XRichardM Posted February 3, 2011 Report Share Posted February 3, 2011 To all who know about these things. Clutch slave ( new in early 2010 ) on my 4A is leaking like a seive AGAIN and dumped all the fluid ( silicone ) Now is this just rubbish pattern parts or could it be something else ? Also, on dismantling I noticed an external return spring on the slave from the operating shaft lever to the support bracket. The parts book doesn't show one but as the slave cylinder has an internal spring pushing the piston out does this mean the throw-out bearing is supposed to be in constant contact with the clutch. Could having the two springs, one pulling and one pushing contrbuted to the early demise of my slave cylinder ? Ta Richard Quote Link to post Share on other sites
stuart Posted February 3, 2011 Report Share Posted February 3, 2011 4a slave cylinder works perfectly ok with a return spring. Try using proper brake fluid of Dot 4 spec as not all repro rubbers like silicon fluid Stuart. Quote Link to post Share on other sites
Alec Pringle Posted February 3, 2011 Report Share Posted February 3, 2011 Not all OE rubbers like silicon fluids either . . . . Cheers, Alec Quote Link to post Share on other sites
Ashley James Posted February 3, 2011 Report Share Posted February 3, 2011 Stuart is correct and I'd advise against using Silicone Brake fluid because it doesn't suit many modern brake rubbers. A friend of mine in RROC/AU had to repair the Governor General's Phantom 6 because the brakes had seized solid after an overhaul. The main agents couldn't work out what was wrong. Silicon Brake fluid had swelled all the seals and wrecked all the cylinders. It took a considerable amount of investigation to discover that there was no guaranteed way of knowing whether or not it could be used in any car, because it depends on the material the seals are made from. My advice is to overhaul all the cylinders, flush the system very thoroughly and replace with conventional fluid. If you have trouble with cylinders sticking or whatever, they can be sent to Past Parts in Bury St. Edmunds for stainless steel sleeving, which is very effective provided brake fluid is changed at least every two years, although one is better. Ash Quote Link to post Share on other sites
RogerH Posted February 3, 2011 Report Share Posted February 3, 2011 ....and thus the great mineral/silicone fluid debate starts again, and again, and again. Roger Quote Link to post Share on other sites
stuart Posted February 3, 2011 Report Share Posted February 3, 2011 ....and thus the great mineral/silicone fluid debate starts again, and again, and again. Roger True but at least we know mineral works every time Stuart. Quote Link to post Share on other sites
RogerH Posted February 3, 2011 Report Share Posted February 3, 2011 Hi Stuart, I'm on your side but people will dabble. Roger Quote Link to post Share on other sites
88V8 Posted February 3, 2011 Report Share Posted February 3, 2011 True but at least we know mineral works every time and show me any car manufacturer who ships cars with silicone. Ivor Quote Link to post Share on other sites
Alec Pringle Posted February 3, 2011 Report Share Posted February 3, 2011 Hi Ivor, pennies count in car manufacturing, silicone fluids are too expensive . . . . I was intrigued recently by comments from an American pal, classic car nut and ex-US military engineer, about hydraulic fluids. When the US military changed over to BFS in 1981, only US-manufactured vehicles were automatically involved - foreign manufactured vehicles having to be considered on an individual basis. Why ? Rubber component compatibility, or rather potential incompatibility. The US military publish an awful lot of specifications with which supplying manufacturers must comply. Amongst them, a whole raft of specs for seals for various hydraulic fluids . . . . some of these seal specs include both glycol and BFS, others include BFS but exclude glycol, yet others include glycol but exclude BFS. There are of course quite a number of other specialist hydraulic fluids, and yet more seal specs - some also compatible with glycol, some with BFS, some with both, others with neither . . . . No wonder we get conflicting experiences from classic car enthusiasts ! Cheers, Alec Quote Link to post Share on other sites
RogerH Posted February 4, 2011 Report Share Posted February 4, 2011 ...and wasn't it the US Army that wanted a hydraulic fluid that could be left in the system year upon year while the vehicles were stored year upon year with no maintenance awaiting the big push - hence along came silicon fluid. Roger Quote Link to post Share on other sites
Alec Pringle Posted February 4, 2011 Report Share Posted February 4, 2011 Hi Roger, storage was the secondary consideration, spin off if you like. Primary priority was the ability to operate anywhere from the Antarctic to the Equator without having to change fluids - not just brakes, military vehicles have lots of other hydraulic systems. Hence the silicones, low temperature operating capabilities . . . . Cheers, Alec Quote Link to post Share on other sites
XRichardM Posted February 4, 2011 Author Report Share Posted February 4, 2011 Thanks guys. I now know the history of silicone fluid but still don't see the point of having two springs, one pushing and the other pulling, on the clutch slave. cheers Richard Quote Link to post Share on other sites
peejay4A Posted February 4, 2011 Report Share Posted February 4, 2011 (edited) Richard, as a new 4A owner I was curious about why there is an external return spring on the clutch. There isn't one on the TR6 and it's the same basic mechanism. I fitted one anyway on the assumption that because the 4A has an adjustable clutch push rod, it made sense for there to be a return spring. I assumed it was a hangover from the earlier non-diaphragm clutch fitted to the TR4. I guess the TR6, which doesn't have an adjustable push rod, relies on the lack of a return spring to make the clutch effectively self adjusting. I wouldn't have thought that an internal spring in the slave cylinder would have enough tension to cause the release bearing to be in contact with the clutch forks - but that's a guess. Edited February 4, 2011 by peejay4A Quote Link to post Share on other sites
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