Hi guys,

Have a NOS (Never fitted) Toyota T50 3T 5 Speed to go onto my A12 Turbo motor. Doing a bit of research (which I probably should of done before) suggests that the box might not hold up to the task.

Generally most people are saying around the 200hp figure. However hp isn't really what kills gearboxes, it's torque. Without getting too far ahead of myself, my target for my engine is 150hp at the rear wheels.

Zigmondo's setup (A15) is making 160nm (118 ft lb). Some have suggested the limit of the T50 to be around 140 ft lb. I'm not sure what mine will put out but I'm getting a little weary.

Thoughts, opinions, experiences???

1. Will your A12 will make more torque than his A15?
2. Got plenty of leeway between 118 lb. ft. and 140 lb. ft.

187 HP @ 7000 RPM = 140 lb. ft.
140 HP @ 5250 RPM = 140 lb. ft.
107 HP @ 4000 RPM = 140 lb. ft.

my ute got 265 atw a15 and only broken one gearbox on the dyno with a lot off testing

I'm racing(on slicks)with 140 rwh using the same gearbox and A12 turbo without any dramas at all and we are not terribly kind on the drivetrain.

I'm just going to put this out there. When I was in my teens, I used to play with toranas a lot. they had the holden banjo diff which is considered a weak point to say the least. You could literally snap an axle (I realise you are talking about a gearbox, but the point is the same) with a stock 173 and a manual gearbox, by jumping off the clutch quickly enough often enough. In that guise the cars would be lucky to run a high 16, probably mid 17 second 1/4mile, so not too quick in that form to say the least.

There was a guy in SA called Rob Flego (I hope I'm remembering the name right) who ran a modded 186 with nitrous with an auto box in the same car. He stuck with the banjo diff, and with being able to launch with an auto, and do so smoothly, it wasn't until he was running into the low 10s/high 9s that he was constantly breaking the things.

My point being there's torque, there's the weight of the vehicle, and there's also 'shock loading'. You're putting the box into a car lighter than its original fitment, which is a plus. The torque will be higher than any NA a series almost without question. BUT, the 'big' deal here is you can control the shock loading. What the box will tolerate in steadily fed in force versus jumping off teh clutch is considerable, and that goes for any gearbox.

If you concentrate (and just to be clear I'm not accusing you of driving badly or anything, just talking about what it is that breaks things) on smooth launches and slipping the clutch a little more off the line, YES, you will go through clutches at a higher rate, but they are consumables and replaceable. Do _that_ and you'll get the box to last a decent amount of time.

People were putting these boxes behind holden 6s in toranas (more torque and heavier car) and they did survive ok-ish if treated properly. THen the supra boxes came along and everyone gravitated toward them. Don't get me wrong people were still breaking them, but it was mostly down to driving style.

Ride the clutch just a little more off the line (which if done right will actually let you build up boost quicker too) and soften the upshifts just a little, no full throttle 'flat shifts' and lift off the clutch a fraction slower after the upshift and you'll get a lot more life out of it.

I have a clubman with a 4AGE 20 valve that drives through a T50
and has never missed a beat.

I understand it is a different thing not being a Turbo setup
but the car is driven hard, revved harder than any turbo will be
and the clutch is quite grabby.

The box just takes it all.

Just remember to run a good quality oil.

Cheers
Geoff

Guess I'll have to give it a go and see!

I broke the input shaft off a T50 once behind an A15
But I put that down to a big overev and the flywheel falling off previously

You could always put a W50 behind it if your keen....I'm doing that for one of my toys
Heavier box though being a cast/steel case