Knocking noise from drive shaft

[BUMMRR325IS]

Could some one shed some light on this ??..... I have a 92 - 325IS with a loud clunking/knocking noise from underneath, near the back. It is in rhythm with the drive shaft.

Under de-acceleration, and going over bumps (speed bumps in a parking lot for example.) causes this noise. during cornering and more so with 4 people in the car.

I've had the shaft out, replaced the hanger bearing, the universals looked OK. What Else ???????

Thanks, Bob

[Jared at Pelican Parts]

Hmm, you say you have replaced the center bearing AND the guibo coupling? This cvould be a bad output shaft bearing inside the differential.

[Javier at Pelican Parts]

Also the driveshaft could be out of balance, have you recently hit anything on the road? if so than you need a new shaft.

[BUMMRR325IS]

How would I check to see if it was a rear wheel bearing ??

[m50power]

I know this may seem out of line but check the rubbermounts for the exhaust system near the cat-converter. There is one on both sides -- if one is broken or missing, the hangar off the exhaust piping can rub the heat-shield, making noises you describe.

[Dave at Pelican Parts]

Rear wheel bearings can be checked by listening for a roaring (sometimes a "grumbling") noise that is much louder when the car turns one direction. They can also be checked by grabbing the top of the tire and shoving in and pulling out. You want very little if any movement, and very little if any "clicking" feeling through the wheel/tire when you do this.

--DD

[stupenal]

Rear shock mounts are a common failure point on our cars. Over time, the rubber construction of the shock mount degrades, causing a "clunking" noise when going over bumps. Mine were in such bad condition that I would hear it whenever I accelerated, decelerated, turned, pretty much in any situation where the car was not stopped. I thought to myself that I might have had a bad wheel bearing, but I spilled out some dough and got the new e46 convertible rear shock mounts (stronger, heavier duty) and replaced them. The noises are now gone. To access the mounts, you have to remove the rear speakers, the rear carpet, and the dust shields over the mounts. Remove a few bolts and you should be able to get it off.

Total cost for me was $15 (I got a set used for only 500 miles and in great shape - the guy upgraded to aftermarket ones) but it shouldn't be more than $50 at the $tealer$ship.

[SteveStromberg]

My 3.0cs did that, Check the Diff mount I bet you find one thats Bad.

Steve

[dsonyay]

Also- check near the flex disk to see if there is a chunk of insulation hanging down and making contact with the drive shaft. That was my problem.

It made a weird thumping noise when I was at speeds below 10 to 15 mph and kinda went away as I drove faster. Most noticable on cold mornings when the material was stiff. Easy fix too. I used a short sheet metal screw with large washer to hold it back into place

[BUMMRR325IS]

You Know what .... I did see a chunk of insulation causing rub marks on the shaft, I didn't think it was heavy enough to cause the noise, ... I'll tac it up ASAP and let you know .....]

Thanks

[dsonyay]

I bet that's the prob. It looks like nothing but does make a racket.

[BUMMRR325IS]

No... not the insulation, after fixing that, it still knocked.

What about a worn out bushing, with metal knocking metal when weight of the chassis shifts ???

[stupenal]

Have you taken a look at the guibo? I'm pretty sure that is the problem, i am experiencing the same thing. Over time, the rubber piece wears out. Here's a picture of a worn out guibo. Actually, first is a link to Rogue Engineerings website where they tell u about the worn guibo

http://www.rogueengineering.com/Merchant2/merchant.mv?Screen=CTGY&Store_Code=RE&Category_Code=GUIBO

Now the pictures of a thrashed guibo beyond all human imagination.