caliper help

[gwcrim]

Off brand here but WTF.............

I have a neat old Yammie RD350 and the front caliper needs rebuilt.  It's a pretty common Yammie two piston caliper from the '70s that splits in two.

How on earth to I get the stuck pistons out?

[Johnniespeed]

Many years ago, I worked with a guy who made a fitting to use the pressure from his grease gun, to pressurize a siezed caliper, I know that did work for him.
 I usually atempt to soak the piston first in PB blaster pentetrating oil , then I try to push it in further with a press. Once I get it to move a little, it is just a matter of working it back and forth.
  I still have a dent in an old Snap on tool box, where I used air pressure and a torch, I do not suggest that combination, as someone ( me ) could have gotten hurt.
 Keep us posted on your progress.
 John

[DoldGuy]

Pressure Regulator

[Motorrad]

Many years ago, I worked with a guy who made a fitting to use the pressure from his grease gun, to pressurize a siezed caliper, I know that did work for him.
 I usually atempt to soak the piston first in PB blaster pentetrating oil , then I try to push it in further with a press. Once I get it to move a little, it is just a matter of working it back and forth.
  I still have a dent in an old Snap on tool box, where I used air pressure and a torch, I do not suggest that combination, as someone ( me ) could have gotten hurt.
 Keep us posted on your progress.
 John

Company I used to work for fixed hydroloc lifts. To unstock the hydro rams they would pump them full of nitrogen till POW   guys were nuts

I'd reccomend a coffie can of diesel fuel. Occationaly warm up the can let it cool etc repeat till unstuck.

[gwcrim]

I have an air compressor but it will only go to 125 psi or so.  Would that do it?

I was also thinking of drilling the piston and putting a zerk in the middle and trying grease.

These things seem to be made of unobtainium.  No replacements, no rebuilt, none on Ebay...........  nothing like old bikes and cars.

[gwcrim]

Do a little searching..........  I even bought the replacement parts from this outfit.

http://www.hvccycle.com/Stuck%20Piston.htm

[kxracer]

There is a firm called Yambits in the North of England which you may find useful for various spares once you get the calipers out.

Dave is the chap who runs it and they are on ebay and the website is www.yambits.co.uk

[KX500freak]

@gwcrim,


the compressor should do just fine,
make sure the tapered end of the nozzle is covered with some pipefitters tape ,
this way no air gets spilled and the pistondrive out happens quicker
 i have been sitting for minutes waiting for a piston to pop out 
they can be real stubborn ,but air ALWAYS wins
if it s not oxidated and became one with the caliper tho

make sure the leaving piston makes a hold against a piece of wood ,
i once searched 2,5 hours just to find out the piston was really gone ?
which costs me 30 fer a new piston grrrrrr

[gwcrim]

I gave it a go last night with the compressed air and torch just (like the HVC website recommended) but it didn't budge.  I'll try again but I'm leaning toward drilling the back of the caliper, driving the piston out, and plugging it with a pipe plug.  My patience is wearing thin.

[gwcrim]

Didn't resort to the drill.  One side came out easily but of course, the outside half took lots of work and th heat and ruined the Yamaha badge.

Life goes on.  My two stroke street bike is running.   

[KXcam22]

I am a bit late but I have always gotten them out using a c-clamp and the hydrualic pressure.  Work them in and out a number of times while applying penetrating oil.  Cam.