View Full Version : Overdrive

04-10-2006, 11:55 PM
I have a 72 TR6 tranny with A type OD. I want to fit the OD to my 76 tranny, as the 76 tranny is completely rebuilt and very tight. Has anyone else done this?

04-11-2006, 12:07 AM
Let me welcome you to the forum, and thanks for posting. I can't address your specific question as my TR7 has it's overdrive built into the tranny in the form of a 5th gear. /ubbthreads/images/graemlins/devilgrin.gif But I'd bet you'll get a response from someone soon that knows just what you're dealing with and can advise you properly. /ubbthreads/images/graemlins/driving.gif

04-11-2006, 04:00 AM
Hello and welcome to the forum. The fact that you already have an A-type overdrive on a TR6 transmission is proof enough that the transmission can accept this type of electric overdrive. The J-type was the norm for this car in the later years but the A-type certainly will fit and work, and is preferred by some because of it's ability to shift harder and faster. Did you do the work on the transmission yourself or did you source it out? Any non-overdrive Triumph 4-speed will have to be modified to accept either overdrive. Contact John Esposito at quantumechanics.com for questions about the conversion and the pricing of either the kits (which he sells for the do-it-yourselfer) or the cost of his doing the conversion. John is one of the best in this area. Again, doable, will require some shaft conversion and other parts. Don't know if you will or can do the work yourself or ask someone like John to do it for you. Doubt that John would just do the conversion without insisting on reworking the overdrive unit in order to warrantee his work but I could be wrong. Too, I believe that there is a shop in your area that work with Triumph trannies. Someone on the forum will pipe up and attest to this. Good luck.
Point of interest, A-type overdrive units are getting more and more difficult to find, and valuable.


04-11-2006, 12:42 PM
The output shaft of a non-overdrive 76 unit is not compatible at a minimum. I think (not positive) that you could swap the output shaft from the 72 unit into the 76, but that may defeat the purpose of the rebuild. You might be better off just going through the 72 unit and seeing what is worn. And with that I will shut up and let people more knowledgeable speak up. Welcome to the board!


04-13-2006, 08:56 AM
Thanks, that certainly is an option. Which may end up being the best choice and keep the original as a spare.


04-13-2006, 09:33 PM
I think you should sell me your set up and buy a later J type OD and transmission thats compatable with your car. dont mix and match earlier OD and transmissions with later cars, just my opinion, take it for whats its worth Free. No warranty is expressed or implied bla bla bla

04-13-2006, 10:02 PM
I did quite a bit of research before deciding on a j-type for my 72. I know that it's not original for the car, but all things considered its a more reliable unit than the a-types. And since I don't ever intend to use the overdrive in competition, I could care less about at what speed the thing shifts into overdrive.