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TR6 TR 6 overdrive swap

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Brinkerhoff

Brinkerhoff

Jedi Knight
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I have a 74 TR 6 that I would like to know if I can fit the earlier overdrive gearbox to . Is this straightforward? The car did not come with overdrive.
 
Should be fairly easy, I think. The early OD used the same rear mount as the non-OD, so that should be OK. Driveshaft and clutch are the same, so they'll mate right up.
You'll need to do something about the speedo drive ratio, and perhaps cut the trans tunnel to clear the angle drive.
 
You should be aware that starting in '73 Triumph changed fromm the earlier A-Type (OD on 2-3-4) to the J-Type overdrive (OD 0n 3-4)which uses different rear transmission mounts. If you want to use an A-Type on your '74 you'll need a conversion kit which I believe is available from Quantum Mechanics. Well worth it though as OD transforms the character of the car.
 
IMO, if you have an early A type overdrive that is good you might consider selling it and buying the later J type which was a little more reliable anyway. Working A types bring a premium from people with TR3's and 4's that want to put overdrive in. J types seem to be more common and don't go quite as high price wise.
 
YYCDave said:
You should be aware that starting in '73 Triumph changed fromm the earlier A-Type (OD on 2-3-4) to the J-Type overdrive (OD 0n 3-4)which uses different rear transmission mounts. If you want to use an A-Type on your '74 you'll need a conversion kit which I believe is available from Quantum Mechanics. Well worth it though as OD transforms the character of the car.
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I could be mistaken, but I don't believe a conversion is necessary to fit an A-type OD to a later TR6 that did not have OD originally. Although the J-type does mount differently; and the later rear crossmember, etc. were different; I believe the A-type mounts the same as the later non-OD gearbox. So the appropriate mounting brackets will already be on the car.
 
BRSLimited said:
J types ... don't go quite as high price wise.
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IMO there is a good reason for that. I drive both, and IMO the A-type is much "sportier" than the J-type.

So much so, that I even tried to get a Stag A-type imported from the UK, after installing a J-type. Unfortunately it never arrived (and Stag A-types aren't quite the same as the ones used on TRs).
 
I owned a '74 non overdrive car before my '72. I dropped an A-Type OD in with absolutely no problems. I like the A type with the greater flexibility in 2nd, 3rd, and 4th. Though there isn't much difference between 3rd OD and 4th. Will it detract from the value of the car? No. Personally, if I sell my TR6, the OD is coming out and will go into the next car I buy.
 
I sure like the idea of getting the RPMs down for both MPG and longevity of the motor.The stock differential ratios for the non OD cars are numerically lower (than OEM OD cars) so you really get even more advantage with the OD addition.
 
vettedog72 said:
The stock differential ratios for the non OD cars are numerically lower (than OEM OD cars)
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I don't believe that is correct, for the TR series. Rather, the optional 4.10 gears were only available in conjunction with overdrive. But just ordering an overdrive would still get you 3.70 gears (or 3.45 if the engine was fuel injected).
 
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