i just purchased this limited slip carrier along with some friction modifier:

1986-12 Mustang 8.8" 31 Spline Traction-Lok Differential with Carbon Fiber Clutch Disks, M-4204-F318c at LRS - Same Day Shipping!

how will i know if i need shims during the install? what weight oil should i use? all tips and suggestions are appreciated. im just tired of having one wheel drive in the snow!

 

Get a shim kit. Every time I've changed a carrier in a 8.8 I've broken a cast iron spacer trying to get them back in. If you can get then in there then it's a small victory. If not, I would already have the kit on hand. More than likely you'll need it.

 

okay. do you think my local parts guy will have a shim kit for the 8.8? it seems to be a popular rear end

 

i just swapped in an 8.8 Ford LS and it fit perfectly with the stock open diff shims. It dropped right in and backlash was perfect.

 

I was just going to say the exact same thing ... put mine in a month ago ... but buy the shims just in case ...

 

If you're going to a smaller parts store or a speed shop they might have them or could get them. If you're going to a big chain store those parts monkeys won't know what you're talking about.

Here's what you need
Ratech 1126 - Ratech Carrier Shims - Overview - SummitRacing.com
Shop around though. There are other brands and you can find them cheaper

 

Dang I was jsut gonna check how many splines we had. Found a LS diff here on C-list for $90...but its 28 spline.

To be on topic: I would def get the shims if you plan to do the swap yourself.

Also, now is the best time to swap out the factory gears for something better. Maybe some 3.73s or so.

 

You can get 31 spline LS chunks on ebay from $75 to $125.....I didn't buy the shim kit and it worked perfectly, but if it makes you feel better. You could always have overnighted if you had to have them....or pick them up from a local shop or the ford dealer. The way I installed....I was swapping in another rear end at the time, was to install the Trac Loc diff while it was on my bench. I installed the Trac Lock with the bearings and races and then I slid the shims in on each side and they went right in with a slight tap with the hammer. Checked backlash and was dead on. Yes you can change gears...but that is a little more involved with the pinion having to be removed and setup. Check all your bearings and axle seals while you are in their though.

One more trick of the trade....you will appreciate this one.....is get you a little bottle of the propane with the torch like the plumbers use, it will come in handy. If you have trouble removing the 8mm bolt that holds the spider gears together...just apply some heat from the torch, not to the bolt but to the carrier where is slides through and tightens and you can remove easily. Also....once you get the carrier out, remove your ring gear bolts and then apply some heat all the way around the ring gear with the torch and it will slide right off with a slight tap. Do the same thing for the ABS exciter ring that is attached to the carrier...if you have ABS. Also use the heat in the same way to install on the new trac loc.....if not you will drive yourself crazy.

 

okay im gonna go and find out if my parts guy has a shim kit. if not i will be ordering one. i would like to keep my stock gears because i like the mpg's that im getting. fomo, i always have a torch on hand. ill take advantage of your advice when i get everything apart. how do i check backlash?

 

With a dial indicator and a magnetic pedestal mount. You fix the magnetic mount to your axle housing and then zero your indicator on the ring gear....after that you slightly rotate the axles back and forth and check you readings on the dial indicator. The ring gear backlash should be stamped on the side of the ring gear...and it will be something like 008 for 8 thousandth's backlash, but I think specs usually have a range from .008 to .015 backlash. Make sure to keep your right and left side carriers and shims marked and that they go back in their respective places on the reinstall. You may want to check with your local fomoco dealer for the shims...I am sure they would have them on hand, but if you are getting a true Ford Diff, I think you will be fine using stock shims.

 

You are in over your head. take it to someone who knows what they are doing, or you will end up blowing the rear end

 

I replaced mine with a factory take out 09 Mustang 31 spline T/L and it was a simple bolt in. What I have seen from other projects is if you stick with "Ford Motorsport" parts it usually will work without having to change anything. Once you get into the aftermarket the tolerances can move enough to change stuff.

I did check backlash before/after and it was the same. Basically you want to know how much the ring gear moves(rotates back and forth) against the pinion. Something like .004-.012 is about normal.

With some luck, you could just swap it and not worry. Checking it is much better as you don't want to ruin a gearset finding out something is wrong. The whole project can be done in an afternoon if you know what you are doing. Get a Chilton book or such to give you some pictures/ideas of what to do.

 

alright. i actually planned on bringing to someone but i wanted to save some money and im usually pretty good when it comes to wrenching on the truck. diesel brad may have just scared me into bringing it somebody lol. i guess im better safe than sorry. maybe my mechanic will let me watch him do it so il be better off for next time i want to fool around with a ford rear end (im pretty freindly with my mech).

 

I agree if it a FMS part, i don't think it will need a re-shim, but I am fairly confident .008 to .015 is backlash. I would just get the measurement from the stamp on the ring gear to be certain....or just pay someone to do it if your not that confident in your skills or if you don't have all the proper tools.

 

i dont doubt my skills, its just that i have no experience with trying to figure out the backlash and i dont have a shim kit. how long could it possibly take a guy at a shop, two hours at most?