Rattle on Decelleration

...I'm thinking it's the throw-out bearing on the clutch - anyone else think the same?

I've got a 97SL2 and I've been noticing a mechanical noise too when I let off the throttle, especially on a downgrade.

On older engines this could be caused by knock as the vacuum advance advanced the spark a whole lot. I wouldn't think the same thing could happen with computer controlled ignition, but it might be worth checking the mechanical timing of the distributor.

In my 2002 SL that kind of sound happens when I release the gas pedal in any gear, often when I slow down to idle at stop. Saturn dealership confirmed that, but could not find the source of the sound...

M/T - Gear Rattle

BULLETIN NO.: 95-T-37A

ISSUE DATE: March, 1999

GROUP/SEQ. NO.: Transaxle - 04

CORPORATION NO.: 99-07-31-001

SUBJECT: Improved Manual :trans-axle Clutch Components and Updated Flywheel Inspection Procedures

Due to revisions in the service procedures, this bulletin supercedes bulletin 95-T-37, which should be discarded.

MODELS AFFECTED:

1991 - 1999 Saturn vehicles equipped with MP2 or MP3 manual transaxles

PURPOSE:

New manual transaxle clutch components have been developed to address gear rattle concerns on 1996-1997 and 1998 vehicles built before and including VIN WZ305219 equipped with MP2 or MP3 manual transaxles. The new components include a long travel damper clutch disc (P/N 21120564) chamfered flywheel (P/N 21120535) and new clutch cover (P/N 21120582). For the purpose of this bulletin, they will be referred to as the 2nd design components. The 1st design components consist of the past model clutch disc (P/N 21120453) flywheel (P/N 21120542) and clutch cover (P/N 21120455). The 2nd design components service Saturn vehicles back to the 1991 model year.

The 1st design and design components are interchangeable with one exception. The 2nd design clutch disc is not compatible with the 1st design flywheel or cover. Therefore, when servicing with the 2nd design clutch disc on 1991 -

1997 or 1998 vehicles with VIN WZ305219 and prior:

IMPORTANT: Mixing Of 1st and 2nd design clutch assembly components during repairs will result in the reduction of the clutch disc life.

^ The 1st design flywheel must be chamfered or replaced with the 2nd design flywheel.*(Refer to "Flywheel Chamfering" procedure listed in this bulletin.) Failure to machine a chamfer on the flywheel could create a noise concern in the manual transaxle as the clutch disc wears under normal operating conditions.

*1998 VIN VZ278819 and greater already contain the 2nd design chamfered flywheel.

^ The 1st design cover must be replaced with the and design cover.

The 1st design flywheel (P/N 21120542) maybe machined to create a chamfer so that it is compatible with the 2nd design clutch disc (P/N 21120564). This prevents a flywheel replacement every time the 1st design clutch disc is replaced with a 2nd design disc. Listed below is the procedure for servicing manual transaxle clutch components. In order to avoid service duplications, check service history of vehicle prior to performing any of the service procedures.

Also, when replacing the clutch disc and pressure plate due to normal component wear, it may be necessary to replace the flywheel assembly to ensure an effective friction surface. This bulletin provides guidelines to help determine whether a flywheel should be replaced.

PARTS REQUIREMENTS:

21120535 Asm-Flywheel

21120564 Plate Asm-Clutch Driven

21120582 Cover Asm-Clutch Housing ADDITIONAL ITEMS:

A protractor will be needed to create a template

S-Series had electronic ignition, there is no distributor.

Lane [ l a n e @ p a i r . c o m ]

Well, I'm definitly not thinking mechanical timing(since there is no distributor....) or throwout bearing(since TO bearing problems generally arise when you push in the clutch - nothing to do with gears themselves).

Excessive rattles could be caused by a worn out upper motor mount though. If it has gotten worse then it originally was, maybe its due to that. Your best bet is to either track down a mechanically inclined friend or if you want to spend the $, go to the dealer and take a tech for a ride.

snipped-for-privacy@aol.comNHRA (BANDIT2941) typed until their fingers bled, and came up with:

Actually, my TO bearing acted just as he described - would rattle when I let off the gas and before I hit the clutch. The bearing has no pressure on it until you hit the clutch, so it can get a bit loose in its arm.

Interesting........I've always heard them rattle while in neutral, as opposed to when driving. To the TO bearing I don't think it matters whether you're actually moving for they symptoms to occur.

Wow! Thanks for all the quick replies!

I have noticed the gear rattle for a while... but other than minor rattle it doesn't bother me.

The rattle that I've been concerned about however is a high-pitched rattle (decelerating at a high RPM in any gear, just used 3rd as an example), and it's definately coming from the engine compartment..

I think I may end up taking it down the dealer just to have a listen... I suppose the best way I can describe the noise is like a rattling chain.

Thanks again for the replies.

Cool, Kirk!

duplications,