Brake caliper overhaul

[muzikill]

Took it to bits today, top piston was seized on RH side and LH side top piston wasnt moving very well. Just shows you even on a bike with around 20k on the clock. Trying to unsieze a piston was a b@stard, pump lever.... push other piston back in.... (repeat). I found i could unfree the siezed one with a pair of pliers. Now i know your going to say it'll be scratched gouged etc. but smarty pants here had bought a leather chamoise to clean the car 2 weeks ago from the pound shop. I cut it into a square big enough to fold over and double the thickness of it and stick inside the piston and overlap the piston edge long enough to stop the plier teeth from marking the inner and importantly the outer rim. As i pumped the brake lever i pulled and wiggled the siezed piston side to side. Another tip was the fact that the lower piston was moving out more so i pushed it back in using a ratchet bar with a larger socket on the end, and with some force this applied back pressure to the siezed top piston which made it move out. Using these methods back and forward the piston freed. Also i'll need to check the rubber boots as im sure i noticed some perishing.

Pics... and how do the pads look after 20k?

[andrewsmith]

untouched in 7 years?

Pretty bad tbh.
I'd look at refreshing the pistons as due course

[DarrenSV650S]

Originally Posted by andrewsmith

untouched in 7 years?

Pretty bad tbh.
I'd look at refreshing the pistons as due course

+1 That's a long time for a caliper service

Pads look good for 20k.

Personally I would take the piston out and give them all a really good clean first before scrapping them.

Sent from my HTC Desire using Tapatalk

[muzikill]

..... Time to get the brake cleaner out. Pretty grotty but it can be reversed so its the perfect time to sort it.

[Bibio]

remove all rubber components then scrub down with WD40 or Paraffin first then use brake cleaner at the end. brake cleaner is ok for fresh disks etc.etc but no good for removing built up grime.

those pistons look good but i would replace the pads as they are a bit old and might have hardened up.

If the pistons aren't too pitted and just grotty leave them in cleaner and see if they scrub up first.

[STRAMASHER]

They look new compared to mine. Cheap garbage calipers hate this time of year. Corrosion in the piston seats kills mine and needs a lot of maintenance.

Never a problem with previous Nissins.





(CopaSlip grease on the pad pins will stop them seizing in place. )

[muzikill]

Magic.. Great advice so far. The pins werent siezed amazingly. I thought wd40 might stain the calipers but if it works im sorted. Ive got some cleaning petrol in a can?. What grease for the sliding part of the caliper? and what should I dip the pistons in to soak them?

Sorry loads of questions!

I agree about renewing the pads - your safety (and other road users') is worth spending a few quid on.

Use red rubber grease (easy to source on-line) on cylinders and rubber shrouds; copper-ease on the back plates of the pads. Be sparing - you don't want anything slippery to get on the pad/disc interface!

A good tip for preventing those front caliper pins seizing in future is to drill a small diameter (ie: smaller than the pins) hole in the blind side of the caliper housing and fill it with grease. A regular dab with ACF 50 anti-corrosion will keep them free. If they do seize then it's easy to tap them out using a flat-ended drift.