hi am after a 7inch sierra diff, looking for a ratio around 4.4, currently got a 3.92 lsd bolt on d/shaft fitted - looking for a sensibly priced second hand unit - chrs mark

the only stock ones near that ratio are 7.5" diffs found in the 2l 8v & 16v ugly scorpios (4.1 and 4.44)

3.92 is the lowest stock ratio for a 7" diff


other than that your talking about an aftermarket crown wheel and pinion set - not common or cheap

linky (I've lost the link to the folk who actually make those)

[Edited on 16/12/09 by mcerd1]

[Edited on 16/12/09 by mcerd1]

not sure if the american solid 7.5 axle uses the same diff crown wheel and pinion as the british IRS 7.5 (granada/sierra) but here are some low ratios and cheap.

4.56:1
http://cgi.ebay.com/ebaymotors/Richmond-6903201-Ring-and-Pinion-4-56-1-Ratio-Ford-7-5_W0QQcmdZViewItemQQhashZitem5ad5905040QQitemZ390130061376QQptZMot orsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

4.10:1
http://cgi.ebay.com/ebaymotors/7-5-Ford-4-10-ring-pinion-gears_W0QQcmdZViewItemQQhashZitem35a5530afcQQitemZ230406949628QQptZRaceQ5fCarQ5fParts

they don't seem to do a 4.4:1

thx guys. I knew that 4.4 ( or thereabouts ) wouldnt come out of a standard sierra, just thought that perhaps by some miracle someone might have a modded one lying around that they might want to sell. I dont know how easy/hard or possible it would be to swap out the 7 inch diff and replace with the 7.5. given that i'm not mechanically minded and would need garage assistance - i'd suspect that any potential saving in going that route would be offset by the labour costs. am not 100% convinced that i'll be able to live with that type of ratio on the road, hence would have been ideal to find a direct replacement to try, if after a few runs its apparent that i cant live with it - pop the old one back in.......once again thx

if the 7.5" diff will fit your chassis and youve got bolt-on driveshafts at the moment, then the 4.44 or 4.1 scorpio diffs would be amost a strait swap (none are LSD as standard )

they have the same 100mm CV joints as the normal sierra bolt-on ones - so you can use the same driveshafts

and if you like the ratio you can build an LSD by swapping it into a cossie 2wd diff (the sierra ones have 108mm CV's, early granada cossies have 100mm ones, but I think you can swap the flanges...)

the 7.5 is a bit bigger/wider - but lots of chassis are designed to fit either (don't know about yours though)

thx for this, seems a bit of research needed into whether it'd be easy to adapt, i dont know of any other owners that havem but then, i dont know any other tigers that are wanting to run a 4.4!

Mark,
The 2wd Cosworth used a 7.5in diff case, unlike the 4x4 which used the 7in case.

As your car uses the whole sierra rear, you might be able to find a cage that you can bolt a 4.4 diff and the rest of your existing kit.

just a thought!

is yours one of those that uses the sierra beam to mount the diff ?

if it is you can get a 7.5" beam for a sierra fairly easily (as above the 2wd cossie's have them, but so do loads of later sierra's)