So, you’re rebuilding your brakes and it’s become apparent that you’re going to have to replace those old pistons in the calipers. If you’re like me, your bike sat for so long the pistons are stuck fast, and won’t budge. Here’s the solution I found.
Warning! If you follow my steps here, you will get the pistons out, but will likely ruin them in the process.
Step One
Disassemble the caliper completely and remove the brake pad so the piston is accessible. (In my picture I still need to remove the brake pad)
Step Two
Weld a large bolt to the inside of the piston
*here come the tricky steps*
Step 3
While the piston and caliper are still hot from the welding, put ice or cold water on the inside of the piston. (The point here is to cool the piston, but NOT the caliper. By keeping the caliper hot, it will expand and give you valuable clearance to get the piston out)
Step 4
With the piston cool, and the caliper body hot, clamp the bolt into a vice and slowly turn, pull, and work the caliper free from the piston.
Step 5
Allow the caliper to cool slowly to avoid warpage from the heat.
This process worked like a charm on my ’74 caliper. It was nice and clean inside and should be ready for a new pistons and seals.
Here's some more pics of the same process for the other caliper:
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Hey Curtis! There is also another way to get those pesky pistons out without ruining them, but it doesn't always work. I have used this method successfully more often than not, however. But before we get to that, I always try to use compressed air first. To do that, wrap the caliper with a heavy rag and mount it securely in a vise. MAKE SURE that the piston is pointed in a safe direction! I have seen brake caliper pistons come out with some force when using compressed air, possibly enough force to cause some damage of one kind or another. They also make a pretty loud "POP" or "BANG" when they finally come out. Once the wrapped up caliper is mounted securely, make sure the bleeder is closed and use an air noxxle with a rubber tip to pressurise the caliper until the piston comes out.
ReplyDeleteOkay, so assuming that you have tried this and it doesn't work, the next thing I usually try is to come up with a grease fitting that will thread into one of the holes in the caliper. Finding a grease fitting that will work can be the hardest part of this method. Once youhave come up with somthing, make sure that all the other holes int he caliper are closed off and use a grease gun (one that fits tightly over the grease fitting) to fill the caliper with grease. Most of the time that piston will eventually come out. This method saves the piston and seals and will also work on those bikes that have pistons made out of materials other than steel, (some Hondas have pistons made our of some sort of phenolic or polymer type stuff.
Glad I found you blog! Hope your cafe body work is coming along alright.