Hello all,
Spending some time lately tightening up the ride on my 2002 XJR and tracking down some pesky noises while I'm at it. Just replaced all the sway bar bushings and end links, both motor mounts, and the transmission mount. Incredible difference in ride quality after these updates. Eliminated my relatively aggressive steering wheel vibration over harsh segments of road and tightened up steering. Overall, a much smoother ride.

However, with these repairs, I was also hoping to eliminate a knocking noise coming from the rear driver's side wheel. To my dismay, the knocking noise was still present. After a quick test drive, my mechanic gave an initial suggestion that it could be a worn wheel bearing, but I couldn't leave the car with him any longer to investigate further. Personally, I don't believe it's a wheel bearing - I don't hear any typical wheel bearing noises, and I was able to replicate the knocking noise when I got home by pressing down on the trunk area above the driver's side rear wheel. Below is a quick video of my test - and you can clearly hear the noise.


The noise is very present in the cabin of the car - sounds like its coming from behind the back seat. From what I've gathered from other threads here, it's likely a worn upper shock mount bushing, but looking to get your advice/suggestions based on what you hear in the video. Appreciate the help, all!

 

Hello DJStronkinson,

I have had also such a "metallic" noise from the rear axle and it turned out, that the pinion between hub carrier and control arm lost all his grease.
So the taper roller bearings corroded badly. It was easy to determine, because there was a remarkable play between controll arm and hub carrier.
After replacing the roller bearings (Part # CAC4610) and the pivot pin sleeve (MNE4520AA) everything was silent again.

I hope that this may help you.

best regards
Sven

 

Thanks for your response, Sven. Do you recall if you were able to replicate the sound you were hearing by pushing down on the trunk above the rear axle?

 

Might try greasing the zerk fittings both sides of the dif; also, the donuts that retain the exhaust system will fail allowing the tailpipe to bang . .

My upper rear shock mounts were destroyed, but I never heard any knocking sound.

 

Thanks, Jhartz. At first, I actually had tried to wiggle the tailpipe to see if it was knocking against anything and it felt pretty tight - I couldn’t get it to make any noise.

Good thought about the diff. I do have some seepage from my rear axle stub seals and I suspect it’s being cause by a blocked breather. I wonder if that could be associated with the knocking I’m hearing...

 

I doubt it.

I think the "solution" here is to have someone bounce the car while you are underneath locating the source of the noise. Per the video it sounds like a very light knock, and doesn't sound like anything "major", but you never know. I'm thinking once you locate the area of the noise, and then pinpoint it, it will be something none of us has thought of, and I suspect it will be an easy fix too.

Interested to see what transpires, keep us updated.

 

My "knock" odyssey was the tapered bearing #15.

 

Yes, it could be also heared, when pushing down the trunk, but it was more distinct, when driving slowly over an edge. For example, when driving rearwards out of my garage, the rear wheels pass an edge of 1 inch height. This was always accompanied by a knocking sound.

@ King Charles: the replacement of the tapered bearing was also the remedy in my case.

 

Thanks to everyone for your thoughts on this subject! Seems like the tapered bearing will be where I'll start for further investigation. I'll come back and update the thread when the issue has been resolved.

 

Back to update the thread as my rear end knocking issue has been resolved. Turned out to be worn driver's side half shaft U-joints. Had them replaced and all is good - no knocking.

Thanks all!