Fox Mustang rear diff

Topic: Fox Mustang rear diff (Read 1877 times) previous topic - next topic

Fox Mustang rear diff

January 27, 2011, 09:29:32 PM

I am about to buy a 87 GT 8.8 complete rear end . Is this a direct swap ? I have read something about the Mustang rear diff being not as wide as my 1988 7.5.

Fox Mustang rear diff

Reply #1 – January 27, 2011, 10:33:38 PM

it will go right in its a little more marrow then the 7.5 but it will fit to make mine look right i put on 1/4 in wheel spacers. of you use the 7.5 brake lines the plate that bolts on the diff cover will need a new hole drilled to mount it to the 8.8 and dose your car have 9in brakes or 10 in brakes? if it has 10in brake i would suggest swaping them on to the new rear. you have to take the diff cover off and pull the axels to do this. and while you have the cover off i would change the fluid and look over it inside (ring gear spyder gears) make sure they are not missing teeth or cracked or anything. and if you put new fluid in put in synthetic gear oil i have pennzoil 85w140 full synthetic and go to your ford dealer and get a bottle of friction modifyer (about 6 bucks for a bottle) this is a additive the posi disks need and it also helps keep the rear quiet. hopefully this helps you a bit

Fox Mustang rear diff

Reply #2 – January 28, 2011, 02:27:46 AM

Quote from: 87tbird5.0;351021

it will go right in its a little more marrow then the 7.5 but it will fit to make mine look right i put on 1/4 in wheel spacers. of you use the 7.5 brake lines the plate that bolts on the diff cover will need a new hole drilled to mount it to the 8.8 and dose your car have 9in brakes or 10 in brakes? if it has 10in brake i would suggest swaping them on to the new rear. you have to take the diff cover off and pull the axels to do this. and while you have the cover off i would change the fluid and look over it inside (ring gear spyder gears) make sure they are not missing teeth or cracked or anything. and if you put new fluid in put in synthetic gear oil i have pennzoil 85w140 full synthetic and go to your ford dealer and get a bottle of friction modifyer (about 6 bucks for a bottle) this is a additive the posi disks need and it also helps keep the rear quiet. hopefully this helps you a bit

Firstly, a little punctuation would make that a lot easier on the eyes, lol

Secondly, forget the 6 dollar bottle of F/M...get one for about 3 bucks at oreilly's or the like.

To the OP: the first three threads (sticky, BTW) have everything covered to make you thoroughly sick of reading about Fox rears, lol.

Now, for some real world experience: I swapped in a Stang 8.8 into my Sport. Had it there for about 3 months till I located a TC rear. I swapped backing plates and drums etc from the 9" to the 10" setup I had on my Sport. I even used the hard lines from the 7.5 on the 8.8, but they took a little finessing to fit decently..I didn't have the lines on the 8.8, the previous owner(s) must've cut them or ripped them off.

I used synthetic gear lube and a bottle of parts store friction modifier. No probs from it, but it was noticeably more narrow than the 7.5 rear, and you can run wheels with more offset (or is it less, can't remember off the top of my head) and make up the difference, or run wheel spacers. Either way, it's doable.

Did I mention the three stickied threads? :D

Fox Mustang rear diff

Reply #3 – January 29, 2011, 05:00:31 PM

i dont have oreillys around here and nappa was out so i had to get it from the dealership. if i didnt have to i wouldnt have i hate going there for stuff. you can run your regular wheels and tires with no spacers and it will clear fine it just looks weird.

sorry bout my long reply b4 i aint much for typing on these

and you have to use the hard lines form the 7.5 because the junction block is on the pass side and the 8.8 line junction block is on the driver and the rubber line is too short. you could get a longer on if you wanted but idk how long it would have to be

Fox Mustang rear diff

Reply #4 – January 31, 2011, 10:17:51 PM

Are you wanting to keep the four lug setup? I only ask as five lug is not much more and can be had cheap. SN95 Mustang (94-98) V6/GT axles, calipers, caliper brackets, caliper bracket to axle bracket, pads, and soft lines. You can most likely get all of it minus the axles for $50 to $100 depending on the recyle yard. They usually don't like yanking axles and want to sell them with the rear end but you can find a set of alxes on any mustang site or here for around $75 shipped. Turn the rotors and pop a set of new pads in the calipers and your in business. Just thought I would stir the pot in case you had thought about it.

Darren