Caliper Piston Removal Trick

I just discovered that a presta style bicycle pump held fimly to a loosened bleeder valve will produce enough pressure to push the piston out. You need to block off the union bolt hole with a non union bolt to create pressure.

 

I just rebuilt mine last Saturday and found that compressed air was my best friend. If you take a rubber tipped blowgun and push it lightly into the hole that the banjo bolt fits into, a quick couple blasts of compressed air pop the caliper piston out quite well.

I -HIGHLY RECOMMEND- that before you consider doing this that you find a way to keep the caliper piston under control when it pops out. I placed the caliper on a table with the piston pointing down and put a thin sheet of plywood into the caliper so that the piston had a sort of backboard to hit against instead of flying out, and potentially hurting someone.

I CANNOT STRESS ENOUGH, IF YOU HIT IT WITH FULL FORCE COMPRESSED AIR IT WILL "POP" OUT WITH ENOUGH FORCE TO INJURE and if you have your fingers in the way of the piston it will remove them quite swiftly.

Warnings aside, this method worked quite well to remove the pistons as I already had a shop compressor handy. I found that it was easiest to let the compressor pressure bleed down a bit and then try to be gentle and the piston came out without any drama at all.

 

I can vouch for the "ouch" factor of not controlling the piston when using compressed air to get it out.

Don't ask...

 

I have to ask! I promise not to laugh, it absolutely shocked me how hard the first one came out.

This actually leads me to another question as well. How much pressure is actually present in a motorcycle brake line under a firm brake lever squeeze? I have always thought of hydraulic pressure in a "high psi" mindset but I had my calipers hooked to a well bled master with only the short anti-dive lines and the pistons wouldn't barely budge.

 

When I cleaned up my brakes last year I just kept pumping the brake lever and used the brakes own pressure to push the piston out. I wrapped the caliper in a plastic bag so I didn't get fluid all over the place. Worked to perfection.

 

I'm having trouble getting mine to quit squeeling. I use this blue automotive spray on the back sides and it works well only for about a week.
Any other sugestions?

 

Brake PSI on cars runs about 2,000 or so--I don't know bike specs, but I would guess about the same. If you couldn't hydraulically push the pistons, you maybe had air in there[???]
for squeaks, the "right" way is re-surface rotors and new pads.
the other way, put the pads on smooth concrete and pull them at 90* to the "grain" for a fresh surface, rub the rotors with very fine sandpaper [400 grit] to break the glaze. You will see the sanding marks for a while, so try to sand with the grain. break them in away from traffic

 

Here's what researchers have to say about brake noise:

This is what we sell (effective preventive measures) to the brake shops we deal with. They say it works to prevent noisey brakes...

"Longitudinal vibration noise" means micro-grooves in the surface of the rotor. When you apply the brake, the pad grips the rotor and sets up a high-pitched harmonic. To fix this problem, hit the rotor with these pads to break up those grooves.

 

Coppaslip on the back of my pads did the job David

 

Mine actually came out pretty slowly because of two things. I was using a bicycle pump and putting out maybe 40-50 psi and the piston had been sitting in there unmoved for god knows how long. In fact, behind the piston, there was a gelatinous goo of old brake fluid.

I could imagine that compressed air would shoot it out with some pretty hefty force though.

Considering the condition of the residual fluid in both the MC and the caliper, would you guys even attempt re-using the lines, or would you replace?

 

Quote: "Copaslip® (often misspelled as copperslip or coppaslip) - the original anti-seize compound. It is a very high temperature (up to 1100°C) anti-seize assembly compound, bentone based non-melt grease with copper, polybutene, and anti-corrosion additives."

I'm not to sure i want to put a non melt grease to any brake part. Thanks
When I put the blue permatex disk brake quiet on the back of my new pads, it elininates all the squeel for a week or so. This leads me to think that the pads are a tiny bit loose in the caliper and vibrate or harmonic instead of a surface problem. My bike has 7K miles on it and the rotors look great.
I thought replacing the small keeper parts would help but they only come with a Yamaha set of pads. I'm already using new EBC pads.
Any other ideas?

 

2. Brake noise (brake squeal / squealing brakes)
Below is an analysis based on our experience of what causes brake noise and how to fix it.


I just found this on the EBC web site.

"A - SHIM NEEDED - 60% of brake noise problems are solved by the addition of a rubber/steel/rubber shim on the reverse of the pad known as a noise reduction shim. Since 2006 all EBC Greenstuff, Redstuff and Yellowstuff pads have been manufactured with shims.

However, if your pad set does not have such shims ask for a set of these free of charge from EBC support, fit them and reinstall pads."

I will ask for the shim and see what they send.
Thanks for the help.
I like this XJ site!

 

Apologies for misspelling the product! Regarding you not wanting to use it is obviously your choice. You asked for suggestions (some people misspell this sugestion) and I gave you one that myself and a number of other bikers I know have used with some success.

 

if the leading edge of the brake pad is a very square sharp corner, round it off about 1/8 inch
don't know why but it worked for me

 

btw if you don't have a good air compressor, a grease gun works very well for forcing out stubborn caliper pistons.... and the fitting snaps right on the bleeder valve.

also, there's no risk of it "popping" out and hurting someone.

 

Here's Bosch's take on why they chamfer their pads...

Most brake pad manufactures are now chamfering their pads to combat noise issues.

 

My brakes used to squeal too. Once I cleaned up the master cylinder, especially the relief hole, the squealing stopped. The brakes were always dragging a little, thus the squeal.