Brake caliper piston holding tool for XJ900

I was removing the pistons from the calipers on my '83 XJ900 Seca using the compressed air method. That worked somewhat, but as they got nearer to the end, I thought about the brake fluid that would likely spray all over the shop as soon as one of them popped. Seemed like there should be a more "controlled" method.

So once again I header to CAD and modeled up these piston "brake shoes" so I could hold the piston firmly while twisting/lifting the caliper body to get them off. It worked!

You insert the two halves into the piston and tighten 3/8" bolts into the holes. (don't overtighten and bottom them out) The holes are tapered, so as the bolt goes in further, it spreads the halves like a set of little brake shoes. You can then clamp the bolts into a vice, grab ahold of the caliper body with two hands, and twist/lift the two apart. It does take quite a bit of force, and you might need to twist back and forth a little to get the seals to loosen up, but the tool showed no signs of slipping.

Model uploaded to Thingiverse at https://www.thingiverse.com/thing:6981717.

(Note: Been having trouble getting pictures to upload, not sure what's going on, but it seems to be something with the site. It just spins for a couple minutes, then the pictures disappear.)

 

Looks like it will let me upload pics with the Upload a File button. The copy/paste method still isn't working though.

Note this tool should also work for any piston with a 37mm inside diameter.

 

Use a grease gun to drive the piston out, and a rag to catch the piston once it pops out.
Bolts will damage the surface of the pistons. It might not seem like a problem, but every bit of damage to the piston face is an invitation for corrosion to form.

 

Thats the beauty of this...the bolts never touch the pistons. They just cause the plastic to wedge against the inside. The plastic is the only contact surface. Also saves having to clean up the grease.

 

Looks like you have a good idea there. As long as there is no damage to the surface, and you are just using the plastic for contact force, I think you have something there. I use compressed or the grease gun trick, but this could be promising. If the puck is moving at is, has to move for this to work. I see the movement trail on your puck in the pick. The back and forth action seems to have worked. Cool.