I spun a bearing in the rearend housing on my 8.8. I found a used 8.8 rear out of a 88 T-Bird. It has disc brakes and new limited slip diff. Will this fit under my stang without changing the rear track width? What issues might I expect to have installing this rear? Should I even buy it?
You can use the rear but will change the width if you use the disc set up. You can always replace all the disc stuff with all you drum stuff of the old rear. Also have to use the stock axles with the drum set-up. And if you still are running the quad shocks you will need to make a new mounting hole for it.
If you dont go over 8 inch rims then you should be alright with the disc brakes. Or do like he said and swap over your axles and brakes. Its not the housing thats longer, its the axles and brake brackets. Worse case scenario you still have a 3.73 posi rearend with drum brakes.
Auto trans Turbo Coupes come with 3.73 gears and manual Turbo Coupes come with 3.55 gears. I choose 3.55 since I do more highway driving.
It takes 2 guys the first day to get the old rear end out and the new one bolted in place. It takes 1 guy another whole day to do the brakes.
You will need a several sets of fittings, I recommend that you get them from Matt90GT's website, http://www.svo73mm.cjb.net/. Read Matt's instructions thoroughly, everything you need to know about the brakes is all there. You need to be patient and follow all the internal links, and there are many of them. You will need 2 fittings in the rear to adapt your old brake tubing to the TC disk brakes. The fittings go between the steel tube and the caliper brake hose. You will need another set of fittings to make a 2 port to 3 port adapter. To make life simpler, just buy the kits from Matt. You could piece them together, but it's not worth the time unless you work at an auto parts store with all the fittings ever made. You will need to drill the quad shock mounting holes 2” below the holes drilled for the Turbo Coupe mounting points. The bolts are metric, so don’t loose them or the nuts. A 15/32” drill should be about the right size unless you have access to metric sized drill bits. Going without quad shocks is not an option unless you have aftermarket parts to soak up the wheel hop.
You will need a proportioning valve, Summit has one for $40 + shipping.
You will need a kit (FMS makes the part) to gut the stock proportioning valve, Summit also has that, about $10.
You will need a new master cylinder, see Matt's site and make you choice. I used a 94-95 Mustang master cylinder. Note that rebuilt 94-95 Mustang master cylinders do not come with a reservoir. That means a trip to the junkyard and some more money spent.
Your brake pedal may be very hard and almost impossible to lock up the brakes. I had to replace the front calipers with 73 mm calipers from a 91 Lincoln Mark 8 to get the braking performance up to par.
Bleeding the brakes will require 2 people and some coordinated effort. I don’t recommend using you wife or girlfriend to pump the pedal – they get offended when you yell at them. I used a homemade power brake bleeder constructed from a garden sprayer and some fittings from Home Depot. It cost about $25 and was worth every penny.
See http://www.mustangcentral.net/tech/brake.html for help with the emergency brake - the stock setup tends to lock up and not release properly.
All in all I have been very pleased with the results.
jrichker covered all the basics. The housing is a bolt in, with the exception of the drilling for the quads. Is this for the 91 coupe or another car? If you want to use the disc, you can run it as is (4 lug) or can use the 94-98 5 lug axles if you redrill the rotors to 5 lug.
The stance is very nice with 17x8 wheels using the wider axles.
You can also use the stock length axles, 4 or 5 lug if you modify the brackets and mount them on the INSIDE of the axle flange with a couple of washers for spacers. Several guys have done this and used the stock Mustang axles. 5 lug will work also with redrilling the rotors. I don't have pictures of the actual TC brakes, but the idea is the same as this one with SN95 brakes:
The TC ones I've seen have cut one of the corners off with one of the mounting bolt holes, leaving 3 to secure it to the flange. But you might be able to slot it like the last picture and keep all 4 bolts.
Thanks for the replys guys! I'm currently running a 5 lug 31 spline drum setup right now. I would like to keep my 31 spline axles, so If I buy the rear I might adjust the brakes to use the stock lenght axles.