Jomac Posted August 22, 2016 Report Share Posted August 22, 2016 Lost all clutch fluid as it would appear that the slave cylinder seals have failed resulting in 'blowing off' the rubber seal through which the push rod exits. Rather than repair I would prefer to fit a new slave. I note there are different makes available (Rimmer Bros have three) and the bore size is mentioned. What difference does the bore size make? What happens if a different size bore is fitted (inadvertently)? Is there any preferred make or ones to avoid? My failed unit is gold coloured with a series of numbers on one side. Many thanks Quote Link to post Share on other sites
RogerH Posted August 22, 2016 Report Share Posted August 22, 2016 Hi Jo, welcome to the forum, Changing the diameter of the slave will affect the amount that the push rod will TRavel in ratio to the pedal TRavel and the pedal effort. I have been using a 0.7" diameter slave cy until recently. This will give greater rod TRavel compared to the more common 0.75" slave. I now use a 0.75" cylinder - haven't really noticed a reduction in pedal effort (the pedal is quite light at present). Also the gears are engaging very well so the rod TRav el must be OK. The 0.7" seals are becoming difficult to obtain. The TRShop definitely do a decent slave. I'm sure the other major suppliers do also. Roger Quote Link to post Share on other sites
BlueTR3A-5EKT Posted August 23, 2016 Report Share Posted August 23, 2016 All TR250-5-6 clutch slave cylinders were 1" bore according to Rimmers. They just offer different qualities/makes. http://www.rimmerbros.co.uk/Item--i-GRID600015 Cheers Peter W Quote Link to post Share on other sites
RogerH Posted August 23, 2016 Report Share Posted August 23, 2016 OOOPs!! there I go again expecting sense to prevail. Sorry, I didn;t know they used a 1" diameter. Go for the OEM part. It stands a chance of being good quality. Roger Quote Link to post Share on other sites
Jomac Posted August 23, 2016 Author Report Share Posted August 23, 2016 Thank you Roger and Peter. I am now curious however. Roger you say that a 0.75" bore will give greater push rod travel than I assume a 1.0"? Am I correct in my understanding and why would this be necessary? I am also interested in less pedal effort if at all possible so does the bore size affect pedal pressure? By the way I will go for the OEM part - after all the existing one is gold in colour - got to keep things matching you know!! Thanks again Peter Quote Link to post Share on other sites
RogerH Posted August 23, 2016 Report Share Posted August 23, 2016 Hi Peter, In my first post i didn't realise that TRiumph had change the slave for a bigger diameter. So the 0,75" is a red herring. 1" appears to be standard. In general - if you get a bigger slave it will be easier on the foot pedal but the rod travel will be less. A smaller diameter will give hard foot pedal but gove more rod travel. The rod travel may become important if you have trouble engaging gear. The Gold slave may not necessarily be the OEM item. Go for OEM every time. Roger Quote Link to post Share on other sites
Jomac Posted August 25, 2016 Author Report Share Posted August 25, 2016 Just clocking in to say new OEM slave fitted and all is well once more! By way of interest I dismantled the old one and is there meant to be a seal, rather like a piston ring, in the groove in the piston? If so it was not there! The inside of the cylinder felt a bit rough and there seemed to be bits of grit in remains of the fluid in the cylinder - perhaps the old seal? Many thanks again Peter Quote Link to post Share on other sites
Andy Moltu Posted August 25, 2016 Report Share Posted August 25, 2016 I thought it was the master cylinders that were 0.70" or 0.75" diameter and the slaves 1" Quote Link to post Share on other sites
RogerH Posted August 25, 2016 Report Share Posted August 25, 2016 Hi Andy, I had my numbers all over the place. I was thinking about TR4A parts. Roger Quote Link to post Share on other sites
RogerH Posted August 25, 2016 Report Share Posted August 25, 2016 Hi Peter, how long had it been in use without the seal. In theory it shouldn't work. Curious about the gritty particles. Roger Quote Link to post Share on other sites
Jomac Posted August 26, 2016 Author Report Share Posted August 26, 2016 Hi Roger Impossible to say how long it was defective. It is not a well used car and there appeared to be an accumulation of 'sludge', caused by gravity, on the outside of the piston - it may have been letting by for a while and then gave up big time. Should the rod passing through the rubber seal be lubricated? I am going to put some silicone grease on it as it appears to be 'dragging' the rubber seal out with the in/out motion. Peter Quote Link to post Share on other sites
RogerH Posted August 26, 2016 Report Share Posted August 26, 2016 Hi Peter, no harm in lubricating the rod. Roger Quote Link to post Share on other sites
Richardtr3a Posted August 29, 2016 Report Share Posted August 29, 2016 How could the piston work without the sealing ring? Please can someone on this forum explain?. Maybe the sludge inside is the failed seal, but it would have to maintain pressure so it must have only decomposed recently. I cured my slave cylinder leaks by sending it to Past Parts who lined it with a stainless steel liner. The new cylinders are sometimes very bad quality. Good luck Richard & H. Quote Link to post Share on other sites
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