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MG TD TF 1500 - Gauges

Can someone school me on the difference between standard and Mk II speedo and tach? I understand early TD had chronometric like TC, only with a different TPM I believe. But I can't figure out the later gauge differences.
Steve Simmons

They were changed from chronometric to modern type around car number TD 107xx for all TD’s.Tachs the same. I think the MkII had a different axle ratio, so the instrument was changed accordingly. Visually and functionality the same. After a long day at Sebring SVRA and TransAm with make up honey do today, I’m too tired to look up the specifics tonight, maybe tomorrow!
George Butz III

Thanks. I have a set of gauges here and there were some Mk II parts in the same box so I want to figure out what I have before I try to find them a new home.

Speedo face reads
British Jaeger
S.S. 582
-
X.65022/25
1600

Tach face reads
British Jaeger
X.65021/4
-
2-1
K.45

Steve Simmons

I fairly certain 1600 TPM is a std gauge for 5.125 CW&P
Certainly a nice pair of late gauges
W A Chasser

Open MG TD MK2 Speedometer? in Archives. Bud
Bud Krueger

My speedo has the 1600 marking, not original but as restored by John Marks. I looked all over the place- including the TD/C supplement in the factory parts book, and could not find a reference showing different speedos or dials for the MkII. Digging in the TD Factory Specs book found two references with different part numbers each for speedo pinion and speedo gear-presumably the ones in the gearbox- "To correct speedo for use with Stan. Speedo Head-required for alternative axle ratios". One set was for 8/39 ratio and the other 9/41. So maybe the actual instruments were the same? George
George Butz III

Interesting. I hadn't heard of Mk II gauges until Tom Lange mentioned them. I'll just assume these are standard. Thanks guys, I didn't want to mislead a potential buyer.
Steve Simmons

Bill did not post the speedo/tach that was on the TD he just sold. Something different. Note the numbers are solid, not outlines




Bruce Cunha

Coming from the TC world, I'm quite familiar with chronometric gauges. I don't recall seeing that exact font before, which makes me think they may be older replacement faces. I'm not sure of that, just a gut feeling.

My current TD has chronometric also (retrofitted long ago) but the faces are the same type I see on TC.
Steve Simmons

Steve the gauges in TD 5779 were untouched and original to the car. Car was laid up since 1961 and mileage was correct. I had not seen that font before either.
W A Chasser

These are, as far as I know the original gauges from TD/C 9606. The font kind of looks the same except mine is a shadow font. Interesting.

J Cosin

The font on those is correct, although I would argue that they aren't 100% original to the car since the colors don't exactly match. One face or gauge may have been replaced at some point. After so many years there's no telling what was done. Even when the cars were only a few years old, parts did go bad.
Steve Simmons

Steve - I apologize for not noticing your earlier question about the difference between TD and TD/C speedometers.

The standard TD diff ratio is 5.125 and the Mark II is 4.875, and therein lies the difference. The stock TD speedo has number SS. 606 and shows 1600 turns per mile, while the TD/C instrument, SS. 598, shows 1525 turns per mile.

The faxctory Service (issue 2, 1951) Parts book shows the standard speedo as A1360 and 500527, and the Mark II speedo as 500829ND, but I don't know if this is for the flat-faced cheronometric instruments, or the dished-face ones that came in October, 1951, about car 10750.

My temporary Amended Parts sheets (there were a series of 6), printed in red, also show that the pinion and speedo gears for the Mark II are X17212 and X24442. Both need to be changed in the transmission, for correct speedo readings.

Hope this hjelps.

Tom Lange
MGT Repair
t lange

This thread was discussed between 26/02/2024 and 01/03/2024

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