Stuck Front Caliper Pistons

[Bug-a-natic]

Hi Gang,
For some time now mi Front caliper piston seals were leaking so I tore it down to change them. My problem is that they are stuck! I've been "soaking" them in WD40 and brake fluid and they are super stubborn. Any ideas to get them out?
Thanks in advance,
Handel Waugh

[WestyPop]

Just the old method (assuming you have the caliper off its mounting & laying on the workbench) of folding a shop rag into a pad c. 1/2" thick & placed between the brake pad faces, leaving your brake pads in place on the caliper pistons, and then hitting the caliper's fluid inlet with a rubber-tipped blowgun and at least 125psi of air off your compressor line. Be sure to keep your eyes protected, mouth closed, and any important body parts away from the accelerating brake pads & pistons. Good possibility brake fluid & a bunch of crud could come flying out also.

If your WD-40/brake fluid cocktail isn't working, you might try a 50% ATF / 50% acetone mix as a penetrating oil formula.

Going back together, however, all must be squeaky clean, preferably with brake cleaner, then air dried. Personally I like re-assembling the clean piston-to-cylinder bore using brake cylinder lube; VW did originally also (calling it "brake paste" in the Bentley manual). The VW stuff has been 'NLA', since probably the late 1970s! The most common brand today seems to be McKay #600. Using it hopefully ensures less chance of sticking next time, but mostly smoother hydraulic cylinder operation right now.

J.R.
'68 Westy
(+ others)

[busman78]

If you do not have air then hook the hose from the bus back onto the calipers, rags in between pistons and push the brake pedal. Just as messy, but it will work.

[Bug-a-natic]

Thank for the replies and the assistance. I will be soaking and proding and pleaing until she gives.

[wildthings]

Personally I like re-assembling the clean piston-to-cylinder bore using brake cylinder lube; VW did originally also (calling it "brake paste" in the Bentley manual). The VW stuff has been 'NLA', since probably the late 1970s! The most common brand today seems to be McKay #600. Using it hopefully ensures less chance of sticking next time, but mostly smoother hydraulic cylinder operation right now.

Looks like the part number for this stuff is McKay 50600 and not 600. Still don't know where to buy it from, anyone have a link. Used to use it all the time and haven't seen it for sale in decades.

[fusername]

it's not what you asked for, but I like permatex and here is thier take on the product
Permatex brake assembly lube (tispeed.com)

one day I will have the guts to pull those things apart.