'65 Positraction diff stumble

[Joep F.]

I recently changed the oil (GL5) in my positraction differential and added the GM additive. Afterwards drove the 8's to work in the additive. However still I hear (and feel in rear axle) stumbling coming from the diff while:

- Driving away after stopping completely;
- Accelerating during cornering. This also will give a shake in the rear axle, like she is stepping a small step aside.

Any ideas how to solve this?

Thanks,
Joep Feldmann

[Wayne P.]

Re: '65 Positraction diff stumble

Repeat the entire procedure using two bottles of additive. If that doesn't fix it, most likely disassembly will be required.

[Michael W.]

Re: '65 Positraction diff stumble

Joep,

I thought you just rebuiled the diff corrrect? Does it still happen after the rebuild?? If yes, did you install the new clutch pack set?

Sander and mine are also just rebuild, but we did not drive yet! We had same issue before, so I hope we will not face the same issue after rebuild.

Sander - what is your idea on this?

[Joep F.]

Re: '65 Positraction diff stumble

Hi Mike,

No I didnt do a complete diff rebuild, just replaced the oil seal and changed the fluids.

Joep

[Michael W.]

Re: '65 Positraction diff stumble

Joep,

Allright, well I also changed my fluids several times last year and the issue what you decribed continued. Same was at Ruud Zeller and Sander. So if multiple fluid changes do not help then the only option is a rebuild indeed (not that costly).

Sander did the rebuild of our 2 diffs, so he can in detail explain what he replaced.

PS how is the weather in MCW? In IST its raining cats and dogs, I understood home is the place to be right now.

[Joep F.]

Re: '65 Positraction diff stumble

Hi Mike,

Ok, I will add another bottle of additive. Hope it solves. Dont really look forward to a complete diff rebuild at the beginning of the driving season.



P.S. Weather in Moscow is fine, sunny and around 20 degrees. Was in St Petersburg last weekend, even better. Holland only next month for me. Probably see you at the NCRS road tour.

[Michael H.]

Re: '65 Positraction diff stumble

I recently changed the oil (GL5) in my positraction differential and added the GM additive. Afterwards drove the 8's to work in the additive. However still I hear (and feel in rear axle) stumbling coming from the diff while:

- Driving away after stopping completely;
- Accelerating during cornering. This also will give a shake in the rear axle, like she is stepping a small step aside.

Any ideas how to solve this?

Thanks,
Joep Feldmann

It may take many miles of driving before the new additive works into the clutch packs. A second bottle is usually required if the old oil was slightly burned or if the car has been sitting for a long period of time.
You definitely won't see instant results so I wouldn't be too concerned.

[Michael W.]

Re: '65 Positraction diff stumble

Hi Mike,

Ok, I will add another bottle of additive. Hope it solves. Dont really look forward to a complete diff rebuild at the beginning of the driving season.



P.S. Weather in Moscow is fine, sunny and around 20 degrees. Was in St Petersburg last weekend, even better. Holland only next month for me. Probably see you at the NCRS road tour.

I will also only be begin June back home. For sure plan to be there at the tour! We plan to join with both Vettes.