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stuck pistons
Posted: Tue May 08, 2012 12:02 pm
by guitarcarrot
simple question:
Can a few sticky/stuck pistons cause brake pulsation?
Re: stuck pistons
Posted: Tue May 08, 2012 8:28 pm
by richr
thats usually warped discs
Re: stuck pistons
Posted: Tue May 08, 2012 11:02 pm
by guitarcarrot
yeah ive heard alot about that, but ive checked runout and it is half the service limit...
then i saw this:
http://www.ebcbrakes.com/automotive/bra ... tion.shtml
so i checked the thickness at random spots with a micrometer precise to a 1,000th of an inch and all identical readings,
ive cleaned the discs with brake disc cleaner still i could no longer bare the squeaking, still to no avail
im loathed to try new pads as i really doubt thats the problem,
but i have two very sticky pistons in each caliper which makes me wonder
ive had to take my mirrors off because they were vibrating and putting hairline cracks in the paint around their mounts,
Re: stuck pistons
Posted: Wed May 09, 2012 7:18 am
by RedexRobB
Well if you can free up the pistons that can only help things i would have thought, weather thats the problem or not is another thing but i would free them up if i were you.
Did you check the runout across the surface of the disc rather than at one point?
Re: stuck pistons
Posted: Wed May 09, 2012 8:07 am
by guitarcarrot
Yeah ill do that then, whats the protocol with seals? If they look tatty get new ones?
Re: stuck pistons
Posted: Wed May 09, 2012 10:31 pm
by stonemonkey
check visually for any wear/cracking/perishing and replace if in doubt. The dust seals on mine were sticking after having not been used for 8 months. I used a g-clamp to push the pistons in, reblead the system and it worked a treat!
Re: stuck pistons
Posted: Thu May 10, 2012 1:21 pm
by pizzaboy
caliper pistons do not stick because of damaged or worn seals they stick because of corrosion in the groove where the seal is located.
The seals also play a role in moving the piston back from the pad/disc.
New seals wont help unless the groove in the caliper body is cleaned
and sticking pistons lead to poor braking efficiency and excessive pad/disc wear and over heating of disc which could lead to warping