Brake calipers- rework or re-buy

[sphen]

I was able to get one piston out of each using the master cylinder. But I had to press them back in partly to try the grease method to get the others.

I’m missing something tho - grease just runs out and down the caliper. Not getting much in and certainly no pressure. What a mess.

[sphen]

Another way to use a grease gun is to remove the coupling from the gun and screw the guns tube lightly into the banjo bolt hole. The 1/8” pipe thread is close enough to the m10 threads to catch enough threads to pump the piston out. Don’t force the guns thread into the caliper or you’ll damage the threads, only lightly hand tight will do.





https://i.postimg.cc/SNxNYvnp/0-D47-E37 ... FDB7-B.jpg

That sorta worked - once it pressurized the grease started oozing out around the unstuck piston and then back out the banjo hole. Then I ran outta grease. Sigh

[robin1731]

Another way to use a grease gun is to remove the coupling from the gun and screw the guns tube lightly into the banjo bolt hole. The 1/8” pipe thread is close enough to the m10 threads to catch enough threads to pump the piston out. Don’t force the guns thread into the caliper or you’ll damage the threads, only lightly hand tight will do.





https://i.postimg.cc/SNxNYvnp/0-D47-E37 ... FDB7-B.jpg

That sorta worked - once it pressurized the grease started oozing out around the unstuck piston and then back out the banjo hole. Then I ran outta grease. Sigh

You need to seal off the banjo bolt. I stack crush washers on a bolt for that. Also wrap the bleed screw with teflon tape.

[sphen]

This is a bit of a zombie thread at this point, but

Ultimately I found a short bolt with matching threads, sealed with Teflon, and got the grease gun properly attached.

[redglbx]

One thing I haven’t seen mentioned here at all is that while using a grease gun to remove the pistons works very well you must replace all the rubber seals that contact the grease and spotlessly clean all the grease from the caliper. No residue at all.

This is because “grease” is a mineral oil based product that will kill brake fluid based seals ! You cannot clean and reuse them, throw them away ! Any amount of contact with a mineral oil based product will cause the brake fluid seals to swell & fail ! Final cleaning of the calipers or any brake parts should be with only pure alcohol or brake cleaner only.

[pidjones]

Yes, need to toss all of the rubber. But on a froze-up caliper that should be done, anyway. I put my grease-laden calipers in a tub (plastic coffee can) of kerosene to soften and remove the grease, then a thorough bath of brake cleaner. For the blanking bolt, one caliper of one of my rescues was a blank fine-thread bolt (THAT caliper didn't leak!) I've used that bolt since then as a blanking bolt.

[robin1731]

Yeah, it's pretty much a given if you are removing the piston everything needs replaced and thoroughly cleaned.

[sphen]

True in my case also - complete rebuild/bath/etc