Ok so I have a feeling my posi is worn out. Up on jack stands in neutral I can spin either wheel and they both spin the same direction. If I put it in gear and put a breaker bar on the right rear wheel the left rear wheel spins the opposite direction. If I put the parking brake on and try to spin the left rear wheel I can get it to move independent of the right (guess my parking brake grabs more on right side). At any rate is that a good test of if it's worn out? Or is that just showing that it allows it to go around corners? I know it spins both tires in a straight line but chooses if it wants to going around corners. Sometimes it only spins one.

 

I think that's the tell-tale sign right there. Then again, it's hard to say.
I lifted this from a Jeep forum. Seems the 4 x 4 crowd has pretty good handle on the D44. My rebuilder was in that group.

A common problem of the Trac-Lok differential is a chattering noise when turning corners. Before removing the unit for repair, drain, flush and refill the axle with the specified lubricant. Add a container of Mopar Limited Slip Additive after repair service or during a lubricant change.

After changing the lubricant, drive the vehicle and make 10 to 12 slow, figure-eight turns. This maneuver will pump lubricant through the clutches. This will correct the condition in most instances. If the chatter persists, clutch damage could have occurred.

The differential can be tested without removing the differential case by measuring rotating torque. Make sure brakes are not dragging during this measurement.


1. Place blocks fore and aft 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 torque check tool #6790, or equivalent tool, to studs.
5. Use torque wrench on torque check tool to rotate wheel and read rotating torque.
6. If rotating torque is less than 30 ft. lbs. or more than 200 ft. lbs. on either wheel, the unit must be replaced.

It shouldn't be too difficult to perform that test. Possibly a torque wrench on one wheel lug would be sufficient. Just be sure what the wheel lugs are torqued to before you start.

 

Are you saying that it always spins both then going straight but sometimes only spins one when going around a corner?

 

Yea I'm pretty sure it spins both in a straight line. Car is off the road until spring so I can't double check the fun way.

 

This is a timely question in that I have suspicions about my own D44 TracLoc. Every now and then at the track its particularly noisy in the burnout box. Examination showed that it's still in good shape but that torque test posted above is something I'll have to try.
I do know though that despite using Shock Proof synthetic gear lube, it stills chatters around corners. The Ford additive took care of that.

 

There are limits to what a clutch type differential can handle. When you go around a corner you have much more load on the outside tire and you are unloading the inside tire. The clutches can only hold so much and in a situation like this they can slip and allow the inside tire to spin.

As for water burnouts, no clutch type differential can hold up to that for very long. This is one of the worst things that you can do to your differential. If you don't believe it then just stand by and watch the FOX body Mustangs and other street cars when they do their burnouts. You will see many of them start out spinning both tires and before the burnout is finished only one tire will be spinning. This causes a lot of heat in the clutches and it heats up the oil. The clutches will glaze over and each time this happens it gets worse.

 

I'm wondering if mine is on the way out just because I don't get any chatter and never have.

As for the test above I'm pretty sure mine failed horribly. Since my ebrake was only holding the right rear wheel I grabbed the left rear tire with my hands and spun the wheel while the right rear did nothing. Assuming burned up?