<VV> Whump, whump, whump

Bill Elliott Corvair at fnader.com
Sun Sep 4 11:52:38 EDT 2005


I agree that U-joints would be the first of my checks, but I'm putting my money on the wheel bearings. I've found these late rear wheel bearings VERY hard 
to diagnose...once the wheel is off the ground often the bearing feels and sounds fine. So I've often replaced them not really knowing if that was indeed 
the problem...but in every single case so far it's fixed the symptoms.

I've been in Corvair for a LONG time...and replaced no late wheel bearings until the last few years...and now I've done a half dozen (on different cars of 
course) in as many years. I think their time has come...

Bill

>So far we have: ring gear, pinion shaft, and tire.  I believe that the  noise 
>is something turning at axle-shaft speeds - this might rule-out the pinion  
>shaft theory.
> 
>Here's a list of things that turn at axle shaft speeds:
>Ring and pinion
>Differential side bearings
>U-joints
>Wheel bearings
>Tires
> 
>Since the noise occurs only under power, not while coasting, that reduces  
>the possibility of the tires being the source of the problem but then it only  
>takes a few minutes to swap with the front tires to check that out.  No one  
>has mentioned U-joints, but if you had one that was bad enough to go "whump",  
>you should be able to spot the bad one with a visual inspection.  While the  
>car is up for that inspection, it's easy enough to wiggle the wheels and look  
>for a loose wheel bearing and to spin the wheel with the drum off and check  
>for roughness.  Once you have eliminated those external possibilities you  might 
>as well plan on pulling the differential for inspection.  I have seen  many 
>ring gears where the top side (out of the lube oil) was rusty after a long  
>period of rest.  I have never had or heard of any side bearing failures,  but I'm 
>sure there are others on the list who have and know what to look for  there.  
>Check the external stuff first.  I had a wheel bearing fail in  my '62 wagon 
>(Eric E. are you listening?) and the whump-whump was so loud I  thought the 
>axle was going to grind itself in two!
>Good hunting!
>Craig Nicol
> 
> 





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