GT6 M Posted September 23, 2012 Share Posted September 23, 2012 I just got fed up with having to keep freeing my front brakes off,with the aid of a G clamp,and brake pedal, so got at it today, after coming back hame, the fronts would not come off at alljust made it home, as brakes were smoking badly.I suspect that alot of others suffer the same symptom.this has happened on a few cars I had, but seems more of a prob on the sliding caliper typeor more specific, this type apply both pads, at same time, unlike the multi piston either side, which onlyputs yan side on at a time if its stickingThis aint for a Triumph, but as most of you got moderns with syam set up, then its also relavent to ye all, Same thing will apply to freeing the pistons on our cars too, but we just got the pistons to bother aboot.the rubber seal seems to like to stick to this sheite, and adds to the problem.NOTE, if ye going to take piston out, then pump the brake pedal {with caliper off disc }this will get the piston to end of bore, so it comes out easy. if ye dont, then it will be very very hard work to shift it other wise. even an air line would not shift these ones, so had to put it back onto car,and pump pedal.after I got it all cleaned back together, I filled the rubber seal full of water resistant grease, also got a rust inhibitor init, so if moisture gets in, its got to get past the grease. it was a marine grade got frae,t Yot spot ont dokPiston condition, covered in baked on sheite / rust stainscleaning up int lathe with fine emery padscauses of crud / sheite, is moisture building up inside of cover, and over time transferring to pistoncleaned up pistonAlso a major cause of brakes not coming off totally is these useless pins, should be stainless.as these rust, if one bungs copper slip,or the like on, then over time, this gaas hard, and causes friction, and the calipers dont slide freely, resulting in brakes staying on. this alang wid the sticking pistons = bad news.sliding pinscleaned up pinsmay be of use to some.rgds Markus Tinkerous Link to comment Share on other sites More sharing options...
thebrookster Posted September 23, 2012 Share Posted September 23, 2012 Marcus, Copperslip does set when it gets hot, so I would never use it on brake parts myself.Have you got some Molyslip? Very similar stuff (cept it has molybdenum instead of copper), but has the saving grace that it does not solidify when it gets hot, it remains gooey?? (Is that the right word??)Cheers,Phil Link to comment Share on other sites More sharing options...
paulsprint Posted September 23, 2012 Share Posted September 23, 2012 Markus. I Use to have this problem on an old Astra Gte I had years ago now. In the end I used white lithium cycle grease that my old man had for his bike. Never had a problem with the sliders sticking again. Copper grease will dry out and gunk up when it gets hot. Link to comment Share on other sites More sharing options...
JohnD Posted September 23, 2012 Share Posted September 23, 2012 Gosh, is ANY sort of grease suitable for use with brakes?As this is to lubricate and help seal a rubber washer/boot, then perhaps the red rubber grease that comes with a master cylinder repair kit? But the merest suggestion of a smear.The manuals usually say lubricate such rubber seals with brake fluid.Brake fluid itself doesn't rot steel, but it will if the water gets into it.A reason to change to silicone fluid???JOhn Link to comment Share on other sites More sharing options...
Nick Jones Posted September 23, 2012 Share Posted September 23, 2012 Be VERY careful using grease around brake system seals.Brake system seals are typically made from EPDM rubber as it is resistant to the polyglycol ethers used in brake fluid. Unfortunately EPDM is very badly affected by mineral oils and greases, which make it swell and fall apart - clearly undesirable in a caliper seal. You should only use grease specifically intended for brake parts - the stuff I have is red and made by Girling.Nick Link to comment Share on other sites More sharing options...
thebrookster Posted September 23, 2012 Share Posted September 23, 2012 If I may clarify, I was responding to the section Marcus talked about Copperslip, which was for the sliding pins he shows. This is for the caliper, and yes I would advocate a very light smear of a suitable grease to aid lubrication. Obviously if you have proper brake grease then this would be preferable, but I cannot see copperslip/molyslip being a issue!!I apologise if this was not clear, I certainly do not advocate the use of grease near seals!! Link to comment Share on other sites More sharing options...
junkuser Posted September 24, 2012 Share Posted September 24, 2012 How would a silicone grease go on all parts exterior to the piston seals Marcus?Don't know if there is a suitable product, just thinking. Link to comment Share on other sites More sharing options...
GT6 M Posted September 24, 2012 Author Share Posted September 24, 2012 junkuser wrote:How would a silicone grease go on all parts exterior to the piston seals Marcus?Don't know if there is a suitable product, just thinking.??? Malc, do you mean how did i lube it.!!I pulled the dust cover seal back, and squeezed it in.Nick I dont think the grease will be actually getting to the piston seal. as thats about 1/4 inch past the outer dust seal, so cant see a prob with my fluid seal be damaged.Unless ye meant the outer dust sheild will be damaged.If that, then no probs, as it had wee pin holes init where the rust had eaten into it.this is where I tink the water / moisture was getting in, so this why i filled it up,M Link to comment Share on other sites More sharing options...
junkuser Posted September 24, 2012 Share Posted September 24, 2012 " filled the rubber seal full of water resistant grease"Sorry Marcus, did not realise that was a silicone grease that you used.Mal. Link to comment Share on other sites More sharing options...
JohnD Posted September 24, 2012 Share Posted September 24, 2012 I too missed that , "I filled the rubber seal full of water resistant grease"This would be that bellows style seal that surrounds the piston? That works like a bellows, getting bigger and smaller as the piston moves? That potentially, at least, will pump the grease back out again as you use the brakes? So that when it's hot, the grease will drip down onto the pad and disc?That's thinking black, worst case, but brakes are 'mission critical'. I'd try again, Marcus, dismantle and wipe away as much of that grease as possible, leaving a mere smear on the rubber/piston join.John Link to comment Share on other sites More sharing options...
marktheherald Posted September 24, 2012 Share Posted September 24, 2012 I've got those siding pins on the rear calipers on my Trooper. Subject of several threads on the Trooper forum. Extreme fix for trouble free operation involves drilling and tapping the bottom of the pin recess and fitting grease nipples...My n/s caliper is pretty well seized but the pins came out with no problem! Link to comment Share on other sites More sharing options...
GT6 M Posted September 24, 2012 Author Share Posted September 24, 2012 Thanks for your concern John, but its going to take some heat to melt this stuff.I did the rears about 2 years ago, they never stuck since, and there is no sign of any greasecoming out the bellows / seals.it will only sqash oot when belows go baxk wards alot, but as brake disc is constantly wearing away,it will expand,so give more room.here rears, same prob with them stickingthese pistons really should be made of stainless, but manufacturers maybe think that folk are not going to have a car as lang as us lot, so it aint a prob !!!the rust that builds up around the ends is alott, so not a smooth surface to seal against.hence clean off int lathe, and then rust proofer grease bunged injust look at the rust in the seal groove belowrears done a while ago, no probs at all sinceM Link to comment Share on other sites More sharing options...
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