brake piston pain how to remove bobbins

[gypsypunk]

has anyone sufferd this the bobbins in the pistons seized in there and it's a long process off drilling them out.

these things turn to concrete and stick in there

http://youtu.be/ymy-JAglogs

[KAT TOY]

looks like it's time for newer ones. you might try putting them back together and using air pressure. careful with fingers.

[rexazz2]

looks like it's time for newer ones. you might try putting them back together and using air pressure. careful with fingers.

or use the hydraulic pressure of the system to push them out

if using air I like to put a piece of wood between to catch the pistons before the completely pop out

I think I remember somebody saying they used a grease gun but IMO that will make a mess to deal with

[shpielers]

or use the hydraulic pressure of the system to push them out

+1. Just redid my front calipers, doing this makes it easy to get the pistons out.

[gypsypunk]

+1. Just redid my front calipers, doing this makes it easy to get the pistons out.

i tried everything thats why i bought the piston remover kit i dont have a powerful enough compressor.
i use a footpump lol

but why are those things/plugs in the pistons just there to seize up
what is there purpose

if these plugs have to be in there i will sell the bike no way am i doing this again for a caliper rebuild.

the worsed rebuild i have ever had to do.

please tell me what these plugs are supposed to do stop dirt from sitting in them so the piston dosent seize.
or is it a anti vibrate feature

[KAT TOY]

or use the hydraulic pressure of the system to push them out

if using air I like to put a piece of wood between to catch the pistons before the completely pop out

I think I remember somebody saying they used a grease gun but IMO that will make a mess to deal with

if they won't budge with hydraulic pressure the're toast.

[gypsypunk]

if they won't budge with hydraulic pressure the're toast.

i didnt try using hydrolic pressure as that means taking it to a garage and spending cash instead i bought a piston removal kit.

the question i am asking is the plugs that go in the pistons what is there purpose.

i will drill them out but out all the bikes i have ever worked on i have never seen plastic plugs in a piston.

i would buy a compressor but i would never use it.

[KAT TOY]

use the master cylinder for the pressure. block the pistons so they can't come all the way out first with wood. separating the halves of the caliper can cause problems.

[shpielers]

Those plugs - no idea how to remove them, post 600's (which is what I have) don't have them. They're just rubber aren't they? Once you have the pistons out, try tossing them in a bit of boiling water for a while to soften the rubber plug/bobbin/whatever it's called and they should be a lot easier to remove. 30-45mins maybe?

[rexazz2]

is this plastic inside the piston or are they actual phenolic pistons

[gypsypunk]

they are plastic and when i dremmel into them they expand and the same with drilling them
horrible things they dont crack they just chip tiny bits
i would have thought drilling both edges would split them and then they would pop out but no it's like they expand and refuse to move.

well i will get them out just takes longer dont want to damage the pistons.



i have

oop's here you go this is what those things look like

http://www.cmsnl.com/suzuki-gsx750-1990-fl_model13706/partslist/FIG-45.html#results

[KAT TOY]

they are inside the pistons, correct? if so they don't need to come out for repair.

[gypsypunk]

https://www.youtube.com/watch?v=tRlQuqnWhbk

previous owner must have glued them in there i bent my hammer trying to prize them out

i took the calipers off the brake disk and pumped them but as i didnt have the right size wood to stop them all popping
i tried a brake pad but just made a mess
i bought a piston remover kit i can use it on all other bikes apart from my kat

i am going to my suzuki dealer and i am going to ask them what is the purpose of these boots/plugs in the piston.
i bet you they scratch there head

[1LE]

Well, the plastic pieces *do* distribute the pressure over more material than if just the ring of the piston was pressing on the pad assembly. I can't imagine that would matter though, since they don't bother with anything like that on cars/trucks.

It would appear that it should help reduce heat transfer from the pad backing plate to the piston itself. Do these brakes get hot enough that it would matter? Also, if they were hot enough to heat the pistons and damage the seals I'd think that it would also just melt the plug.

Dunno. Just theorizing...

[gypsypunk]

if they were hot enough to heat the pistons and damage the seals I'd think that it would also just melt the plug.

Dunno. Just theorizing..

thats a exellent theory i though maybe they were in there as a anti sqeaking mechanism or maybe just to stop dirt getting caught up in the piston cup.

and as the kat is a sports tourer there is no reason why the brakes would be used the same as a racing bike.

mind you i couldnt imagine touring anymore than a hour as the 1990 kat as handlebar position kill my wrists.

thats another thing i need to look at