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TR5/TR250 Gearbox difference between TR4A and TR250

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heliguy

heliguy

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I should know this, but can't seem to find the info i need. Is there a difference? And if so, what would it be?
I have a line on a reasonably priced 4A, but its going to need a tranny. I have a spare one from my 250 project, and if i can keep the purchase price down, SWMBO will probably go for it!
 
I think the only difference is that the flange on the TR250 bellhousing has reinforced holes so that you'll need longer bolts to attach it. I have both here out in the cold if you need specifics but I am not motivated to go out right now.
 
Thanks Peter,

I don't need the specifics, just a " yes, the boxes are interchangeable" ( with the correct length bolts)
Sounds like i may be in luck...
 
I agree, boxes are interchangeable. As I recall, the mounting flange didn't even get all that much thicker; although it was beefed up several times after the TR250. But if it did, you may also need to update the 3 studs in the back of the engine block.
 
I don't know the exact difference, but I believe that the gear boxes for the 6-cylinder cars are very slightly longer than those from the 4-cylinder cars. It can only be about 1/4 of an inch or so. My TR3 has a TR6 overdrive gearbox and it fitted with only a slight struggle!
 
Nick, that difference in length showed up between the TR3 3-synchro and the TR4 4-synchro box.

Based on personal experience, I strongly recommend drilling new holes (or extending the existing ones) in the rear crossmember when fitting a 4-synchro box to a TR2-3. Otherwise the strain on the mounts will shorten their life.

We won't talk about how long it took me to realize why my mounts broke so quickly :crazyeyes:

Randall
59 TR3A with TR4A clutch, TR6 gearbox, TR3 top cover, TR4 OD
 
TR3driver said:
Nick, that difference in length showed up between the TR3 3-synchro and the TR4 4-synchro box.

Based on personal experience, I strongly recommend drilling new holes (or extending the existing ones) in the rear crossmember when fitting a 4-synchro box to a TR2-3. Otherwise the strain on the mounts will shorten their life.
Click to expand...

Did Triumph change the mountings on the TR3B's (the TCF series) when they installed the four synchro box??
 
I've wondered that myself, and never found a definitive answer. But my guess is that they just used the TR4 rear crossmember, which I believe has the holes slightly farther back.
 
Moot point now.....................car was just a bunch of bad body work in loose formation..........
 
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