Dr. Hugo Posted August 18, 2010 Report Share Posted August 18, 2010 HI, Maybe the cross shaft weld sheared at some stage and someone re-welded it.... However having said that, if one formulates the hypothesis that this is not the case, what else could it be? The mechanical relationship in the total distance between the piston in the slave cylinder and the clutch pressure plate release mechanism is incorrect it would seem, or simply the position of the lever arm when the clutch begins to engage, assuming the rod it standard. If one assumes that the thrust bearing is a standard part, then possibly the anomaly is in the clutch pressure plate mechanism and the physical position of this is not in a standard position, due to either the brand or type of pressure plate mechanism(is it a clone or repro unit ?) or an excessively machined flywheel face, altering the relative position of the whole pressure plate assembly and therefore the facets on the pressure plate where the thrust bearing interacts with the pressure plate. However, it may just be your cross shaft and or pin, and ultimately it is the reationship of the lever arm on it and the hole for the pin in it which will have to be checked to determine if the cross shaft is the cause and the pin itself checked as suggested. Best regards, Hugo. Quote Link to post Share on other sites
randall977 Posted August 18, 2010 Author Report Share Posted August 18, 2010 'Machined flywheel face' - it's the first new idea and it would pull the mechanism away but it would have to be machined very heavily (like you say). Does the WSM have a dimension for the thickness of the flywheel? I'm 99% confident all the internal components are original spec. Quote Link to post Share on other sites
Ian Vincent Posted August 18, 2010 Report Share Posted August 18, 2010 The attached photo is of TR3a clutch lever. There is a new friction plate and the original pressure plate plus the flywheel is 'as original'. The gearbox/bell housing is from a 2000 saloon. I know that the thrust rod should be attached to the centre hole on the drop arm but it was a better alignment on the bottom hole. I figured it would be easy enough to change if it wouldn't work properly. Rgds Ian Quote Link to post Share on other sites
randall977 Posted August 18, 2010 Author Report Share Posted August 18, 2010 Thank you for the photo Ian - mine looks vey different - it's way out! I have almost removed the gearbox again... I think the problem must be the pressure plate - although it looks fine and has been looked at by a specialist it must be out of spec. I believe I have bent the taper pin again (I think this is what I will find tomorrow) and it's because the force required to activate the pressure plate is too great (though I don't know why). I tried the clutch again tonight with the slave in the new location but it made no difference - it's as if the pressure plate is refusing to fully lift off the clutch plate. I don't believe the fly wheel has been skimmed. I will order a new Borg and Beck clutch kit and fit a replacement cross shaft. So much for trying not to spend too much more money! Quote Link to post Share on other sites
Chris Mountford Posted August 19, 2010 Report Share Posted August 19, 2010 Hi again, Yes it is possible to break the drop arm off - happened to me 30 years ago with a Dolomite Sprint with a Borg and Beck clutch- rediculously heavy clutch operation - same components but the drop arm is cranked. You seem to be having trouble with these tapered clutch fork pins bending. I cannot imagine how this happens as they are v'hard and shear in service. If they are bending as you wind them in, you do have an alignment problem. Does the shaft look to have been drilled out of line or something like that. They are not as 'hard' as the originals - I bought one a few years ago with a tiny sticker on it saying ''made in Ch na'' Didn't inspire confidence. I still reckon you may have an alignment problem with arm and fork, may also be worth checking you have the correct length release bearing carrier (sleeve). Chris Quote Link to post Share on other sites
randall977 Posted August 19, 2010 Author Report Share Posted August 19, 2010 Hi Chris, all the components are original... I have just ordered a new Borg & Beck clutch assembly which includes the pressure plate, clutch plate and thrust bearing. I am also going to fit another (not new but in good condition) cross shaft, fork and pin. So basically I will have replaced every component...it will have to work then! Below is the existing pressure plate - it's original and appears to be okay...but maybe it's not??? The clutch plate is new (supplied by Moss) - it looks like the original one but could it be too thick? Below is my thrust bearing carrier - I believe it is correct for a TR4 - can anybody confirm? I have toyed with the thought of swapping it for a TR4a one which is longer and thus would remove a lot of play but I guess they used a short one for a reason on the TR4? Quote Link to post Share on other sites
Ian Vincent Posted August 19, 2010 Report Share Posted August 19, 2010 Another thing to look at are the pins in the release fork. They should be round but over time they develop a flat where they act on the thrust bearing. They are a press fit into the fork so you can either replace them or do what I did which was press them out and rotate them by 180 degrees before pressing them back in. I used some loctite bearing super glue just to make sure they were going to stay put. Rgds Ian Quote Link to post Share on other sites
Alec Pringle Posted August 19, 2010 Report Share Posted August 19, 2010 What appears from the photo to be significant wear on the three 'fingers' isn't going to help . . . . Cheers, Alec Quote Link to post Share on other sites
Smokey Posted August 19, 2010 Report Share Posted August 19, 2010 What caused the wear on the fingers? It almost looks as if the bearing seized at some point. Quote Link to post Share on other sites
Dr. Hugo Posted August 19, 2010 Report Share Posted August 19, 2010 Hi Again Christian, I had wondered as per my previous email about your pressure plate assembly. I have a tr4A, the unit in mine, as I recall, when I had it out, looked quite different to yours, with the 3 worn looking activation arms, mine had an array of many arms. Mine though was made by PBR in Australia, which are direct clone of Borg & Beck I was told. The other types here are made by Exody. I think there is a large variation in the spring pressure forces in various types of pressure plates,some are repro clones made by a number of MFR's. Back to the basics though, the oddity about your problem is that despite your attemps to adjust the mechanical play out of the system, the dynamic range(mechanical motion range) of your push rod, was not enough to fully disengage the clutch. That range is fixed by the clutch pedal mechanical geometry and the ratios of the bore sizes of the master and slave cylinders. The effective dynamic range, translated to the ratio of pedal motion to thrust bearing movement, could be altered by moving the link to the top arm hole and you might get better disengagement, but that would be non standard. Your trouble is highly suggestive of a pressure plate/clutch plate problem then. In general it is wise to replace both the pressure plate and clutch plate as a kit, both made by the same manufacturer, or else engaging/disengaging problems may occur, and perhaps that is your main problem, mismatched components, assuming of course that the notorious fork pin is not in some partially sheared off state. Best regards, Hugo. Quote Link to post Share on other sites
randall977 Posted August 19, 2010 Author Report Share Posted August 19, 2010 The TR4 clutch pressure plate and TR4a are very different. My pressure plate is original, the thrust bearing is original, the only thing which isn't original is the clutch plate itself (supplied by Moss). The one thing that was different about the new clutch plate is that the central spline was the opposite way round to the original - the central spline is not equal on both sides - it protrudes further on the bell housing side. On the new clutch plate the central spline protrudes more towards the engine - I couldn't see that it would make any difference though as it didn't come into contact with anything - but why was it changed? The clutch plate as a unit can only go on one way round - if you put it on back to front the springs push against the flywheel and the plate will not lie flat... Quote Link to post Share on other sites
RandallD Posted August 19, 2010 Report Share Posted August 19, 2010 I can snap some additional pictures for you on the TR4 release bearing tonight if you need them. The bearing should be flat, which yours appears to be. You do not want to use a 4A-TR6 release bearing, someone did before me on my TR4 and it will ruin the pressure plate by wearing the fingers away - perhaps that is why you have wear as well on yours? Regards, Randy Quote Link to post Share on other sites
randall977 Posted August 19, 2010 Author Report Share Posted August 19, 2010 Hi Randall, no it is the correct bearing and always has been. The carrier however is deeper on the 4a but should be able to take a 4 bearing - this would reduce the distance the cross shaft lever would have to move. Christian Quote Link to post Share on other sites
Geoff359 Posted August 19, 2010 Report Share Posted August 19, 2010 (edited) Hi Christian, I have a spare engine (1962 TR4) and I have just taken the clutch pressure plate off. The driven plate looks much like yours and is the same way round (raised springs to the gearbox). I have measured the lining thickness with a micrometer(the plate looks fairly new) and it is 8.6mm near the edge. If yours is near to this then the driven plate is not too thick. This would seem to confirm that your clutch is assembled correctly. Hope this helps - if you want any further measurements, just let me know. Geoff Masterman PS Thrust bearing and carrier are the same as mine. Edited August 19, 2010 by Geoff359 Quote Link to post Share on other sites
RogerH Posted August 19, 2010 Report Share Posted August 19, 2010 Hi Christian, I don't want to cause a panic but is the friction plate, you show, of the 'three' rivet design. It has three rivets holding it all together. This was cause for great concern a short while back and would fail easily and regularly in the 5 & 6. Can anybody confirm it is the same style ????? Roger Quote Link to post Share on other sites
stuart Posted August 19, 2010 Report Share Posted August 19, 2010 Hi Christian, I don't want to cause a panic but is the friction plate, you show, of the 'three' rivet design. It has three rivets holding it all together. This was cause for great concern a short while back and would fail easily and regularly in the 5 & 6. Can anybody confirm it is the same style ????? Roger No thats not a 3 rivet one. They only have three rivets holding the entire outer plate on. The one in the picture has them all the way round. Stuart Quote Link to post Share on other sites
RogerH Posted August 19, 2010 Report Share Posted August 19, 2010 ...thank heavens for that. At least Christian has something going for him. Roger Quote Link to post Share on other sites
randall977 Posted August 19, 2010 Author Report Share Posted August 19, 2010 Hi Geoff - very useful information - I will check dims tomorrow when I access the inside of the bell housing...for the fourth time! Quote Link to post Share on other sites
RandallD Posted August 19, 2010 Report Share Posted August 19, 2010 Hi Randall, no it is the correct bearing and always has been. The carrier however is deeper on the 4a but should be able to take a 4 bearing - this would reduce the distance the cross shaft lever would have to move. Christian Oops, sorry I was too focused on the bearing itself and didn't realize you asking about the carrier. It still concerns me on the amount of wear you see on the pressure plate fingers - perhaps as has been suggested it was due to a bearing seizing up at some point? The wear on the fingers does add to the issue with the throwout lever, though I doubt it is the sole cause. Quote Link to post Share on other sites
Smokey Posted August 19, 2010 Report Share Posted August 19, 2010 Wear on the fingers, depending on the degree of wear, could cause the symptoms you are describing - the wear moves the release point of the shaft lever counterclockwise. Is that a new pressure plate? Quote Link to post Share on other sites
Guest ntc Posted August 19, 2010 Report Share Posted August 19, 2010 (edited) What appears from the photo to be significant wear on the three 'fingers' isn't going to help . . . . Cheers, Alec Agree Alec Can you measure the wear point's? Edited August 19, 2010 by ntc Quote Link to post Share on other sites
Geoff359 Posted August 20, 2010 Report Share Posted August 20, 2010 Hi Christian, Further thoughts; when you remove the clutch again (!) place the pressure plate assembly face down on something soft (e.g. old carpet, put something round (old release bearing?) on the forks and then put your weight on that. This should operate the clutch as if you were pressing the pedal. I suggest this to make sure you don't have partial (or full) seizure of the springs which could be caused by one or more broken release springs or something (loose washer or nut) jammed in the mechanism resulting in failure to release. If you get the full movement (.47" or 11.94mm or close to that, according to the WSM) then you will know it's not the pressure plate that's at fault. Good luck! Geoff Masterman Quote Link to post Share on other sites
randall977 Posted August 20, 2010 Author Report Share Posted August 20, 2010 I hope to remove the gearbox tonight or in the morning so I will full inspect the pressure plate then... I've bought replacements for it all so am just going to swap it all over - it would be nice to find out what's wrong but it might be the case taht I never do - as long as it works! Quote Link to post Share on other sites
randall977 Posted August 20, 2010 Author Report Share Posted August 20, 2010 Took the bits off again found the second taper pin bent (which is a real shame as it was original - held up much better than the (apparently) hardened new one). The new pressure plate prongs stick out quite a bit further than the one which is fitted...the new bearing looks a bit meatier. I'm pretty confident that my problems are almost over. The two clutch plates are quite different in appearance - the latest one is not as the WSM but probably is where it counts. I'm going to fit the new new one as it is as the WSM just to be sure! Over. Quote Link to post Share on other sites
TR 2100 Posted August 20, 2010 Report Share Posted August 20, 2010 (edited) Took the bits off again found the second taper pin bent Surely the question is - why was yet another taper pin bent? Sounds as if something was fouling something else, preventing proper movement of the clutch. Which you would need to resolve before you re-assemble. AlanR Edited August 25, 2010 by TR 2100 Quote Link to post Share on other sites
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