Austrian Impreza

iTrader: (9)

Another question about the STI Gearboxes!
I have read some infos on the strenght of the gearboxes from STIs V5/6, but do not know if these gearboxes are really stronger or not...
I think the old V4 gearboxes are not as strong as the normal WRX 99/00s.
Please let me know details and thoughts about it.
Many thanks again guys!

911

I have been assured by David at www.apiengines.com that the V5/6 are stronger in several respects. Not as strong as a 6 speeder, but the best of the 5 speed Impreza boxes.
I trust what he says.
I think (not know) that the gears are wider in first 3 gears and the bearings larger. I think the synchro's are 'better' too.

Graham.

Austrian Impreza

iTrader: (9)

Thanks for that information Graham!
Does this mean the V4 STI gearsets are also as strong as the V5 and V6?
I read in another thread that that might not be as reliable!

911

The V3/4 boxes I think are the same, and are all 'weak'
This is a relative term though.

I hillclimb my V3 with about 400 bhp and 340 lbft of torque with very sticky race tyres.
I run the car without any mechanical sympathy on the track, so '5500 rpm / dump the clutch' starts are normal using a stock AP organic clutch.

Zero problems for 2 years in any of the driveline components.
An early UK gearbox might not survive this but Sti's were made of better stuff!

For increased reliability API stated the V5/6 boxes were a significant improvement.

Graham.

Austrian Impreza

iTrader: (9)

That sounds good, so a STI V5/6 is the way to go, if needed!

Maybe the WRX MY99/00 gearboxes are as strong as the STI V3...

Bt the best I think are the Type R/RA boxes, the do have the widened 1th,2nd,3rd gears but the old bellhouse, but I think that does not matter?!?

911

Not sure, but apart from the ratios, the material specs are the same i think for the RA boxes.
Graham.