gnotte Posted June 4, 2009 Report Share Posted June 4, 2009 Hello all, having spent some days cleaning ,derusting, brushing parts, I decided to take a break today and to rebuild the galipers, an easy small job I was thinking... The cylinder bore was perfectly clean, I trial pushed the piston without the seal to ensure it enter freely in the bore and it did ,I then fit a new sealing ring and new dust cover and lubricate them with silicon brake oil and then try to push the piston through the seals but after 4 hours of frustation I have been unable to fit a single piston. Is there someone successfull with this task who can give me some tips. Guy Quote Link to post Share on other sites
stuart Posted June 4, 2009 Report Share Posted June 4, 2009 Hello all, having spent some days cleaning ,derusting, brushing parts, I decided to take a break today and to rebuild the galipers, an easy small job I was thinking... The cylinder bore was perfectly clean, I trial pushed the piston without the seal to ensure it enter freely in the bore and it did ,I then fit a new sealing ring and new dust cover and lubricate them with silicon brake oil and then try to push the piston through the seals but after 4 hours of frustation I have been unable to fit a single piston. Is there someone successfull with this task who can give me some tips. Guy Dont use silicon fluid Stuart Quote Link to post Share on other sites
Alec Pringle Posted June 4, 2009 Report Share Posted June 4, 2009 Quite so, Stuart. I've been reading by email my old friend Nik Dando's saga with his calipers and SBF, and doing my best to assist with advice - Nik could give you some fairly colourful chapter and verse on the topic ! After 3 months of hassle he's now going back to Glycol . . . . . Cheers, Alec Quote Link to post Share on other sites
johnny250 Posted June 5, 2009 Report Share Posted June 5, 2009 Hello all, having spent some days cleaning ,derusting, brushing parts, I decided to take a break today and to rebuild the galipers, an easy small job I was thinking... The cylinder bore was perfectly clean, I trial pushed the piston without the seal to ensure it enter freely in the bore and it did ,I then fit a new sealing ring and new dust cover and lubricate them with silicon brake oil and then try to push the piston through the seals but after 4 hours of frustation I have been unable to fit a single piston. Is there someone successfull with this task who can give me some tips. Guy That's odd, should go together easily. Make sure the bleed nipple is out..... I used teflon coated pistons i seem to remember and silicon fluid with no problems john Quote Link to post Share on other sites
angelfj Posted June 5, 2009 Report Share Posted June 5, 2009 Quite so, Stuart. I've been reading by email my old friend Nik Dando's saga with his calipers and SBF, and doing my best to assist with advice - Nik could give you some fairly colourful chapter and verse on the topic ! After 3 months of hassle he's now going back to Glycol . . . . . Cheers, Alec Sorry, but I must say RUBBISH We recently rebuilt my 3A calipers with new seals, SS pistons AND Dot 5 Silicone - No Problema!!! Quote Link to post Share on other sites
stuart Posted June 5, 2009 Report Share Posted June 5, 2009 Sorry, but I must say RUBBISH We recently rebuilt my 3A calipers with new seals, SS pistons AND Dot 5 Silicone - No Problema!!! I resemble that remark . Actually I suspect that the seals may be old or NOS stock and the SBF probably made them swell up hence the inability to fit. Stuart. Quote Link to post Share on other sites
Alec Pringle Posted June 5, 2009 Report Share Posted June 5, 2009 Hi Frank, Rubbish ? A rather peremptory statement, if I may say so. Nik Dando and his TRs I've known for more than 30 years, a chap of more expertise and experience than many contributors to this forum, although he's far too modest to make any such claim. Stuart is not without experience of SBF, as a professional restorer he has considerable firsthand knowledge of the stuff in a variety of applications. I used to be very much in favour of SBF in its early days, a fair amount of experience in workshops and as a factor has led me to take a more critical approach - problems can, and do, appear to arise with regrettable frequency. Perhaps because so many classic car hydraulic systems were designed specifically for glycol-based fluids, which are not identical in characteristics or behaviour to silicon-based fluids. As you say, you've experience no problems with the calipers of Grey Lady . . . . but is she running on the road yet, and are the hydraulics behaving perfectly ? Cheers, Alec Quote Link to post Share on other sites
graeme Posted June 5, 2009 Report Share Posted June 5, 2009 (edited) Hmmm, got to agree with Frank here. Following another thread on SBF causing me some concerns, I decided to strip my complete braking system which has been on the SAME SBF for over 8 years. All parts of the system are in perfect condition, no rust anywhere, the fluid was completely clear, it was rescued and allowed to settle, no sign of any water content at all. The seals were all in good condition, but, as a matter of course I have now changed all the rubber components and reassembled with new SBF. I think that DOT 4 fluid would have caused corrosion in the system and would have needed changing several times in 8 years. I have experienced brake problems with systems less than 8 years old using DOT4. ie leaking cylinders, master cylinder failure etc. I appreciate people have experienced problems, but I suspect it is because they don't change all the components before changing to SBF. It is obvious that the manufacturers would not recommend SBF, it lasts a long time and decimates their market for replacement parts. Cheers Graeme Edited June 5, 2009 by graeme Quote Link to post Share on other sites
Alec Pringle Posted June 5, 2009 Report Share Posted June 5, 2009 Hi Graeme, good to hear of your positive experience. I'm sure you're absolutely right that failure to renew all components, or at least all seals and hoses, before switching to SBF has been a bugbear for many. There's also the aspect of 'new old stock' components which may not be compatible with SBF, and it does seem as if not all new stock is invariably compatible with SBF either. That can be a real problem. Cheers, Alec Quote Link to post Share on other sites
gnotte Posted June 5, 2009 Author Report Share Posted June 5, 2009 (edited) Thanks all for your comments, at least I know that it should be an easy fit. There are some more thread that debates the use of SBF and it was not my intention to reopen the discussion about it, there are people against and other using it for many years without any problems, as I renew all the brake system I think it is the good time to give it a try. Stuart, you are probably true, pushing the piston through the dust cover is very strong and then it jams against the sealing ring, so, that looks like the seals are too thick. Nipple and bridge pipe are removed and all the oil ways have been cleaned with compressed air. Johnny250 and Angelfj did you use a special tool to fit the piston or could you insert it by hand ? I will reorder a new set of seals. Guy Edited June 5, 2009 by gnotte Quote Link to post Share on other sites
johnny250 Posted June 6, 2009 Report Share Posted June 6, 2009 Johnny250 and Angelfj did you use a special tool to fit the piston or could you insert it by hand ? I will reorder a new set of seals. Guy It was quite a few years ago now, but I probably used a bit of rubber grease on the dust seal, and a flat piece of wood to aid pushing the pistons in. They do of course have to be perfectly square to the bore. john Quote Link to post Share on other sites
gnotte Posted June 6, 2009 Author Report Share Posted June 6, 2009 Many thanks John, I put a few rubber lubricant on the seals instead of SBF and the piston goes in by hand easily. Cheers, Guy Quote Link to post Share on other sites
Alec Pringle Posted June 7, 2009 Report Share Posted June 7, 2009 Well done Guy, that does illustrate the relative lack of lubricity of SBF . . . . a common complaint is of pistons 'hanging up' as brakes are released. Cheers, Alec Quote Link to post Share on other sites
Richard V Posted June 7, 2009 Report Share Posted June 7, 2009 Sorry, but I must say RUBBISH We recently rebuilt my 3A calipers with new seals, SS pistons AND Dot 5 Silicone - No Problema!!! Stupid question, but could someone clarify please, as internet searches and use of different terminology on various forums give conflicting info; DOT4 is old style fluid, so not SBF. DOT5 is SBF. DOT5.1 is old style fluid, so not SBF. Red rubber grease (e.g. Miller oils product) is compatible with all of the above when assembling seals. Are these statements correct? Cheers, Richard. Quote Link to post Share on other sites
stuart Posted June 7, 2009 Report Share Posted June 7, 2009 Stupid question, but could someone clarify please, as internet searches and use of different terminology on various forums give conflicting info; DOT4 is old style fluid, so not SBF. DOT5 is SBF. DOT5.1 is old style fluid, so not SBF. Red rubber grease (e.g. Miller oils product) is compatible with all of the above when assembling seals. Are these statements correct? Cheers, Richard. Yes although not sure about the compatability of SBF with the rubber grease as I dont use SBF EVER! Stuart. Quote Link to post Share on other sites
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