Re-assembly is the reverse of the dismantling process and is described in detail in the instructions. Once the balance wheel and support are back in place the coil can be re-fitted. Next, the wires from the coil can be plugged into the circuit board terminals and the modified input tag re-fitted. The clock can then be tested by applying 12 volts from a battery or power supply. As power is applied, the balance wheel will rotate then freeze for a few seconds before beginning to oscillate. The circuit board must be shielded from bright light for correct operation. If all is well the coil wires can be fixed to the circuit board by heatshrinking sleeves over the terminals. Finally, the clock back and setting stem can be re-fitted with its four screws. Re-assembly at the back of the clock is then complete and all that remains is to re-fit the dial and the hands (Photo 6).

Photo 6 – The finished clock with kit fitted ready for refitting into the Rev Counter.

I found the kit to be well made and supplied with very clear fitting instructions. The videos on the website show exactly what is involved before you take the plunge. Now thanks to Clocks 4 Classics after 70 years my clock is finally tickety- boo!

Peter Cole

Ed’s Note: Peter has no connection with Clocks 4 Classics other than being a satisfied customer.

He has been able to negotiate a 10% price reduction for readers of TTT2 who order a repair kit quoting this article.

Clocks 4 Classics are based at:

1 Millbank Cottages
Nicholls Lane
Stone
ST15 8UA

“It all started one day in late February of 1960 when I received a phone call from my friend Gary Blew asking if I was interested in buying an MG TF. He said that an insurance agent he knew, told him about a TF that had gone through a fence after sliding off a road during a snow storm in the mountains of Southern Oregon, which could be bought at a reasonable price. Other than knowing that the right rear fender was damaged and the right front fender and one wire wheel had to be replaced and it was drivable, I knew nothing about the TF. I decided to make an offer low enough to be able to recover my purchase price by selling parts from the TF if it was damaged beyond repair. My offer was accepted and I found myself the owner of a red 1954 MG TF 1250 (pictured below with Dale driving and friend Gary Blew alongside).

After taking possession of the car, I found that the cowl had been damaged, causing the windshield to slope toward the passenger compartment, making the top not fit properly. I also discovered indications that the car had been wrecked at least once before. The left side panel of the engine compartment contained a label from a Philadelphia, Pennsylvania auto parts house, indicating it had been replaced, and also there was some damage to the right front chassis extension, that fortunately had no impact on handling.

It took several months to get the Michigan car title straightened out and get the car registered in my name in Oregon, so I was unable to get any work done on the TF before I entered the Army at the end of the summer. In my absence my parents had the body work required to fix the damage done in the accident done in Southern Oregon and replaced the top at their upholstery shop. The TF (pictured below in Dale’s garage before it left for the restorers) was painted dark green at that time.

The next spring, I went home to Southern Oregon and after my visit, started driving the TF to Maryland, where I was stationed. The trip was uneventful until, on U.S. 40 in eastern central Ohio, the piston rings in the number two cylinder gave way and allowed oil into the combustion chamber, fouling the spark plug and leaving the TF running on three cylinders. Having to be back to Maryland by the time my leave was up in a couple of days I had no choice but to keep on driving.

Although it lacked power, the MG kept on going on three cylinders until I reached western Garrett County, Maryland in the late afternoon, where the engine suddenly started to hardly run at all. I pulled off the road and found that a push rod for an exhaust valve had broken and the combustion chamber of the cylinder with the broken push rod was under pressure when the intake valve opened, putting a back pressure into the intake manifold, making the engine hardly run.

Replacing the broken push rod with the push rod from the intake valve of the cylinder with the fouled spark plug got the engine back to running on three cylinders by the time it was dark and I made the rest of the trip without any problems. Not having the money to hire any work done I bought an MG TD-TF shop manual and got my introduction to XPAG engines by repairing the damage to the number two cylinder in the base hobby shop, which I later used to replace a broken axle shaft. Several years later, after I could afford the parts and machine shop costs, I used a friend’s garage to overhaul the entire engine, replace the clutch and overhaul the brakes.

I remained in Maryland after my Army tour of duty was completed and it was there that two of my friends and I discovered we had birthdays within two weeks of each other. We decided to hold a joint birthday party, with anyone having a birthday in August eligible to host the party. In order to not leave anyone in our circle of friends out, we then decided that anyone who had a birthday within six months of one side or the other of the date of the party would also be eligible to host the party. As a host of the party you were to receive a cheap inappropriate birthday gift from each attendee. 

One of my birthday gifts one year was what the giver said was a “Shop Manual” for my British Racing Green 1954 MG TF 1250. The “Shop Manual” I received was a small Little Golden Book of Mother Goose rhymes. From that my friends started referring to my MG TF as “The Mother Goose”. Over time the name of the green TF morphed into “The Green Goose”. 

After making two additional trips across the U.S., each with its own story, and over 97,000 miles on the odometer, followed by years of neglect, (see photo of engine bay) it was time for the TF to be restored.

Years of neglect!

After searching for a restorer that had a good reputation for restoring MGs and was located at a reasonable distance from our Southern Maryland home, we settled on Vintage Restorations in Union Bridge, Maryland following a trip to the facility.

In the fall of 2015 when Vintage Restorations started doing the restoration John Tokar asked us what color we wanted the car to be painted. My wife Carol and I felt that, since the car was essentially being rebuilt from the ground up, it should be painted its original color of MG Red.

When the restoration was finished in late spring of 2017 we received an email from Vintage Restorations asking us if the car had a name. Carol and I did some thinking about what the name of the car should be, as the name of “The Green Goose” did not fit a red MG TF 1250. It was then we thought that in a sense our MG is not a Goose at all, but a Phoenix as, with the talent of the staff of Vintage Restorations, it arose out of the ashes. Unfortunately, neither of us could come up with any name with Phoenix in it that had the ring of “The Green Goose”.

As it now is the same color it was when it left the factory and is no longer green, Carol and I came to the conclusion its name should revert back to its original name of “The Mother Goose”.

The Mother Goose is now being driven around Southern Maryland. It is a pleasure to drive and draws comments wherever it goes.” (Pics of Dale’s restored TF taken in the driveway of his house follow).

Dale Flowers September 2017

Ed’s note: TF3559 (HDC46/3559) was built on 25^th February 1954. Red with red upholstery, it was exported to North America along with the rest of production (38 cars) on that day.

Ed’s further note: For those not familiar with the Nuffield car number prefix system first introduced by Abingdon on the ZA Magnette, the TF and the Riley Pathfinder in 1953, the following information is contained in Anders Ditlev Clausager’s Original MG T Series :

Dale’s TF (HDC46/3559) can be ‘de-coded’ as follows:

H for MG Midget, D for open two-seater bodywork.

The third letter ‘C’ signified paint colour (Red, MG Red). The other colours are:

A – Black

B – Light Grey (Birch Grey)

E – Green (MG Green or Almond Green)

H – CKD finish (primer) found on CKD (completely knocked down i.e. literally a kit of parts) cars

P – Ivory

The ‘4’ after the ‘C’ indicates the specification class, in this case North American export cars, usually LHD where:

1 – RHD home market cars

2 – RHD export cars

3 – LHD export cars

5 – CKD cars with RHD

6 – CKD cars with LHD

The final number indicated the paint finish, in this case ‘6’ – cellulose finish on body and synthetic finish on wings (normal on all TFs other than green) where:

3 – all-cellulose finish (normal on green TFs)

5 – primer finish, found on CKD cars.

Dave Bulmer wrote the following article about his TC restoration for the Preston and District MG Enthusiasts Club, He kindly offered it for publication in TTT 2 and I have lightly edited it.

“We moved to this area from Northwich (Cheshire) where we had lived for 30 years to be closer to our family. A requirement for me in finding our new house was that it must have a double garage, a luxury not before enjoyed.

Having been retired for some years and having the time but not the facilities, I now fancied owning and restoring a classic car. I owned 4 MGs as everyday transport in the 1970s and 80s; in fact, my first car at age 18 was a Midget. Some say it’s in the blood, so an MG to restore it had to be.

I liked the older ones, especially the J2 and PA but as a restoration for a beginner thought that a TA or TC would be best as everything is available.

We had some building works done on the house and to my surprise a green TA resided on the development. One day I saw a chap in a wheel chair looking at his TA so went over to introduce myself, it was of course Bill Ryding (see note at end of article) and we got on well from the start. The next thing was to find one; not that easy if you want one for restoration, but Bill had loads of connections and came up with a list.

There are always a few TCs available in various conditions, more often than not older restorations that need doing again; the problem is, the owners often have an optimistic view of what they are worth and if you pay their valuations plus the restoration costs, you have spent well over what the car is worth. Anyway, I found one in Devon that was realistically priced, a runner but rough. I had it trailered home and drove it round to Bill’s place for him to have a look; he was really pleased to see his TA and a TC on his driveway. I asked him would it be difficult and he asked me if I was any good at DIY. I said I was OK and he said that will be fine then. Then it was back to my garage for the strip down.

Sadly, Bill did not live to see the car finished.

I started in October 2016 and I took reference photos but as it turned out, when it came to putting it back together, not enough. I did not intend to go flat out at working on the car but spent about 4 hours per day 4 days a week over the winter. I wanted it finished by spring 2017. Bill had put me in touch with Andy Shultz (see Editor’s note at the end of this article) who advised me and worked on the car in my garage on jobs I found difficult to do or did not know how to do; for example, removing and replacing all the suspension bushes. He told me everything takes longer than you think and he was right. Once stripped to the frame one of the longest jobs was getting it and other parts clean after decades of oil as the result of leaks. The frame was surprisingly light so I could turn it over. 10 litres of degreaser later and it was ready for POR metal prep then paint in POR 15.

An inspection of the tub showed the timber was sound, it had been off the car in 2009 and repaired. The panels went off for stripping at Ribble Tech (see note at end of article) and on Andy’s advice I went to see Heaton’s for the paint work. Andy delivered the tub and that would be stripped back to bare metal. One of the front wings was found to be full of holes that could not be seen before stripping, an option was to try and source another but that could be as bad as you can’t tell until the paint comes off. I did reuse the wing in the end as Heaton’s filled all of the holes using the traditional “lead loading” method.

Finding a re-chroming specialist can be a problem as they are getting thin on the ground. I went to one in Manchester but did not like the look of it, and one in Leeds that turned out they only chrome don’t repair, so there was no alternative but to send the items off to a traditional metal finisher and Andy recommended Castle Chrome in the Midlands who repaired the radiator and headlamp shells as well as chroming 20 or so other parts.

The wiring loom came from Autosparks who supply to Moss etc., but with the ones supplied by Autosparks to the usual parts retailers, you don’t get the built-in conduit and have to unravel the metal to get it round the wiring, whereas Autosparks build it in when manufacturing – that’s the sort of information you get from people who have done a rebuild themselves.

While the tub and parts were being painted the frame was then built back up to a rolling chassis. One of the key things I learnt was to plan the work so that items that have a long lead time like paintwork or re-chroming can be allowed for.

Everything was refurbished, repaired or replaced. I chose a 2-tone red finish that was available on the pre-war cars but is not correct for the TC. I also had a bespoke aluminium dash with instrument surrounds made reminiscent of the early cars, again, not correct for the TC but I like it that way. The carbs that came with it worked but the spindles were so worn thus letting in air and affecting the slow running and balance. I decided to part-ex them for a fully refurbished set as re-bushing only the carbs is expensive in its own right and would have meant sending them off and waiting quite a few weeks.

The car was built in 1949 and exported to the USA; it is known that it resided in New York State and later in Ontario Canada. It came back to the UK in 2006 which is when the previous owner acquired it and he applied for an age-related registration from DVLA. The engine was changed some time in its history we don’t know why, a guess would be it froze and cracked the block because there is evidence of the radiator being repaired as if blown out by freezing. The engine is an XPAG from a Wolseley which were commonly available. For some reason the engine mounts were fabricated instead of having the correct TC engine mounting plate and mountings fitted. This was rectified in the rebuild for the correct parts. The car has the 5 speed all synchro Ford Sierra gearbox and VW steering rack which is surprisingly good, fitted by the previous owner.

I am happy with the result and enjoyed the rebuild, though there were times of frustration in re-fitting the body panels as they did not go back as well as expected. The learnings for me were; it’s going to take longer than you think, it’s going to cost more and you need contacts that can advise and help. The TC will always be a popular car which is understandable given its 1930s look; I am pleased I have one.”

Ed’s note:

BiII Ryding was the President of Preston and District MG Enthusiasts Club. Readers might recall that his TA was featured in an earlier issue of TTT 2. Following a leg amputation, Bill was able to carry on driving his TA thanks to Andy Schultz of Cuerden Classics Limited. Andy fitted a Morris Marina engine with automatic gearbox to the TA – almost certainly the only T-Type with automatic transmission!

CUERDEN CLASSICS LTD

Stoney Lane House, Stoney Lane, Lostock Hall, Preston, Lancs, PR5 5XQ

Tel: 01772 627120

Proprietor – Andy Schultz

Email: andy(at)pr55xq.freeserve.co.uk

Recommended by T-Type owners in the Preston area.

Ribble Tech is Ribble Technology (Preston) Limited. This company specialises in the chemical and thermal removal of paint, powder and various other coatings from steel, aluminium and other ferrous and non-ferrous metals. Dave used this company to bring the TC’s panels back to bare metal ready for Heaton’s, a paint shop in Bamber Bridge who specialise in classic cars, to paint the car in the 1930s two-tone colours.

NTG Motor Services Limited

Dave asked me to give NTG a mention as most of the parts were sourced from this company and he especially mentioned that Paul at NTG was a great help.

Some pictures of the restoration follow, starting with how TC9011 looked when it was up for sale in Devon.

TC9011 (VAS 442) as purchased and as finished.

Strip down and build back up.

‘Engine-turned’ dash a la J2

For some time now, I have been hearing a creaking and groaning from the rear axle area of my TF, particularly when moving off from rest. I thought it might just be creaking rear brake springs or possibly the rear axle spring U-bolts simply needed tightening up. With a long weekend trip coming up I decided to investigate.

I had previously purchased 4 new polyurethane spring pads that fit at the top and bottom of each rear spring (see illustration). These replace the standard rubber pads that tend to distort and deteriorate quite quickly. I also purchased 4 new U-bolts (SAX 093), 4 new locating plates (SAX 093B) and 2 U-bolt axle capping plates (SAX 093C) from the Club. The reason for the latter will become clear as we progress.

Dismantling to remove the old parts is straight forward as per the TD/TF Workshop Manual, remembering to support the weight of the car by blocking up with stands or secure jacks under the chassis forward of the rear spring. On my car, there are 8 5/16” BSF plain nuts locked together securing the U-bolts each side but your car may have 4 nyloc nuts doing the same job. Having cleaned up the U-bolt threads with a wire brush, the nuts are easily removed. This allows the spring assembly to gently drop down and assume its natural camber position while the axle hangs from the rebound straps. The U-bolts, locating plates and old rubber pads can now be removed and examined for wear.

Surprisingly for an area of the car that is normally thought to be firmly bolted together, I found wear marks in all the parts. The locating plates showed the U-bolts had been fretting against the hole sides elongating them laterally by about 1/32” (photo 1). The U-bolts showed clear fret marks of a similar depth where they sit in the locating plates. particularly at the upper plate position (photo 2). Furthermore, the U-bolts showed shiny wear marks at the top underside of the U where they had been fretting against the top of the axle, wearing two quite deep grooves each side of the axle casing. Now the reason for buying the 2 axle capping plates becomes clear, they are shown fitted in photo 3. These items became a standard fitting on the MGA for precisely the reasons shown up in the service life of the TD and TF.

Photo 1 – the U-bolts have been fretting against the hole sides in the spring locating plates elongating them.

Photo 2 – showing the corresponding fret marks on the sides of the U-bolts.

Photo 3 – showing one of the axle capping plates fitted on top of the axle.

This component wear confirms what we know now, that the TD/TF rear axle is not particularly well located laterally, allowing sideways movement to occur during cornering. I have read that the axle can move up to 1” across the car in extreme circumstances, causing vagueness at the back end. I am pleased to say I don’t think my car had reached that stage.

Reassembly is the reversal of the strip down process and both sides were easily reinstated in about 4/5 hours. A short road test revealed that the creaking and groaning noises seem to have gone and the car appears to steer more precisely.

I had previously fitted polyurethane rear shackle bushes to replace the standard rubber items. The Club also supplies these uprated items, part no. SAX 064c, (set of 4).

Roy Miller

Ed’s note: Roy’s article first appeared in the September issue of the MG Octagon Car Club’s September ‘Bulletin’ and has been reproduced with their kind permission.

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(Click images for bigger)

Introduction

Firstly, apologies for the time taken to produce this article. As I looked at the results, questions arose as to the effect on mixture caused by different carburettor configurations which required a more detailed analysis of our data. This is where the time has been spent. However, this analysis has highlighted two issues with modern fuel which I will cover in the second of these two articles.

A previous article talked about how the low temperature volatility of modern petrol causes the hot restart and related problems with classic cars. Suck, squeeze, bang and blow showed how cyclic variability could increase exhaust temperatures, making the problems of low temperature volatility worse. This article looks at how the SU carburettor works and how it can be adjusted to improve the combustion process, helping to reduce under-bonnet temperatures.

SU Carburettor

If you own an unmodified, classic MG, it will probably be fitted with one or more SU carburettors. These are a marvel of engineering. Originally designed by George Herbert (Bert) Skinner and made by his younger brother Thomas Carlyle (Carl) Skinner, the SU carburettor was first produced in 1908. Unchanged in the way they operated, SU carburettors were fitted to production cars until 1993.

The original SU carburettor had the connection to the inlet manifold at the top with a sloping suction chamber; the carburettors fitted to MGs have the connection on the side with a vertical suction chamber. Apart from this difference, both the suction chamber on the left and the float chamber on the right are clearly recognisable on this original SU carburettor pictured below.

(This picture has been reproduced with the author’s permission from the book Skinner’s Union published by the S.U. Carburetter Company Ltd).

In operation, the SU measures the volume of air flowing into the engine and mixes this with a metered volume of finely atomised petrol droplets to give a precise Air to Fuel Ratio (AFR) for all throttle settings and engine revs.

With non-ethanol blended petrol, the theoretical AFR is 14.7:1 i.e. for every 1 gm of petrol you need 14.7 gm of air for all the petrol to burn. However, maximum power is achieved with an AFR of between 12.5:1 and 13.5:1, having an excess of petrol or a mixture that is richer than the ideal. For clarity, the RELATIVE AFR RATIO is quoted in this document. This is the measured AFR divided by the theoretical ideal. Numbers less than 1 correspond to a rich mixture and greater than 1 a weak mixture.

The SU maintains an accurate AFR Ratio between 0.85 (richer) and 0.95 (maximum power) over a very large range of air flow rates from tick over, when virtually no air is flowing, to full throttle at 5,000 rpm or more, when some 3 cubic meters of air are flowing through it every minute. However, an observant reader will note the SU carburettor is a volumetric device, it measures the volume of air and petrol; AFR is defined in terms of mass. The volume of a given mass of petrol or air depends on its density. While the density of petrol changes very little under normal operating conditions, the density of air can vary with ambient temperature, barometric air pressure or altitude. Fortunately, the SU is also relatively insensitive to changes in air temperature and air pressure, allowing our cars to work in the winter and hot summers, at sea level and when driving over the top of alpine passes.

What is amazing, it achieves all this with only one moving part!

Unfortunately, for many, the SU carburettor is something to be left untouched. Once set up, it will continue to work for many miles, but it does benefit from regular maintenance. Also, changes in modern fuel mean that they may now require re-tuning in order to achieve optimum performance.

Investigating how modern petrol affected the operation of the SU carburettor was one of the objectives of the Manchester XPAG tests.

How does an SU Carburettor work?

The main function of the SU, measuring the air flow is achieved by a piston fitted inside the suction chamber.

Sitting on top of the carburettor body, the suction chamber (see next pic) is the most recognisable characteristic of an SU carburettor. The major difference between a modern SU and the original is that the original SUs used leather bellows instead of a piston. Around 1914, improved engineering allowed the leather bellows to be replaced with a close-fitting suction piston.

The carburettor body can be thought of as consisting of four different areas (P1 to P4, see the diagram):

• P1 – where the air flows into the carburettor. This is at atmospheric pressure.

• P2 – the area below the suction piston is called the choke. Here the air is at a lower pressure than atmospheric.

• P3 – the area beyond the piston and before the throttle. This contains an area called the Vena Contracta a recovery zone around the rear of the piston where the air pressure returns to atmospheric.

• P4 – the area beyond the throttle butterfly. On small throttle settings, the pressure in this area can be a near vacuum, especially at high engine revs, increasing to virtually atmospheric pressure when the throttle is wide open.

The bottom of the suction piston partially blocks, or chokes, the airflow into the engine, causing the air to travel faster through the choke, reducing its pressure. As a result, the air pressure inside the choke is lower than atmospheric. In practice, this low-pressure area extends up and around the rear of this piston in the Vena Contracta.

Without any seals that could cause friction, the top of the piston is a close fit inside the suction chamber and is free to move up and down. The bottom of the suction chamber is open to atmospheric pressure and there is a drilling through the suction piston, either at the bottom rear or underneath, connecting the low-pressure area of the choke to the top of the suction chamber. When the engine is running, there is a pressure difference between the top and bottom of the piston which causes it to move upwards.

As the piston moves up, the choking effect is reduced, allowing air to flow more slowly. This in turn reduces the pressure difference between the top and bottom of the suction piston. If the piston moves up too far, the pressure difference cannot support its weight and it falls, increasing the speed of the air flow and the pressure difference. As a result, the piston settles at a height where the pressure difference between atmospheric and that in the choke equates to the weight of the piston. A constant pressure difference is maintained regardless of the volume of air flowing into the carburettor, hence the reason the SU carburettor is sometimes called a constant pressure device. In practice, the height of the piston is a direct measure of the volume of air flowing through the carburettor.

Strictly, this statement is not true. On early (pre- 1950s) carburettors, the piston was made of bronze or brass weighing about 8.5oz, later carburettors (as previously shown) had aluminium pistons with a steel insert to give the same weight. In these carburettors the downward force is fixed and independent of the height of the piston. These really are constant pressure devices.

In the 1950s, the heavier pistons were replaced with lighter aluminium pistons with a long spring fitted to increase the downwards force to around 8.5oz. As the throttle is opened and the piston rises the spring is compressed, increasing the downwards force. A greater pressure difference is needed to support this increased downward force which, in turn, reduces the area of the choke relative to a fixed weight piston. The implications of this are discussed in the next article.

Connected to the bottom of the piston is a tapered needle that fits into a fixed diameter jet. The jet is filled with petrol to a set level, controlled by a float and needle valve in the float chamber. The float chamber is open to atmospheric pressure via the breather tube and the pressure in the choke is lower than atmospheric, causing the petrol to “squirt” out of the jet into the choke. The volume of petrol is controlled by the pressure difference and the annulus between the tapered needle and jet. The taper on the needle is such that the correct volume of petrol enters the choke for every piston height or volume of air flowing though the carburettor. Petrol leaving the jet enters the high velocity air stream in the choke, breaking into droplets and dispersing as it travels through the carburettor.

This is how the SU carburettor delivers an accurately metered volume of finely atomised petrol droplets into the inflowing air to maintain the correct air / fuel ratio.

Damper and Float Chamber

The two other auxiliary parts that make up the SU carburettor are the damper and float chamber.

The guide rod in the centre of the piston is hollow. From about 1947, MGs were fitted with a damper connected to the screw cap at the top of the suction chamber. This served two purposes:

Firstly, it slowed the rate the suction piston could rise when the throttle was quickly depressed, temporarily enrichening the mixture to improve acceleration. Secondly, it helped stop the piston vibrating due to rapid pressure changes in the manifold when the inlet valve opens.

It is important that the oil in the hollow piston guide rod is checked and topped up if necessary. The oil should be filled to a level just below the top of the hollow piston rod. A slight excess will overflow the top of the hollow rod and lubricate the guide. However, overfilling the damper will cause the excess oil to be sucked into the suction chamber and onto its walls which can cause the suction piston to stick.

The sole purpose of the float chamber is to keep the petrol level in the jet constant. As the fuel level drops, the float, also drops allowing the needle valve to open and more petrol to flow into the float chamber.

Tuning SU Carburettors

There are a number of adjustments that can be made to an SU carburettor to optimise performance. Traditionally, the aim is to increase power output by delivering the maximum volume of the optimum air / fuel ratio into the engine. Techniques include larger bore carburettors, lighter springs in the suction chamber to reduce the choking effect or removing the air filter. However, the tests at Manchester have shown this approach may not give the best overall road performance.

Remember in the Suck, Squeeze, Bang and Blow article how the effects of increased cyclic variability reduced the number of cycles with the optimum power timing? Poor atomisation and vaporisation of the petrol during the induction stroke, leads to uneven mixtures around the plug during the critical time it fires, increasing the cyclic variability.

At Manchester a nebulizer was fitted between the carburettor and inlet manifold. This forced the petrol leaving the carburettor to break up into evenly sized droplets approximately 10-20 micrometres in diameter, similar to those delivered by fuel injection systems. Using a branded forecourt 95 octane petrol running at full throttle gave the following percentage change in power output compared to the engine running on the same fuel without the nebulizer.

Below 3000rpm, the nebulizer improved power output by around 1% demonstrating benefits of improved fuel atomisation at these engine speeds. Unfortunately, the nebulizer used for these tests also constricted the airflow into the engine, explaining power reduction at higher rpm.

Race tuned engines run at full throttle and high rpm. Under these conditions there is a large volume of mixture entering the cylinder with high levels of turbulence and compressive heating. It is likely the degree of fuel atomisation is not such a problem. However, when running under 3000rpm with part throttle settings typically used for normal road driving, the degree of fuel atomisation has an effect. For road use, carburettors should be tuned to maximise turbulence and atomisation even at the expense of a slight reduction in full throttle power.

Adjustment

There are only four main ways of adjusting an SU carburettor. Two are relatively easy, adjusting the jet height or fuel level in the jet, the other two require changing the suction piston and spring or the tapered needle. Despite this, it is possible to tune the SU to work with a variety of fuels.

In addition, if your car is fitted with a damper, it may be worth experimenting with different viscosity oils and using one that gives the best acceleration response and smoothest low rev driving.

Changing the Mixture

Jet height

Adjusting the height of the jet has the effect of changing the mixture over the whole rev / throttle range.

On the bottom of the jet assembly of earlier carburettors is jet stop nut which can be screwed up or down to adjust the jet height. Screwing the nut DOWN increases size of the annulus around the jet and tapered needle allowing more fuel into the air stream and making the mixture RICHER. Screwing the nut UP makes the mixture WEAKER. On the more modern HIF carburettors there is a mixture adjusting screw next to the jet assembly that performs the same function.

Tolerances on the needle and jet are very tight and when adjusting the jet height using the nut, only make changes by turning the nut 1 flat or 1/6 turn at a time.

Incidentally, pulling the choke to allow cold starting dramatically lowers the jet, increasing the size of the annulus and making the mixture much richer.

Replacing the tapered needle

The other adjustment to the mixture is performed by replacing the tapered needle. While this is a simple operation, with hundreds of available needles with different tapers, retuning the carburettor is not a simple task. This should be left to the experts. Fitting a needle with a different taper changes the mixture at particular rev range and throttle settings.

There is a very informative book “SU Carburettor Needle Profile Charts” available from Burlen Fuel Systems, this lists all the needles and their profiles. The charts give the needle diameter in 1/8” steps down the needle. A lower diameter gives a richer mixture.

Measuring the required needle diameter under various loads and engine speeds with different fuels, was one of the tests performed at Manchester. Sorry to those who race XPAG engined cars, this data only covers up to 3750 rpm, a typical maximum for road use. This will be covered in the next article.

Maintenance

Once set up, SU carburettors should be maintained, I suggest the following yearly schedule. For cars with twin SUs service one carburettor at a time and do not interchange the parts.

1. Remove the suction chamber and clean the inside, I use white spirit. There is no need to oil.

2. Clean the suction piston. Be very careful not to bend the needle.

3. Replace the suction chamber in the same orientation as it was originally and check the piston rises and drops easily. If you are VERY careful, you can use the damper to lift the suction piston by unscrewing it and moving it to one side and using it to lift the piston. Let it fall. It should drop back with a “clunk”. With twin Sus, both pistons should fall at the same rate.

4. Ensuring the ignition is switched OFF (otherwise you will get petrol everywhere). Remove the float chamber lid and float. Clean out any debris or water from the bottom of the float chamber. This is very important if you are using ethanol blended fuel. Watch out for the later articles.

5. Apply a little light oil to the throttle spindles.

Conclusion

The SU carburettor is a marvel of engineering and, if properly maintained, will give many years of service. The tests at Manchester suggest there are minor tweaks that will improve the way the engine runs on modern petrol and have identified two areas where problems occur.

The detailed findings from the tests and suggested tweaks will be covered in the next article. Carburation – Part 2.

Ed’s note: The author of the above article (Paul Ireland) has had another ten of his luggage racks made, but they have sold quickly, some going abroad and at the time of writing he has only three left. Price is £325 plus carriage. Please contact Paul at paul(at)ireland-family.org (Please substitute @ for (at)).

  

Richard Hirst, whose car graces the front cover, has penned this article for us. In doing so, he traces the history of Cooper Cars and that of his own car, MDM 64 which was featured in the December 2001 issue of Classic and Sports Car.

Many MG enthusiasts who visit Silverstone find their way to the XPAG Specials display and so will have some idea of the foundation of Britain’s race car industry.

Soon after the end of WW 2 there was a workforce who could design and build as never before. With the skills and enthusiasm and the advantage of surplus parts and now empty airfields, there was a newly found desire for affordable exciting transport.

This was the start of the “Specials builders”, a few of whom formed companies producing small volumes of sports cars. This created associations like the 750 Car Club, who were able to organise competition events. The area around South London saw at least 20 of these small companies, one of which was Cooper Cars of Surbiton.

Charles Cooper had run a car showroom and repair business and having been a trained engineer before the war, he was capable of building a very smart 2-seater 750 sports car for his son John. This No1 Cooper is still a regular entrant at several classic car events.

This was followed by the type of racing car that made the name of Cooper famous; these were small, lightweight, motorbike engined single seater racing cars, which were so successful that it became necessary to produce them in batches of six and later twelves.

All these early cars had a ladder style chassis made of recycled airfield huts! They had independent suspension, rack and pinion steering, and chain driven JAP air cooled 500cc engines which were mounted just behind the driver.

As the cost of racing this type of car was so modest, the number of races, sprints, and hill climbs attracted new companies to join in the sport. This 500cc model was soon to be joined by a more powerful 1000cc version, and it was from this that the Cooper company were able to create a two-seater sports racer. This had a model code of T14, which is an indication of the company’s growing output. With this growth came difficulties in maintaining supplies of steel, which was still rationed, and yet aluminium was not, so Coopers had as many components made of aluminium castings as possible, many of which are still in use today.

This two-seater sports version used the same chassis but had the radiator and engine in front of the driver, gearbox alongside, and a differential in place of the chain drive box, surrounded by a lightweight aluminium body. Whilst a number of different car engines were tried, it is believed that all of the 12 cars built subsequently used the MG XPAG engine and gear boxes.

My Cooper MG in this article was probably built by Coopers using one of the last ladder framed chassis or possibly converted from one of their 1000 cc models. It was specially built for Horace Porteous, who was a garage proprietor from Abergele North Wales.

Because of its later build date in 1952 it had a code of T21 – initially using 2 different Rochdale fibreglass bodies, which were not ideal! It is an interesting note that the neighbouring AC company used the same chassis layout for their then new ACE sports car, which used both AC and Bristol engines.

When my father first became involved in motorsport, he initially drove an L-type MG Magna, which was soon to be replaced by a Cooper MG which we happily shared and enjoyed success at many local speed events. Many years and cars later I read that a Cooper MG was included in an H&H auction in June 2001 and had to go in the hope of winning it with my bid – which did in fact happen!

Having owned one before it was easy to decide the priorities this time….. less weight, more power and hopefully no oil leaks, which seems to have been achieved.

The MG XPAG engine suits the car very well, it’s simple and sturdy and accepts a high level of tune without falling apart. To minimise any oil loss, I have used modern seals at each end of the crankshaft, opened up ways for the oil to return to the sump, and in turn reduce the build-up of internal pressures.

I am using a Laystall cylinder head, fast road cam, steel crank and rods and lighter fly wheel. The major improvement in power and drivability has come from the inlet side of the engine, by feeding cool air to the twin 1.5” SU carburettors and careful choice of needles seems to work well.

Whilst the output has never exceeded 100 BHP, the torque figures continue to improve, and the longer special inlet manifold has made a significant gain in performance, so is well worth the effort.

Power is transmitted through a close ratio 5 speed Ford gearbox to a chassis mounted differential and short drive shaft. With the increase in power and reduced weight, the car is an ideal, very quick road car which being almost 70 years old is quite remarkable and like most front engined racers of its time still looks wonderful.

As a postscript, it was Cooper’s loyalty to Nuffield products which sadly began their decline in the Formula 1 world, as others moved on to Cosworth power. Thankfully, John’s great enthusiasm for the Mini has kept the great name alive today.

XPAG engine: cool air supply from space above radiator in nose and heat shield under inlet manifolds.

Front suspension arrangement: top transverse leaf spring, fabricated upright, lower wishbone. Note magnesium brake backplate.

Magnesium Cooper wheel with cast in brake drum (clearly shown in previous pic.)

Cockpit details: shaped seats, ex-Moss steering wheel and Cooper fabricated pedal assembly.

Ed’s note: What a delightful car!

From a study of the Classic and Sports Car article, MDM 64 is thought to have started life as a 1100 cc single seater, itself based on a 500 Formula 3 car with the engine in the front. It sported two different Rochdale bodies in the past; the first, an all-enveloping glassfibre C-type body, which, in words of the day “rather over-whelmed it”. The second, a more elegant and flattering F-type body which was fitted by Cyril Porteous of North Wales, who used the car for hill climbing. Porteous also changed the 1140cc Morris Ten engine for the XPAG 1466cc power unit, which it still has.

It was advertised for sale with the Rochdale F-type body and XPAG engine in the 25^th November 1955 issue of Autosport with a price tag of £895.

During the 1960s and early 70s it was owned by A F Rivers-Fletcher, who discarded both Rochdale bodies.

The bodywork you see now was fashioned during a restoration by Adrian Rice Carrosserie Sportif of Small Dole, West Sussex.

The results of a rolling road test follow (click graph for bigger). Compare them with the ones in TTT 2 Issue 44!

TC9147 (LKX 499) If the owner of this TC cares to contact Sam Christie, Sam has an old MoT certificate for this car, dated 28^th May 1992. Also, a receipt for the purchase dated 23^rd August 2007. Vendor: The Occupier, Brookfield Cottage, Whitbourne, Worcestershire WR6 5SS – Purchaser: Phil Lomax (now deceased) of Frampton Cotterell, Bristol. The items were found in a TC Instruction Manual.

s_christie04(at)yahoo.co.uk {Please substitute @ for (at)}.

TC???? (MDH 938) This car was previously owned by TA owner, Tim Parrott’s neighbour, as a student in the 1960s. The car is shown on the DVLA web enquiry facility as on the road. If the current owner sees this would s/he please contact me at jj(at)ttypes.org {substitute @ for (at)}.

TA???? (DPX 61) David Patten would like to trace this TA owned by his grandfather.

David is at david.patten(at)tlssclaims.com {please substitute @ for (at)}.

TD25840 (YMG 98)

The last issue recorded how this car was used as a workhorse by its owner ‘Ron’ and described the unusual circumstances of its sale. The present owner, John Woodward saw the ‘Lost and Found’ article and contacted the editor. Both parties have now corresponded with each other and are due to meet up on a mutually convenient date.

TA3232 (MG 6641)

TA3232 was Ian Baker’s first car in 1963. He’d love to be able to track it down. If you can help Ian is at ian.baker42(at)gmail.com {substitute @ for (at)}.

TD25404 (MTX 279) John Bastin writes from France:

“In 1964 my wife and I went on our honeymoon in the MG, driving down through France into Italy, then back over the Alps into Switzerland, then Germany and back home.

We were camping, and it was our first visit to France, and the first time‌ driving on the Continent, so was quite an experience as you can imagine. In those days not a lot of people drove abroad, but nowadays it’s quite normal.

I’m informed the vehicle is on the road (i.e. not SORN’d) and would be interested to learn what it’s been doing since my ownership.

I now live in France and often think about my first trip here. My current car is a Porsche 944 cabriolet (28 years old) so I’m still enjoying a soft-top”.

If you can help John, please e-mail him at john.bastin(at)neuf.fr {please substitute @ for (at)}.

TB0520 (GRB 19)

Stewart Jackson used to own this TB. It was used as a Police car during the war (as were GRB 17 and GRB 18). Stewart kept the body plate as a souvenir (Body no. 2041/10803). He’d like to return it to its rightful owner.
stewartjackson1934(at)gmail.com {please substitute @ for (at)}.

Original Engine for TD0518

Greg Tandy gltan2(at)msn.com {please substitute @ for (at)} has the original engine for this TD. It is numbered XPAG/TD/LHX804. If not sold soon it will be going on eBay.

Supply of MG T-Type Ash Frames (including Timber Parts)

Supplier, Andrew Denton gets the thumbs up from Ian Veale, who recently bought some bits for his TC restoration. “He was friendly, helpful, reasonably priced and the parts I received were top quality. I couldn’t recommend him highly enough.” Andrew Denton, phone 01757 617455.

Some TA Clutch Tips! Mike Green of NTG Motor Services appreciated Brian Rainbow’s article in Issue 44. He points out that the springs and circlip for the spigot bearing carrier which Brian thought are unobtainable can be supplied by NTG as a set with springs and 3 separate circlips which function equally well, see:

http://www.mgbits.com/contents/en-uk/search.php?searchphrase=d058k

Mike added that NTG also stock a number of other parts for the TA clutch.

NTG’s new advert, which can be seen on the back cover, includes a pic of their catalogue – their 21^st Edition!

‘From the Frame Up’ – Latest Catalogue

Doug Pelton kindly sent me a copy of his latest ‘11^th Edition Catalog’, which has been out for a couple of months. It can be downloaded from his website https://www.fromtheframeup.com (140+ pages if you print it), or purchased for $5.00 plus shipping. To receive a free copy, place an order over $50.

The latest edition now contains many TA and TB parts.

High Axle Ratio for a TA

The following has been received from Adrian Sheppard:

In 1937 my TA was one of the faster cars on the road, overtaking rather than being overtaken. Those days are long gone, and the cruising speed is on the slow side for motorways and A roads. I look with envy at the XPAG engined later T types with the transforming solution of fitting a 5 speed Ford gearbox. There seems little chance of the same solution being found for the MPJG engines of the TAs.

Recently I took my differential for re-furbishment to Roger Furneaux and discovered that 9:39 ratio crown wheels and pinions are available as a replacement for the standard 8:39 ones. I sucked my teeth a bit at the cost but decided to go ahead anyway as I average between one and two thousand miles per year on motorways and A roads.

This is my assessment for anyone else considering the change. On the positive side, cruising at 55 mph rather than 50, with occasional bursts to 60+ mph means I am more comfortable and less of an obstruction to other traffic. On the downside, hill climbing in top gear is a bit poorer. I also find myself being more heavy-footed than previously, and hanging on to the lower gears longer before changing up.

In conclusion, for my pattern of use of the car, the advantages significantly outweigh the disadvantages. However, for cars which do not do many miles on fast roads, it probably isn’t worth the expense and trouble of making the change.

Dave’s Donuts (no you can’t eat them!)

The following has been received from David Heath:

If your rear wheel splines are worn, like mine, it’s Klunk Click every trip! To replace the hubs/wheels is expensive, which got me thinking. After some experimenting I developed Dave’s Doughnuts.

Simply it’s a foam rubber ring which fits between the brake drum and the wheel. As you tighten the spinner the ring is squashed tightly in the space. The rubber forms around the drum 1/2 nuts on one side and the spoke nipples on the other, stopping the wheel moving to and fro.

I have used them for years and it stops the klunk click by 99%. If you go trialing they may not be man enough but in normal use, they work surprisingly well.

Cost is £15 per pair inclusive of UK postage. Please order via The Editor jj(at)ttypes.org{sub @ for at}

New Technology Meets Classic Vehicles
Brittrix, Ltd.

While you likely have seen many modern vehicles whose tail lights seem brighter than you might expect, chances are that they are running with LEDs. Not only are they considerably brighter than the original incandescent bulbs, they draw considerably less current.

Why is this important to owners of classic and vintage vehicles?

Many older vehicles used rear facing lamps which were designed in an era where there was far less traffic, the lighting regulations were far less stringent, and there was a lack of distracted drivers behind the wheel of their near-autonomous Detroit iron. No cell phones, blaring surround sound, nor screaming kids in the back seat.

Also, the electrical systems were designed for cars without all the conveniences of modern cars. Thus, even in the best of circumstances the classic vehicle electrical systems are challenged to keep up with the needs of their lighting – extra tail lights, turn signals, driving and fog lamps all take their toll on vehicles with marginal charging systems.

The answer is brighter lights and less demand on the electrical system. Enter the LED.

Can I use the LED bulb as an answer? Yes, but there are a few disadvantages.

Most LED bulbs are constructed in such a way that in order to gain an advantage in the level of brightness, they need to place many LEDs into a very limited space. This means that most of the LEDs are placed so that they face the side of the bulb, not facing to the rear. LEDs are very directional. That means that the majority of the light is sent sideways, not to the rear where it is needed. The result is that the LED bulb is only marginally brighter than the incandescent bulb it replaces.

Another disadvantage is that many LED bulbs are only suitable for cars with a negative ground electrical system. This is fine for most modern cars, but many of our British cars built before 1962 utilized a positive ground system. So if one tries to use a negative ground bulb in a positive ground system, either the bulb will refuse to work, or the bulb will go up in smoke.

Third, many of the LED bulbs emit only a white light, yet the lenses in our classic vehicle tail lights are either red or amber in color. Since the light emitted from white LEDs actually is made up of a full range of light in the visible spectrum, when that light passes through a red or amber lens, much of the light emitted is filtered by the colored lens, resulting in a significant loss of brilliance.

The answer is a purpose-built LED light board which is specifically designed to match the pattern of the tail light lens.

All of the LEDs on an LED light board which need to be seen from the rear are indeed placed to emit light to the rear, not on the side where that light output is useless. They are available in either positive or negative ground, so will work with whichever system your classic vehicle requires. Finally, the light emitted by the LED light boards are matched to the color of the lens in your tail light, usually red for brake and tail, amber or red for turn signals, and white where there is a provision for license plate illumination. This ensures the maximum light is directed where is needed – aimed at that text messaging teen driver behind you.

“But don’t I need to change the turn signal flasher if I convert to LEDs?” Not necessarily. Assuming you still use incandescent bulbs in the front turn signals, a change in flasher is not always necessary. The average turn signal bulb draws enough current to trigger the flasher. And even if they don’t, there are fully electronic flashers available at your local car parts store which will be a direct replacement, or require only a very minor wiring change. Some can even be wired in either a positive or negative ground car.

“But are they really brighter than either incandescent or LED bulbs?” Absolutely! The best of the LED bulbs I have found have 12 LEDs facing all to the rear and produce around 12 candlepower. By comparison, our inserts use up to 44 LEDs and produce as much as 300 candlepower.

“So how much power savings can I see?” The 1157 incandescent bulb draws 1.75 Amps. (21 watts / 12 volts = 1.75 Amps). By comparison, our typical brake circuit draws 110 milliamps (.11 Amps). You would need to install 16 light boards to equal ONE 1157 bulb. This is to say nothing about the heat generated by the 1157 bulb, which takes its toll on the vinyl and rubber parts in the lamp. Touch a lit incandescent bulb and you will understand. The LEDs are cool when lit.

“But won’t the LEDs blind the driver behind me?” No, the LEDs emit the majority of their light over a moderately narrow field (about 30 degrees). So if the following car is outside that range, they will notice the bright brake light, but not be blinded by it. If they are too close and within the range of the brightest light, you want them to be unable to avoid being dazzled.

Brittrix, Ltd. designs and manufactures LED light boards for most classic MGs from 1934 to 1962, and nearly all classic Minis. Other British vehicles often use the same tail lights, so there is a good chance we have a tail lamp insert for your British car or truck. We are always looking for additional opportunities so if we don’t have a light board for your particular British car or truck, get in touch. View our current offering at www.brittrix.com or email us at [email protected]

Ed’s note: That’s it folks, our last issue for 2017.

First issue for 2018 will be February, due out around about mid-January.

Keep safe and well……………Safety Fast!

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