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Triumph TR6 - 'A' type overdrive in a TR6


I found an used 4 sp+O.D. (A-type) from a TR250. The price i is acceptable but I do not know the status of that part. I have three questions:

1- Is it an easy fit in a '75 TR6 and should I change the driving shaft?
2- Is there a way to cheack OD on bench prior to install it?
3- If I have to repair OD, is it difficult and expensive?

Thank you for your help?



P.S. I know that 5 sp conversions with Supra or Ford Type 9, but I am reluctant to go that route...
J. G. Catford

Not sure about question #1 as I have never done that, but it should be "relatively" easy.
Question #2 about all you can do if it is allready removed from the car is check the oil being drained out of it, look at the filters and the general condition.Does it turn? Why is it being offered for sale, as overdrives are usually a sought after option.
Question #3 I can answer this one.......YES!

Mitch Smith

In answer to your questions

1] it will fit but you need to make a rear mounting adapter.[ Moss in the UK can supply this]. You don't need to change the driveshaft.
2] not without specialised test equipment
3]Repairing ODs is not really a DIY job and it's expensive to get done, particularly on an A type [in the UK anyway]

Personally I don't think this is the way to go, a '75 car should have a J type which is usually easier to source.

R. Algie


Why the 'hesitation' on the toyota conversion. If you are looking for practicality this is it. To keep with what was available, go with a J-type od unit. If you want originality, stay with what was installed at the factory (listed on the original build sheet).

There has been much discussion over whether these cars should be maintained as 'original' or if they should be improved with modern technology where available. Personally, I have always thought this was a matter of individual choice. I have heard it said that when queried about this, some of the old time TR, MG and AH factory folks felt the cars should take advantage of modern technology just as the factories would have if the cars had remained in production.

How many guys are still running around with bias tires on their daily drivers?

My wife's '75 which she bought new is being rebuilt as close to original (except for the suspension) as I can make it - this is what she wants. She even wants the cardboard radiator ducting instead of the nice aluminum one I made.

If I ever get around to rebuilding the '74, it will get the Toyota 5-speed, some electrical upgrades, rear disc brakes, upgraded front brakes, full poly bushings, an uprated spring set, new seats (not sure yet), and a re-designed dash with chrome bezel white face guages. noe of this is necessary, but it is what I think I might like. Well, at least for today.


Jean - To test an overdrive, it can be mounted and driven with a powerful drill with a chuck that you attach to the input shaft. My neighbour helped me on the last two overdrives we did by testing it in his lathe. He made a blanking plate to keep the oil in the overdrive and I have the pressure gauge to check the oil pressure. For an "A" type overdrive it should be about 325 psi pressure.

Don Elliott, 1958 TR3A with overdrive, Montreal

e-mail : - 58tr3a AT
Don Elliott


Don( yellowdog), your remark is good as I bought a car with Remington F78x14 and a 100 Km drive was like going to California. These tires almost new are resting in my garage and the car with radial is a charm to drive. But for transmission swap, as this transformation is more expensive than a good OD trans., I am not found of the idea of loosing car originality to that point.

Dan ( MTL) good way of testing thw OD, you gave me.

Than you to you all, I have matter to think.


J. G. Catford

There is a Buckeye Ohio Triumphs site that explains what is needed.

Let me know where you are and I can send you my gauge and fittings if you need them.

Don Elliott, Original Owner, 1958 TR3A'str3.jpg
Taken at VTR in Colorado in 2001
Don Elliott

This thread was discussed between 05/02/2006 and 07/02/2006

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