ATE Caliper piston removal...

[cosmikdebriis]

I would normally just push brake pistons out using the brake lever but in my case they were so seized it wasn't happening (without the risk of blowing a seal somewhere).

Levering them out was impossible because of the rounded groove.

So the method I used was... (and apologies in advance if anyone has already posted this).

You will need a drill (preferably a pillar drill), 7mm drill bit and an 8mm tap (preferably taper and plug).

Split the caliper. Then, drill a suitable sized hole (7mm for M8 thread) down through the bottom of the piston, tap a thread in the piston, insert a bolt and wind it in, pulling the piston out.

There are some obvious words of warning here. as you drill through the piston you will feel a clunk as the drill goes through but then hits the caliper. Obviously you need to stop a bit quick

If the thing was really tight then you run the risk of pushing the bolt through the back of the caliper though I'd expect the thread to give way first.

Personally I used BSCY thread as it's much finer than metric but I would have though metric would do and is much easier to come by.

Any thoughts, comments, constructive criticism appreciated.

[Rob Valdez 79 R65]

You have an engineer's' mind.  Good work!

(so the screw did not come through the caliper?)

[Bob_Roller]

I used compressed air to remove the pistons from the caliper.

You need to wrap the caliper in old shop rags / towels, as the fluid that comes out with this method, seems to get everywhere, it also helps keep the piston in the same room !!!!

[disco51]

+1 on the compressed air.  I ended up using a bike pump with a homemade fitted rubber o-ring and a rubber wood clamp to get a good seal.  Ended up needing close to 50 psi to get the thing out.  Luckily, it didn't shoot across the garage.

[Barry]

They must have been truly stuck to not be able to pump them out with the brake lever. Even when not completely seized usually only one piston moves so  I  Put a G clamp around that one and pump the more reluctant one out.

Bring back drum brakes !

On the other hand they can seize too.  Never put a car away for long term storage with the parking brake on.

[cosmikdebriis]

Believe me I tried every method known to man before resorting to destroying the pistons. It was a last resort.

Funny thing is, bike had 9 months MOT when I bought it but I'd guess those pistons have been stuck for some considerable time judging by the corrosion.

The other caliper wasn't quite so bad so perhaps it passed on one side.

[Tony Smith]

Believe me I tried every method known to man before resorting to destroying the pistons. It was a last resort.

Just in case you ever need to do this job again and are faced with horridly stuck pistons.
 
Go to an industrial supply house and buy a grease nipple that fits either the pressure feed to the caliper. Whilst there buy a good strong engineer's "G" clamp.

Fit clamp to piston of your choice and then apply grease gun to nipple - the pressure available to you from even a cheap grease gun greatly exceeds anything you could ever generate with the brake master cylinder or with air.
 
Please, please, please do not use a flexible coupling to the grease nipple - if you must then wrap it with cloth and wear gloves and safety glasses. 30 years ago the flexible coupling I was using for this very job burst and injected my thumb with a small amount of grease at thousands of psi. It took several very painful and expensive lots of surgeries to remove all the grease, then debride the scar tissue to give me back normal range of movement and "normal" appearance of my thumb.
 
Needless to say I do not use flexible line grease couplers for anything now.