Dry scraping, rattle kinda sound.

[RoyBatty]

First off, all systems on the car are working smooth and correct with no other indications of a problem.

Just in the last week I noticed this dry, rattling, scraping kind of sound only when in second or third gear. It only happens for about a second or two as you pass thru a specific RPM range.
Pushing the clutch in seems to stop it.
It can only really be heard when you are driving past something that reflects the noise back to you. Such as others cars parked along the road or a retaining wall on the side of the road.

I'm thinking throw out bearing.
Anyone else have any suggestions?

[divace73]

I had something like that and it ended up being the cat, the inner honeycomb had come loose and would only rattle at certain frequencies.

Just check everything is tight under the car and the try and rattle the cat (if you have one??) when cold.

[So Cal Mark]

no cat on the coupe, it's too old. The throw out bearing shouldn't be turning unless you have the clutch pedal depressed. Since it's only in 2nd and 3rd I would expect some type of resonance, similar to what a bad cat can produce. Since the exhaust on that car has a mount to the transmission, it could be an exhaust noise

[RoyBatty]

Thanks, but exhaust is all new just over a year or so ago. It's all secure and had no loose hangars joints and there are no contact points that would cause this rattle. Oh and it doesn't have a cat installed.
Thanks for contributing tho.

[RoyBatty]

Hi Mark, this is on the spider.
I've tried moving the exhaust is every manner with the car jacked up, and can't come close at all to reproducing the sound.
It really sounds like something inside the bell housing.
Even with the clutch released, doesn't the throw out bearing have some spin induced to it by the clutch spring fingers?
Oh I just remembered, when I engage the clutch, the throw out bearing does make a chirp/squeaking sound until I release the clutch.

[So Cal Mark]

if the clutch free play is adjusted properly, the release bearing won't turn until the pedal is depressed. A release bearing will quickly fail if it's turning constantly. Does the clutch fork have the return spring attached? A missing spring can allow the fork to rattle, or allow the release bearing to contact the pressure plate

[RoyBatty]

Thanks Mark,
In my previous post I meant to say pressure plate spring fingers.
And I will admit that earlier in the life of this clutch/pressure plate/throwout bearing combination, I may have had things adjusted a little too tight, causing the throughout bearing to be spun up when the clutch was released.
I just got back from a 3 day drive from anchorage,ak with my son. He was based at JBER.
I'm going to have him drive it past me as I listen for the rattle from both sides.

[RoyBatty]

Ok,
I still haven't been able to pinpoint the source of this noise. But after a bunch of on the road experimenting and jacking up the spider several times to try and shake everything underneath the car, I'm going to make a guess.
I "think" that the springs in the clutch friction disc have lost their tension.
I believe these springs are installed as a torsional dampening mechanism to lessen the shock of the clutch engagement.
I'll be ordering a new clutch/ pressure plate/ throw out bearing kit soon.
Fun times coming.

[76was124]

Did you check the drive shaft pillar block bearing? Flex could cause the drive shaft to rub on your parking brake cable/bracket with changes in load. You will see scrape marks on the drive shaft if it does.