Limited Slip going bad?

andymiller · 01-15-2008, 03:59:23 PM

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?

Gary S · 01-15-2008, 04:55:32 PM

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.

andymiller · 01-15-2008, 07:48:00 PM

Quote:

Originally Posted by Gary S

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.

Gary S · 01-15-2008, 08:43:42 PM

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.

andymiller · 01-15-2008, 10:10:50 PM

Quote:

Originally Posted by Gary S

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..

tom3 · 01-15-2008, 11:47:43 PM

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?

andymiller · 01-16-2008, 05:58:05 PM

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

tom3 · 01-16-2008, 07:38:02 PM

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?

andymiller · 01-16-2008, 08:54:39 PM

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.

fiscus · 01-17-2008, 11:44:58 AM

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.

old zeder · 01-17-2008, 12:33:00 PM

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

andymiller · 01-17-2008, 01:55:55 PM

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?

fiscus · 01-17-2008, 02:40:12 PM

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.

79camaro2001 · 01-17-2008, 03:03:49 PM

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

If you are selling it why worry?

andymiller · 01-17-2008, 03:21:01 PM

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