Date: Mon, 17 Apr 2000 01:08:00 +0200 From: Robert Brown <rjbnopsamnetNOSPAM.se> Subject: Re: More 900s clutch grief...sigh! (long, sorry)
Hi Don, comments embedded below: StepHydro wrote: > All right all you fine helpers, I finally got the clutch replaced in my > daughter's 1988 900s 16V, 5spd. Yep, I've been following (and posting a bit of help for) your predicament ;-) > > > It took me longer to do this clutch job than is did to remove the engine, > rebuild the transmission, and replace the engine unit. Miserable job, which > didn't have sufficient clearance, even with the 4mm thick holding ring I made. > But I did get it on. > > Now, there is a serious operational problem.When I release the clutch, there is > a great "grab and lurch" just as the clutch starts to engage. Here is the > cause: > > On the slave cylinder body, there is a plastic sleeve with a large circlip. The > device serves as a wear indicator for the clutch disk and I suppose as a dist > protector for the body of the slave cylinder. When the clutch pedal is > depressed, the slave cylinder body carries this sleeve out past the nose of the > slave cylinder body. I believe that it should not be doing this. The plastic sleeve (wear indicator) should fit on the slave cylinder housing, held on by the circlip. It should stay there regardless of pedal position. This means of course that the sleeve should be oriented so that the bulk of the sleeve is aft of the circlip, not fore. On the housing there is a ridge at about the same level as where the three allen key bolt heads start. Distance from this ridge to start of plastic sleeve / circlip should be 9mm for a new clutch. As the clutch wears over the years, the rest position for the thrust bearing will progress towards the front of the car, forcing the sleeve forwards too. When you get to 2mm distance remaining, the clutch should be replaced. > The extension (or gap) is on the order of 2.5mm when the > pedal is fully depressed. Should be no gap, since the sleeve should sit very snugly on the slave cylinder housing, always. > > > When the pedal is released, the plastic sleeve comes "forward" and contacts the > nose of the body. At this point, quite a bit of additional release of the pedal > is necessary to allow the pressure plate diaphragm spring to overcome the grip > of the circlip. When that happens, the pressure plate moves quickly, taking up > all the stress built up by the diaphragm spring, and the car lurches. I guess you mean that the plastic sleeve prevents release of the diaphragm spring and then suddenly lets go. Hard to picture this without actually seeing it. Let's hope that I'm interpreting the story correctly ;-) But I'm also wondering what kind of thrust bearing you received in the clutch kit. It's hopefully identical to the one you removed . . . > > > Now, in taller gears, one can gingerly depress the pedal and avoid the long > travel that causes the glitch. However, starting off, it is so disruptive that > I don't think my daughter will be able to drive it safely. I am certain the > when the plate wears enough to allow the sleeve to withdraw permanently > forward, then the lurch will go away. What also puzzles me is what is causing the plastic sleeve to travel aft when pushing the clutch pedal in. The slave cylinder piston should be able to move freely without taking the plastic sleeve with it. Remember, we've got this dirty great circlip holding it onto the slave housing, right? > > > Finally, it appears that the slave cylinder assembly pushes the sleeve too far > forward. I have thought through the assembly process and assured myself that > the exposed end of the piston *was* sticking through the sleeve and that that > end of the piston was engaged in the rubber "teeth" of the release bearing > inner surface. That piston has a step on its (toward the engine) outside > diameter. The shoulder of that step engages the palstic sleeve. The piston should not be engaging the plastic sleeve (though the more I write this, the more I begin to wonder if I haven't remembered this wrongly, but let's see what you say about that). > the sleeve > moves to and fro as the pedal is pushed and released. I can see that if the > sleeve was back (forward, that is :-) against the nose of the slave cylinder > body, this wouldn't happen. However, when I tried to get it back there prior to > assembly of the whole clutch, the force required seemed enough to break the > sleeve. should I have gone ahead and forced it? I think that the part of the sleeve under the circlip is spit to allow a certain amount of expansion, so you can force it on, as long as it's not so insanely cold that the plastic cracks. OTOH no risk in Tennesse in April. > If so, can that be done in > situ?? Should be easy, as long as the sleeve isn't on back to front. Just another thought: It also sounds as if you had to force things a bit to get the old clutch out, which could have resulted in the clutch contact surfaces on the flywheel getting deep scratches. I managed to get some small scratches there when I changed mine and it had one hell of a judder for a while when starting. Three weeks' use fixed that though. This is all guesswork. Would be great if you could post a reply saying how far on/off track I am on this one. Good luck, Robert Gothenburg > > > Help is greatly appreciated in advance. > > Cheers/Don Carron > Rockford TN USA
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