iainjames Posted June 24, 2022 Report Share Posted June 24, 2022 I noticed my clutch pedal overnight was no longer operating without pumping the clutch i changed the slave cylinder but that did not sort it. So I ordered a master Cylinder from Ebay was £30 or so unbranded like they all are. Fitted this to the car and the clutch works fine now however it is heavy not unmanageable but enough to make my leg ache. Could it be the cheap master cylinder. It was not heavy before I am thinking about getting one of the TRW ones that are £62 are these any better. Any help appreciated. Link to comment Share on other sites More sharing options...
NonMember Posted June 24, 2022 Report Share Posted June 24, 2022 How high is the bite point? Different from before? One possible cause of a heavy clutch is that the new master has a larger bore than the old, but that would also give more clutch movement for a given pedal movement, so the bite point would be higher. Maybe not as noticeable as the weight, though. Link to comment Share on other sites More sharing options...
Mjit Posted June 24, 2022 Report Share Posted June 24, 2022 The new master cylinder bore could be smaller than the old one. You should be able to check that without making a mess - you can measure the old one on the bench and should be able to pop off the dust caps and measute the open end of the new on on the car. I think if it was that the clutch bite point would also move...down(?) Actually trying to get my head doing maths, pressure = force/area so if the new master cylinder was a SMALLER bore the force required on the pedal would be LESS to get the same pressure - but the pedal travel would be GREATER to push the slave cylinder piston far enough to disengage the clutch (lower bite point). And conversly if the new master cylinder was a LARGER bore you'd require MORE force but the pedal travel would be LESS (higher bite point). Was the clutch weight the same before/after changing the slave cylinder? If it was it's probably just the master you need to look at but possible the new slave has a smaller bore - which I think would have the same effect as a larger master cylinder (as it's the ratio of master/slave cylinder bores rather than their absolute sizes). Link to comment Share on other sites More sharing options...
johny Posted June 24, 2022 Report Share Posted June 24, 2022 Might say the size on the side of the MC - think yours should be 5/8" but the cheap copies are usually for Landrovers and 3/4" bore.... Link to comment Share on other sites More sharing options...
iainjames Posted June 24, 2022 Author Report Share Posted June 24, 2022 it is the 3/4 bore the bloke selling them said that was a plus point and yes biting point is a lot higher which is a plus point. Has anyone used a TRW one they are British made but twice the price I will change it because in traffic its a right pain literally Just realised TRW are American but they get good reviews. Link to comment Share on other sites More sharing options...
johny Posted June 24, 2022 Report Share Posted June 24, 2022 Yes less movement but more effort - nothings free😒Got one on my brakes instead of 0.7" and happy with the result... Link to comment Share on other sites More sharing options...
Mjit Posted June 24, 2022 Report Share Posted June 24, 2022 I've often wondered if one of the Wilwood 5/8" master cylinders, either with integrated or remote resevoir would fit - though mainly for quality reasons as unlikely to be cheap and thankfully not had any issues with mine for years (frantically touching every bit of wood in the house). Link to comment Share on other sites More sharing options...
johny Posted June 24, 2022 Report Share Posted June 24, 2022 Thought all of that type were standard fitting but then arent Wilwood American? Link to comment Share on other sites More sharing options...
Josef Posted June 24, 2022 Report Share Posted June 24, 2022 6 hours ago, Mjit said: I've often wondered if one of the Wilwood 5/8" master cylinders, either with integrated or remote resevoir would fit - though mainly for quality reasons as unlikely to be cheap and thankfully not had any issues with mine for years (frantically touching every bit of wood in the house). I have a Wilwood one on my Herald after the non brand replacement lasted all of 5 minutes. Got an original Girling sleeved for the Spitfire though which would be my preference, providing it lasts (which hopefully it should!) Link to comment Share on other sites More sharing options...
RogerH Posted June 24, 2022 Report Share Posted June 24, 2022 Have you considered using a servo to take the pressure off your leg. Roger Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 24, 2022 Report Share Posted June 24, 2022 i would stick to the std design the 0.75 - 3/4" will work ok but as you found the pedal effort is increased , there is also the possibility of over stroking the clutch there are many of the right size available from all normal suppliers or even make up a set for with a clear reservoir from places like car builder solutions or merlin motor sport pete Link to comment Share on other sites More sharing options...
johny Posted June 25, 2022 Report Share Posted June 25, 2022 Could go to a 0.7" bore as a compromise between the old one and what you have now. Believe they were used on some Triumph models like the TR6... Link to comment Share on other sites More sharing options...
iainbja Posted June 27, 2022 Report Share Posted June 27, 2022 quick update the American TRW master cylinder instantly sorted back to nice light clutch used an adjustable rod out of the master cylinder so clutch now biting half way not buried in the carpet. Did not even need to bleed. Link to comment Share on other sites More sharing options...
johny Posted June 27, 2022 Report Share Posted June 27, 2022 Great. I take it the MC linkage definitely has some looseness with the pedal released? Link to comment Share on other sites More sharing options...
iainbja Posted June 27, 2022 Report Share Posted June 27, 2022 Yes I adjusted the rod so its just not pushing on the clutch. Its an unusual mix of 1500 engine with early herald type gear box and j type overdrive using a 1974 model year American clutch plate fits the Toledo as well i think. I have always struggled with too low a clutch but now its spots on Link to comment Share on other sites More sharing options...
Mjit Posted June 27, 2022 Report Share Posted June 27, 2022 Out of interest where did you get the TRW m/c from/what model? Link to comment Share on other sites More sharing options...
johny Posted June 27, 2022 Report Share Posted June 27, 2022 24 minutes ago, iainbja said: Yes I adjusted the rod so its just not pushing on the clutch. Its an unusual mix of 1500 engine with early herald type gear box and j type overdrive using a 1974 model year American clutch plate fits the Toledo as well i think. I have always struggled with too low a clutch but now its spots on Ive got an adjustable rod on my brakes and it is quite handy for taking up unwanted play👍 Link to comment Share on other sites More sharing options...
iainbja Posted June 27, 2022 Report Share Posted June 27, 2022 30 minutes ago, Mjit said: Out of interest where did you get the TRW m/c from/what model? It was from Ebay put Triumph Spitfire clutch master cylinder in and along with all the unbranded ones the TRW one is listed for £62 was £99 when I looked up the price on the internet. My car is a late mark 4 so 1300 engine with the herald style box but with synchro on all gears plus a J type overdrive. After 180k miles the original engine and box were getting worn out. I had a 1500 engine in the garage so got an exchange gearbox form td fitchett mine was a rare box with J type in the uk. However in America they got the 1500 engine before us and they did use the older box with Jtype like I have hence the special clutch Plate. I fitted at the time a new master and slave and whilst it works towed a caravan etc the clutch was always too low just not enough travel so reverse tended to grate a bit going in and it got slowly worse. Now with my socket on the end of the slave cylinder rod and a couple of mm more on the master cylinder the clutch is the best it's ever been all gears really easy light and no longer on the floor to get the gears. Not sure how long it will last but for now it feels right. Link to comment Share on other sites More sharing options...
daverclasper Posted June 27, 2022 Report Share Posted June 27, 2022 On 24/06/2022 at 21:03, Pete Lewis said: there is also the possibility of over stroking the clutch What is over stroking and why is it bad Pete, if easy to answer? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 27, 2022 Report Share Posted June 27, 2022 I think it means you get too much pressure at the slave cylinder from too great a stroke / press of the pedal and you can blow the piston out of the end of the cylinder, or at least wreck the seals or burst the hydraulics. Link to comment Share on other sites More sharing options...
johny Posted June 27, 2022 Report Share Posted June 27, 2022 No, I think its more to do with the clutch assembly itself as you only need to disengage the clutch so if then the slave cylinder keeps on pushing further the thrust bearing can damage the coverplate spring fingers.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 28, 2022 Report Share Posted June 28, 2022 15 hours ago, johny said: can damage the coverplate spring fingers.... Jonny beat me too it Ha ! Link to comment Share on other sites More sharing options...
iainjames Posted June 28, 2022 Author Report Share Posted June 28, 2022 next week doing the scotland 500 that will be a test of the clutch. Link to comment Share on other sites More sharing options...
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