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Tr7 transmission in a tr3 anyone?

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Hi just curious if anyone has swapped a tr7 5 speed into a tr3? If so any insights would be appreciated regarding the clutch, pressure plate, pinion etc. I a not sure if anyone sells the adaptor for the bellhousing end or for the gearbox end to weld onto the existing tr3 bellhousing.


Thanks in adavance.

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one of my club mates owns a TR5 with a TR7 5-speed gearbox.

Hi bought the car this way from a GB car mechanic located at Germany and has been told it is „not much effort“.

This could be an interesting investigation and report on this forum.

Perhaps you know I did that with a MX-5 gearbox, this also works, the effort is „relative high“ (depends on your skills).

Or you buy a ready to bolt set from Vitesse Ltd / GB. I guess you don’t want to go that way?

Ciao, Marco

Edited by Z320
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Thanks Marco, I have seen the mazda conversions and know the HVDA toyota, and Vitesse mazda conversions. Just wanting to keep it to triumph as that can protect the classic car status here.

If I was going to go that way I likely would do the complete engine and transmission swap, which I have thought of as originally my engine was seized but have gotten it free now with a lot of work. So being someone who has been criticized for thinking a wee bit much about things I am looking at my options. Also I found at tr7 locally with no engine and that has the transmission etc still for pretty cheap.

I will definitely keep you posted though, As I have found very little, well actually nada online about such a swap. Should be fairly easy to mount the bellhousing to an adapter and then to the gearbox. The only questions then are more around which clutch etc to use.

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As something of a purist, I wonder why you would consider fitting a TR7 box!  The gearing and Overdrive of a standard gear box is such that it suits the power curve and rev range of the 4cyl engine, the TR7 box does not.

If the standard gear box is in good condition and fitted with a 3 bearing (modified) lay shaft then it should be OK! or am I missing something?

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My mate told be they are about the same, he is very pleased with it.

And due to the data sheet they are, probably you will not notice the difference.

Please keep in mind all TR2-6 PI share the same gb ratios (4 and 6 cylinders) and are no rocket technic.

Edited by Z320
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Hey Marco, Marshall is the name as it says. I have been stalking the forum for a bit. I have a 1962 tr3 from Washington state, off the road since the 80's engine was seized, now is free. I am not really a purist, as the engine was seized I considered a variety of swaps some already done, nissan, mazda, toyota etc. Now the engine is free, I am going to get the block checked and fully tear it down to see what I have. As for the transmission I have driven TR3's, MGA's and while an overdrive is nice, they are simply not available. As such I had heard through an old friend of my fathers that the tr7 transmission had been put in one for a 5 speed. If someone has an overdrive that won't drain the bank I would definitely consider it. I am in Vancouver Canada, not a lot of triumphs around. In fact it took me 4 years to find one that was a reasonable price and not a total rust bucket. I previously had a tr4 with a tr6 engine in it, the owner before me had done it, sold it years ago when I was in my 20's.

Finally going to put the time into this car, all the money is going for the garage/workshop to work on it...lol.

Also will be building the engine up to have a bit more torque and hp, stiffening the frame up, discs f/b, upgrade rear suspension. I want something fun to drive and will be on the highway a fair bit going up to our cabin, so having the extra gear is something I want.

Also the tr7 whole is 750 so take the transmission out and I can likely sell the rest and end up even.


I have also driven an hvda conversion with the toyota transmission, and a supercharger on it, really liked it.

That sums it up! Thanks for the input, and anything I do will be something easily undone. I am just surprised that I can't find anyone that has done this. And putting a triumph transmission into an older triumph is much more in keeping with potential modifications early in the life of this tr3.

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