rear diff
 

Im no where near getting the running gear together for my roadster, im just about to start the chassis, but i have found a rear diff, believe it to be off a scorpio 2.0 it has a 4.27 ratio would this be suitable for a roadster with a duratec engine?

the only reason i ask is that the diff is at work and will be getting binned if i dont have it and trying to get away with not buying a donor.

4.27 very low ratio,would be good for acceleration but reving highly on motorways etc.Would think a 3.92 or 3.62 would be better.
Are you sure its 4.27 and not 3.27?

deffinatly 4.27 par no. is 95GG LA 427. i just wanted to make sure it would be suitable as i dont know much about rear diffs yet and cant seem to find much info on that ratio.

if it is 4.27 i would be happy to swap it for a 3.92???

Identify diff ratios ?
 

Just woken up this thread to avoid starting another.

My car was built from 2 Sierra donors, a fairly late 1600 and an earlier 2 litre car. I'd like to work out what ratio diff i have, where is this marked ?

Usually there is a little silver tag on the back cover attached through one of the bolts if u are lucky.The last 3 numbers on the tag will be the ratio ie 362 or 393 etc.
If not take the rear cover off the diff and it is usually etched into the crown wheel(the large one).
If not the mark one of the side flanges and then rotate the front drive flange until the side flange does one full rotation.Keep note of how many revolutions you do :D

Divide the number of teeth on the crown wheel by the number of teeth on the pinion and this will give you the ratio to 1,in the abscence of id tags.