Hi. Does anyone have a max power and torque capacity for the ford 7" and 7.5" diff as they are in standard form. Thanks.

When I was at R&R they said 7" was good for up to 300bhp and 7.5" 500bhp.

HTH

Jim

thanks Jim, I worried how much tyre size and weight would affect things

Weight of car and traction available will make a MASSIVE difference.

A sierra 7.5" diff will no way survive 500hp in a car with any semblance of traction. I have seen these destroyed in 400 hp sierra cosworths in very short order.

A ford motorsport 9" diff will struggle with a genuine 500hp.

In both cases the std diff build will not be good enough. You will need the ford book that describes the detailed prep of these diffs. it is all in the "prepare a sierra for motorsport" book from Ford Boreham.

You have to remember that a lot or the hp claims in the fast ford world are utter bull5hit and that the stress on the diff at really high power levels is huge.