Stewart H
Registered user
Hi gang, its salt season again, the time of year when you approach your beloved bike only to find that the brakes are stuck on and it will not roll, the cure is to clean those pistons and seal grooves to get rid of the mysterious white corrosion that magically appears at this time of year, so how to get those pesky pistons out of their bores? "just pump the lever" a good idea that works for one piston, and according to soddes law that one will of course be the piston least affected by the problem. heres how I do it.
Tools required,
A screwdriver with a handle of appropriate size
A small G clamp
An airline blow down gun and suitable air supply.
Here it all is laid out, the screwdriver is hiding on the left of image.
this one has a nice wedge shaped handle, what I do is insert the handle of the screwdriver between one pair of pistons.
Then I position the G clamp so that it holds in place one of the remaining pair of pistons.
now all that is needed is to introduce some compressed air into the port on the caliper and the piston will pop out of its bore, note it is best to pack rags around the piston to avoid brake fluid and flying pistons.
Voila! the piston should pop out of its bore enabling you to effectively clean the piston and bore, in my case the culprit was salty corrosion in the seal groove, so the seal was pried out with a blunt probe enabling cleaning of the groove. a smear of red rubber grease and bob is your uncle.
Normal common sense is required, to clean pistons and bores, I favour an old well used Scotchbrite washing up pad and old brake fluid, I was lucky that having carefully removed and cleaned everything this fix required no new parts, new seals may be required, observe absolute cleanliness when working on hydraulic systems, upon reassembly bleed the system and check for leaks.
Stewart
Tools required,
A screwdriver with a handle of appropriate size
A small G clamp
An airline blow down gun and suitable air supply.
Here it all is laid out, the screwdriver is hiding on the left of image.
this one has a nice wedge shaped handle, what I do is insert the handle of the screwdriver between one pair of pistons.
Then I position the G clamp so that it holds in place one of the remaining pair of pistons.
now all that is needed is to introduce some compressed air into the port on the caliper and the piston will pop out of its bore, note it is best to pack rags around the piston to avoid brake fluid and flying pistons.
Voila! the piston should pop out of its bore enabling you to effectively clean the piston and bore, in my case the culprit was salty corrosion in the seal groove, so the seal was pried out with a blunt probe enabling cleaning of the groove. a smear of red rubber grease and bob is your uncle.
Normal common sense is required, to clean pistons and bores, I favour an old well used Scotchbrite washing up pad and old brake fluid, I was lucky that having carefully removed and cleaned everything this fix required no new parts, new seals may be required, observe absolute cleanliness when working on hydraulic systems, upon reassembly bleed the system and check for leaks.
Stewart
