F18Rep

For the longest time I have had a noise on one of my cars. I've replaced bearings, half shafts, rotors, parking brakes. I finally found the problem - I've overlooked this at least once maybe twice in the past.

Take a peek at these two stub/hubs, notice a difference? The bearing journal (or whatever it is correctly called) is made differently for the two stubs. One is under cut in the area near the inner part of the bearing. My only guess is that this one belongs on an early car (not the 85.5 that I pulled it from). Weird, because these parts had the same PNs.

What finally clued me in was that I noticed that as soon as the axle nut was loosened, the wheel got really wobbly and once I had the hub off, the stub pushed out of the bearing by hand (I usually have to whomp on it to get it free).

I can't explain this, can you? Bruce

KuHL 951

How did the bearings look even though you replaced them once? It looks like the 'turned down' one on the right had the original groove like the left one but has worn down severely from something wrong in the bearing. If the 'undercut' was factory how would they get it past the bearing ID without being loose as a goose?

FRporscheman

I had the same problem on my '84 for a year... I replaced the bearing, and it blew again in a week, replaced the CVs/axles, and finally tried the stub axle and shazam.

That pictured stub axle... defies logic.

F18Rep

Steve... Its been awhile (3 years) since I first worked on this but as I recall the first bearing looked OK, dry but OK. But I'm starting to think you're right though - worn down severly - as the cause. It the only thing that fits. I'l sure watch for that the next time.

For others with rear end rumble - the easy way to check for this would be to loosen the axle nut and yank on the sides of the tire- there should not be a whole of wobble. Some yes, but this small amount of wear on the stub resulted in almost an inch of movement at the edge of the tire.

And BTW, the car drives a whole lot better with a good stub too. Bruce

StraightSix

I think what happened to the stub axle on the right side of the OP's photo is similar to what happened to a hub from my DD Civic. I had a left front wheel bearing go bad, and found a similar "groove" on the Honda's hub. I kwew the hub need to be replaced, but crammed the car back together anyway since it was the only car I had running at the time. A couple of month later, I started hearing a noise that sounded like the differential was going south. So, I did a transmission swap and the same noise returned a week later. The bad hub was causing the noise. The hub on the Honda is a press fit, so when the inner race goes bad and locks up that causes the groove that I saw on the Honda hub.

I would surmise that something similar happened to the OP's stub axle. One of the races locks up and then machines a groove the same width as the bearing race. Then, the stub axle isn't properly supported in the bearing due to extra clearance and the inner half of the wheel bearing is then subjected to an oscillatory load.