John Vine Posted July 11, 2015 Share Posted July 11, 2015 As a follow-up to my recent clutch problems, I'm pleased to say my car is now back on the road, and running beautifully -- which is more than can be said for my bank account!I collected the car, plus a bag of old parts, last Thursday. My prime suspect (the slave cylinder) did not appear to be the problem at all. It still operated smoothly, and hadn't been over-extended in any way (for example, the crimp on the central guide tube was intact and undamaged, and the bellows moved smoothly).The fault was the centreplate, which was worn completely down to the rivets, but only on the flywheel side. The other side looked in pretty good nick. The friction material on the flywheel side had completely disappeared. It seemed to have been shredded into something resembling coconut fibre, and this was lodged around the edge of the cover and under the diaphragm springs.There are some photos here -- not a pretty sight!Edited 04Sep23: Due to Photobucket's refusal to support free photo storage, the above link no longer works. Here are the photos:Flywheel (scored):Centreplate (flywheel side):Centreplate (clutch-cover side):What could have caused just the one side of the centreplate to self-destruct in this manner? The only thing that comes to mind is that I'd completed the last 100 miles of my earlier journey without any clutch, following failure of the master-cylinder seals. Provided I could keep rolling, that was OK, but whenever I was forced to stop (junctions, traffic lights etc), I could only continue by starting the engine while in first gear. Could this have generated excessive strain on the centreplate?JV Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 11, 2015 Member Share Posted July 11, 2015 Glad you're rolling again. Jonathan Link to comment Share on other sites More sharing options...
John Vine Posted July 11, 2015 Author Share Posted July 11, 2015 Combien?Très bonne question -- un fameux montant d'euros! Bien plus de 3K.JV Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 11, 2015 Member Share Posted July 11, 2015 Did you offer drachmas?;-)Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted July 11, 2015 Share Posted July 11, 2015 Make nice paperweights. Nice to meet you both. Link to comment Share on other sites More sharing options...
John Vine Posted July 11, 2015 Author Share Posted July 11, 2015 Did you offer drachmas?Of course, but they just laughed. Tell me, why did you edit out the "combien?" from your post? It makes my response look odd to say the least! Thanks, Ian! And good to meet you two, too (sounds like an item of ballet apparel.)JV Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 11, 2015 Member Share Posted July 11, 2015 Sorry, thought it was too personal and possibly painful.Jonathan Link to comment Share on other sites More sharing options...
TJG Posted July 11, 2015 Share Posted July 11, 2015 Pleased to hear you have got it sorted John. I would have given long odds on a cover fault after reading your earlier posts. I have never seen a clutch plate fail in that manner during forty years spannering so I'd be very interested to learn the reason why as well, I doubt the last hundred miles had much to to with it.Tony Link to comment Share on other sites More sharing options...
Graham King Posted July 11, 2015 Share Posted July 11, 2015 John, I had exactly the same happen on my k-series (200bhp+), in my case it was the non-flywheel face that disintegrated, was all sitting in either the bottom of the bellhousing or caught in the fingers of the clutch cover. The k obviously has a cable clutch so the symptoms were different, but essentially the clutch pedal was significantly higher than normal and the change felt very odd, but I did manage to drive the car home but the track day had to be curtailed. It was only when I got the engine out could I see exactly what had happened. I was on a track day at the time and between myself and my son we had missed a few gear changes during the day so I assumed the clutch had been decelerated and accelerated abnormally and when being re-engaged it had experienced loads in excess of what it was designed for so had simply broken up. Graham. Link to comment Share on other sites More sharing options...
John Vine Posted July 12, 2015 Author Share Posted July 12, 2015 Sorry, thought it was too personal and possibly painfulMost considerate -- thanks. Not personal at all, but certainly very painful for my bank account!JV Link to comment Share on other sites More sharing options...
John Vine Posted July 12, 2015 Author Share Posted July 12, 2015 Tony: I plan to send my photos to CC for their opinion. I'll let you know what they say.Graham: Very interesting. I've been known to bounce off the limiter from time to time (very rarely on the road, though), but I do try to make smooth and synchronized changes. When it happened, all the free play in the pedal simply disappeared and the clutch began to slip furiously. At the time, I put that down to a slave problem. But, of course, the symptoms match exactly the loss of friction material. As well as the slip, the CRB would be pushed back 3mm or so, and the displaced fluid would end up increasing the height of the pedal. The one good thing to emerge from all this (apart from now having a pristine clutch) is that I no longer feel I had done something silly when I set up the new master cylinder 300 miles earlier. Maybe, instead, I've been abusing the clutch over the last seven years without realizing it? After all, the R400 does call for some spirited motoring. The odd thing is that I drove my old 1.8K SS-R in a similar fashion (trackdays included) and that (original) clutch is still going strong after 70+K miles!JV Link to comment Share on other sites More sharing options...
John Vine Posted October 4, 2015 Author Share Posted October 4, 2015 An update....I sent my old clutch parts to AP Racing for their comments. The actual cause of the failure remains something of a mystery, but two possible causes have been suggested: excessive heat due to clutch slip, and excessive revs.To me, clutch slip seemed unlikely as the earlier master cylinder seal failure led to a permanently engaged clutch. However, there always remains the possibility that I'd abused the clutch earlier in its life.As for excessive revs, the plate is rated at 8000 rpm, whereas my limiter cuts in at (I believe) 7800. That's alarmingly close! I'm left wondering if that margin is a little too thin?AP Racing have been absolute stars over this. They've cleaned up the clutch cover (100% serviceable) and refurbished the centre plate to their higher 9000 rpm rating -- all entirely free of charge. So, I now have a spare clutch assembly. I call that excellent service!JV Link to comment Share on other sites More sharing options...
SM25T Posted October 4, 2015 Share Posted October 4, 2015 Good news John. Link to comment Share on other sites More sharing options...
ChrisC Posted October 5, 2015 Share Posted October 5, 2015 Is it possible to fit a clutch plate the wrong way round? Link to comment Share on other sites More sharing options...
SM25T Posted October 5, 2015 Share Posted October 5, 2015 I think the centre boss is not the same length each side ? Link to comment Share on other sites More sharing options...
ChrisC Posted October 5, 2015 Share Posted October 5, 2015 The sigma one I changed last year, did have a "engine this side" marking, so just wondered. Link to comment Share on other sites More sharing options...
John Vine Posted October 5, 2015 Author Share Posted October 5, 2015 Is it possible to fit a clutch plate the wrong way round?It is, and it's likely not to work because of the offset construction. Either the flange that carries the torsion springs or the central splined boss will prevent the friction facing contacting the flywheel. You can see the offset in my clutch pics here. I think most centre plates are inscribed "FLYWHEEL SIDE" or similar -- certainly mine is.JV Link to comment Share on other sites More sharing options...
7 wonders of the world Posted October 6, 2015 Share Posted October 6, 2015 I think if the std plate had a rating of 8K its failure level would be way higher - there will always be a safe tolerance, and the *k wolud be a safe user limit only, and SFAIK this is the same plate used in the R500 which redlines at 8600.Out of interest what was changed to upgrade the plate? Link to comment Share on other sites More sharing options...
John Vine Posted October 7, 2015 Author Share Posted October 7, 2015 AP said they had fitted "steel back facings, good for 9000 rpm". As soon as the bits arrive, I'll have a look and report back.JV Link to comment Share on other sites More sharing options...
John Vine Posted October 17, 2015 Author Share Posted October 17, 2015 Well, a box arrived from AP. They'd included, FOC, what looked like a brand new centre plate (here and here). Brilliant service!Edited 04Sep23: Due to Photobucket's refusal to support free photo storage, the above links no longer work. Here are the photos:Coverplate side:Flywheel side:I don't know what the two tabs on the left of the flywheel-side face are. Could they be some sort of balance weight?JV Link to comment Share on other sites More sharing options...
ECR Posted October 17, 2015 Share Posted October 17, 2015 Balance weights seems a good thought, I can't imagine what else they'd be for. Interesting that the friction material is marked Valeo (clutch makers amongst other things ....) Link to comment Share on other sites More sharing options...
John Vine Posted October 18, 2015 Author Share Posted October 18, 2015 Interesting that the friction material is marked ValeoPerhaps AP get their facings here?JV Link to comment Share on other sites More sharing options...
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