Brake Calipers - Pistons won't come out and need new seals

[400_Rider]

Howdy guys

Well today I am tackling my brake issue where by when I am riding after only 10 mins my brakes get stiffer and stiffer and eventually lock on solid.

I have checked over everthing and bled the system twice now all seams ok, what I did notice though was I was not able to push the pistons back all the way in.

So today I again drains the fluid only this time I removes the calipers and take the pistons out to have a look.

When I split the calipers, one half I managed to get the pistons out but man one of em was a real pain to get out, seamed to be really stuck.

When eventually it popped out and made a shotgun noise and about took me head off I noticed the top seal was stretched and sticking out, A-Ha ! Could this be responsible for my braking problem ??

Heres some pics :





So I have two q's

Q1. While I managed to get the pistons out of one side I am unable to get the pistons out the other side, my method is a foot pump and press air into the holes to force the pistons out but on the other side its just not having it, anyone got any tips how to get the pistons out please ?

Q2. Where can I get the seals from for these calipers ?

Many thanks,

Matt

[400_Rider]

Scratch that I have found a solution

I just bought one of these off evilbay :



Ad says :

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New Improved Design ! - Now with automatic locking ratchet

This tool is used to extract a hollow brake piston when cleaning or replacing caliper seals.

It is inserted inside the piston and squeezed to allow the knurled faces of the tool to grip the inside of the piston, a ratchet mechanism automatically holds it in place, the piston can then be freed and withdrawn.

Suits piston ID in the range 16.5 - 40mm

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I have never had a problem before getting pistons out but its hard to get compressed air into one side of the caliper I have found on the NC35 so am gonna give this a try, will report if it works and how well when I receive it

One last thing, I still need to know where to get seals, anyone ?

Thanks

[cbr400rrn]

Try Davidsilverspares they should have them in stock, or Graeme France, Rick Oliver perhaps

[400_Rider]

Lovely thank you mate

[Cammo]

I usually take the pads out when the calipers are still on the bike and squeeze the brakes to force the pistons out a fair way before dissasembling them.

After that if you're carfeul you can pull them out using a piece of cardboard or similar between the pliers and top lip of the pistons.

They should be a pretty tight fit usually.

[viper_biker]

2 bolts, 1 nut and a strong pair of grips. Excuse the poor drawing, but it should illustrate the point. Put the 2 bolts into the piston with the nut in the middle and with the grips squeeze them together so that they apply pressure to the inner walls of the piston and turn the caliper slightly around whilst pulling up and it should free the piston.

[Neosophist]

i have a rather large compressor I attatch the the brake fluid hose via a connector I made then shot about 12bar of air through them, but make sure you put a piece of hardwood to stop the pistons comming too far out (you can twist them out with grips and cloths after they move almost all the way out)

I did it first without a wedge and the pistons came out about 200mph nearly breaking things, keep fingers well clear :D

[400_Rider]

This is all really useful info guys, thanks very much

[jwkurtenbach]

I had a similar problem when I used aftermarket braked levers. It turned out that the levers were a little different. They didn't fully release from the master cylinder. I took a little metal off the lever where it contacts the master cylinder plunger.

Jim

[400_Rider]

Cheers for that Jim, I have new tyga levers and this never happened before so I will inspect the operation of that too, but defo 1 seal is ruined in my calipers so its been a worth while doin em as routine maintenance