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TR4/4A gearbox exchange TR4A to J-TYPE

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pvergon

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hey, it's been a long time since i last wrote but finally i'm in desperate need of help.

i'm in the final stage of overhauling the engine of my TR4A. it spent 8 yeards in a swamp but it is the original one so i decided to rebuild it's original engine.

unfortunately i couldn't find a TR4A gearbox so i had to buy a 1974 TR6 J-TYPE gearbox, and i'm wondering what kind of trouble will i have to face and if it's possible to exchange these two gearboxes.

Can anyone out there let me know if this can work?

thank you .... paul
 
I don't have input about how to mate the Jtype to your TR4, but I installed a Jtype in a GT6 recently and know a little about jamming "foreign" bits into these cars.

Most definitely, you'll need a different length propshaft, which isn't hard to do. Just get the measurements right and take it to a machine shop for cutting. Be sure to get sliding yoke, which allows an inch or two extra for fitting the shaft.

Also, test the OD as much as possible before installing it. If you can, bench test the whole gearbox before it's installed. There are a couple of good websites with this kind of info here:
https://www.buckeyetriumphs.org/technical/JOD/JOD2/JOD2.htm

and here: https://www.vclassics.com/archive/laycock.htm

You're going to love the Jtype. Relatively easy to repair, nice reduction in revs for cruising, and effectively, a six-speed gearbox.

I wish I had more to offer for this conversion, but I don't know TR4s very well, other than the fact that they're one of the best looking Triumphs.

Please keep us informed on this and take lots of digital photos. I've never heard of anyone doing this conversion, looks very interesting.

Good luck!
 
Paul , I would suggest you get on line and sell or trade the J for the A, since in my experience there is no good way to use the J in the 4 chassis. Lots of guys are looking for the j so you should be OK as far as buyers goes. It may take some searching to find a nice A type but short of a regular 4spd that is all you can do.
MD(mad dog)
 
Aloha, I just finished an overhaul of my TR3B and installed a TR6 w/Jo/d. Only problem I had was a new back mount for the J. It was very easy. Go to Buckeye Triumph club for great info on J o/d and tarnnys. Mahalo, Iceman
 
MD ... and what do you think will happen if i bought a TR6 stainless steel exhaust system???? i was originally going to install a TR6 1974 engine to my TR4A and finally decided to go with the original engine. this was 6 years ago, which is why i bought the engine, exhaust and J type transmission.

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