LSD Diff question

[Garth]

Looking for a ford 3.92 diff to convert to LSD. Come across a LSD diff from a ford sierra cosworth looks the same as all the others I am loking at . Checking what ratio it is. Does anybody know what the ford LSD was/is like? thanks

garth

[djg]

On the train, so looked on webhere. Found this lots of usefull info.

Doug

[Garth]

thanks Doug - very useful - the Sierra diff I saw is 7.5" so will not fit!

[garybee]

2WD Cosworths used a 7.5" diff' (as did the Granada/Scorpio) whereas 4WD Cosworths used the 7" unit.

 

There are issues with fitting the 7" Ford LSD to your Caterham though. If you want an easy life, the 'no stress' option is to get an open Sierra diff' and fit an aftermarket limited slip unit into that. If you want to fit a standard Sierra LSD you will at the minimum have to swap to a different type of joint on the inner end of your driveshafts (assuming you have normal Caterham shafts, for all I know you may be doing a conversion on a Sierra of course).

 

If you decide you want to fit a Ford LSD and you want a 3.92 ratio unit, you're looking for one from a 2.0 4x4 Sierra. These are a bit rare, I luckily picked one up a few months ago but you may have a lot of trouble finding one. 3.62 units are much more common. These mostly came from XR4x4 Sierras and most of the 7" Ford LSDs you see for sale will be of this type.

[LesG]

Agree with Gary above, most of the 7" Ford lsd diffs will be 3.62 final drive, but if you have a standard Caterham open diff on a 5 speed gearbox, it'll be 3.92, and you can just swap the crownwheel and pinion (as I did).

 

The trouble does come with the driveshafts; if you have the earlier type when Caterham modified Sierra shafts, then it's easy-peasy to swap your inner cv's to bolt-on lobro joints and hey presto!

 

If you have the later type Caterham-only driveshafts; all the best! ☹️

[The Pikey]

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Edited by - Jason Fletcher on 7 Dec 2012 22:00:03