Long story short....I took my truck to "Speedee Oli Change" and they put conventional fluid in my Limited Slip Diff, now its fried and making all kinds of noises. I'm looking for any advice or direction on how to rebuild an 8.8 Limited Slip Diff. Thanx in advance!!

 

First off, the differential MAY not be fried. Most likely isn't.

It's only been the last few years that differentials came with synthetic lube, (limited slip or not). It's perfectly OK to use non-synthetic in a rear differential. All but my newest (2008) have regular lube. Having said that, with a limited slip rear, you do need to use a friction modifier additive. This makes the clutches operate smoothly so you don't get those noises and vibration in the rear end that you have. It's my theory that your shop DIDN'T add this.

Here's the thing... The friction modifier's only purpose is for driving comfort. By not using it, you're not hurting anything.

The noises you're hearing are probably your clutches "chattering." It'll do that mostly going around turns, (different wheel speeds). Adding the friction modifier NOW, could/should eliminate that.

NOW, if your still convinced that something is wrong with axle, rebuilding an 8.8 is very straighforward IF you have decent mechanical ability, a dial indicator with a magnetic base, a torque wrench, impact wrench, a Vernier caliper (micrometer), time and patience. It's even easier if your gears are not-worn (re-useable).

Basically, you take off the wheels, brakes, diff cover. Pull out the center shaft in the diff, remove c-clips, pull out the axles, remove the bearing caps, and shims (keeping track of where and how many they came from, and writing down their thickness after measuring with the caliper). Mark the bearing caps because they have to go back on the same way. Pull out the carrier (differential).

By this point, you should know if you have to replace gears (VERY VERY doubtful). Many trucks go over 200,000 miles on the original gears, and they still look good.

Swap the ring gear and ABS sensor ring over to the new carrier, (or old carrier after your dealer has re-clutched it). Press the NEW bearings on, (only use new bearings), reinstall, using the same shim thicknesses as before, and check tolerances with the dial indicator. Make adjustments if necessary, and check again.

There's a little more to it than this, but it's pretty basic. If you have to change the ring and pinion, it gets far more involved, but it's still do-able.

This site has alot of information on your axle. They sell the parts, and have a great tech-line. The website also has all the torque-specs and backlash specs you'll need. You will need new bearings and races, a shim kit, and I recommend new ring gear bolts (only if you have to remove the ring gear)
http://www.ringpinion.com/Default.aspx

Again, You may not have to do any of this. Take the truck out in the dirt and see if it still makes 2 strips. If it does, add the modifier, and give it a while to soak in. You should be fine.

 

Driver could be right - it might not be fried.

However, my truck does call for something like 140 weight in the rear, along with the limited slip additive driver was talking about. My advice would be to drop out the regular oil they put in there. See what it looks like inside the carrier, and go from there. If everything looks good and you aren't seeing any heavy shavings, fill it back up with gear oil, put in the limited slip additive, and you should be good to go. You can do it all yourself with all the fluids for around $50 (the gear oil I used was about $18 each, along with the silicone sealant and additive for another $10-15).

 

JRV had a good point I forgot to mention. Trucks over the years have called for everything from 75w90 to 85w140 weight oil. In my bigger truck I run the 140, in my 2008 F150 I run what ever came in it. Haven't changed it yet but I think its 75w90. I run 80w90 in the front of all my trucks.

A heavier oil will reduce your symptoms. Good point JRV

 

Thanks for the quick response guys, but..... the reason I think I've got some damage going on is because of the noise that started shortly after. The only way I can explain it is that it sounds like a solenoid clicking or maybe an alternator with bad bearings. Also, on my rear end there is a metal ID tag bolted to the cover that clearly states "Synthetic Only". How the guys at the lube place missed this I dont know.

Also, the noise doesn't start untill the truck has been driven for a few minutes, and under acceleration.

 

I made the same mistake. I dumped the oil and ran my diff without the additive for about 3 months. I think that the sound you are getting, the clicking you are talking about, is the clutches chattering. Mine would do the same thing, but only once the diff was hot.I would dump in the additive and go from there.

 

Where can I find what weight oil to use asuming I have the origanal rear end

 

Thanks for your response!! I'm going to try adding the friction additive and see if it stops making the noise. But, should I drain the conventional oil out and put in synthetic? I'm asking because of the metal tag bolted to the diff cover that states "Synthetic Only". Luckily I haven't been driving it since this happened, which has been about 5 months. I still fire it up and let it run every other day and drive it around the block. At the most I'd say that I've put maybe 100 miles on it since. And by the way... the dirt test was passed about 2 weeks ago when I took it for a spin around the block and got it sideways on dry asphalt. Both tires broke traction and smoked. So do you think there's a good chance it'll be ok?

 

The only reason they put "synthetic only" on there is because the rear-ends on these trucks are filled with synthetic from the factory, and they don't want you adding regular oil to the synthetic in the event that you're a little low. You can use either. If you're like me, every 30,000 miles or so, it gets changed anyway, so I use regular stuff.

I'd probably drain out the fluid and change it all, only because to add the modifier, you'll have to get some of the fluid out anyway to make room, (provided the shop filled it up to the fill hole. Unless you get a suction gun and draw a little out from the hole.

Now with that friction modifier, It needs time to get into the clutches and work. Don't expect it to work instantly. Add it, take the truck out on the highway and get the rearend hot. Tow something, put some miles on it. The improvement will be gradual, but noticeable.

P.S. If you broke both tires loose on dry asphalt, there is NOTHING wrong with that rear end. Some brand new limited slips won't do that. Especially sliding into a turn where one tire is loaded much more heavily than the other. You're fine. Stop worrying.

 

Thanks driver, you and everyone else have been very helpful and informative. I'll change the fluid and add the friction additive this weekend. I'll keep yall updated and let you know how its goes. Once again thanks for ALL the help!