How can you tell if your limited slip rear end is going bad?

I've been starting to notice a peg leg every now and again, and the other day at the track I only had rubber build up on one side. Is there a way to check without digging into the rear?

Whats the repair if so? and how much am I looking at?

GM service manuals have a procedure for checking clutch preload. You raise one wheel and attach a torque wrench to the other one. Preload specs vary from book to book, but if you see around 40ft/lb or less, your clutches are slipping too easily.

GM service manuals have a procedure for checking clutch preload. You raise one wheel and attach a torque wrench to the other one. Preload specs vary from book to book, but if you see around 40ft/lb or less, your clutches are slipping too easily.

That SUCKS!!!! I just tried it and the tq wrench is breaking at 39-40ft/lbs.

Depending on the type of posi you have, you might be able to replace the preload spring (or springs) with heavier ones. That will delay teardown of the unit.

Depending on the type of posi you have, you might be able to replace the preload spring (or springs) with heavier ones. That will delay teardown of the unit.

How much work is involved with this? Where can I find a IPB of a stock locking 71 rearend? I have to look up the stamp code again, I have misplaced my notes on the rear.

Do you have to removed all the guts from the rearend to replace the springs. I have not been into my rearend, I had a local mech setup my gear for me, its this something I can do, or better left in the hands of someone that knows what their doing? It about time for me to change the fluids anyway..

Should have the S spring in it. Remove cover, center pin, axles. The spring can be taken out pretty easy, hard to get back in. I use a couple pieces of sheet metal against the side gears and a big C clamp to draw it in. The clutches are pretty easy to replace at this point. Might do a general rebuild if parts are available?

How whould I know if a heavier S spring will help? Just install a much heavier spring than stock then see what I have?

This is a picture of what the clutch plates should look like, note the swirl pattern on the disks. If yours are worn smooth I would say they are shot?
http://i7.ebayimg.com/01/i/02/df/51/79_1.JPG

Is there any way to diagnose the issue for sure before pulling everything??

Can I change the fluid and add a few jugs of posi fluid and see if that helps? That be under $100,

Before I spend $500 to replace the locker.

But what would a rebuild cost for clutches and everything and having someone else do the work?? I'm not much on working on axles and inards of the rear.

The clutches are about $100, and you probably need to change them. They don't make stiffer S springs, but a new one might be better than your old one.

Here you go Andy carrier should look like this one the newer units have coil springs, I don't know if the old or new style is better.
Just putting all new parts in was better

http://memimage.cardomain.net/member_images/7/web/2599000-2599999/2599371_76_full.jpg

http://memimage.cardomain.net/member_images/7/web/2599000-2599999/2599371_77_full.jpg

http://memimage.cardomain.net/member_images/7/web/2599000-2599999/2599371_132_full.jpg

If the fluid is old whould this have any effect on locking?

I had a rear gear set installed over 2 yrs ago and did not change the fluid since installing the gears.

Is there any benifet changing the gear oil and seeing what happends, or did not chaging the oil eat up my diff?

I don't think changing the gear oil will help, but if you do, try putting in regular gear oil with no limited slip additive, might help the clutches grab a bit better.

If you are keeping the car why not do it right and rebuild it.

If you are selling it why worry?

To be the most honest, I don't have the cash to replace the unit, so tip toeing around the issue before dropping $400-$500 seems the right thing to do right now.

Asking questions to get the knowledge is free, so better to ask as many as possible before shot gunning parts.

I have no issues asking a "dumb" question if I have no idea what I should do

To be the most honest, I don't have the cash to replace the unit, so tip toeing around the issue before dropping $400-$500 seems the right thing to do right now.

Asking questions to get the knowledge is free, so better to ask as many as possible before shot gunning parts.

I have no issues asking a "dumb" question if I have no idea what I should do


in this case i recommend you save your money and just let it slip til you can get teh cash to do it right. No sense in wasting money!

I had a buddy with a Ford pickup that had 50K miles and his was slipping. He changed his fluid and it fixed the problem.

Just wondering if that would help out, or if its really the diff going south.

One quart of gear fluid is around $5, how many quarts is in there, 2-3? Posi fluid additive another $5. A pump to take it out cant be more than a few $$$. So youre looking at $25-30 max and thats on the heavy side. Give it a try.

Just went to NAPA last week, gallon of gear lube is about 9 bucks, tube of posi additive was the same. Be worth 18 dollars to give this a try but I doubt it will help. Definately pull the cover and clean it up as much as you can, check the magnet.

I'm planning on doing it today, and use brake clean to clean in up.

Is there anything to look for that will be visable looking for damage?

you really cannot see the clutch faces unless you take it apart. if u can see some of them see how smooth they are. they should have rough swirl marks all over them. mine were getting very smooth, so i bought new clutch packs from gm and rebuilt mine last year.

GM service manuals have a procedure for checking clutch preload. You raise one wheel and attach a torque wrench to the other one. Preload specs vary from book to book, but if you see around 40ft/lb or less, your clutches are slipping too easily.

I just replaced my fluid and still have the same results. I in all directions this time and have different results.

Drivers side forward is 40in lbs
Drivers side reverse is 52in lbs
Pass side forward and reverse in 53 in lbs

Is there a reason for only the left side being soft?

What needs replaced? Clutches? OR replace the whole posi unit, its a borg warner orignial

probably need to replace clutches. i got the clutches from gm and went ahead and replaced the spring while i was at it.

I got a buddy that has a new Auburn posi he wants $200 for.
Is it cheaper and easier than replacing clutches for $100+

Good News!!!

Changed the fluids yesterday and added a bottle of the slip juice, and it seems to be working alot better. Did multiple starts from a dead stop, and heated the tires up a couple times and both tires were getting equal movement.

Have to give it a better shakedown when its not so cold, but its working.

I got a buddy that has a new Auburn posi he wants $200 for.
Is it cheaper and easier than replacing clutches for $100+

If you put the auburn posi in there then you will have to set the gears again and that cost more money.

If nothing is wrong with the unit replace the clutch unless you really want to do that.

Comes with 4:56 is I want them, Probably just replace the clutches when needed

if you cruise alot i wouldn't put 4.56 gears in the car.

but if you are racing it more then cruising then that would be the way to go.