removing stock pistons from a caliper?

[OaklandStrom]

I bought a set of 4 pot Tokico calipers, as part of a brake upgrade for my Strom.

Of the 4 pistons, one pops out with air pressure - then there's nothing to hold the air, and the other pistons stop moving. They are stuck pretty well.

What's the trick to getting them out without galling the piston?

Any leads on cheap gasket kits?

[larryboy]

Ues an old brake pad and a couple of little C-clamps, use the air and slowly let out the clamps keeping the pistons equal until they all pop out at once.

[OaklandStrom]

A great solution, in 5 minutes.

Some days, I love this place.

Thanks

[MPH]

I had the exact same issue doing the exact same mod.

I wound up splitting the caliper and with my fingers plugged (or tried to plug) the holes through which the pressurized air was escaping, and it was enough to drive the last piston out.

I used stock Suzuki seal kit.

Good Luck.
Mark

[manic mechanic]

As recommended above, C-clamps. Push the expelled piston in slightly and hold in place with the clamp. Then use air to pop out the reluctant one.

Sometimes I've needed to use a clamp to push in the piston in order to loosen it in the bore and seals, then it's easier to pop out.

[GreaseMonkey]

One of my closest-to-serious-injury moments happened because I was using air on a caliper piston.

Especially on a stuck piston, once you have enough air pressure to get it moving it already has a surprising amount of energy behind it. If it is truly stuck screw a grease fitting into a flare nut and use a grease gun to pop it out or just connect it to the master cylinder and pump it out.. Cleaning a couple tablespoons of grease out of the caliper is going to be faster than finding something a week later that atomized brake fluid has landed on, or fixing whatever the piston ran into on the way out.

[Mgbgt89]

Originally Posted by GreaseMonkey

One of my closest-to-serious-injury moments happened because I was using air on a caliper piston.

Especially on a stuck piston, once you have enough air pressure to get it moving it already has a surprising amount of energy behind it. If it is truly stuck screw a grease fitting into a flare nut and use a grease gun to pop it out or just connect it to the master cylinder and pump it out.. Cleaning a couple tablespoons of grease out of the caliper is going to be faster than finding something a week later that atomized brake fluid has landed on, or fixing whatever the piston ran into on the way out.

+1

I've about taken a finger off using air. Using a master cylinder to drive the piston out is the way to go. I usually grab small blocks of wood for multi piston calipers to keep them equal. just keep putting thinner and thinner blocks in. The C clamp trick sounds more efficient though.

[theDoktor]

Now that the pistons are out, an answer to your second question: I bought my seal kits at Ron Ayers on-line site. Decent price- about $16 per caliper, as I recall. Delivery was quick too. I wouldn't buy new pistons unless the old ones are really torn up.

Is your bike a Vee or a Wee and what year? On the Wee's after 07, using an earlier year master cylinder (larger diameter) helps the braking nearly as much as the caliper upgrade. Don't know about the Vee, but I'm sure another inmate will chime in as needed.

[OaklandStrom]

The wooden blocks would no have worked. Only one piston would move at a time. I ended up using air, but still have all my fingers.

I don't think I need pistons. One has a nick in the surface, but it's high enough on the piston, I don't think it will go past the seals.

It's an '05 Wee. If the brakes still aren't great, I'm going to add a master cylinder from a bike that the calipers came from.

Originally Posted by theDoktor

Now that the pistons are out, an answer to your second question: I bought my seal kits at Ron Ayers on-line site. Decent price- about $16 per caliper, as I recall. Delivery was quick too. I wouldn't buy new pistons unless the old ones are really torn up.

Is your bike a Vee or a Wee and what year? On the Wee's after 07, using an earlier year master cylinder (larger diameter) helps the braking nearly as much as the caliper upgrade. Don't know about the Vee, but I'm sure another inmate will chime in as needed.

[juddspaintballs]

Grease works best once you take it off of the master cylinder. I stick a thin block of wood inside the caliper because the pistons don't have to come out evenly together, they just can't come all the way out. It's surprising how easily the grease method works and it only takes about 60 seconds with some spray carb cleaner to get it all out of the caliper. If you're rebuilding calipers you're gonna hafto clean them out anyways.


Here's the metric bolt I drilled and tapped for a grease fitting a few years back.

[manic mechanic]

Now that you have the pistons out, remove the seals from the caliper and clean everything meticulously. I run it in a parts cleaner with bristle brushes to get the biggest amount cleaned up, followed by red scotchbrite fot the bores. Then I'll use some old dental picks from my dentist, (or you can find serviceable ones at some flea markets or even gun shows) to clean out any residue from the recesses for the seals. I use compressed air to blow all the junk out of the caliper, then rinse well with brake cleaner. Repeat cleaning as necessary. Then I'll install the new seals and put a little clean brake fluid on them with a cotton swab. I'll clean the pistons with solvent and scotchbrite and rinse with brake cleaner. Then I'll put a little brake fluid around the edges that will go into the caliper in order to permit the piston to slide past the new seals easier. Purs the piston all the way ionto the caliper and repeat for as many pistons as you have. Complete reassembly of the caliper, install the brake pads and install the assembly on the bike. When ready, then fill and vent the brake system.

[OaklandStrom]

Originally Posted by juddspaintballs

Grease works best once you take it off of the master cylinder. I stick a thin block of wood inside the caliper because the pistons don't have to come out evenly together, they just can't come all the way out. It's surprising how easily the grease method works and it only takes about 60 seconds with some spray carb cleaner to get it all out of the caliper. If you're rebuilding calipers you're gonna hafto clean them out anyways.

Actually, grease doesn't work best if the pistons are stuck. These are 4 piston calipers, with one piston working much better than the others. I stuck a wood wedge between all 4 and hit it with air. ONE piston moved. The another one. However, the pistons on the side of the caliper without the bleeder or banjo bolt didn't move. At all.

So, I used a C clamp to hold the free piston, and hit it with more air. One more piston moved. Wedges don't do jack if only one piston moves - that one has to be held back. It doesn't matter if you hit them with grease, air, or brake fluid.

In the end, it took air, clamps, and lots of messing around to get all 4 (8 actually) free.

Here's the metric bolt I drilled and tapped for a grease fitting a few years back.

Nice work!

[OaklandStrom]

Seals are out, and I soaked the caliper halves in straight PineSol. After an hour of soaking, I used a toothbrush to get them really clean, then a hot water rinse, and blew them dry, and blew out the passages.

Second caliper is in PineSol now, and in the morning, I'll clean them and throw in the pistons and hardware.

PineSol degreases so quickly, it's almost scary.

Seals are on the way. I have dental picks, and every toolbox should have a set. I think mine are "General" brand, which is decent stuff for not too much cash.

Originally Posted by manic mechanic

Now that you have the pistons out, remove the seals from the caliper and clean everything meticulously. I run it in a parts cleaner with bristle brushes to get the biggest amount cleaned up, followed by red scotchbrite fot the bores. Then I'll use some old dental picks from my dentist, (or you can find serviceable ones at some flea markets or even gun shows) to clean out any residue from the recesses for the seals. I use compressed air to blow all the junk out of the caliper, then rinse well with brake cleaner. Repeat cleaning as necessary. Then I'll install the new seals and put a little clean brake fluid on them with a cotton swab. I'll clean the pistons with solvent and scotchbrite and rinse with brake cleaner. Then I'll put a little brake fluid around the edges that will go into the caliper in order to permit the piston to slide past the new seals easier. Purs the piston all the way ionto the caliper and repeat for as many pistons as you have. Complete reassembly of the caliper, install the brake pads and install the assembly on the bike. When ready, then fill and vent the brake system.

[OaklandStrom]

My seal kit arrived. It has two diameters, as well as two thicknesses. The old seals were so hammered, I didn't realize there were different thicknesses.

So... I have GSX-R750 Tokico calipers. Where do the thin and thick seals go?

And I got seals for $12, and reasonably fast delivery from this place:
http://thecaferacer.info/