getting pistsons out the caliper??

[newguy]

How do I get the pistons out of the caliper without doing damage?? mine seem to be stuck

 

[fayeslane]

Compressed air in thru the hole the brake hose attaches to. Go gently as they can pop out with a vengeance and cause damage.
Good luck








.

 

[newguy]

I think the pistons are seized up from standing a few years open with the brakeline disconnected.
Should I manage to screw up my caliper completely, is it worth replacing it with one of these
http://cgi.ebay.com/ebaymotors/BMW-...3610760QQptZMotorcyclesQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/BMW-...2548104QQptZMotorcyclesQ5fPartsQ5fAccessories

I understand with a few mm machining on the mounting they fit quite well??

If I cant find a 2pot replacement??

The pistons are fairly chipped. One of the above calipers will cost me less than buying 2 new pistons.

 

[fayeslane]

I fitted an R1100Rt twin pot caliper to my R100GSPD. Bolts straight on to the mounts with about 3 mm of machining required to center it over the disk. Should be heaps of references on this forum if you do a search.

Chuck old calipers into a bucket of diesel for a week and then have a go at them. If they have been exposed to the elements for that long you can hardly hurt them by giving them a soak

 

[DrFarkoff]

Chuck old calipers into a bucket of diesel for a week

Nope don;t do that !!! Do I detect an old engineer there Fayeslane?

If you put them in Diesel you will just make the rubbers swell and make it even harder to get out

Bolt the calliper together fit a set of newish pads and clamp them around an old disc (or flat iron bar where the disc would be) and pump out with a brake master cylinder

The brake cylinder will pump almost anything out as it is Hydraulic pressure and the pads and disc will limit the travel so that one piston does not pop out and loose all your hydraulic pressure before the other moves

Then split the callipers again and you can use the out 3 or 4 mm to grip the piston if required as that is outside the seal

 

[(RIP) pastyman]

Agree but should'nt that be a "oldish" set of pads so that the pistons come out further. They are still hardly likely to pop out. just my onion

 

[DrFarkoff]

Agree but should'nt that be a "oldish" set of pads so that the pistons come out further. They are still hardly likely to pop out. just my onion

Tell ya what pasty man How about we go for a half wornish set of pads

My thinking was of getting at least one started then the other would follows and thickness could be reduced as required perhaps I should have mentioned that

 

[fayeslane]

Nope don;t do that !!! Do I detect an old engineer there Fayeslane?

Nope, not so old ex farmer. Diesel was the magic elixir, cheap and available -but I hadn't considered the rubbers swelling.

The apparent condition of the calipers, pistons etc sound like the twin pot option is a good idea.

Compressed air is good the calipers are off the bike but agree that hydraulic pressure is the way to go if the system is intact.

 

[Sean Kelly]

Hi

If compressed air is not available, I have managed to free several stuck pistons using one of those plastic, cone shaped air-bed inflators attached to a foot pump.

Sean

 

[(RIP) pastyman]

Tell ya what pasty man How about we go for a half wornish set of pads

My thinking was of getting at least one started then the other would follows and thickness could be reduced as required perhaps I should have mentioned that

 

[Timpo]

Use a grease gun. Gives a controlled effect so you can keep an eye on progress.

T.

 

[fayeslane]

Use a grease gun. Gives a controlled effect so you can keep an eye on progress.

T.

Yep, have used this technique successfully The clean up is a bastard though

 

[newguy]

Use a grease gun. Gives a controlled effect so you can keep an eye on progress.

T.

Bolt in the brake line and pump through the bleeder?

 

[DrFarkoff]

Bolt in the brake line and pump through the bleeder?

No JUst hook the calliper up to the master cylinder onthe bike

BELIEVE me Much less messy and less effort!!If you ahve difficulty bleeding the MC disconnect the main hose and hhold it about tank level and pump fluid keep the calliper near to hand and once you have fluid out the pipe connect the calliper without setting the pipe down leave the bleed nipplie open a wee bit and pump fluid thru

Only when you have clean fluid thru lower the calliper and tighten the connections and slip it over the disc then a wee bit of clear tube and just make sure you have no air bubbles

 

[fayeslane]

Alternatively pump the fluid into the system via the bleeder using a syringe and force the fluid back up to the master cylinder. I think this is called reverse bleeding and is useful on systems where it is difficult to eradicate all the air by conventional bleeding eg old Ducatis. Has the advantage of pushing the air in the direction it wants to go.

BE CAREFUL as always when using brake fluid cover up all paint work.

 

[newguy]

I've taken the forks apart and there was no spacer to be found, only the spring. Am I to assume that the fork has aftermarket springs fitted??

 

[ELIMINATOR]

Shame, you're too far away. At work i have an Hydraulic water pump, that i can get up to somewhere over 1200psi. I have successfully removed stuck pistons quite easily.