jimbbski
jimbbski Dork
12/13/17 3:02 p.m.

I purchased an old car this past summer and with it came some old parts like a set of front brake calipers.  They were rusty but looked rebuildable so I ordered a couple of rebuild kits and a couple of new pistons. Well the pistons were stuck/rusted in place and would not move.  I ended up destroying one piston getting it out but decided to find an easier way on the second caliper.

Since I own a TIG welder I elected to simply drill a hole in the back side of the caliper and use a long punch to drive the piston out of it's bore. I then tapped the hole I drilled and installed an allen style pipe plug in the hole.  Now that's not going to seal so I then welded the plug in place and since I set the plug below the surface I filled the depression completely.  The calipers were cast steel so welding on them poses no issues. I wouldn't expect pistons to stick as bad when the caliper is aluminum.

 

Someone may ask: "Why not just just buy new calipers?".  Since the car is old some parts are NLA and rebuilt calipers are one item like that.

Knurled.
Knurled. MegaDork
1/14/18 2:05 p.m.

This is a regular RX-7 caliper failure mode.  The caliper body rusts outside of the seal and locks the piston in place.

 

So far, I've had good luck with unbolting the caliper, starting the engine to get maximum brake assist, and shoving the brake pedal.  If 1200+psi of fluid pressure won't make it budge, nothing will smiley

Kramer
Kramer Dork
1/18/18 4:52 p.m.

Screw a zerk into the bleeder fitting, using adapters if necessary.  Then a grease gun should pop it out.  Or drill and tap the piston and use a screw as a puller.  Then replace the piston. 

Toyman01
Toyman01 MegaDork
1/18/18 4:57 p.m.

Grease guns put out an immense amount of pressure. Like 15000 psi. Don't blow up the caliper. 

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