Shudder???

944_85 · Jun 2, 2009

Hello All

Firstly, I am new to the forum and new to the Porsche world. I have bought my 944 at the end of last year, had to do various fixes, and took it for it's first drive on Saterday. Now the fun, and cost, start to fix the things I didn't note when the was standing still in the garage.

I noted when I was having my first drive, that take-off's got more difficult as the drive continued. I am sure when the car was cold, it was not the case. However after about 30 miles, I had trouble taking off smoonthly. I would start to release the clutch, then the car starts moving smoothly. Then there is an intermedeate phase while I am still releasing the clutch, while the car shudders. And after that the clutch is basically all the way out, and the car is moving.

Ysterday I had another test drive, and paid more attention to this. When the car is cold, take off is smooth and there is afsolutely no shudder. Going for a 15 miles test drive, and it is still smooth. However let it idle for a while on the driveway until the fans come on, and then the shudder is there.

Is this the clutch or something else?

Diver944 · Jun 2, 2009

This sounds like a classic case of the rubber centre of the clutch breaking up. As it gets warm its unable to take up smoothly and you get this shudder, it's often at its worst in stop/start traffic on a hot day. My own S2 will do this if I get caught in a traffic jam for a long while, but it's been doing this for 11 years and nearly 100k miles.

Clutch changing is not cheap on a 944, the part itself will be circa £4-500 and can involve 10-15 hours of labour .

Sorry [&o]

zcacogp · Jun 3, 2009

Morne,

Welcome. You made it over here from PH - I'm zcacogp over there as well. Thanks for coming across.

As I said, it does sound clutch-ish. BUT, as Mr Smith ('im up there ^^^) (not God tho') said, they can soldier on for a long time like that.

I have never had a decent explanation as to why it happens. As I said on PH, mine did it for 25k miles over 2 years, and was a royal pain when in traffic. However it still worked fine. A replacement clutch was a preventative measure on my part as I couldn't run the risk of failure, and the new clutch is nicer to use (and highlighted that the old one was possibly slipping fractionally, but not such that I noticed). However the rubber centre of the old one was fully intact and there was around 0.5mm of wear left on the drive plate - there was nothing visible to suggest the reason for the juddering.

If you live in the country and don't spend much time in traffic, you could well run the risk and live with it. Alternatively, if you spend a lot of time in traffic then a change may be in order. Snag is (as mentioned), clutches don't come cheap - the parts are pricey (c£400), and it's a BIG (but easy) job.

Oli.

Big Dave · Jun 3, 2009

Scotty.
Firstly the rubber is in the centre of the clutch plate ,NOT on the friction part. + secondly there is a inspection hole on the side of the gearbox [ usually has a rubber bung fitted , but sometimes it goes missing], im guessing its come out of there....

James_G · Jun 3, 2009

A very good point. Based on what I remember, there's no easy hole for it to escape from, although there is a way of checking the lining thickness but I thought that it was necessary to at least remove some form of plate first. If that's the case, (and I might not be) maybe that cover is missing.

Definitely I'd be annoyed if this had happened to me, but these are old cars that may or may not have been driven sympathetically, and presumably you knew that it hadn't had a new clutch when you bought it. At the very least in that situation I would have classed it under the heading "may need attention soon", as indeed you should be doing for your wishbones if there's no evidence of them having been changed either.

For reference my clutch was changed at 99k miles, but my wishbones soldiered on for another 48k miles.

Meanwhile, is there any other evidence underneath the car and are you absolutely sure that it's not the funny rubber/foam stuff that surrounds the gearlever mechanism in the cabin? Doubtful I know, but you have to ask.

Glad you are enjoying though, this issue aside.

zcacogp · Jun 3, 2009

The rubber in the clutch is, as BigDave said, in the centre of the spline drive from the drive plate. It is in place of the usual three or four 'cush drive' springs in a 'normal' clutch, and Porsche updated the clutch design after the manufacture of 944's ended such that clutches had the more normal spring arrangement. Therefore any clutch replaced in the last x years will have springs and not rubber. I think that the swap from rubber to spring was made about 8 years ago, but am not 100% sure. And of course, a clutch changed since then may have used a part which had been lying on the shelf for a couple of years, so may yet still be rubber.

As I understand it, the rubber was not the ONLY thing holding the clutch together - there was also metal, and if the rubber falls out entirely then there is a remaining metal-to-metal drive which comes into play, but which will be as fierce as h3ll and have about 50 degrees of lash - namely it will drive, but be very very unpleasant to drive and be in.

Yes, if the rubber starts to collapse then the rate of collapse will be exponential I'd imagine. And there are holes in the bellhousing (where the release lever goes in) which will allow fragments of rubber out. I'm not aware of there being an inspection port there, but there may be. That would be another obvious candidate for letting fragments out. (The measurement of the wear on the clutch is done by the slack position of the release arm, as I recall.)

red_gm, I'd be annoyed, but such is owning an old car. Rough when it happens just after you bought it. They could be (as James said) foam rubber from somewhere else, but those pictures look pretty solid, like clutch-centre rubber. If the general consistency is that of a tyre, it's clutch centre. If the consistency is that of something you may wash your back with in the shower (i.e. bath-sponge-esque) then they could be from the large foam block that surrounds the gear level mount on the torque tube.

If you do go down the replacing route there are posts galore on here and lots of people who can give you advice. It's a big job but not a hard one and two chaps can do it in a weekend with a good workshop and some hard work. Or, as you said, it's second-mortgage-spent-at-the-indy time.

Oli.

zcacogp · Jun 3, 2009

ORIGINAL: red gm
would it be reasonable to suggest that some of this rubber was getting in the way of the clutch disengaging, causing the problem selecting gears ?

Yes, very likely.

A story told on here by Fen (the late, great Fen - why doesn't he post anymore, anyone?) involves a rubber clutch failing and making the gearchange impossible, so he abused the clutch slightly, making the rubber fragments move out of the way and enabling him to drive the car again (clearly needing to be changed very soon afterwards.)

Oli.

zcacogp · Jun 3, 2009

ORIGINAL: sc0tty

Just seen your update Oli, luckily I don't use my car that much, I and rarely get stuck in traffic thank god !

Scotty,

OK ... lucky you! On mine, I took the shuddering as being an early indication that the clutch was on the way out, and worried about it, and got around to changing it a couple of years later. In practice, it was fine to drive for that time and very rarely did it (the symptoms only exhibited themselves when the car was hot, and you do indeed learn to 'drive around' it, by using more welly on take-off and so on.)

Having said that, the improvement with the new clutch was very noticable and it made the car a lot nicer to drive. And it freed me of the niggling feeling that the car was always about to break down. (Well, that feeling is still present but for other reasons!) The clutch is smoother, lighter and more positive, and I think the old one was slipping slightly in retrospect - mainly because it will now break traction in second on a dry road if you boot it while in gear whereas previously it wouldn't.

In short, the change was worth it but not essential! And I suspect it will soldier on for a long time with the judder present, if you can live with it.

Oli.

924nutter · Jun 3, 2009

Nah! At least I don't use lumps that small!

944_85 · Jun 3, 2009

Reading through the various replies, it seems that I have to keep in mind that my 944's clutch is on it's way out, and start to save for the replacement. As this is only a weekend car, I am not concerned about the "sitting in traffic" matter.

Are there any risk driving the car like this? Besides the clutch just one day deciding that it is totally "dead".
Any other parts which can be damaged, by delaying the replacement?

I have not had the chance yet, to get the car on a lift and measure the clutch via the inspection hole. But will do in the next week or two.

zcacogp · Jun 3, 2009

ORIGINAL: 944_85
Are there any risk driving the car like this? Besides the clutch just one day deciding that it is totally "dead".
Any other parts which can be damaged, by delaying the replacement?

Very unlikely to damage anything further. When you change the clutch you change a handful of other bits as well (seals, bearings etc) which would be the most likely things to be damaged by ruining the clutch, so that's not a problem. I guess the biggest concern would be that you somehow wedge a piece of rubber into the end of the torque tube, that I'd have thought that VERY unlikely, and even if you did then I'm not sure if it would cause any damage at all.

Drive it 'till it fails. Make sure your RAC membership is up-to-date. All will very likely be well. Particularly if you never use the car for a journey when you must get there.

Oli.