Hello, I've been lurking on this site for the past couple of years since I got my 1st 944n/a 3 yrs ago. Last year I traded it for an 88 944S.

I've been doing my own repairs, as I have on every vehicle I've owned in the past 20+ years, and trust my own abilities more than most mechanics that I've dealt with. However, this car has me stumped !

My 1st 944n/a ran smooth at all rpm's, but on this 944S I have a heavy vibration in the shift lever @ 3100 - 3200 rpm that I've been trying to fix with no luck. I've searched the archives for a solution many times already. I suspected one balance shaft to be 170 deg out, But - NOT! Here is what I do know (or think):

1) The vibration is engine related - it can be felt in all gears including neutral, regardless if the car is in motion or dead stop, clutch in or out - always at 3100 - 3200rpm plus a high freq. buzz at idle.
2) It is not the motor mounts - I replaced the 16 yr. old originals with genuine Porsche mounts - no change.
3) Does not appear to be balance shafts - The belts were replaced by the P.O. 1000km before I purchased the car by a local respected Porsche specialist. - I rechecked the tension (optibelt tool) and the balance shaft alignments are correctly timed exactly on the marks (@TDC as verified by flywheel mark and cam cog) - Yes, I removed the bolt and washer to determine that the bal. shaft keyways are in the correct orientation as described in the Porsche workshop manual, "Clarks garage" and by the pictures posted here by many of you.
4) I do not think it could be related to the rubber centred clutch disk - it is still tight - no clunks - no signs of deterioration, and the fact that the vibration persists when the car is stopped in gear and clutch pedal depressed - i.e. clutch not spinning - so it can't vibrate.
5) I do not think it could be the torque tube for the same reason as above (#4)

Any ideas, I'm at a loss?

Thanks
Dan

 

Lurker, eh? Whatever.

Classic balance shaft symptoms. Take it to Jack at G-tek (755-7884) and see what he says. He won't charge you for checking it out, and he know these cars a lot better than you do.

 

i agree, its sounds like a balance shaft off a tooth.

Does the car rev freely? That's another symptom of balance shaft timing problems.

 

Having the lower balance shaft pulley installed in the wrong keyway typically causes this. Pull off the cover and if you can see the letter "O" in the round hole of the cover washer the pulley is installed wrong.

Edit: Sorry, I missed that you checked this.

 

If it is coming through the shifter, have you checked the condition of the shifter?

Nylon bushing, or the horizontal shaft being worn could maybe cause a harmonic type vibration....

My guess........

 

My instinct tells me that it must be the balance shafts, but I've checked twice now, and the alignment is perfect according to the manual.
The shift lever is good - no slop or binding in the linkage - always nice smooth shifts (my old 86 n/a had the worn linkage - so I know that feeling) in fact the lever is starting to loosen up due to the vibrations.
The engine does rev freely all the way to redline with lots of power - except it does have some trouble getting through the vibrations in the 3100-3200 range.
The car was very well taken care of by the previous owners - low milage (130000km's) and no sign of being winter driven.
Any other thoughts ?

 

How about the rollers? Does that year have some kind of auto tensioner?

 

i need to bring this thread back alive for vibrations even know everything is timed correctly and the O's are in the correct holes on sprockets, it is engine related any more suggestions?
Thanks
Josh

 

Seems to me that one way to rule out the torque tube bearings or shaft bent as the source would be to keep it stationary. Place the car in gear, any gear, clutch in, and parking brake on to hold the rear wheels stationary. Now rev to 3200 rpm. If the vibrartion is gone, then the torque tube is the culprit. However, if the vibration is still there, then it could be the flywheel/pressure plate assembly has worn out of balance.

 

Josh,

You need to post more details.

 

Possible clutch rubber center going bad?

 

This problem seems to be the flavour of the month.... I have the same problem (89, S2). In the process of having new CV's fitted in the hope of solving the problem. I get it back on the weekend hopefully.

 

I almost guarantee that the problem is the rubber center of the clutch. There is an old thread in the archives that had a guy replace and check everything before finally figuring out that this was his problem. If the rubber center is bad then it vibrates even with the clutch disingaged, im not sure why.

BTW I have the same problem on my 944S and I will be doing the clutch this fall.

 

Guys you are replying to a post of 10-5-2004!!!!

 

And its still a relevent issue!