Alright guys, I lowered my car a couple inches 2 weeks back and started having bad drive shaft thump. So I pulled the axels, swapped the cups, and everything seemed great. The only thing I noticed when I was doing the cup swap was that the output shafts on the diff seemed loose. When I put pressure on the axels, there was play where they come out of the diff, about 1/32" or so. I figured this may be normal and put everything back together. Swapping the cups seemed to fix the problem and everything was good, until today.

I noticed my rear left brakes were making an on/off squeeking noise as I slowed to a stop and as of today, when I make a hard right there is some bad klunking coming from the rear left. Any thoughts on this? When I spin the rear left tire I can feel an on and off dragging from the rear diff, im wondering if im feeling a broken tooth? Its been wet the last couple days and I havent ripped on the car at all, so I dont think I broke anything recently. Does this sound like a pretty typical rear diff problem? My main question would be to confirm the play on the output shafts, should they wiggle at all?

 

*edit.

I also noticed thumping from the rear left when I was engine braking in 1st and 2nd, generally when there was negative torque on the rear end. I thought it could be the axel cups acting up under reverse torque.

If its normal for the output shafts to wiggle, it could just be the cups and I need spacers too.

 

With both wheels of the ground, in gear, when you spin one wheel, the other wheel should spin in the opposite direction.
You will feel a little drag - normal.
That way the propshaft & final drive is not spinning, so you can't check the pinion-ring contact.

To do that, both wheels of the ground, out of gear, (BE SAFE! USE JACKSTANDS!) get under the car and turn the propshaft by hand.
If the pinion moves in and out while switching direction = no good.

Btw..
The rear axle is a "floating" axle.

Driven by the splines in the diff (#5) and supported in the hub (#6).
The drive splines in the diff look like this:

There is no real tight bearing support for the axle in the diff.
You see the oiling hole in the picture.
That's there because at some point the axle is rotating at another rpm than the Torsen, so you need lubrication there and.. a little play to get the oil in between.

In the hub the axle IS supported.

 

Hmmm, thanks for the info. Appreciate it. I was hoping the axel nuts werent torqued enough and it would be an obvious fix. I just finished replacing the rear brakes and double checking the torque on the axel nuts and they're good to go. I'll try turning the prop shaft and looking for pinion motion. Im leaning towards the possibilty that im just seeing drive shaft cup wear on the reverse torque surface.

The thumping resembles the thumping that used to be under accel, now that i've flipped the cups, its showing up on engine brake decel.. this might be my problem.

 

There is "clearance" slop in the factory gearset. The bearings cannot take any lowering as you found out, and has been documented for many years. There are a lot of great pictures on how the cups get worn. Once the noise starts bugging you, replace them.

 

Jordan did you use the revised torque spec for the axle nuts - 220 ft lbs ?

Not sure what else to recommend other than making sure your brake guide pins are properly lubed, since some of the issues seem to be around the brake areas. Your description doesn't sound like a typical bad differential, I'd say it is something else.

 

I replaced the rear brakes, took off the axel nuts, re-greased them with never seize and retorqued them to 220. The drivers side turned an additional 1/8" or so. No more noise so far.