In the recent few months I've been having an issue with the borg warner axle that I sawpped into my 89 firebird a few years ago. Over the winter the axle developed this clunking noise whenever I would turn with a certain amount of force. I had diagnosed this to be play in one of my axle bearings when I was able to move my rear passenger wheel in and out of the axle when the plate was still tight.

I had bought a set of axle shaft bearings and seals from hawks motorsports and installed them as directed in the instructions found with them. Now both of my axles have this play in them and the noise occurs much more often. After a series of emails, photos, and videos with technical support I've been lead to believe that this is normal. The noise however, is concerning every time I drive.

The last time I had the axles out I noticed some light scoring on the top outer edge if the bearing race and im not sure if it has grown since. The posi inside the differential itself is almost completely worn out at this point as it takes very little force to spin the wheels independently of eachother.

I'm unsure if I want to put any more money into this axle or if I want to return to a 7 5/8 like what was originally in the car. Or maybe im looking in the wrong place entirely, im not sure anymore.

Any thoughts or advice would be much appreciated. I have a video of the moevement I'm talking about but im not sure where to upload it since I can't here.

-Steve
1989 Pontiac Firebird
305 4 barrel
5 speed manual
borg warner 7.75 rear end
3.23 or 3.27 ratio, I cant recall at the moment

 

U are probably familiar with positraction, be it discs like the posi or the Detroit locker style, do clunk on turns. U, although have a different problem.
Did u change the diff fluid & add a posi additive?

 

I don't recall any in-out play on the axles in my BW rear end, either before rebuild or after. Just the nature of how the axles are secured to the housing with the pressed bearing and retainer plate, if done correctly, it shouldn't move at all. The axle seals are different left to right and some suppliers list them as the same and people have had issues with that. I don't know if using the incorrect seals will cause this issue you are describing, but I suppose it could if the seal thickness isn't correct.

But, as you say, if your posi is also shot, then you are probably into a complete rebuild of the entire axle assembly anyway. Unless you are wanting to keep the BW rear for a particular reason, it will be more cost effective and easier to rebuild a GM 7.625 rear and use a brand new posi carrier. I'm sure you can find a donor housing for next to nothing and just buy all of the internals and build it.

 

The retainer plates should have preload on the bearings to hold them in place. Should be little to no movement.

 

Thats what I wouldve expected, but I was told that while the rear end is still cold there is a little in and out movement for heat expansion reasons, and that as long as it cant move up and down or side to side, its fine. I wouldnt expect Bruce at hawks to try and lie to me about that so I want to believe the axles are fine. As for the seals, they came in labeled bags and I kept them on their respective sides.

I read on another post that auburn cone-style posis will make a similar noise when theyre worn out. I was planning on rebuilding it anyway but Im afraid of throwing more money at it and not fixing the problem

 

The retainers do have preload on them, enough to flex them out ever so slightly, but im still able to move the axle slightly.

 

It's been about 10 years since I rebuilt my 9 bolt rear, and the car is currently at the paint shop, otherwise I would go out to the garage and check for in-out play and report back. I remember having to pull the axles out with a slide hammer because the wheel bearing outer race had an interference fit into the axle housing and the bearing inner race was pressed onto the axle shaft, with a collar pressed on behind it. Did you press a new collar on behind the bearing when you installed the bearings and seals? With the inner race pressed onto the axle shaft and the outer race pressed into the axle housing, I don't see how the axle shaft is going to move in-out enough feel and even more so clunk. Maybe some play in the bearing itself, but that would be a really small amount that I doubt one would be able to feel.

A C-Clip style axle, like the GM 7.625, would have a slight amount of in-out play. Even still, clunks are not normal with that type either.

When you put the axle back together, were the inner and out races interference fit? Did you have to install the axle/bearing into the housing with a few hits of a dead blow hammer?

The posi carrier could be clunking as you suggest, although that isn't a common sympton of worn cones. Broken, maybe.

Other things to look at are suspension mounts/bushings (control arms, panhard bar, torque arm, shocks, etc.)