Kelly
Lifetime Supporter
I still haven't driven my car much but I've noticed a clunking at low speed after driving the car for more than say 45min. It can come from either side. It does seem to be coming from the rear axles or hub. So what is it that causes it?
Richard, I've been following the thread with interest and we have several things in common.
I have a similar problem and I too borrowed Kirby's pulling tool. The clunk has confounded me and unfortunately, this driving season for a variety of work and family related reasons, I've only had the car out twice, so the condition persists.
I actually have a recording of the sound because it is quite attention getting and I simply cannot get myself comfortable with driving a car at speed that has a potential drive train or brake issue. It used to be that the noise was faint to non-existent when the car was cold but now appears very early to almost immediately in the drive now. Symptoms seem temperature related.
I’ve had the car for several years. The first season no issue. The noise showed up shortly after a tire change and 4-wheel alignment. Not sure it was related. As I mentioned in my earlier post, I began trying to systematically isolate various causes. So firstly I inspected all of the suspension mounting points then suspended the car and checked bearing clearance on all four corners by feel on each wheel. My theory at that point was possibly brake pad printing on the (or slightly warped) rotors and I thought excessive bearing clearance might aggravate the condition since the thump is at definitely at wheel frequency.
I put a dial on the rotors but the bearing clearance was such that I could not get what I thought were reliable readings with the rotors on the car so off the rotors came. Well sort of. The Allen-headed flat head screws that hold the rotors on the hub when the wheel is removed were stuck on two of the four corners and they were soft as could be like many of the other SPF fasteners I’ve concluded. After liquid wrench and heat failed, I simply had to take a sharp chisel and work the outer diameter of each bolt until I got them loose followed by order #1 to McMaster Carr for some higher grade 400 series stainless replacement hardware.
So after measuring the run-out of the rotors off the car and concluding that was not it, I also removed the e-brakes as they had been mentioned a possible source.
Neither of these was the cure so I moved onto the wheel bearings as Kirby had told me he had to adjust his several times and others have mentioned that often the wheel bearing races are not seated properly at the factory. Kirby was also generous enough to lend his pulling tool to me. Again, I had several of the very small Allen/button head screws on the wheel bearing retainers/locks seized and had to resort to extreme measures to remove them (McMaster order #2 for replacements; if anybody needs some, I have 100 pieces now).
The axle on one side pulled very easily as Kirby described. The other was very tight. The anti-sieze on the threads of Kirby’s tool was applied by me. I had a lot of tension on the rear passenger side assembly and thought it should come so I did give it a whack with a hammer as mentioned above and got it loose but it pulled fairly hard.
Anyway, inspect and re-pack all wheel bearings, reassemble, and still no joy. The noise is still there; perhaps worse. So now my theory is a CV joint going South. Since the noise seems to be coming from rear passenger upright, I switch the half shafts from one side to the other thinking if it’s one of the 4 CVs, maybe the noise will jump sides. The grease in all 4 CVs looked good, no obvious issues with them upon visual inspection. Back together, out on the road, and still persists the thumping as prominent as ever!!!
So to re-cap, as noising initially appears at wheel rotation frequency, it only occurs when I apply brake, actually somewhat light brake because if I lean on it a little it does not clunk/thump upon more aggressive braking. After I get things good and heated up, it’s more pronounced upon braking but I can also make the sound occur more faintly buy weaving back and forth hard within the lane, and I can hear the sound in the rear passenger corner during one direction of the weave. Also, when it’s good and hot, it can make some noise as I pull off of stop and turn at low speed. It almost sounds like a rubbing chattering noise. As an owner of many LSD cars, I recognize this as the limited slip packs not slipping (it has a contemporary RBT-2). I don’t know if this is a related or separate issue. If that was the only problem, I would not be too concerned about it. If the root cause of the noise was the LSD, I also don’t understand why it only shows up under (light) braking and not otherwise under acceleration. Somewhere along the line I switched the lube in the transaxle to a Valvoline synthetic blend. I did add LSD additive. On a similar note, I did the same thing in my Pantera, and as the zf heats up after driving it, it seems to shift more poorly. I may go back to dino-lube in my transaxles.
Sorry for the ramble guys but I’m stumped and it seems on-topic with the thread. I’m open to any suggestions.
I have several mpegs of the noise but can’t get them to upload.
Best,
Kelly
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