TA/B/C Front brake twin leading shoe (TLS) conversion (continued…..)

Preparing the wheel cylinders. The wheel cylinders that I have chosen to use, are those listed for the Marina 10cwt van or pick-up, being Girling 64678875 (N/S) & 64678876 (O/S), however previously I used the Vauxhall Victor type, which are 64676115/6, sharing the same bodies, which are now looking a bit scarce, both types having 7/8″ bores so are identical in size to those on TD/TFs.

What I have found since starting this build, is that there is yet another alternative, that has both the same bore size & the same fixing hole positions, the only obvious difference being that it has a rectangular boss for the 3/8″ UNF ports, which are 64678928/9, these also have a larger flat mating face around the fixing holes so that a gasket can be employed between the cylinder/backplate but I must stress that I haven’t done any more, than confirm the hole positions/bore size.

I have also found, that pattern cylinders, marketed by both Borg Beck and Quinton Hazell, are freely available, listed as direct replacements, for those listed above first but when enquiring further, are only 3/4″ bore, as they are listed for numerous models of cars so “one size fits all” or not, if you wanted 7/8″?

A modification is required to one of each of the two different handed wheel cylinder ports, as shown, if you want to reuse the original front brake hoses, which is to enlarge the inner port, from 3/8″ UNF, to 7/16″ UNF.

The picture shows how a piece of 3/8″ UNF studding can be used to easily locate a stripped- down wheel cylinder, in a machine vice so that it is mounted vertically, prior to first opening the beginning of the existing hole, to a depth of about one thread, to 7/16″.

Next, drilling the remainder of the hole carefully to the correct tapping drill size for 7/16″ UNF, then without removing the cylinder from the vice, using the chuck to hold the taps, the threads can be tapped by hand or to simply start the tap off squarely.

The two copper link pipes are 3/16” diameter, being formed from lengths cut to 13.25″ so as to get tight to the bottom mounting bolts and out of harm’s way.

The bleed nipples are stainless, being fitted into the front ports and are really easy to bleed, due to the layout of the cylinders, being one in front of the other, instead one above the other, I suppose that bleeding would be even quicker, were you to jack the front of the car up, more than just getting the tyres clear of the ground?

Fitting the wheel cylinders. Because of the significant differences between the TC and Marina backplates, 5mm thick mild steel spacers are required to place the centreline of the wheel cylinders correctly in-line with the brake shoes.

The pictures show that they are a simple spacer but the area shown within the red circle, requires a significant chamfer to be created; this is to allow the end of the brake return springs to move sufficiently, to allow the spring to rest, when the shoes are centralised, without any side loading.

Easier to do this now, than to have to do it later, as I did, with a mini grinder!

These spacers only require a light weld along each end and when they are attached, just leaving the return spring mounting plates to be fitted.

Unfortunately, you will once again need to check the plates for flatness and most importantly, that they have not dished because the cylinders need to be perpendicular to the drum face so out with the straight edge, then perhaps back to the press?

Modifying the brake shoes.

The brake shoes employed on this conversion, are those used on three vehicles, manufactured in the same time frame, the most exotic being the Morris Marina 10cwt van or pick-up, then the Triumph Toledo 1300 and lastly the Vauxhall Victor. They all used 9″ diameter Girling brakes so their diameter is compatible with the first 3 models of T-Type, having only S.L.S. brakes.

New old stock shoes are available at the moment, for varying prices but by now their linings will be a little on the hard side, not to mention containing the dreaded “A” word so the first thing to do, is to go outside, hold the linings over one of the many holes in the top of your trusty B & D workmate, then using a punch, remove the rivets by punching them out through the linings, then please be responsible about disposing of the 4 old linings.

The existing adjuster pegs need to be then removed so a bit of sawing, drilling & punching, then with the use of either a lathe, milling machine or a pair of odd leg calipers and a hacksaw/file, carefully remove 1/8″ from each edge of the shoes because they are 1/4″ wider than is required, as can be seen in the pictures of before, then after.

On the trailing edge of each shoe, I decided to fit 1″ square packers, made from 16 swg stainless steel but mild steel or brass should be fine, these are attached simply using 1/8″ aluminium pop rivets but to make a neater job, I countersunk the back 16swg plate’s 2 holes, to allow the rivet to spread into it, then allowing me to flatten it into the countersink, leaving it looking similar to its head.

I marked out 4 plates first so that the holes would be away from the guide slot in the back of the wheel cylinders, first drilling them just under 1/8″, then carefully clamped the 3 layer sandwich together, with some long nosed mole grips, before drilling each assembly individually 1/8″ and riveting them so as to avoid mixing up any of the parts.

When the plates are attached, I filed them to match the radiused profile on the end of the shoes, then filed a shallow chamfer up the sides of these curved edges, to allow the sandwich to move freely in their slots in the back of the cylinders, giving them the ability to rock a little, both up and down, to aid correct alignment of the shoes with the drums.

The original Marina brake plate had them sitting on a ledge, only allowing them to move into the drum, against the hold down springs but I wanted it to float a bit more than that.

The piston end of the shoe is guided by one of the original triangular guide plates, as previously removed, rewelded into a new position so the shoe sits centrally, as originally intended but can pivot both ways a bit, against its central hold down springs.

The new adjuster pegs/pins are simply cut down stainless steel M8 bolts, nuts and washers, as shown, luckily in the 2 bottom shoes, they make use of an already existing hole from the previous peg but on the top shoes this is not the case because this area on the backplate is not flat, which is what the new adjuster requires.

The position for the top shoe adjuster pegs can be determined by first fitting that shoe, with its return spring to the modified back plate, along with the lower shoe the same, then by having the brake plate uppermost, under a bench drill or mill, first making sure by rule measurement, that the shoe is seated centrally with the edge of the back plate, the either 3/8″ or 2.5mm hole, for the adjuster cam, needs to be carefully spotted through, onto the brake shoe.

This is safest perhaps being done by rotating the chuck with just your hand, in the reverse direction, as you only require it to mark the centre position of the hole, then with the shoe removed so that the mark is visible, the position for the new adjuster peg/pin, needs to be 11.5mm towards the lining, from the mark left by the drill, this should then only hold the shoe off of the bottomed cylinder by about 0.5mm, hopefully ensuring that the finished assembly will easily enter the drum, even if a brand new one, with plenty of adjustment remaining.

After previously having used a woven lining material, that works well on steel motorcycle brake drums, I found their annoying squealing noise, when just feathering the brakes so bad, that I switched lining materials to the type recommended by Frans Sitton, being Ferodo DS3920, which is a great improvement, being done this time for me by Villiers Services, who despite what is going on with Covid, turned them around in a respectable time and were reasonably priced too.

As standard, DS3920 comes in a 5mm thickness so is ideal for slightly worn drums, being only about 0.2mm or 8 thou oversize, it is a soft material, of a greenish colour so easy to file some nice gentle chamfers on, giving you a nice progressive feeling.

Brake Shoe Adjusters, Hold Down Pin Assemblies & Return Springs. The modified brake shoes employed on this conversion, were retained by hold down pins, passing through short slots, about midway along the steel shoe, these slots are reused, without any modification required but had previously used different length pins, as well as different springs to those now used. The amount of work to get everything to fit, depends on the gauge of pin acquired, as I have only just discovered because 42mm long pins, suitable for use on Fords, can be supplied as either a heavy gauge pin, with a 9mm diameter head or one which is lighter gauge, with an 8mm head, the latter will avoid some fiddly filing, as mine were the heavy ones.

In the picture of the hold down pin components,  the coil springs are I believe for British Leyland, being 14.5mm in diameter by 22.5mm long, at each end of these springs are “Girling Type” hold down washers, which if you have the better pins, will not require slight modification, with a needle file, the spring clips, that hold it all together, are for Fords, either Fiestas or MK5 Escorts, maybe others as well, these will require squeezing down a bit, as shown, then the whole lot goes together OK.

The brake shoe return springs used, are the type employed on the 3 original vehicles concerned, being Girling SS2.

Adjusters are however a complete “foreigner”, in more ways than one, being intended for use on “Willys Jeeps” but readily available, as pattern parts. What I have chosen to do with them, is to not use the nuts & spring washers, as supplied but to substitute stainless steel nyloc nuts, with Dowty washers.

This has 2 advantages, the first being that it enables the area of thread within the nuts to be sealed so if copper grease is used, it should always come undone – but I also found through use, that the Dowty washers act like a friction washer, enabling the adjuster to be rotated, then staying in position, in a similar way to the original adjusters, making their use a very simple affair, just needing a tiny spanner by comparison to the original brake.

The last few ‘fiddly bits’. These are quite fiddly bits to make and fit, the return spring plates but very important to get right, easy with a milling machine, otherwise some careful sawing & filing required, with maybe a little bit of mini grinding to finish off.

As with much of this, it needs to end up right, fitting well, my first attempt was not good enough, as it needs to fit closely around the shoulder of the wheel cylinder mounting points, to give enough metal around the area for the return spring holes to go, you can improve this slightly by only marking the position for these holes with the jig.

When marked, carefully eye things up and like me you should be able to move the hole positions over a millimetre or so, gaining some more metal where needed around the holes.

When drilled, you will need either to be patient with a rat tail needle file or use a mini grinder, to chamfer the hole, as required on one side only at the top and on the opposite side to that below because the spring needs to be seated horizontally to be parallel with the bracket, allowing the shoes to sit down on the guide plate, at the piston end of the shoe, before even the hold down pins are fitted.

Also as previously mentioned, the return springs need to swing across, slightly past the position required when the shoes are centred, to ensure there are no side loads, causing any bias to the shoe position, when the shoes retract.

That is how you get it to be a “floating” brake shoe, with a bit of patience so why rush, when if you take the time now, you can more confidently rush later!

The finished job.

Ed’s note: A couple of updates from Steve Priston as follows:

There is actually a fourth popular model of car that employed the same nine-inch brake shoes, making them even more plentiful. This is the MK1 Cortina Super, from the 1200s up. Also, EBC make the required shoes new, at about £35, part number EBC6235, so sustainable for a good while but original NOS shoes are a lot cheaper!

If anybody is seriously interested in tackling this conversion a paper copy of the template can be made available for a modest cost, as well as many more pictures.

There are, also, some laser cut blanking discs available for the hole left by the original wheel cylinders and arrangements could be made for some more infill plates to be folded-up locally as long as his costs are covered.

Steve Priston has collected some of the required components, for his future use, whilst they are still plentiful and relatively cheap, as he is intending to make one more set. Whilst he is not in position to actually manufacture currently, due to an impending house move, he would be willing to source kits of parts for those who might prefer it or could pass on the relevant eBay/part numbers.

Steve is willing to share his knowledge and experience gained in the manufacture of this TLS conversion. He can be contacted at: steve.priston(at)virgin.net [Please substitute @ for (at)].

2 thoughts on “TA/B/C Front brake twin leading shoe (TLS) conversion (continued…..)

    • Steve Priston says:

      Ron,
      Thanks for showing an interest in these brakes, as you are to date the only person that has done so, which I find a little surprising, what with the current situation providing a lot of “garage time”.
      The final picture shows my own TC fitted with them, now using a better performing Ferodo material, having been on the car since the summer before last so 2019 & yes I find them a significant improvement over the originals, they have a great deal of feel, under normal braking but haul the car up a treat (in a straight line), when you need to stop with any sense of urgency.
      I am waiting for Trad Harrison to try those featured on his 1350cc supercharged TC, to see how he gets on, as he has already resorted to using a servo, as well as fitting alfin type drums, on the car’s original set-up but he only received these brakes just before Christmas so will hopefully, having now got them fitted, be trying them out soon.
      John James, who put me in touch with Trad in the first instance, like myself, is eager for some feedback, to see how Trad gets on so hopefully this will be published in the near future.

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