disk brakes are new to me. I'm working on an XS2. My front caliper was frozen up. With help from this group, I got the seized pistons out. They each had a band of rust around them, so I replaced them with new ones from Mikes'sxs. I cleaned everything up well and installed new seals. I put a slight coating of disk brake grease on the walls before installing the new pistons. I was surprised at how tight they fit. I had to drive them in with a mallet and a block of wood. I was surprised, but assumed that it was normal. I reinstalled everything and bled the brake and everything seemed to work OK. But later, when I went to roll the bike to a different spot, the front brake was tight enough on the rotor that it would not roll. Once I decided that it was because of the brake, I removed the caliper and it rolls just fine. Is this somewhat normal with new seals and pistons? If not, what needs to be done? THANKS
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pistons in XS2 front brake caliper
- Thread starter tmikeyb
- Start date
Remove the caliper from the bike , remove the pads, do not remove / disconnect the hose. pump the brake lever until the piston comes completely out. remove the seal and clean it all , be suer to remove any rust or crud from the seal grooves in the caliper housing. I don't know what disk brake grease you used but don't use it again. Use only brake fluid to lube inside the brake system, caliper or M/C. You should be able to push the piston in with your hands no need for mallet. try assembling with just the piston seal in case the dust seal is causing the problem.
Today I took the whole thing apart and cleaned everything very well. I was able to dig out quite a bit of rust specs out of the grooves. That must have been the problem because it all seems to be working OK now. I have good brakes, and they release well enough that ai can roll the bike by hand. I was able to insert the pistons by hand with no seals in place. With the seals installed, it still took a little tapping, but nothing like before.
Hi Everyone, what would you suggest to remove pistons from 74TX650A front caliper? Already removed caliper from bike, already split caliper, letting it sit with some penetration oil. I see a few pliers type tools to grip inside piston. Worth a try or is there another way? Clymer says compressed air but no luck there.
Thanks for your input - very much appreciated!
Thanks for your input - very much appreciated!
I know that not everyone agrees, but I think using compressed air to remove stuck caliper pistons is just a bit too dangerous.
It's a bit messy but I prefer to pump them out with a grease gun. Mess can be minimised by being organised. Grease gun will work where air has failed, the pressure generated by grease guns can be much higher than shop air.
It's a bit messy but I prefer to pump them out with a grease gun. Mess can be minimised by being organised. Grease gun will work where air has failed, the pressure generated by grease guns can be much higher than shop air.
I have never had an issue using compressed air. Holding a rag over it usually alleviates any issue. When it pops, the pressure dissipates. The secret to getting them started is normally squeeze them in with a clamp. That usually breaks them free, then it’s just a matter of working them in and out until they pop.
If using compressed air, never stick your hand between the piston and caliper body. As mentioned you can use a rag or a piece of wood to “catch” the piston as it ejects from the caliper body. Compressed air from a small compressor may be 150+ psi. A grease gun can easily generate 5,000+ psi. Grease is messier but has a greater ability to unstick a piston, with greater control.
Good suggestion to push in first - thanks
Here's the end result of this whole issue. I contacted Mike's XS and explained that my new pistons were slightly larger than my originals. They told me that the ones they had sent me were correct, and would not consider that they were too large. But, when I told them I wanted to return them for credit, they did agree to that. I then ordered new stainless steel pistons from a company in England who was selling them on ebay. They fit perfectly and that was the end of the problem. So the whole problem was due to the new pistons from Mikes being too large. They did refund my money, so I'm not upset with them.
