Not the kind that make my 2 year old little girl giggle, but clunking from the diff of my stock 10 bolt.

I noticed it after my track day last week. I'll try to get a video of it tonight. If I have the engine off and let the car roll backwards down my driveway, I hear clunking. Probably not supposed to do that, huh? I did get some nasty axle hop a couple of times, I know that's hard on it.

If it's bad, I have a stock axle off my 99 parts car. I just need to swap the brake lines and brakes over. I believe that's the only difference.

Never mind. I forgot I have weld in relocation brackets. I'll just sell the 99 rear end to help fund a new diff.

Quick question. While the car is on the lift, I tried to turn a rear wheel with the car in gear. Wouldn't spin. In neutral, they both turned easily the same direction. No noises or anything. I then tried to hold one wheel with bricks under it and turn the other wheel, I couldn't get it to turn.

Is there anything I can do to check the diff? I'm if I have to pop the cover, what do I need to look for?

Are you sure you don't have enough friction modifier in the oil? Otherwise, pop the cover off an check the spider gears for breakage, or cracks.

Yeah I'm pretty sure I used Royal Purpal which already has it.

I'll pop the cover tomorrow. If the posi is bad, maybe I'll just take the posi out of the parts car rear end and put it in my rear end. I really don't want to spend $400 on a nice lsd right now.

What year rear end is it? The LT1 cars had clutch type limited slip differentials in them (which is how yours seems to be acting) and the LS1 cars had the Torsen diff in it (which acts like an open diff when it's up in the air, one wheel spins forward and one backwards).

I think this is it.





It's an LT1 rear and, supposed to be stock. I bought it used because I wanted to change from 3.73's to stock 3.42's, and at the time it was cheaper just sell my entire rear and buy a used rear end with stock gears.

I honestly don't know much about LSD's.


So are the torsen diffs better than the clutch type? Are they interchangeable? My parts car has an aftermarket aluminum cover, so I've been wanting to swap covers anyway.

I'm doing a Track Nights in America in 3 weeks at CMP, same track I was just at, and I'd like to fix this diff as cheaply as possible. The stock LT1 isn't making enough power to really need a nice LSD right now. It's manageable.

Ok I've been reading. The torsen out of my 99 parts car is better and will bolt up to my 97 rear end. The housings are the same.


I have absolutely no idea how to do this, but I'm doing it today

I'll keep searching but does anyone have any information (write up) that will help me remove one lsd and reinstall it again?

A good clutch type LSD is always better than a Torsen. A dead clutch type LSD is similar to a Torsen (depending how dead it is). You'll need shims and all and typically you'll have to have the rear end set up with the current gears on the new diff. It's not really a drop in (in most cases). Sometimes you get lucky, many times you don't.

Really? Everything I read said torsion is better for road racing. Well either way, I've got a free one, so might as well use it.

I'll take the cover off my diff tonight and see what parts fall out. I need to learn how to work on a diff anyway, may as well be now.

I do need a write up or something though.

The thing with Torsen is that they essentially work by internal friction, and after X miles simply wear out because the metal wears down. Then you replace them. (Someone correct me if that's wrong, but that's what i understood). Other units have clutch discs to replace, the gears and stuff don't wear down.

Yep I think these are bad noises.


http://youtu.be/RXAt9vjdhdc

The older, high bias Torsen T2Rs are better for road racing than most clutch pack/cone type diffs, but not the low bias, stock, Torsen T2s.

The problem is that Torsen stopped making the Rs for our 10 bolts a while ago, and even the latter ones they did make had bad case cracking problems, IF you could even find any of those.

I pulled the cover off. I was fully expecting parts to fall out nothing did. You guys heard the noise it's making, right? Well here are the pictures. I only hear that noise when turning, even slightly. Do you guys see anything wrong in these pics?

Looks fine but if the clutch packs are shot that won't be visible till the diff is torn down.

The noise in that vid sounds more like a Ujoint to me - did you check them? Also possibly an axle bearing.

Well it's dead silent when rolling straight. I looked quickly at the ujoint and it looks fine. Doesn't look like its hitting anything. I'll take a closer look later as well as check the pinion for movement.

U joints look good and there's no play that I can tell coming from the pinion.

But, I noticed when I grab a wheel and rock it back and forth, I can reproduce what I think is the noise I heard.


http://youtu.be/HaOs1jpYAXY

The noise you're making in the second video is from the space between the ring and pinion gears. You get them making that noise because you're rocking the wheel back and forth.

The sound you hear in the first video happens when the car is going forward only, not changing direction.

How are the front bearings?

They are fine. Noise is definitely coming from the axle area. When I took that first video, in the car and letting it roll with the steering wheel turned slightly right, I could feel every clunk. It's like the rear end was binding or something. But when I drove it today, everything seemed fine. I can kinda hear some noise back there at parking lot speeds, but the exhaust drowns out most of it.

Like I said, that noise only happens with the wheel turned, even just slightly. The car is on the lift, when I spin the wheels, they are both moving together, there is no noise.

I'm kinda at a loss here. I had royal purple in there, which has the modified already. Could that be causing a problem? Maybe I should just fill the pumpkin with a different flavor of gear oil and see if it likes that better. If it is still making a racket, I could take it to somebody who knows what they are doing and pay them $50 to diagnose it. Or, since there wasn't any metal shavings, just keep running it and see what happens.

What gear oil do you guys use?

I think I misunderstood what you were saying.

Me rocking the wheels back and forth was the only way I could make a noise similar to what I heard when rolling down the driveway. Is it normal to make a healthy diff do that? I'm guessing mine has a little more slop than what's normal (just a guess, I've got no idea). Maybe the LSD was binding, or slipping or something causing the pinion to kind of load up then unload, causing the clunk?

Someone one ls1texh said synthetic gear oil with the addative already included can cause chatted with auburns. It's better to use regular gear oil then add the gm friction modifier.

Does this sound right?

Ok so I picked up some friction modifier from GM and some Mobile 1 synthetic gear oil. It's half the price of Royal Purple.

I'll dump it in the pumpkin sometime over the next few days and see what happens.


One question, will adding more friction modifier make the LSD less effective?

The guys on ls1tech say I need to use regular gear oil, not synthetic. I'll try that unless I hear otherwise.

With a clutch LSD, always use non-synthetic. Many already have friction modifier - be sure to read the bottle to confirm. Some have no additive, then you would add the gm friction modifier. The more modifier you add, the less effective the LSD will be. The less friction modifier you use, the noisier the diff will be (more chatter). When I used the POS auburn racers diff, I used standard gear oil with no additive. It made horrible noise, but if you use friction modifier in those things the tiny clutches burn out quickly.

I'm a fan of Torsen style diffs for track use. They last longer before wearing out, but can't be rebuilt like a clutch pack. I kept burning through auburn diffs (cone clutch) and won't go back. Currently using a Detroit truetrac. Not the best, but aftermarket support for these tiny 10 bolts is slim. Don't blame them for not wanting to support these junk axles.

Oh I couldn't care less how much noise it makes, I just want it to perform as well as possible.

So are you saying I should find regular, non synthetic gear oil with no addative? It won't damage it? I know it'll be noisy, but will it actually perform better?

I've been searching the web for way too long now on whether to use friction modifier of not and what I have concluded is there is a lot of crap information out there's.


From what I gather, the best is to use 80w90 non synthetic.


And I'm not going to use the friction modifier. Some say it will wear the auburn quicker, some say it won't but it will make it have more lock up, which is what I want. I know it will be noisy.

Since eventually I'm going to put a better LSD in there anyway, I really don't care about longevity, so I figure I have nothing to loose.

I'll do this tomorrow.

Probably why Torsen stopped the production of the T2Rs for our app, along with the axle not being used for ANYTHING anymore. and their case quality/metallurgy issues.

They DO make the T2R for the Blue Oval 8.8s though, both for the independent set ups as well as the stick axles.

I run an Auburn Racers cone type diff in my roadracer and I run Red-Line Shockproof (the heaviest version) without any modifier. It will make noise when its coming off track if it has been really heated up. Once cooled down, turn a left and a right circle at low speed and it goes quiet again. They all do that. And they last a couple or three of season's worth of serious abuse and then slowly deteriorate. If you can afford a Racer's version (call Nancy at Auburn, it will not be sold anywhere else) it will be replaced for the same cost as the repair parts for an Eaton clutch, with a 4 year no questions warranty. The new one gets another 4 year warranty. I keep two circulating to never buy a whole diff again.

Update: I filled the diff with Lucas regular 80w90. I did mostly highway driving with a couple of parking lot maneuvers. I notice a little noise in tight turns but nothing bad. On the way home I made a hard right turn from a stop and got on the gas hard. The LSD locked up hard and sideways I went. The same LSD with the expensive grape flavored synthetic gear oil, I would have lit up the right tire.

I'll drive it more tomorrow, but so far the diff actually seems pretty happy with no friction modifier. Much happier than the synthetic stuff.

Yep, a lot of the synthetic stuff is, well, pretty slippery. That's the feature the vendors are going for. Works great, unless you actually need some friction, then the synthetics usually fail miserably. I think that may have been a problem with my 9-bolt (yes, bolt), but it seemed it gradually-developed the one-wheel-peel, so hammering on it for 10 years in an autocross environment with slicks may have had something to do with it. Red Line synthetic is my gear oil of choice, too. It seems to do well in our Tru-Trac in the 9" that's now under the car.