Have any of you knowlegdable chaps changed the insides of a sierra diff, I've got a 3.91 (I think) in a 7.5" diff however I want to transfer the gears out of a 3.14 (7" diff) which hopefully should make my v8 rush better to drive. Is this something the Diy'er can do or is its best left to the experts.
cheers

Leigh

They are not interchangeable, the 7.5 inch is the crown wheel diameter.
You can use the 7 inch crown wheel and pinion ( they are matched pairs) and get it put on any other LSD 7 inch but cannot swap the internals from 7 1/2 to 7.

So you ned a complete axle from a 2.8
V6 sierra 4x4 and get AB Performance to swap the crown wheel and pinion
Bingo 3.14 LSD

Firstly if you dont have a 3.14 already, good luck! They are rare as hens teeth and thus when they do come up for sale, go for shed loads.

Also are you sure thats the correct ratio you need for a V8? What gearbox do you have because most people that hanker after a 3.14 are those with bike engines who need the high ratio to give decent top speed / cruising.

I have a wheel, dif, gear ratio calculator in excel that may help, U@U with email and i will send it. All the guys i know with V8's use the 3.62.

I've already got a 3.14diff, and have a lt77 gearbox. I only picked the 3.14 up as it seemed to be the most popular one for the v8 rush - could be wrong though. Snapper - the gear calculator would be handy I'll send you my email address

cheers

Have you ever been out in the Dax V8 demo car?
I think it has a 3.62 (with an R380 box ?) - which Gary at Dax thought was to low - 1st is definatly far to low

3.38 or 3.14 do seem to be the most popular (as always it depends what you want - crusing or track)

You should find a 7" LSD in any 4x4 sierra or 4x4 granada (inc. sierra and escort cossie) most will be 3.62
both mine came from XR4x4's - a 3.92 from a 2.0l and a 3.62 from a 2.9 V6 (sorry can't part with one yet)

heve a look throught this guide on the sierra owners forum - it'll help you get the right parts:
http://forum.fordsierraclub.co.uk/viewtopic.php?t=5843&highlight=diffs

here is a gear calc for you:
http://locost7.info/gearcalc.php

-Robert

[Edited on 13/9/07 by mcerd1]

Cheers for the info Robert

Leigh

You definately want a 3.14 in a V8. I'm eventually going to stick a 2.88 Jag LSD in mine (with hybrid driveshafts).

ATB

Simon