New axles too short?

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Miszny

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Hi

What would be the result of too short axles in 8.75 with old style sure grip?

In my case car is spinning tires in right directions when lifted off the ground, but will not drive when on the ground with driveshaft spinning.

My previous axles were longer as you can see in photos.

F4A63397-21B8-4BB8-92FF-C4C2DD7E2C24.jpeg


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I know the differential is all good, has new gears and bearings also. Not the 1st one I built.
I am guessing that spider gears are not engaged with shorter axles and sure grip clutches make the wheels spin when lifted.
Can this be it?

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They won’t be engaging the inner side gear. The preload is why it is spinning while in the air. The fix is new longer axles. Or use your old axles. Kim
 
Yes some sure grips,the early ones have 2 piece side spider gears later units have 1 piece.
The 2 piece the axle doesn't make it far enough into the second set of splines. Dr Diff helped me out on this subject.
Same happened to me when I went to a early sure grip from a open, using the stock open axles.
 
Longer axles fully cured the problem.
Problem solved. Great.

What length axles did you have to begin with and what did you end up with And what were/is the gap between?

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Problem solved. Great.

What length axles did you have to begin with and what did you end up with And what were/is the gap between?

Frankly I didn’t check, axles I got were exactly half inch longer than the ones that came with this housing. The shorter ones had some spline damage from minimal spider gears engagement.
 
I had the same issue a few years back. The issue stems from the fact that no A-body 8-3/4 came with big bolt pattern brakes and the way that the axles are measured (from the outer flange to the end of the splines)

SBP A-body brakes used a 1-3/4" wide drum, but BBP brakes used a 2.5" wide drum. The axles have a different offset from the wheel bearing to the face of the wheel flange to account for the wider drum. But since axles are measured from flange to spline end, if you cut a BBP axle to stock A-body 8-3/4 length, the axles will end approximately 3/4" short of the normal position.

Photos in the link below

Brake shoes help (8 3/4 BBP)

The measurement marked Axle Offset is the difference between the two.

flange_diagram-med.jpg
 
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