Anyone ever heard of it? I was reading in my Mid America parts catalog where the inside axle spindles, if they're worn, can cause it. That's a new one to me, but my car is making a funky noise from the rear, and I'm wondering if that could be the cause of it. What the heck does "chatter" sound like, anyway?

Cheers!
Wendell Allen

 

Do you have gm posi lube in the differential? I had changed mine twice with a generic brand and it was making clunking noises from the rear. Then i heared you should put only gm brand in. So i did and it went completely away. It is still quiet. Eric

 

Chatter sounds just like the word or you could call it a stutter. Either way, you can also get chatter if your gear oil in the diff. is old. If it chatters only when you make a turn then it is the gear oil. Change it and make sure you use posi additive or use Mobil 1 synthetic. My vette would chatter when turning so I changed the gear oil to Mobil 1, took it to a parking lot and turned 6 to 8 really tight 360 degree turns in each direction to work the oil into the clutch packs and everything has been great for the last 30,000 miles.

 

Thanks guys. Another friend saw my post and mentioned that as well. Sounds like that might be it. It does it worst after it warms up. And it does do it worst when I turn. But it also do it from a stop at low speeds. Up till about 20 mph. But I also have a hi pitched whine on the highway, so I'm thinking it's just the same noise speeded up. I'll replace the fluid tomorrow night and see how it goes.

Thanks again for all your help. I'd have NEVER figured this on out on my own.

Cheers!
W

 

I think Moroso has a posi additive also,but the GM is better having used both.

 

Pickup 2 bottles of the GM posi additive and should take care of your chatter :yesnod: , your hearing your posi clutches sticking ;)

 

i get this when i floor it ???:(

 

Do you guys think the synthetic gear oil is better than the gm gear oil and posi additive?

Eric

 

Use the GM stuff. Nothing else. Like it was said earlier :_dupe: use 2 bottles of GM diff lube and 1 bottle of GM posi additive. It worked for me! :smash:

 

Wendell: The posi additive is a great idea. I wonder about the wine, lift the rear off the ground, how much play does each wheel have? Grab the tire at 12:00 and 6:00 (hand location not the time) and see how much side yoke play you have at the diff. My side yokes wore past the retaining clips inside the diff. You should keep this play to a min. :cheers:

 

Obviously it is a matter of opinion but I prefer synthetic because of its better durability and efficiency. There are a lot of guys who will argue both ways on this but I've had no problems with my posi and it (the synthetic) has been in the car for over 3 years and 30,000+ miles.

 

I'd be very surprised if oil or posi additive fixes it.

What you descibed is probably the cross pin and case failing. With time the cross pin elongates the hole in the case. It's time for a new posi unit.

I've had the same where you get noise going forward and reverse and up to 20 mph several times.

 

Not exactly what I wanted to hear, but for about fifteen bucks I'm gonna give the lube thing a shot. If that doesn't work, I'll have to regroup. Seems strange though that the unit would be failing. The previous owner told me yesterday that the unit only has about 5K miles on it since it was last rebuilt. It's clean and I can see new sealer on the housing cover. Guess I'll just have to cross my fingers.

 

Do have a hopped up motor and wider tires? If you do don't expect the stock type or even Auburn posi units too last very long. I've been just driving to work and do a full on freeway on ramp and when the auto tranny would bang the next gear all heck brakes loose..

So I limp on into work and limp it home and the posi case is elongated, cracked, and broken. One good thing is I never have to rebuild them I just throw it away and start over with a bigger better model

 

Horsepower? Wish I had that problem. But unfortunately mine's only slightly modified. Mild cam, headers, intake, and 650 Holley. No heads or anything "exotic" like that. Maybe some day... :rolleyes:

 

You will probably have to suck out the old oil (The differentials don't have a drain plug). Also, is it clear that you need to add the GM positraction additive (It is actually called "limited slip differential additive") to the gear oil that you put into the differential? Put in the positraction additive first. That way, you won't have to leave room for it. :) Also, you should drive the vette to heat up the rear before changing the oil, just like you heat up your engine oil before changing it.

I had some chatter that was most noticeable after coming off the freeway (so differential was hot) and making that first low speed turn. Fotunately, it disappeared after changing the differential oil including the posi additive.

Also, the detailed step-by-step instructions for this job include driving in tight turns (figure 8s, ideally) after you finish.


[Modified by MNJack, 8:48 PM 12/30/2003]

 

:confused: these rear ends last 30+ years behind big block engines.

i don't believe these stock posi units are that easy to destroy. The rear end on my car has chattered for the past 25 years and IMHO it doesn't mean a damn thing other than you have a tight set of clutches. And thats a good thing.




[Modified by turtlevette, 9:40 PM 12/30/2003]

 

TurtleVette - When you start adding HP and modified auto trannies the stock rearends don't last.

My original 79 rearend wasn't even good enough to be returned as a $375 dollar core before it had 50,000 miles on it with only 400ish hp.

The sorry excuse for yokes that GM installed had worn off passed the C- clips. It was making bad noises and when I pulled the rear cover off it was just full of metal paste oil. The outer case was ground down from the yokes rubbing.

So i ordered a HD unit out of houston texas with Richmond 4.11 gears and those $450 custom hardened yokes. That lasted a couple of years before the posi case broke. Then I was breaking new ones every year or two along with twisted off half shafts and broken U-joints.

That's when I first found out about http://www.tomsdifferentials.com I now buy the @ $700 dollar posi units along with all the other heavy duty parts and since I gave up on racing for the most part this last rearend is 3 years old.

Two out of three items still running at three years is pretty good for me. First my racing 700R4 tranny went so I installed the $3000 super model. That tranny was so good that it blew apart a big buck posi unit. so I straightened it out and that's when my motor went out again this time with smeared melted pistons. So I put @$8000 into a 383 stroker motor with all kinds of high tech ideas.

It last about 2 years, but the tranny and rearend are still holding up. I did have to replace another HD half shaft and all the U-joints again. That's not a big deal though.

I have a couple of friends that their Vettes have left big pieces of rear ends on the pavement. So IMO if your stuff is lasting our driving styles must be a little different!:LOL

I kinda quit counting how many motors, trannys, and rearends I've had in my Vette in the last 24 years. Maybe 8-10 of each.

 

well my name says it all. I don't have enough power to destroy a tranny and surely not a rear.

I assume you have the cast iron rear and not the 80-82 aluminum. I wonder how these guys with the C4s and C5s with blowers make out.

Have you ever thought about puttng a cooler on or do you have that already?

 

Yes, I have considered all kinds of options for rear end coolers. Mine gets so hot that you can't touch it 15-20 minutes after it shut down.

My rear tires in this picture are 315/35/17 on 11X17 wheels this is smoking the tires coming out of a turn at the local road racing track at 60-70 mph - posi units don't like your big tires rapping under like this