I went to the dealer and got the spec sheet. It says I have a positive locking rear end. I did a hole shot the other day and only the driverside wheel is the only one spinning. Would a posi rear end work at all, if something was wrong with one side? The truck has over 400,000 miles so I realise it may have been changed at some point.

 

With 400,000 on it, it's safe to say it's just plain worn out.

I have over 200,000 on my old girl and it's a one wheel wonder and has been for awhile now.

It's a simple rebuild to put a new clutch kit in it. Will be one of my jobs before winter arrives.

Jeff

 

Factory posi is not a very "tight" posi anyway. Could be perfectly fine and still not burn both on the pavement. Relatively simple to replace clutch packs but getting the carrier and shims back in the housing might be a little interesting if it requires a "case spreader".

Very easy to inspect the diff to verify the posi hasn't been swapped out. Just pull the diff cover and look. Should be visible preload springs that push the side gears out towards the carrier.

 

Try it on wet grass and see what happens. Then try in on gravel and see.

 

1.Place blocks in front and rear of both front wheels.
2.Raise one rear wheel until it is completely off the ground.
3.Engine off, transmission in neutral, and parking brake off.
4.Remove wheel and bolt Special Tool 6790 to studs.
5.Use torque wrench on special tool to rotate wheel and read rotating torque Trac-lok Test - Typical .
6.If rotating torque is less than 22 N·m (30 ft. lbs.) or more than 271 N·m (200 ft. lbs.) on either wheel the unit should be serviced.

In other words if you can spin wheel while off the ground then your clutches are toast.

 

Thanks for the info. The 96 I had prior to this had a posi that worked well. I wasnt sure if they wore out or just failed all together. Looks like I got another entry on the chore list.

 

If you have a true "Posi" then you have a big problem, something is broke... Everyone seems to be referring to the problems of thier "Limited Slip" rear axles.

 

The spec sheet from the dealer said it is, but who knows if it's the original axle after 400000 miles. It was a fleet truck. If I pop the cover how can I tell?

 

Yes, your Limited Slip unit could have worn clutches in it, but you might first try changing the fluid. I have a 96 with 268K on it, and the LS is still tight as a drum on it. I was pulling the GN yesterday and found I need to add some more friction modifier, as it was popping under power when turning corners. When a lighter load is on it I can regularly hear the tires scratching a little when turning corners, yet it will still spin one tire in wet grass sometimes.

The Power-Lok LS unit in the Dana axles is a quite stout, effective unit. I investigated lockers of several brands and discussed all of the options with several knowledgeable people here, ad elsewhere, and decided to go with the Power-Lok when I wanted to upgrade my 99 open diff.

Anyway, back to your problem. If you want to pull the cover to see what's in there, Google images of a D70 LS unit so you can see what to expect in there.

If you have the LS unit when you pull the cover, I don't know of a way to check the clutches without pulling the carrier out, but if you change the lube and do not add any friction modifier to the new lube, it may tighten up. You'll have to run it it for a while with new lube before you decide that something may be worn out.

What may have happened is someone else changed the lube then it was chirping and they added too much friction modifier. Something people don't realize is it take a long time for the friction modifier to get into the clutches and you can add to much if you don't give it enough time to work itself in there.
What I mean by a long time is about a month between friction modifier adjustments.

Chris