porschegrp5

I have a rattling noise when a neutral. The noise seemed to disappear when I pressed the clutch in. I am trying to determine if its coming from the transmission or possibly the throwout bearing next to the clutch. The other scenario is that it might be a bearing in the input shaft in the transmission. I am not too well-versed in these matters.
Can someone help me, to diagnose this problem
I would appreciate your suggestions.
Vince

aben8057

Vince,

Are you sure its not from an exhaust shield?

Darren

Clutch disc rattling? Is it the original clutch disc or aftermarket? Mine rattles like crazy, aftermarket stuff...

porschegrp5

I'm going to check the exhaust shield. The noise does not appear when the engine is cold. Clutch disc rattling? That is a possibility. It has a racing clutch just a few months old. I was told by the previous owner, it has a vertex racing clutch. Does your rattle occur when the neutral and disappears when you depress the clutch. This is a difficult problem to diagnose. The transmission shifts just fine. I guess I'll just keep driving it until something else develops. Could it be throw-out bearing?

Paul 996

Did the PO also put in a lightweight flywheel. Because that is exactly what you are describing. Otherwise it is the throwout bearing but that is usually part of the clutch kit replacement and you say you have a fairly new "racing clutch".

peavynation

My vote is TO bearing, unless there's something noisy about this racing clutch setup.

Darren

Yes it sounds this is exactly what my "racing" clutch does. It's irritating and noisy.

Paul 996

Darren,

What kind of clutch are you running? Spec Clutch's? I am about to order a sprung Spec4.

AmirShaikh

I had this happen on a different car...I beat on the clutch a little (aka dump clutch) and it went away...i have a feeling in that case some crud got stuck in the TO (no clue for sure though).

On another car, I had a twin disc + lightened flywheel does that....the lightened flywheel was the cause of a rattle.

..wait I just realized I repeated what Paul said .

flyingpenguin

What happens when you have a lightweight flywheel (ie. single mass) is that the pulses from the crank are not dampened by the flywheel and transfer directly to the tranny's input shaft. Under "no load" conditions (ie. when in neutral) this results in an annoying but otherwise fairly harmless chatter.

I have a 2000 996 C2 with an AASCO LWFW and Spec stage 2 sprung clutch disk. The sprung disk absorbs a little bit of the vibrations, but not entirely. I replaced the tranny oil with Redline Heavy Shockproof gear oil, which significantly reduced the chatter, and no adverse effects on the shifting smoothness.

JP

Darren

I have a Sachs LWFW and clutch disc.

savannah996

well its not good to internet diagnose but; it is possible that;
1. noise is from aftermkt clutch & flywheel
2. input shaft bearing. (when you press the clutch the input shaft/clutch disk slows down) so if they malfunction you can get a noise too)


it is important when the clutch was replaced to observe/note new noises. and if you didnt replace the clutch & the previous owner cant tell you, none of us can guaranty what is going on.

jrgordonsenior

TO bearing if it disappears when you depress the clutch...

Darren

Right...and it just so happens the car recently had a racing clutch put in? If it's a rattle thats what it is, don't worry about it, turn the radio up

Macster

Unlikely to be release bearing cause it would get loud when you depressed clutch pedal.

Noise most likely coming from clutch disc rattling about a bit on the transmission input shaft.

The splines have to have a bit of play and things are just a bit on the loose side the thing can rattle.

Normal though I will admit the noise a bit disconcerning. I hear it once in a while from my 02 Boxster and I think oh oh then remember to depress the clutch pedal and it goes away. Stays away too when I release pedal.

Even hear on from my Turbo, in fact it is worse from the Turbo even though Turbo has just 17K miles and the Boxster has 225K miles and AFAIK the Turbo's on its original clutch and the Boxster I know is on its original clutch.

Sincerely,

Macster.