Vibration....help!

[tifosiman]

OK, I need some help diagnosing a problem. I let a friend of mine (female) drive my car two days ago, and she kept "popping" the clutch and when down shifting, she didn't "blip" the throttle to make the revs match the downward gear selection. This continued for about 20 minutes until I could stand it no longer, and after repeated attmpts to explain the error of her ways, I took over and drove it home.

NOW, today, I hop in it to drive to work, as it is a nice day, and there is a very noticable vibration that resonates thru the shifter and the clutch pedal at 3000 rpm. This also occurs when just reving it up above 3000rpm when standing still, not even moving.

So, what do you guys think? Is it?:

A. Clutch center gone (although the clutch has less than 10,000 miles on it)?

B. Balance shaft issues?

C. Some other expensive issue.....

Thanks in advance,

Upset Tifosiman

[JH924S]

sounds like a balance shaft problem to me, my mechanic said when theres alot of shifter vibraton at high revs it usaully the BS.

[tifosiman]

Damn. And how expensive or difficult is that? It was probably just time for it to go, she couldn't have caused that, right? (the car has 75,000 miles on it).

Tifosiman

[JH924S]

i dont see how she could have but it is just what it sounds like what my mechanic explained to me.

[85944na]

i have a similar vibration, but it's no my balance shaft belts, they have been checked. I'm at school away from my car, and my car is at home in the garage so I dont drive it. I plan to fix the vibration in the spring I think my flywheel is warped

[tifosiman]

Thanks, I have an appointment Thursday to take it in to Ken Farler at Farler Performance, one of the few authorized Porsche Mechs around. If he can't figure it out, then I'm hosed. (you chould see this shop, it has so much "eye-candy" there----several 951's, several 930's, and a bad-ass twin-turbo...)

Wish me luck. I may have to say "Hi, I'm Ben. Ben Dover".

Tifosiman

[T86951]

Sounds like your balance shaft belts has jumped a couple teeth. I had that happen once, mine jumped 4 teeth) and a vibration from idle up through about 3500 real bad about 3000. Thats not a clutch problem.
And no she didn't cause it, you ever seen them race 944's and 951's, talk about what looks like abuse but they take it.
I thought my muffler had broke off and was vibrating the whole car when that happened to mine. My mechanic said he couldn't figure out howit jumped the teeth. He just let the tention off the belt and lined it back up.
Belt is most likely too loose and jumped , have you had it retentioned?
Now I guess its possible its in the torque tube or somewhere in the drive line. put it in neutrel and rev it up and if it does it then I couldn't see how it could be in the drive line. Do that also with it in gear and the clutch in . If it does it both of these ways I would bet on the belt.



[This message has been edited by T86951 (edited 11-06-2001).]

[drew1]

If it vibrates with the clutch mashed in probably something on motor side of clutch, maybe balance shafts out of time but that would vibrate all the time.

With clutch let out & standing still, its a good chance its the torque tube.

drew1

edit: I would still look up in the bell housing for peices of rubber.

[This message has been edited by drew1 (edited 11-06-2001).]

[tifosiman]

It's not the torque tube, it does it when the car is moving or when I push the clutch in and rev it as well. What little I've read about it here in the "search" mode leads me to believe it's balance shaft issues. Hopefully it's just a belt slippage, that would be nice....that can't cost TOO much money, although I know that's all relative (to a Porsche). Suspensions and other stuff I'm OK wrenching on myself, but this is something I don't want to tinker with, I think. So, off to the Garage.

Tifosiman

[Penz944]

Yea, it can not be the clutch because it was replaced 1000 miles before I sold it to you and it was replaced with the new spring center clutch. I would assume like most others that it could be the balance shaft belts? It always had a slight vibe at 3 when I had it but it was hardly noticeable to I never worried about.
Good luck finding out whats wrong.

------------------
My old 944, now it belongs to "tifosiman."
My 944 page

[perry951]

If you are skipping teeth on the balance shaft belt.. you have a problem, or it is mot tensioned well at all.

Perhaps a blessing in disguise. You can take the chance to do the timing belt as well.

If there is no vibration sitting still and revving, then I would look at the driveline. She could have glazed the cluch if she was a litthe harsh on it.

The way to fix it is to:
A- Have the flywheel and pressure plate resurfaced and a new disc put in

B- Accel from a stop allowing the clutch to slip a little for a second or 2. This will wear off any high spots caused by a touch of glazing.

I have used the B method many times before on my old Talon when someone else drove it.

[tifosiman]

Thanks for the input guys! I'll let you know what it was when I get it back. The Timing belt was done not too long ago, but it can't hurt to redo it at this time as well. I'll give you all a full report, including cost...

Tifosiman

[Lawrence Coppari]

Have to wonder about the balance shafts that are turning at 2X engine speed. If you don't match engine speed to drive train speed, the balance shafts have to suddenly match engine speed. The belt has to do this. If you have ever turned a shaft with your hand, you know there is a lot of inertia. The shafts are about an inch in diameter with a knob at the end made of differing pieces of metal so it is imbalanced. Suddenly changing the speed of these things could easily cause a loose belt to slip a notch or two. The things are substantial.

If I had to guess, my guess is the top shaft has slipped a cog. The bottom one has more of a wrap of the belt than the top one does.

[tifosiman]

That's the best explanation I've ever heard. Thanks! I'll keep that one in mind when I talk to her next.........

Tifosiman