1966 differential

[1Redctoo]

I have a non posi differential in my '66 vert. When I jump on it the LEFT rear tire is always the one to break traction and smoke . Every other car I've had that was non posi would smoke the RIGHT tire . Im wondering if someone might have changed the internals to a posi setup and that maybe the clutch plates are bad. But , thats just an uneducated guess, really i haven't a clue ! Any ideas ?

[c4c5specialist]

Hi there,
Normally, if you have positraction, you will see a red tag on the side of the differential, showing that you have it.
This would be located on the fill plug or near it.
Please let us know what you have.
Allthebest, c4c5

[1Redctoo]

C4C5-no tag near the plug, code on diff is " AK " which is non-posi .

[c4c5specialist]

HI there,
Ok, well then, yes you can install a POSI differential into that housing.
While time consuming, its very much worth it to do.
Normally, after all your settings are done, its a VERY efficient and powerful rear axle.
Allthebest, c4c5

[1Redctoo]

If someone already did that , how would I tell ? And.. what would make the LEFT tire ALWAYs loose traction ? Could it be worn positraction parts ?

[c4c5specialist]

HI there,
If you jack the car up in the rear to get the tires off the ground, put the car in neutral.
Then, you have someone spin one tire, while you hold the other. If there is positraction, it is going to be VERY hard to hold the tire and very hard for the other person to spin the tire because of the friction from the clutches.
Allthebest, c4c5

The counter torque from the engine lifts the right side of the car. This is the reason for the spinning right tire. Can not explain the spinning left tire. Any others with the same experience?

[Itshakes]

I think you have it wrong. The torque from the engine lifts the LEFT (Drivers) side.

[aquaholic]

i always did it by jacking up the rear and spinning the tire like c4c5 said. however, the way i always determined it was if both tires spin in the same direction it's a posi. if the other tire spins in the opposite direction of the one you are turning, its not posi. i, never tried to hold one from spinning.

[aquaholic]

isn't the 66 base model differential a limited slip clutch type diff? where the wheel with the least amount of resistance spins until the other wheel musters up enough torque to overcome the clutch and spring in the diff and spin also.