Building a rear...

The Fox

New Member
Mar 30, 2005
Port Elizabeth
I still have a 7.5 rear. I'm gonna grab an 8.8 from a junkyard and just use it as the carrier for some 31 spline Mosers and not sure what brand differential. Here's my question. WHAT DO I NEED?

Because the way I think of it you just buy your differential, buy your axles, take the old axles out, take the old diff out, put the new diff in, slide the new axles in, call it a day.

I'm sure this is gonna be one of those things where u need some random tools and some kinda stuff that will just make me mad. Thanks.

BTW, if anyone know us of the cheapest/dependable LOCKING differential let me know. I heard there are full posi lockers that are "open" when turning. I don't understand it but let me know. Thanks

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I'm converting to 5-lug on 87 coupe. Here's what I'm doing:
Junkyard 31 spline from an Explorer. Gonna rebuild it and pack it as tight as possible and get the heavy duty S spring.
Superior 31 spline 5-lug axles. Got them from Summit with bearings and lugs for about $250. Best price I could find.

A friend of mine has this same setup and has been racing it for two years now running mid-low 11's.

If you're keeping the same gears that are already in the 8.8, you'll need to shim the differential and check for backlash when you reinstall it. For that you'll need a dial indicator.

If you're replacing gears, that will take more work, but can be done especially if you have it out of the car.
Best way to do that is to put the rear in a jig to hold it still though...
the later model exploders, I mean explorers came with 31 spline carriers and axles (later 90's, w/towing package). The carriers aren't super expensive, and they can be rebuilt. The ez lockers, tru traks, ck out for more info on the different types of diff's, this should help you make your choice.

as far as packing the diff tighter; be careful, if you put too much into it, you'll end up with axles that barely fit into the carrier and then it'll end up eating itself...I'm going through that right now, so I found a NIB 03-04 Cobra carrier off eBay for $175, and on payday grab a set of superior axles from Summit...then go spend another $225 at the shop having them install all the parts.

I would do it myself, but honestly, I'm getting sick of being covered in 90wt and smelling like crap for two days while it wears off