I've just bought a full donor "package" mainly cos I don't have space to strip down and the remove an old Sierra.

Anyways, I'm not that familiar with diffs and I'm trying to figure out if the one i have is ok or not. I understand what diffs do and why but not neccesarily the how.

I have a 3.62 LSD from a sierra xr4x4.

So, if I turn (by hand) the plate the propshaft attaches to, should both sides turn (it's not attached to any driveshafts or anything)??? One of the sides is also baiscally rock solid, it don't seem to want to turn at all, is that right???

2nd question - will the smaller master cylinder be ok for disks all round or do I need the big xr4x4 one?? I opted for the small one as the big one looked, erm, well, a bit big!!

and finally.........the xr4x4 had 5 stud hubs, so will the 4 stud ones I bagged instead mat up ok??

Thanks for any advice.

Proper noob stuff I know but first build and all that.

All ford Sierras (even the Cosworth) had 4 stud hubs only the Granada had 5 stud, check your doner parts carefully, the Granada rear end is also wider than the Sierra.
Sorry to worry you but best you get every thing checked out now.

If you turn one wheel on a non LSD the other will turn the reverse way on a LSD it will turn the same way.
If the diff tag is still attached then look for AA or AAA in the code.
Late Granada's did not have LSD as they used traction control instead

I was just told that late scorpio's changed from 5 stud to 4 stud, does that sound right to anyone else?
I took an LSD of an XR4X4 and can confirm it was deffo 4 stud, sorry dude.

With the Ford viscous coupled LSD, if you turn the input flange, both output flanges should turn in the same direction.
If you grip both output flanges and try to rotate them in opposite directions, you should be able to do this only with a great deal of effort (as you are turning the viscous coupling).
All the above is assuming that nothing is connected to the input or output shafts.

Ah right, that seems to make sense. He did have the 4 stud hubs but I think he just wanted to give me the 5 studs because the 4's were still on another motor.

So only one output flange turns and the other is rock solid is it goosed or just in need of tlc??

Thanks

My one did that at first, i got it from a scrap yard and it was just a bit stiff so don't panic just yet.

Cheers mate what did you do to loosen her up??

I've had about 5 or 6 diffs kicking around the garage over the last couple of years, whenever i get one i drain out the fluid, take off the back and give it a clean then refill with fresh fluid, then just work back and forth a bit.