Caliper rebuild, fill & bleed - how much?
Discussion
anonymous said:
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Pretty much, this is why I keep a selection of old pads so that I can jam them in to test against a convenient spanner, plus after a full rebuild you should be able to push all the pistons back in easily by hand.Going back to your rebuild I presume you used a liberal amount of red rubber grease when putting everything pack together?
Private Pile said:
Toxic, no Idea if I'm right or not but I've always used red rubber grease on my calliper rebuilds. I rebuilt a rear a few days back and could easily move the pistons by hand. Hope you get it sorted.
I have to agree, I have never heard or red rubber grease contaminating the brake fluid. Especially as it is designed specifically for use on brake seals, the caliper rebuild company linked earlier in this thread also sell seal kits that come with a sachet of it so you would like to hope they know what they are doing.can confirm using lots of red rubber grease will contaminate your brake fluid - it will literally turn red. You don't really need it but if you have it a thin smear on the seals before you slot them home is ok. Otherwise lube with a little fluid
if you've thoroughly stripped them, cleaned and reassembled the calipers then it sounds like a bleeding issue. Back fill with large syringe works well - my favoured technique is to flick the brake lever repeatedly, bleed, repeat until firm and no bubbles come out at caliper end or up through the little tube that connects the master cylinder and reservoir
if you've thoroughly stripped them, cleaned and reassembled the calipers then it sounds like a bleeding issue. Back fill with large syringe works well - my favoured technique is to flick the brake lever repeatedly, bleed, repeat until firm and no bubbles come out at caliper end or up through the little tube that connects the master cylinder and reservoir
not sure red rubber grease is bad as such, just that brake systems are meant to be filled with brake fluid (for it's particular physical properties) and not red rubber grease....
if you use it, when you next come to strip your brakes you will find that it's all magically disappeared from round the seals - mixed in with the brake fluid I guess, use enough of it and your brake fluid turns red.
if you use it, when you next come to strip your brakes you will find that it's all magically disappeared from round the seals - mixed in with the brake fluid I guess, use enough of it and your brake fluid turns red.
anonymous said:
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My two pence as an amateur. Conflicting advice often occurs when you can't see an obvious effect. I think before you worry about advanced bobbinery you should make sure it actually is impacting you. As I said earlier I would swap the discs to confirm whether it is the caliper, or disc that is causing your problems. If you've done that another way, great stuff.
If it's the caliper it's time to have it apart and have another go at it. If it works, forget the bobbins and clean regularly.
If it's the disc, bin them and buy a new pair. Pricey yes, but if they're so corroded they no longer float they're done. Get a decent pair and clean them regularly and they will last a long time.
Same goes for red grease. If it was that bad it would be bloody obvious across the thousands of times it's used by mechanics and engineers. We're also assuming it's contamination is actually detrimental to the fluid. I don't argue you can perhaps not use it, personally I don't like working with brake fluid however.
I'd not replace pads for a new disc unless they're close. The pads will bed in, some may disagree.
Edited by Prof Prolapse on Wednesday 6th July 11:18
anonymous said:
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The disc bolts are in shear, so whether they stretch or not (they don't and won't) doesn't matter.Check to see whether there is any offset built into the bobbins. I imagine not though, otherwise it would be very easy to confuse sides. Speak with AP racing (Silverstone) to get an idea.
Toxic, can you mark the tyre with chalk where it stops. I mean, is it stopping at the same place every rotation?
For the record, my discs are handed, marked L and R.
for the 10 minutes it'll take I'd also redo the bobbins.
And as Prof said, you could also remove a calliper / disc / swap them over to see if the problem remains / changes / disappears.
For the record, my discs are handed, marked L and R.
for the 10 minutes it'll take I'd also redo the bobbins.
And as Prof said, you could also remove a calliper / disc / swap them over to see if the problem remains / changes / disappears.
Firstly, I'm just an amateur. I service my cars and bikes, I've fitted timing belts and rebuilt a car engine. But I'm just a diy'er. So it's just advice, not gospel.
Also, the newest bike I've owned is 1993.
First thing I would try is the bobbins. It's quick and easy. I'd use the bolt / washer/ brake cleaner/ wd40 method. There's a few videos on you tube.
I'd also try un bolting the good calliper just to elimate it.
If the discs aren't handed try swapping them over, just to elimate.
I wouldn't think it's a master cylinder problem as that would affect both callipers. Could also be a brake hose collapsing internally but I doubt it.
I'd try and elimate all the good, working parts so you can concentrate on fixing the fault.
I'll have a look later at your you tube videos.
What I can say tho, your not far away from fixing it.
Also, the newest bike I've owned is 1993.
First thing I would try is the bobbins. It's quick and easy. I'd use the bolt / washer/ brake cleaner/ wd40 method. There's a few videos on you tube.
I'd also try un bolting the good calliper just to elimate it.
If the discs aren't handed try swapping them over, just to elimate.
I wouldn't think it's a master cylinder problem as that would affect both callipers. Could also be a brake hose collapsing internally but I doubt it.
I'd try and elimate all the good, working parts so you can concentrate on fixing the fault.
I'll have a look later at your you tube videos.
What I can say tho, your not far away from fixing it.
anonymous said:
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It sounds very much like minor run out or thickness variations on the disc, but that shouldn't be enough to cause the disc to heat up by itself, it has to be actually binding for that to happen rather than lightly touching for part of the rotation.Sorry if it's been asked and answered already but do the pads move nice and freely within the calipers? If a pads starts out a bit tight (i.e. slightly oversize) then it's very likely to get worse as it gets hotter.
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