Hydraulic brake insert

[rosscla]

Just acquired a second hand one of these -



how difficult should it be to move the piston in / out?

I'd have thought it might slide fairly easy but not that I'd have to take a hammer to move it....

[englishman]

it should move easy ,only put rubber grease or brake fluid on it as to ease it up ,normal grease it wont like,it may just of sat about for a bit

[rosscla]

hmmm...have hammered it in and out a few times now and it's got a bit easier...but still not convinced it would go in and out on it's own if fitted...

Any suggestions?

[englishman]

have you any pictures??

[rosscla]

Ok I spent a couple of hours hammering it in and out last night (ooo err)... much to my missus delight (titter ye not)...

Anyway not I can get it the piston in by hand but it requires a fair amount of pressure, I can now push it out from through the banjo hole and if i push it back in it pops nicely if the hole is covered... I guess I'm not going to know if it releases in practice till I try it in the brake and bleed it.

Here's some pics -

This is the actual one in question -



I used a punch to push the piston out a little -



All the way out -



Couple of shots of the caliper -

[englishman]

i would say take the seals out ,clean under them as much as poss ,and then try it ,it looks like its had a hard life!!

[wack 63]

Same here,take the seals out then try the piston in the bore.If it is free then the seals could have swollen or the grooves are corroded or under size.All pistons are tightish anyway but the hydraulic force is great to push them out and they only retract a small amount when the pressure is released.

[rosscla]

Next stupid question then is I suppose they just ease out with a small screwdriver or similar?

[wack 63]

Yes but a seal pick is easier.

[rosscla]

Yes but a seal pick is easier.

I had to google that - it's like a dental pick