Gearbox, Diff Ratios and Driveshafts
 

Having some issues trying to get my car sorted out.

Recently killed 2nd in my old box. This now broken box did about 3400 rpm @ 100kmh. I believed this box to be a 4.11, and had a replacement 4.11 put in. This new box is running at about 3000 rpm @ 100kmh. So the most likely conclusion is that the old box isnt a 4.11. The rear diff wasnt replaced, so now im looking to replace the diff to match.

My questions for the gurus are:

1) What ratio is my old box and rear diff likely to be?
2) If I replace the rear diff, will i need to replace the rear drive shafts also?
(I believe this may only be the case if i get a non-GC8 rear diff)

Anyhows, i just wanted to make sure I had this sorted before i went and replaced the rear diff. Any help is much appreciated. :)

Cheers,
Smokey

I think your old box may be a 4.44. I have a 4.11 Now in my Legacy GT and it sits at 3000rpm at 100kph

4.444 RA Spec.

stock 4.444 ratio's arent that short anyhow.

The simple answer would be to pull out your rear diff and count the teeth, then if you don't have a 4.11 go to JWS or MMS or RT and buy the correct crown wheel and pinion to suit your needs.

If you actually had an RA box chances are your diff centre is plated or LSD of some description and you would probably want to keep it instead of putting a poverty pack diff centre back in.

always thought u had a v3 sti box smokes?

just digging up an old thread. anyone know what my ratio is?

i think i'm on around 2800 rpm @ 100kmh

3.54

thanks. any ideas what sort of box/diff i'd most likely have? i always thought i had a v3 sti box.

the rpm is determind by not only the diffs but your 5th gear which vary from model type and year, eg sti v5 had 4.44 with a 5th gear of .73, while some of the sti ra had a shorter 5th gear and so on, theres a few varations.. make sure the front diff ratio equates to the same as the rear...