wvandenberg

Recently purchased a 1995 993 Carrera, which has had it's clutch replaced with a RS clutch within the last year/less than 5000km. It's supposedly an upgrade; more durable etc. However it seems noisy, esp at low revs & low speeds. Kind of a grating noise that disappears as revs rise. I've been told this is typical of RS clutches; any comments anyone?

Martin S.

I have had an ANDIAL (Former California shop, now out of business) LFW and RS clutch package for many years...in fact it has 50,000 miles on the package...lots of track miles...it just keeps going.

The stock dual mass flywheel was a compromise as many things are in cars. It is quiet...but it can separate and fail. Mine got real clunky before I replaced it.

When the engine is running and you are stopped, and in neutral, put the clutch in. If the clattering gear noise goes away, welcome to the world of Light Weight Flywheels.

To get rid of the noise, recommend a FD Motorsports sport cat package with Stage III mufflers. You'll be so enraptured by the sound of the car's exhaust, you'll not notice any extraneous clutch/flywheel noise.

Guest89

Yes, I have Stage III mufflers, Wevo engine mounts (blue pillow), Motorsound airbox, and just recently added the RS clutch and lwfw along with FDM goldenrod and ssk. Gear chatter is perceptible, but I really like it. Mine doesn't at idle (or at least I can't hear it at all), but it does at low revs when pulling off. Can barely hear it with windows up.

911PERVY

Quite normal you get that noise at low revs with the single flywheel setup. Try getting from 800rpm to 6000rpm as quick as you can, that should take your mind off the noise!

doc_porsche

+1

mhm993

The lwfw sounds like a bag of bolts as you pass around 2000 rpm. Great upgrade for the track, kind of annoying on the street, perhaps.

jhg41977

I have a 96 with the lwf and rs clutch. I also added rs engine mounts. Its a bit moist at low rpms when you are chugging along. I hear the cure is a louder exhaust, so I called FD motorsports and ordered a 200 cell sport cat with stage 2s. That should take care of the noise.

Mike J

The noise it not the clutch, its the transmission since vibrations from the engine side are now not damped by a DMF. Funny, the experiences here seem to be a bit different than mine. With my RS clutch (on my previous car) its obvious that, in neutral with the clutch out, you can hear the transmission get noisy as the gear sets vibrate and clang against each other. If you push the clutch in, the noise goes away since the transmission is now not rotating. When you engage first gear and you take off, the noises go away and the transmission is quiet unless I am booting it -> then I can get a bit of gear lash noise at lower rpm's (weird sound - not rattling but a bit of a whine) which goes away as the RPM's rise. That might be what you guys are talking about.

Again, its not the clutch making the noise, its the removal of any dampening that the dual-mass flywheel used to do since on the RS clutch the flywheel is one piece.

Cheers,

Mike

Cupcar

The flywheel is the problem, the RS and C2 use the same clutch pressure plate.

The reason the gears make noise is that the crankshaft is not turning smoothly like an electric motor but undergoing periodic oscillations with the accelerations and decelerations as each cylinder fires. This oscillation makes the gears rattle against each other. The dual mass flywheel has two masses coupled by rubber which damp these oscillations but the greater mass slows throttle response - and adds around 15 pounds to the car as well.

JPS

Not to hijack, and I know it is ok, but WHY is the metal on metal of the gears rattling ok?

porsche_fan

So a quick follow up question.

Once a LWF is installed, I understand why you get the noise at idle sitting in neutral with the clutch pedal out (gear lashing due to the lack of dampening). However, the noise that you hear at low rpms while accelerating (up to 2,000 rpm, and then disappears as the revs rise), is that noise also coming from the transmission?

jhg41977

Mine rattles under hard acceleration in first and second gears up to around 2200rpm. From what I have read this is normal and is due to the reasons above, gears and shafts rattling about.

Mike J

The in-neutral idling seems to vary from none to fairly loud. I just did a RS clutch, and the transmission is quite quiet in neutral. I do not know if this varies because of temp, oil type, wear, or what - but it does vary.

My understanding is the noise you hear when accelerating at low RPM is gear lash in the transmission, of which outside a rebuild or trying different oils you cannot do anything about. That also seems to vary from completely absent to quite loud.

On my Targa, I had both noises (transmission - fairly noisy when hot, a bit of a transmission whine pulling at low RPM's), and drove it a good 35,000 miles on the RS clutch before selling it with no apparent issues. That was over two years ago and the clutch/transmission is still working great.

Cheers,

Mike

porsche_fan

Thanks, that is helpful. As Mike suggests, it does appear to vary quite a bit. In my car, the sound at neutral is not very loud (you really have to listen for it) but the noise under low rpm acceleration is definitely noticeable.

I found this transmission fluid (mixture) recommendation for BMWs: http://www.uucmotorwerks.com/html_te...nny_rattle.htm

Anyone have thoughts on this? Has anyone tried this or something similar? If you were to try it in a 993, would you put 2 quarts of each?

Cupcar

The sound is due to the fact that the crankshaft is not going around in a smooth rotation. Each cylinder firing accelerates the rotation for a bit then it slows a bit before the next cylinder firing creating an oscillation in rotation of the crankshaft.

This oscillation in rotation of the crankshaft rattles the gears - literally.

The dual mass flywheel has a mass connected to the crankshaft that is separated by a spring system to another mass which is connected to the clutch and thereby the transmission. The spring working between the two masses damps the oscillation.

As the engine turns faster, the period of oscillation becomes shorter and the noise disappears.

Higher engine performance in this case does not equal NVH control.