Chuck Jones

I know this subject has made the rounds a couple times, but I've gone out and done some runs looking for specifics.

There have been a number of guys complaining about a high pitched vibration in the clutch pedal.....Some have advised that Porsche says this is "normal", others have said that their accumulator was replaced, or the clutch was replaced, but the vibration has continued. There was some talk about the power steering fitting failing and causing a vibration...how a power steering fitting in the engine translates to a vibrating clutch I dont know.

I went out and got a smooth stretch of roadway....and took the 02TT X50 thru the gears from both hard and soft launches. What I noticed was that the vibration only came on under load right when the tach hit 4,000rpms. This was the case in 1st thru 4th gears.....each time on cue under load at 4K the vibration became very noticeable in the clutch pedal. You can also feel it if you let the clutch all the way out in 3rd and keep it at 4000rpms, then lightly put your foot on the clutch and press in very slightly....the vibration feels like a buzz in your foot. It didn't occur when cruising in 6th even when I tromped it....so it's the lower gears under load.

Is this a condition that you other folks are encountering? Have any of you replaced a part or had some adjustment made that took the vibration away? To me a vibration means something is out of round, unbalanced, or loose.

chuck

Dock

I haven't experienced this in my '02 Turbo.

Is there any vibration in the accelerator and/or the brake pedal at 4000 RPM? Can you feel the vibration in the steering wheel, or seat, or through the shift ****?

Chuck Jones

No...I was attentive to any other vibrations in the shift lever, steering wheel, or dash....and it was only thru the clutch pedal at the rpm as I indicated. I hope that if it is the clutch, the CPO will take care of it and not classify it as a wear item like they did for the radiator hose that blew.

Kevin

CPO info..

http://www.porsche.com/filestore.asp...letype=default

Chuck Jones

Thanks for posting that Kevin....I was unaware that there was anything written up on the CPO...just that when I got it to the dealership, they'd tell me whether or not it was covered.

In reading thru the list, I can see that the clutch isn't covered....goes along with the radiator hose, and rear struts that went out on me and weren't covered. But can't complain too loudly if the BIG items are covered....at least until this September.

TustinJim

I haven't studied the RPM and vibration connection, but your description is similar to how my TT operates. It's not all the time, but it's there, along with a high pitched whine at start-up.

adam_

Hey Chuck-

It would seem that if it was JUST the clutch assy it would be there in every gear. The fact that it is only there with certain gears indicates to me that it may be related to the gears themselves and the power that is being conducted along that specfic mechanical connections- you just FEEL it through the clutch.

It could also be a weird combination of transmission mount loading and suspension loading that hits a resonant frequency only at certain speed/rpms. Tranny mounts good?

Adam

Last930

Could it be that you are depressing the clutch pedal just enough to make the T/O bearing contact the pressure plate? I have always been taught to keep your foot off the clutch pedal unless you are in the process of shifting.

Chuck Jones

If it was the TO bearing, wouldnt' I feel it as soon as I depressed the clutch rather than having it not start vibrating till it hit 4000 rpm.?? Also, after I've shifted, if I get it up to 4000-4500 rpm then slightly ride the clutch pedal, I can feel the vibration....but again, if it was the TO bearing, I should be able to feel it as soon as I depressed the clutch when starting out in first. Other than that...it seems to run just fine. I always drive tuned in to the car's sound and feel...and this just feels wrong.

Last930

I have had 2 cars where I had to replace the T/O bearing, both seemed to work fine with no noise when fully depressed, but both made weird noises and vibrations when the clutch was engaged (foot off the clutch).

You probably know this, but as I understand it the T/0 bearing sits there in the actuating arm, not spinning, until there is some pressure on the clutch pedal, which pushes the bearing against the pressure plate to disengage the clutch. That starts the T/O bearing spinning until the pressure is released on the pedal. A poorly adjusted clutch pedal can keep the pressure on the t/o bearing so it always spins causing accelerated wear. That would be felt as a vibration at first and i would think it would change with the RPM. This is just my opinion however, there are experts with much greater knowledge of the 996TT clutch on this board!!

Kevin

Chuck, at one point you are going to have to make the decision to start to replace parts if you want to solve this issue. The three parts that I would replace would be the clutch slave which the CPO warranty WILL replace, and at the same time purchase the accumulator and have them screw it on the new slave cylinder. I would also replace your power steering reservoir. You most likely will have to pay for the pump reservoir and accumulator.

Chuck Jones

Thanks again Kevin....I believe you are right. I went out today and took it thru the gears. It's only after 4,000 rpm that I feel anything....then that annoying high frequency vibration starts.

I guess my question is how do I get them to replace the clutch slave under CPO unless they actually agree with your assessment and prescribe that solution? I guess you're saying that the power steering reservoir and the accumulator are going to be classified under the CPO as "wear items"?

From my exposure to the so-called CPO "warranty"....I show up and leave the car, and they then call me and advise me of what they feel is covered based upon some rather nebulous criteria.