Caliprs cleand, Install Pstns nxt - How much force 2 insert?

Hi All,

Well with your guys help, I got my pistons out, cleaned the caliper bores & grooves and installed new seals. Everything is good and lubed with brake fluid.

But I can't push in and seat the pistons with just my fingers. I got them started, squared them up and then pushed down a little bit before it got too hard. With such a clean bore and new seals, I would think there would be some resistance but not this much.

Is that normal?

This is an '82 XJ750 Seca. The upper caliper assy (with the plastic shroud) slides on a rod and this assembly contacts/slides on top of the caliper using a stainless steel rub plate. What should I lube the plate and pin with? I have some silicone grease - would that work? What other kinds of grease might work? I also have lithium bearing grease and white grease.

Man this forum is priceless!

Thanks,
George

 

Did you lube the piston, new seals and bore with fresh brake fluid? If not, you ain't gonna get far. Pop them out, inspect everything to make sure the seals are still square, slather brake fluid on everything and try again.
***Edited by Robert. This next step is concerning your slider pins, NOT your pistons! Thanks.***
A good brake caliper grease is recommended. You can source a small tube from most good automotive supply houses. Just remember one very important thing. Only leave a thin film on anything. Excess grease can contaminate the brakes rendering them less effective. Wipe the grease on and wipe it off with a finger. There should be a slight film left behind.
You can use lithium grease in a pinch, it has good water and heat resistance properties.

 

Keep the Caliper Piston BOTH Square and True. Don't let it tilt.

An easy way to accomplish getting the Piston pressed back in tp the Caliper is to use a C-clamp.
Place a large Socket inside the Piston.
Use the C-clamp protecting the finish in the Caliper with Duct Tape.

Turn the handle of the C-clamp slowly and press the Piston home.
If it tilts, loosen the C-clamp and tap the Piston centered again.
Once a third of the Piston makes it beyond the Caliper Seals ... the Piston will likely stay lined-up and allow you to press it all the way into the Bore.

Use copious amounts of clean brake fluid to lube the Piston's outside diameter as you press it back in the Caliper.