WTF....Popping Sound From The Diff...

[Viet Nam Vett]

The diff in my 65 was rebuilt by Bair's Corvette. They did an excellent job. The diff has never made and noise. It only has abot 4000 miles on it.

Of course it was filled with the propper amount of Posi Clutch additive and then the Gear oil. Before my trip to BG I had the car on a lift at my favorite gas station and we checked all nuts and bolts and fluid levels. The diff was fine.

Now here's what's going on. Just before I got to Bossvettes house in Ohio.. I noticed that after a stop for gas..when I started to pull away from the pump in a straight line I'd hear the diff popping or ratcheting...maybe for a few feet or so ..then it would stop.

Again..after cruzen at 70-75 MPH and then another stop for fuel..the same thing..WTF..??

At one point I did about 5 Lock to Lock left turns ..and then 5 Lock To Lock right turns to try and pump up the diff fluid into the posi clutches. This didn't help.

Anyway..It acted up on the way home also. Now since I'm home I have only had it out once this past week end. Didn't make any noise.

So I'm baffeled..why did this start on the trip ..and only after a steady cruz speed...
any answers..???

 

[Chrisr]

Hi VNV!!!!

I'm no mechanical genious, but my guess would be heat has somethng to with it. Maybe thinning out the oils back there, or something?????

BTW, looking forward to seeing you at the Boardwalk and Smithville shows again this year!!!!

 

[ßill]

Are you sure that it is the differential, and not a "U" joint. There are 3 of them near the differential. Might be something to check out

 

[magicv8]

Add posi fluid, then drive to a parking lot. Make a right turn full loop, then a left turn full loop. If the problem doesn't go away, you may have had a shim wear/crack and drop out of the carrier.

 

[Viet Nam Vett]

Hi VNV!!!!

I'm no mechanical genious, but my guess would be heat has somethng to with it. Maybe thinning out the oils back there, or something?????

BTW, looking forward to seeing you at the Boardwalk and Smithville shows again this year!!!!

Thanks .. Will see yo their..

 

[Viet Nam Vett]

Are you sure that it is the differential, and not a "U" joint. There are 3 of them near the differential. Might be something to check out

Thanks Bill ..I did crawl under and check ..all seems tight. the outer U joints have french locks and there tight. And the iner U Joints are Cap bolts also tight. And last but not least the pinion U joint is also tight. These were all checked before I left and are still ok.

 

[Viet Nam Vett]

Add posi fluid, then drive to a parking lot. Make a right turn full loop, then a left turn full loop. If the problem doesn't go away, you may have had a shim wear/crack and drop out of the carrier.

Yeah.. thanks magic... I did the figure 8 thing on the trip as mentioned ..but maybe I'll add anoter bottlle of posi fluid and try it again..

The rear as stated has only 4000 easy miles on it. So worn shim is hard to understand ...but I'm sure with my luck it could happen...:L

 

[motorman]

amsoil gear lube is the best to use and we found out when road racing corvettes as it was the only gear lube that let the posi live. i have the same amsoil gear lube in my silverado for 110,000 miles with no posi problems. l also add the GM posi additive

 

[gmjunkie]

Yeah.. thanks magic... I did the figure 8 thing on the trip as mentioned ..but maybe I'll add anoter bottlle of posi fluid and try it again..

The rear as stated has only 4000 easy miles on it. So worn shim is hard to understand ...but I'm sure with my luck it could happen...:L

Change the lubricant,Add bottle of Additive, And do your figure 8's Backward!! Trust Me!! It will work better!!My 78 dose this every time I get it out after a long Storage!! I service it drive it a couple thousand miles,and I put it up for another year or two!!

 

[Viet Nam Vett]

Change the lubricant,Add bottle of Additive, And do your figure 8's Backward!! Trust Me!! It will work better!!My 78 dose this every time I get it out after a long Storage!! I service it drive it a couple thousand miles,and I put it up for another year or two!!

Backwards......

 

[Viet Nam Vett]

amsoil gear lube is the best to use and we found out when road racing corvettes as it was the only gear lube that let the posi live. i have the same amsoil gear lube in my silverado for 110,000 miles with no posi problems. l also add the GM posi additive

Thanks Clem... I asume I should be able to get Amsoil at your average auto parts store..and you used 90W ...??

 

[studiog]

Would a bad wheel bearing be a possibility??

 

[Viet Nam Vett]

Would a bad wheel bearing be a possibility??

Possible.... Good call.....But the Trailing Arms were rebuit with all new parts by Bair's Corvette. It was definitly coming from the diff as I felt the jerking thru the seat.

 

[67HEAVEN]

Could this be the "infamous" bad front differential mounting cushion allowing the diff front-yoke to move up and tickle the underbody?

Have you checked for marks above the yoke?

 

[Viet Nam Vett]

Could this be the "infamous" bad front differential mounting cushion allowing the diff front-yoke to move up and tickle the underbody?

Have you checked for marks above the yoke?

Nice try Linkage boy....But...all parts are brandy new under their including the snuber cushion. But since that's a good call...I'll check that to be sure. You never know.

That's why I was doing circles in the gas station when we stoped for fuel. Every one thought I was lo-co...

:L

 

[Tampa Jerry]

Rear

Go with the above. Change out your (hot) rear end fluid after a thorough drive and add two bottles of GM posi additive and fluid. Lock the wheels and drive in reverse 8 to 10 times and forward 8 to 10 times. I did that on my 68 until I almost threw up. My kid had a blast. Solved the problem. Jerry

 

[midyearroadster427]

hmmm

sounds like it does it when its heated up.. had one like that in a chevelle...after driving for a while...the rear would chatter like hell...it ended up being bag clutches in the posi unit. just a thought

 

[motorman]

Thanks Clem... I asume I should be able to get Amsoil at your average auto parts store..and you used 90W ...??

amsoil is not sold in parts stores only thru amsoil dealers. check amsoil website for a dealer in your area.

 

[Fuelie]

I had the same problem in my '65 a few years ago. Draining the fluid, and putting in 2 bottles of GM additive along with fresh fluid, combined with the multi figure 8's corrected the problem. (I did not drive it in reverse though)

Take care,
Brian

 

[Viet Nam Vett]

I had the same problem in my '65 a few years ago. Draining the fluid, and putting in 2 bottles of GM additive along with fresh fluid, combined with the multi figure 8's corrected the problem. (I did not drive it in reverse though)

Take care,
Brian

Heh Fulie,
Was your problrm the same as mine.? In other words.... Starting out from a stop in a straight line caused the jerking and poping and then would stop after out 3-8 feet..??

This was after a 70 mph long run and then a stop.