Printable Version | Subscribe | Add to Favourites
New Topic New Poll New Reply
Author: Subject: making a high ratio diff?
bi22le

posted on 5/4/16 at 09:25 PM Reply With Quote
making a high ratio diff?

I have a 3.92 push in non-LSD and would ideally find a 4.++ ratio but these seem very rare or non existent. Knowing that the sierra bits are generally all the same is there potential to split my 3.92 use a different pinion (for example) and create the higher ratio i need.

Essentially im now track on and never use 5th. I would like to gear it down to approx 130 to gain better acceleration.

Thanks for any help.





Track days ARE the best thing since sliced bread, until I get a supercharger that is!

Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1

Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I

View User's Profile View All Posts By User U2U Member
CNHSS1

posted on 5/4/16 at 09:55 PM Reply With Quote
Iirc 3.92 is the smallest pinion (14t?) so its as high as you can go with ford bits.
SBD and Raceline make new CWPs, 4.1, 4.4, and i think even a super rare 5.1.
Last time i checked they are circa 500 quid though.

Could you change the rolling radius of the rear tyres instead?
If you use 13" rims somw carwful checking of tyre data sheets will find smaller rolling radius. As an example changing from 205/60-13 to 235/45-13 will be similar to 3.9 to 4.1 and wider footprint for more grip (needed when you have a short diff!)





"Racing is life, everything else, before or after, is just waiting"---Steve McQueen

View User's Profile View All Posts By User U2U Member
MK9R

posted on 5/4/16 at 10:09 PM Reply With Quote
You can't mix and match pinions and crownwheels, they won't match/mate





Cheers Austen

RGB car number 9
www.austengreenway.co.uk
www.automatedtechnologygroup.co.uk
www.trackace.co.uk

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
mcerd1

posted on 6/4/16 at 08:37 AM Reply With Quote
As above you can't mix and match crownwheels and pinions, they are made as matched sets.


You can get 4.1 and a 4.27 ratio from the late 2.0 scorpios (one in the 8v and the other in the 16v)
But these are all 7.5" diffs and not exactly common...


otherwise you've got the choice of aftermarket crownwheel + pinion sets, an aftermarket close ratio gearbox or smaller tyres....

[Edited on 6/4/2016 by mcerd1]





- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

View User's Profile View All Posts By User U2U Member
marc_cowley

posted on 6/4/16 at 11:20 AM Reply With Quote
Rx8 rear diff is 4.4 in the s1 or 4.7 in the r3 I believe,big job to change though.





C30 T5

View User's Profile E-Mail User View All Posts By User U2U Member
wylliezx9r

posted on 6/4/16 at 11:43 AM Reply With Quote
I originally had a 3.62 7" LSD. I am currently in the process of swapping it to a scorpio 7.5" 4.1. Not that much work involved as my diff bracket is wide enough to suit the 7.5" as well. However I had to grind some of the webbing off the casting to fit and if your prop does not have a slider the nose is about 10mm longer on the 7.5".





I spent a lot of money on booze, birds and fast cars. The rest I just squandered.
George Best

View User's Profile E-Mail User View All Posts By User U2U Member
ReMan

posted on 6/4/16 at 03:06 PM Reply With Quote
Your doing a 4.1 with a zx9 engine?





www.plusnine.co.uk
∙،. ˘≈ﺣ

View User's Profile Visit User's Homepage View All Posts By User U2U Member   ReMan 's ICQ status
bi22le

posted on 6/4/16 at 07:57 PM Reply With Quote
quote:
Originally posted by ReMan
Your doing a 4.1 with a zx9 engine?


Yeah, thats crazy, fancy swapping it for mine?!?!





Track days ARE the best thing since sliced bread, until I get a supercharger that is!

Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1

Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I

View User's Profile View All Posts By User U2U Member

New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [ 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.