will010100

Coming off track yesterday there was a loud clunking noise coming from the rear of the car, but I was unable to tell which side. I thoroughly checked the tires and rotors they are all fine. I drained the differential and the fluid is like new with nothing on the magnet (I put new fluid in it before this event). The ring and pinion seem okay. Would there be debris in the oil if the LSD was damaged?

I visually inspected the driveshaft and axles but have not removed them yet. Upon initial inspection, they appear to be okay: no apparent lash, boots are intact with no twist or leaking.

So here's the real conundrum. After checking the tires, I drove around the paddock and the noise became harder to reproduce as the car cooled . Now that the car has completely cooled, I cannot reproduce the noise at all. The car isn't legal, tagged, or insured so I cannot easily get it hot without wasting a track day.

I have an M-Factory 1.5 LSD and I'm told they can get noisy when they are hot. That being said, I've been using this LSD for 3 years and it never did this before. Also, the noise occurs in straight lines the same as turns. At the end of this video I make a hard turn an there is no noise.

Here is a link to the video. I included coming down pit lane and you can hear the clunky sound didn't start until I entered the paddock.

jyeung528

hmm...i'm stumped.

will010100

The noise disappeared as mysteriously as it appeared. I checked everything I know to check. Then I drove it in tight circles on a paved surface for 5-10 min to put heat in the differential to see if that made any difference, but the noise never came back.

I have a hard time believing debris stuck to the tire could make that much noise without immediately knocking itself off (in the last 10 seconds of the video, you can see it shakes the car enough to vibrate camera). Yet, this is the only explanation I can come up with.

The only thing I know to do is to return to the track and see it it returns. If anyone has any other theories for me to test, I'm all ears.

jyeung528

something caught on your drivetrain and fell off?

etdub

Hey I think I'm having this same exact problem!

I developed a screeching noise making left hand turns. No noise on right hand turns. After coming off the track into the paddock, I had the clunking noise pretty much exactly the same as your video. I took the car out for another session, and the beginning was fine but developed the same problems toward the end which leads me to believe it's heat related. I drove home and had the same squealing but not clunking noise for about 15-20min until it just completely stopped. Can't reproduce it now.

Mike's

Check the HUB NUT i had something similar happen recent one side was not to torque spec and gave me a rotating clunk every so often

also if you can check the hub flange for run out could be shot wheel bearing

jyeung528

wow. interested to know if you guys figure it out.

weenrock

Do you still have the brake shields attached? Perhaps the brake shields got super hot, warping them and rubbing. The sound seems rotational.

jyeung528

sounds like a good guess.

etdub

I do have the heat shields still attached. Sounds plausible. I'll check that and the hub nut torque the next time I can get under the car. Thanks!