Scott924S

The car reads 55,000 but the odometer stopped long before I got the car last year. Previous owner estimates more like 70,000 or so. I got very little in the way of records but the car did come with an extra engine, transmission and clutch (perhaps a sign that the PO knew problems were imminent). Probably not the best way to purchase a car, but for the price I paid and the smiles it has put on my face this past year, I have no regrets.

My hunch is that it still has the original clutch and that the vibration could be caused by its deterioration. Still, I want to rule out every other possibility before I dive into that project!

theiceman

are you absolutely sure your balance shafts arent 180 out ?

Mark Hubley

A good point, but yes, absolutely. After I replaced my front seals, the car ran smooth as silk (well, at least as smoothly as a Porsche 2.5 4-cyl can run) for a few weeks, including three days at the track. I can't see any way that a balance shaft would suddenly shift 180 degrees.

I checked the keyways, had my Obers all lined up properly, and had the timing marks set spot on.

Scott924S

Like Mark, I am also 100% sure balance shafts are correct. I know this because I am the one who installed the last balance belt and balance shaft sprockets, I am aware of the labeling issue Porsche had with regard to the lower balance shaft and how to correct for it, the car has run fine for a year since I replaced the belt, and the balance shafts were the first thing I rechecked when the vibration started last week. The marks are as I set them a year ago.

Mark, are the vibrations you're experiencing more prominent in lower gears? That is the case for me. Just wondering if that might be a clue of sorts...

Mark Hubley

Car now runs like a charm! I picked it up from Tif's in Annapolis today. They changed the clutch (along with pressure plate, etc. Flywheel was OK), and here is what seems to have been the source of the vibrations:



When I changed the clutch on my 944 back in 2006, I thought it was missing a big chunk of rubber. This is noticeably worse. I'm told that various pieces were caught up in the pressure plate.

I'm kind of bummed that I didn't do the work myself, but I've had a lot of other things keeping me very busy lately. I want to get one more track weekend under my belt in October, and I didn't know if I'd be able to get things done myself in that amount of time. I'm happy with the work that Tif's did. It cost me $3K, which also included a new starter and clutch slave cylinder, and they replaced a fuel line while they were at it. That's about what I was expecting.

Scott924S

Wow! That would do it for sure!

I've driven my car a few times since my last post and what now seems to be more worrisome for me is the amount of driveline slack and noise that occurs when engaging the clutch and between shifts. Did your car experience anything like that?

I'm glad you got your car sorted out. I'm a little scared of how much it cost you though. If it turns out my car is suffering the same fate, I think I will make it an over-the-winter project so I can still afford to heat my house at the same time

Mark Hubley

Before taking the car to the shop, I did notice the shifts were a bit "clunky." This may very well be the same thing you are describing as "driveline slack."

When I hold the clutch shown in the picture, I can rotate the central part (into which the driveshaft goes) quite a bit relative to the outer friction disk. That's because so much of the rubber is gone, and the rest is coming apart. So, when the clutch engaged, that rotation would give me a "clunk" that I could hear and feel.

I think you're heading for a new clutch. If you drive the car before replacing, I think there's a significant risk of you getting stranded.

Replacing the clutch isn't that bad a job. Do you have a garage? Before becoming chair of my department, I generally felt that I had some time to spare, but not so much money to spare. Now that I'm much busier with work, I still don't have that much money to spare, but I have even less time! So, I shelled out the cash.

Dougs951

Glad to see you got it sorted, and I hope to see you tomorrow at the Challenge.

Mark Hubley

Doug--I'll see you there in the morning, and I should have the 924S on display! Not sure that I'll stay all day. I may have two dinner tickets to give away to someone who wants them.

ZR8ED

Driveline slack or clunking on shifting is likely your clutch using the "limp home" safety tabs....your done..stop driving it, or at least drive it very gently. My rubber centre was shot, and the driveline would clunk if I was not extra smooth with the clutch take up. $3k and all was well again. Goodluck!

Scott924S

Sounds like I have my diagnosis then. I had assumed that since the the driveline slack and accompanying clunking sounds were coming from the back that I had a separate transmission issue.

From what I gather, replacing the clutch isn't difficult as much as time consuming, and since time is more plentiful than money right now, and I do have a garage, it's time to get to work!

Thanks, Mark and everyone else, for sharing your experiences!

eesquared

I have a 1983 944 . I recently replaced the timing belt and balance shaft belt and various tensioners and idlers. I checked the marks on the balance sprockets and they are on marks. I have a vibration at about 2800 rpm and I think it is related to the balance sprockets . When i put the sprockets back on i followed the diagrams with the 0 and not 0 keyways on the shafts. Can the washers that cover the sprockets be turned wrong?