trails

iTrader: (41)

banny sti

iTrader: (68)

The P1 box is indentical to a sti 5/6 gearbox down to the gearbox code. It does not have a longer fifth, I swapped my sti 3 which has the same ratios as the sti 5/6 gearbox and there was no difference. Seems to be an urban myth that the P1 box has a longer 5th gear.

Banny

trails

iTrader: (41)

thanks for the correction Banny, a quick bit of research and;

UK 5 Speed (3.9:1 ratio diffs):

1st = 3.454
2nd = 1.947
3rd = 1.366
4th = 0.972
5th = 0.738

Sti (4/5door/P1) 5 Speed (4.444 ratio diffs):

1st = 3.166
2nd = 1.882
3rd = 1.296
4th = 0.972
5th = 0.738

I must have been confusing them with RA boxes...

andy97

iTrader: (1)

For those who want to run 300/300+ its false economy to keep changing gearboxes without upgrading to a ppg or alike. Having experienced the smoothness and how quiet a PPG helical box can be, there can be no other choice.

Api ppg customer

Andy

stevie1982

iTrader: (16)

so it seems once the gearbox has been changed there will not be much difference between the sti and uk car!

looks like if i keep it a nice 6 speed or ppg will be installed

harvey

iTrader: (48)

As the UK final drive is 3.9 and the STi 3-6 and P1 are 4.44, the UK car has much longer legs.
Regards breaking gearboxes, a lot depends on the owners mechanical sympathy. My experience is that the TY752 boxes will handle something up to 320 ft lbs but will break soon after that. TY754 boxes will run over 400 ft lbs treated reasonably.
Blocks. There are quite a few cars well over 500 bhp on open deck blocks that I am aware of and the block and later cranks do not appear to be an issue when power is increased.