[Txbobcat]

I recently had a 273 gear and posi installed in my 65 catalina rear end. Since then when I turn left even at a slow speed I get a clumping noise in the left side of the rear end. It doesn't do it turning right or going straight down the road at all. It sounds fine really no noise at all only when turning left at like a corner when taking off from a dead stop. Any suggestions or ideas what might be wrong? Ujoints are good.

[cruzingratiot]

axel bearing
or wrong oil

Limited Slip Axle Lubricant Additive - 4 oz.
Genuine GM Fluid 88900330

[1969GiPper]

Originally Posted by cruzingratiot

axel bearing
or wrong oil

Limited Slip Axle Lubricant Additive - 4 oz.
Genuine GM Fluid 88900330

Using the wrong oil or not using the correct additive will result in the exact symptoms you described. If you change the fluid make sure to get all the old stuff out. Have seen cases where fluid had to be changed, then driven and then changed again before problem would go away.

[Txbobcat]

I put in 85/140 Walmart oil and got the gm posi lube don't know if it was that exact number you have posted above.
When I get back in town I will be sure to get the right stuff and change it out.
You guys are good I thought I had something real bad happening. Thanks for your help
How long after the change can I expect it to be quiet again?

[gary bennett]

i had that on my lincoln. i pulled the axels, and all the posi plates, cleaned with lacquer thinner, then reversed all plates & installed. put in new oil and additive. no more problems

[66bonne]

Vote here or the GM posi lube.

Jim

[hurryinhoosier62]

Originally Posted by 66bonne

Vote here or the GM posi lube.

Jim

Dittos, Jim.

[mgarblik]

When you get the fluid changed and additive in, try to find an open parking lot and drive in a figure 8 pattern about a dozen or more times. That will scrape the clutch discs off some and hopefully force the proper lube in the clutch packs. It may take some time before all the noise goes away.

[Deadhead]

Go with both the GM additive and the GM non-synthetic gear oil.

I had the same thing happen last time I did a rear. Forgot to provide my guy with the stuff. Was able to get away with just draining & replacing. Pontiac rears in particular seem to only tolerate this combination.

[1969GiPper]

Originally Posted by mgarblik

When you get the fluid changed and additive in, try to find an open parking lot and drive in a figure 8 pattern about a dozen or more times. That will scrape the clutch discs off some and hopefully force the proper lube in the clutch packs. It may take some time before all the noise goes away.

Agree. The supreme test to see if the problem has been corrected is to go for a drive on the highway and get the rear end really warmed up. Exit the highway at a location where after you come to a complete stop you can immediately make a hard left turn when starting up again. If the problem is fixed you should hear/feel nothing. If the problem is still there then drain the lube out again and refill and make sure to use the additive.

[Goatracer1]

Before you go to all the work of changing new oil do like MGARBLIK wrote. Even with the best fluid you can buy it is necessary to do several figure 8's in both direction to get the fluid in between the clutch plates. This may fix your problem without replacing the fluid. Before I retired and was working as a mechanic this was a common fix. This may also happen after a long highway trip. You would notice it as you came off the exit ramp. Just do the fig. 8's to get rid of it.

[Txbobcat]

I had done the figure 8s quite a bit probably 100 times or more. I probably have less than 300 miles on this rear end since the install. I went from a 241 gear ratio to a 273 which feels a whole lot better. After I get this changed out I will report back. Does anyone know the correct weight gear oil? If the dealer does not have the right posi lube is there someplace else to buy this?

[Deadhead]

There was a seller on E-bay who was a GM dealer selling the oil. I will have to check in the garage later to see which I bought from him. It was substantially less than they wanted at my local dealer.

[stevep]

Originally Posted by Goatracer1

Before you go to all the work of changing new oil do like MGARBLIK wrote. Even with the best fluid you can buy it is necessary to do several figure 8's in both direction to get the fluid in between the clutch plates. This may fix your problem without replacing the fluid. Before I retired and was working as a mechanic this was a common fix. This may also happen after a long highway trip. You would notice it as you came off the exit ramp. Just do the fig. 8's to get rid of it.

Exactly.

[Jeff Hamlin]

Originally Posted by Txbobcat

If the dealer does not have the right posi lube is there someplace else to buy this?

I've been using the CRC on the last few with no issues

[Txbobcat]

Yesterday I changed out the oil and sprayed some brake clean on everything but not a lot. I got the gm additive from the chevy dealer and was going to buy the gear oil as well but he said all they carried was synthetic. So went to buy the gear oil and I found some valvoline 85 /90 that said limited slip on the bottle. I didn't know they made different gear oil like that but I grabbed them.
Got everything installed and inspected and took it for a drive. It used to make a lilltle noise while backing up but I heard nothing. Took off to the corner and turned a sharp left and nothing. Went to the park and did my figure 8s about 15 of them and left before someone called the police. Went driving thru neighborhoods turning left or right at every corner I came to and no noise at any time. Wow I cant believe a gear oil change could make this much difference that quickly.
I had this posi installed by someone else a few months ago. I did give him the gm additive and Walmart gear oil to install. I am willing to bet that he did not put the posi lube in causing the problem. Thanks everyone for your advise. Gotta run I am going to wash it put the top down and do about 50 miles on it.

[66bonne]

That's good news Bob.

Jim

[Ragtop Man]

Gotta say - Best subject line in a long time.

[AROWHED]

Recently my 65 GP posi rearend started chunking on turns..even though it has a mere 5000 miles on a new 3:55 gear, installed with 80/90 gear oil and GM posi additive. Drained it out, added new oil and another bottle of posi additive, now $14 at local GM dealer. Seems to have cleared up again. Just thought it was odd it occurred after so few miles.

[Deadhead]

Moisture is a big enemy. I know you put a ton of work into it, so I doubt that is your issue, but might be. Could be that more sitting & less driving condensation builds up inside.