MG TC Dash Instruments – Let’s Face the Facts

2 Jul

Through the years, many parts have migrated between models, to include the dash instruments. It was a bitter realization that TC7670 had MGA gauges as part of a classic 60’s restoration. So the hunt was on from the start to find an original set of gauges for my car. Today the same hunt continues for others. But what do you need to look for? And how do you identify a proper TC instrument? The answer lies in the face.

Below is a summary of the face markings for each instrument.

Speedo: BRITISH JAEGER / S. 461 / 1675 / MILES PER HOUR

S.461 is the original part number. 1675 represents the internal gearing or cable turns per mile (TPM). The later TD speedo is often found in the TC because it appears to be correct with the “flat face”. However, it has the markings of S561 and 1600.

The #1600 is very telling and should be a red flag for TC owners. This # highlights that the TPM is calibrated for TD. If used in a TC, your indicated speed will be wrong. Also, for those that have changed the rear axle gear ratio in your TC, the speed may be in error also. To solve this problem, a repair shop can recalibrate the internal gearing to your specific car.

Finally, some export models were calibrated for kilometers per hour (KPH) instead of MPH and the faces reflected this.

Tach: BRITISH JAEGER / K.30

Primary TC identification is made with the K30. Often, this particular instrument gets confused with the very similar TD tach face with K45. The TC/TD clock faces are also the same. However, the TC clock has an extended stem below the dash for reset. The TD clock stem is on the back of the clock.


The TC rev counter (British Jaeger K30)

Amp: Early & Late Faces

a. MADE BY JOSEPH LUCAS Ltd BIRMINGHAM ENGLAND / AMPS / -20 to +20 (early TC)
b. AMPS / -20 to +20 (Late TC)


Early and late TC ammeter faces

The above early markings were also common to the pre-war TA/TB gauges except that they had AMPERES spelled out. During the post-war period this was shortened to “AMPS”. The transition to the late face occurred at an unknown time, (1946-47?), when the Joseph Lucas markings at the top of the gauge were dropped. The face then took on a “plain” appearance with only AMPS and +/- 20. This same gauge carried over into early TD production. Then there was a final variation changing the range to +/- 30 for the later TD. Today, many restored instruments proudly display the Lucas markings.

Oil Pressure: LBS. PER SQUARE INCH / BRITISH JAEGER / 45854 (X45854)

The oil gauge will generally spark a discussion as there are sightings of 3 different oil gauge faces. (Please reference the oil gauge photo to follow the following points.) TA/TB oil gauges had the # 45854. This numbered face continued well into TC production with a confirmed sighting in early 1948. At some later time an “X” was placed on the number as a prefix yielding “X45854”. Other markings remained the same. Finally, a 3rd oil face followed which added “Made in England” at the top and a new number “OG/54” under the needle. The X45854 remained but was relocated on the bottom of the dial. The telling fact for this face is that OG/54 was the newer British Jaeger “replacement code” for the oil gauge. This 3rd face would be considered an aftermarket item.

Today, if you are looking for instruments, be happy with what you find as they are becoming more difficult to locate. However, if you are trying to restore the instruments as appropriate for your TC then face the facts and consider the above information.

As always, I welcome comment. Doug Pelton, doug ‘at’ fromtheframeup.com

Acknowledgements: A special thanks to John Marks, Vintage Restorations and Fred Kuntz & Craig Seabrook, Whitworth shop for sharing their knowledge about our gauges.

Editor’s Note: Thank you Doug – as always meticulously researched and with wonderful photographs.

Mention of John Marks in the acknowledgments reminds me that it would be useful and complementary to Doug’s article to follow on with a piece written by John about the colour of TC instruments which appeared sometime back in The Sacred Octagon. I have John’s permission to do so. Apologies in advance to those who have read the article before!


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9 Responses to “MG TC Dash Instruments – Let’s Face the Facts”

  1. Owen Frankland 18. Jul, 2011 at 4:37 pm #

    I have to take issue with the comments regarding TPM figures on speedo faces.

    It’s a common misconception that fitting a speedo with an incorrect TPM figure will result in incorrect indication of speed.

    The TPM figure only relates to the odometer, not the speed reading. There are no gears between the speedo cable and the needle, just a spinning magnet. The speed at which the cable spins is governed by the gearing in the speedo drive in the gearbox.

    Changing the rear axle ratio or wheel/tyre sizes will result in travelling at a different speed from that which is indicated, and the correct way to put that right is to change the gearing of the speedo drive in the gearbox.

    TPM stands for Turns Per Mile, not Turns Per Mile Per Hour.

    • Bob Owen 31. Jul, 2011 at 7:55 am #

      The TC speedo is chronometric so there is gearing for the speed indication. A chronometric speedo counts the number of shaft revolutions each second and sets the pointer according to the result, updating once a second. There is no magnetic coupling.

  2. Paul Barrow 20. Jul, 2011 at 9:46 am #

    That said, it is a most excellent article and one that is very transportable into the MG Y/T world. Thank you Doug for that and Owen for the clarification.

  3. Owen Frankland 01. Aug, 2011 at 6:24 pm #

    Oops! Sorry guys for the false info. I plead insanity caused by too much time in a TA with the wrong type of speedo.

  4. george mcmurray 22. Jan, 2012 at 9:01 pm #

    I am restoring a 1946 tc, chassis no 1192 and the instruments were restored by vintage restorations in 1991. The chap i bought the car from had not finished the project, but had gathered up a lot of the parts needed. He sent the instruments to John Marks and the rev counter and speedo are still in there bubble wrap packages, the amp and oil gauges are still in there little boxes. The rev counter is K39 with the vintage label still on it, job no 85/7454 feb/91 and not k30.The speedo is s/461 and 1675 TPM, the amp gauge is L72 36153A 153 with made by John Lucas Ltd at the top and patented at the bottem it has amperes on the face. The oil gauge is 06/54 with made in England on the top and could have been replaced before 91 because it had to be restored then. I wonder if there is any reference on the k39 on the rev counter.
    yours truly george mcmurray
    membership no 113735

  5. Stuart Ratcliff 14. Oct, 2012 at 8:44 pm #

    I have two Rev counters, one has a clock that is removable from the rear with a separate face and the other shares the face with the tacho and is in the instrument case.
    Can someone fill me in on the the different applications for these two instruments please.

  6. Vincent 29. Oct, 2013 at 12:52 pm #

    Hello. I’m looking for an original TC tachometer, the British Jaeger K30 one. I’ve a paire of TD gauges to exchange…
    Anyone has something interesting for me?

  7. Anthony Pistorino 07. Jul, 2014 at 6:16 pm #

    Mg td 1961 . I have the amp meter apart for cleaning , and also the clock from the rev counter. Just light cleaning of the faces and a few squirts of Aerokroil for lubrication . Can anyone tell me how to hook up leads to bench test these two instruments? Thank you in advance for any info.

  8. Vince 30. Sep, 2014 at 3:39 pm #

    I’ve recently aquired a MG TC tachometer which is a bit different from the one on the picture: it is a British Jaeger, without mention of “K30” but with “Made in England”… also the clock shares the same face as the tacho, there are no separeted faces. Finally the needle are not the same as per your picture.
    My question: is my tachometer another version or is it a recent remanufacturing?

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