Mk1 A-type gearbox behind a 2500

[tr250]

So the plans are to swap the bad GT6 engine with a 2500 from a late TR6. My rusty Mk1 has an A-type gearbox that works great. I know the main shaft is a smaller diameter requiring the GT6 driven plate, but will the gearbox stand up to the HP gain...obviously not throw you back in your seat HP but more.

Have others done it?

I have a late 2500 intake manifold. I'm assuming the carb clearance will be tight. I have a plethora of ZS carbies. Were the HS6s much narrower?

Regards

Todd

[david_lall]

From all I have heard the A-type overdrive is stronger than the J-type. Hence overdrive on 2nd, 3rd & 4th whereas on the J-type Triumph restricted it to just 3rd & 4th.

I have an A-type on my Mark 2, 2.5PI, operating on 1st, 2nd, 3rd & 4th - I very rarely use overdrive in 1st, just occasionally in mountains with the caravan. Now, 70,000 miles on the overdrive occasionally slips rather than engaging, and sometimes it's reluctant to engage but I would say that's only around 5% of the time, so it's annoying rather than a problem.

[Clifford Pope]

I've got MK1 with an A-type box driven by a 2500 Mark 2 engine.
When I replaced the clutch I discoverd that a PO had mismatched the clutch components, causing it to not fully release the springs so it wore out quickly.
The clutch kit was standard 2000/2500, but the release bearing mounting bolted to the gearbox had come from some other car and projected too far, fouling the bearing carrier. It needed quite a lot grinding off to get a proper clearance.

It is often said that it is torque that strains overdrives, not power. So on that argument use of power in low gears would be less harmful that abusing the bigger engine's slugging abilities in overdrive top.

[Andy Thompson]

Don't worry about the input shaft being smaller than the Tr6 - all saloons 2000/2500 PI etc use the smaller input shaft and all gearboxes for saloon are effectively the same inside - that said I would just use the overdrive in 3rd and 4th with a 2500 as the 2000 A type which you have has slightly less engagement pressure.

I would be more worried about the gearbox than the overdrive - they always wear quicker in 2500's - torque kills the layshaft bearings eventually - towing or racing in the gears accentuates the problem - cruising in 4th they last forever

[tr250]

Alrighty then...let the stripping begin. I say that in the most modest manner of course

Regards

Todd