Rotational Noise/Clunk
 

Spent the morning chasing a rotational noise that is more or less a low volume clunk. Now I need some suggestions as I could not sort it. Paying a pro is the last resort.

Symptom:
Rotational "clunk" that is audible but cannot be ascribed to a given wheel/corner
Braking enhances noise
Turning wheel to right enhances noise
Less noticeable in straight line or turning wheel left
Can't feel it in steering wheel or brake pedal
Do not think it's tires

Today's Efforts:
Raised car and checked wheel bearings wiggling and turning wheels
Fronts had more play than I like and snugged them a hair
Verified tightness of CV joints. Fine
Eyeballed front rotors and saw no evident high spots/shiny spots

Tomorrow's attack including any suggestions from you guys:
Raise azz end, jackstand. Run in 2nd gear and have wife hit brakes with clutch in. I listen.
Pull rear wheels, check caliper bolts and caliper holding screws
Put eyeball of death on calipers looking for high/shiny spots

So, please fire away with suggestions. As Ross Perot said, "I'm all ears".

I can’t tell from your post, but is the noise coming from the front or rear?

can you tape the noise or video..it?

Ivan

It seems to be coming from the rear. Not sure which side

Raining now but I will try to get a video/recording tomorrow when things are dry. I will get my wife in the car to help pinpoint the origin as her hearing has fewer rock concerts than mine.

dude ,you better not play while searching for the noise AC/DC.
Ivan

Noticed an error. Rotor holding screws. Should be tight as they were loc tited when emergency shoes were done 2 years ago.

No AC/DC. More a Classic guy - Who, Cream, Tull, Doors.....

https://photos.app.goo.gl/D4NquVpu3KRZNynDA

Let's try this for sound.

Arreghhh. I will try to upload again.

I give up trying to drop a video, Been trying for 45 minutes and I am frustrated and done. Between google, android and Pixel phone it's a cluster. Thinking a trip for a new i phone.

https://youtu.be/s-McKxnJ6ys

Maybe......

it does sound to me like a CV joint..not being loose but inside the cage...
Ivan

Ivan;

Thanks for the input. Is there a way to verify a CV issue before I drop a lot of $$ on a new pair of half shafts from our host?
Surprised as these were replaced about 20K miles ago with new Loebro half shafts and I lubed the **** out of them.

i would take them of the car and inspect.That means you have to slide the rubber boot off-to the center of the shaft(remove the small clamp-)If you have boot with a flange.
After mark the cv joint which way it came off.Remove the circlip on the end and take the cv joint apart.It is possible that the cage is broken.I do not think you have to buy the whole shaft just one cv joint if you find which is bad.Also was it even lubricated?

Ivan

Thanks. I will have a look tomorrow.

Yes, I lubed them when I installed them after trans rebuild. Liqui Moly LM47 and they were packed.

Other than lube issues, what causes failure? I sure don't beat on the drivetrain and the boots are intact.

If you suspect rear CV - perhaps check the mounting bolts are all tight...maybe they have loosened up a little since you swapped the shafts out previously?

I looked at the paint marks on the CV and the bolts and still aligned. I will get the torque wrench on them to verify tightness before I go farther.

Thanks

ok i listen again several times..you said you checked the rear wheel bearings.. if you turn right there is more noise....now come to think of it-and your axles are fairly new- possibly to focus on your rear left wheel bearing.....all tight,right

Ivan

the reason is ,if the cv joint would be really bad it would make more like scratchy noise not dung dung noise

don`t worry about the torque..they are tight enough;-)
Ivan

Suggestions for checking rear bearing. I lifted the car and pushed and pulled the wheel looking for play. It seems to have neither axial or radial play.

ok i know you have checked that......can you lift the rear of the car and try to spin the rear wheels?Of course it would be better on the ground but i do not know your set up.I would do it like this .I `d lift the left rear and start the car shift 1-2-3- with the right wheel on the ground...it will only spin the left-but only if you do NOT have limited slip differential!!

Ivan

The fact that it seems to be rotational and increase when there’s braking - It sounds like some kind of movement when pressure is applied. I had a similar shake and clunk in my 124, it turned out to be that most of the bushings in the rear were shot and the rear was basically coming loose especially when braking.

It could be a CV, but I imagine if that was going then you would be hearing more of a click sound and it should be especially evident when turning.

Couple of other things to check. Check the sway bars, especially the rear, I had a clunk in the rear that ended up being a loose link, it sounded like that, but less rotational. Check the banana arm bushings, check torsion bar cover bolts, check and make sure the struts are torqued correctly.

When bearings go they are pretty damn loud, it should almost sound like a whoa whoa whoa whoa hum with maybe some screeching. Ask me how I know.

Only other thing I can think of is if the caliper itself has some kind of play in it and isn’t bolted down properly. And not for nothing but check and make sure the rear hub bolts are torqued properly.

Thanks to all for advice. After running it with the rears wheels off the ground and still hearing it, I gave up and checked it into the hospital.

I found absolutely nothing loose. Anywhere. Pulled pads and rotated, shook rotors, spun and listened. Put it back together, ran as noted above and decided it is a DIY checkbook project.

Hopefully answer soon.

I strongly dislike giving up but also dislike spending $$ to fix what I think it is only to find it is something else.

Porsche hospital called. They claim to have isolated the noise to a rear rotor. Their suggestion was to replace my vented, cross drilled Zimmermans with stock rotors at all 4 corners. They strongly dislike crossdrilled rotors for some reason but I am not willing to replace 4 rotors when I can get by with 2.
So... I ordered a new pair of Zimmermans from our host and will replace just the rears when they arrive. Nice morning project.

It could be possible that the backing plate is bent slightly and rubbing on the rotor.
I had this happen to me when I replaced the rotors on my Toyota Tundra. When I pulled the old rotor off, the emergency brake shoes were catching on the drum part of the rotor and in turn pulled the backing plate slightly outward. I removed the new rotor, lightly tapped the backing plate back a little and bingo no more rubbing.

Mike never have i heard that the drill rotor will make a noise..i wonder who else is going to pitch in about it

Ivan

if there is a point of contact - it should be reasonably obvious, no?

I believe there is a point of contact/ high spot on one rotor but it did not seem excessive. I will have a better look once things are apart and I can view both sides of the rotor and run a dial indicator over it on the bench.
I will get a look at the e brake assy and backing plate as well.

Same rattle
 

I have exactly the same rattle and have been throwing parts at it like crazy. It seems to be in passenger rear. Please, what did you find to be the source???