front diff swap.....to a different ratio ->
#1
when swapping from 4.44 to 3.545 front diff, is it just the crownwheel thats different, or the little pinion gear too?
im thinking both? which would mean swapping the gearshaft too
any ideas?
thanks, ian.
p.s. dont want to swap the whole box, as its v.low milage and close ratios....which i want to keep
and yes, i know to swap the rear diff too
im thinking both? which would mean swapping the gearshaft too
any ideas?
thanks, ian.
p.s. dont want to swap the whole box, as its v.low milage and close ratios....which i want to keep
and yes, i know to swap the rear diff too
#2
Scooby Regular
Join Date: May 1999
Location: SSO2003 2nd, SSO2005 1st, SSO2006 2nd, TACC Rd4 5th 4wd: In my car ;-)
Posts: 2,637
Likes: 0
Received 0 Likes
on
0 Posts
I think you'll find that the 3.54 is only listed for the UK rear.
UK cars, whilst listed as 3.9, actually have a 3.54 rear crown wheel/pinion, because the final drive is actually 1.1:1, not 1:1 like the jap cars.
So, the lowest you can put in the front, is 3.9, and then you'd have to match the rear.
Front cw/p's are pretty cheap (relative) under £200 new, but the backs are blo*dy expensive. I think my rear 3.9 cost circa £450 + vat.
If you use second hand parts, be VERY carefull. You won't be able to tell how worn they are, until you fit, and check the clearances.
Also, this isn't really a "DIY" job, the cw/p's need shimming.
Mark.
UK cars, whilst listed as 3.9, actually have a 3.54 rear crown wheel/pinion, because the final drive is actually 1.1:1, not 1:1 like the jap cars.
So, the lowest you can put in the front, is 3.9, and then you'd have to match the rear.
Front cw/p's are pretty cheap (relative) under £200 new, but the backs are blo*dy expensive. I think my rear 3.9 cost circa £450 + vat.
If you use second hand parts, be VERY carefull. You won't be able to tell how worn they are, until you fit, and check the clearances.
Also, this isn't really a "DIY" job, the cw/p's need shimming.
Mark.
#3
hi mate, thanks for the reply
what i should have mentioned is that i have both the front and rear diffs in the shed. they are from my legacy (uk turbo)and have done 59000miles and mint.
i swapped the box and diffs (to STi RA ones) when i stripped 2nd gear as i couldnt find a legacy box.
i want to keep the close ratios, but the very low (4500 @ 85mph !!) gearing is doing my head in now. only does 125/130 @ 7000rpm redline now too
cheers, ian.
what i should have mentioned is that i have both the front and rear diffs in the shed. they are from my legacy (uk turbo)and have done 59000miles and mint.
i swapped the box and diffs (to STi RA ones) when i stripped 2nd gear as i couldnt find a legacy box.
i want to keep the close ratios, but the very low (4500 @ 85mph !!) gearing is doing my head in now. only does 125/130 @ 7000rpm redline now too
cheers, ian.
#4
crown wheel and pinions come as a set and define the final drive ratio.
mark is righjt in that the UK impreza turbo has a rear final drive of 3.54 in the diff housing then a 1.1:1 transfer box between the diff and the gearbox.
I have no idea why they do this, but overall it gives a final drive of 3.9
the crown wheel has 39 teeth on the front, and the pinion 10 so yes they are both required.
I still wouldnt want to do the job myself though, but then I never do.
mark is righjt in that the UK impreza turbo has a rear final drive of 3.54 in the diff housing then a 1.1:1 transfer box between the diff and the gearbox.
I have no idea why they do this, but overall it gives a final drive of 3.9
the crown wheel has 39 teeth on the front, and the pinion 10 so yes they are both required.
I still wouldnt want to do the job myself though, but then I never do.
Thread
Thread Starter
Forum
Replies
Last Post
Mattybr5@MB Developments
Full Cars Breaking For Spares
28
28 December 2015 11:07 PM