Front Caliper Rebuild

[vongiese]

Holy cow - thought I'd rebuild my caliper....sounds real easy....NOT
There's 2 replaceable rubber parts - The Boot and the seal. The manual says install the seal in the cylindedr wall, then install the boot, then lube the piston with brake fluid an insert it into the cylinder. Not that easy! Well the boot is too tight to easily slide over the piston. So I tried installing the boot on the piston - slide it to the end of the piston, and try to get the boot to set in the groove on the cylinder but that didn't work very well. No room to work that seal into place....
Any tricks or tools for this job? or just stick with spending the bucks for a rebuilt caliper......
bummer

[vongiese]

doing some searching and came up with this .... i was sort of trying to do this and having trouble - see figure 15 on this site...I'll try tomorrow but not sure there's enough room to get a grip on it and insert the boot lip in the cylinder....guess I'll have to scrub it all down and put it in a vice.
I'll let you know how I do tomorrow.
this would make a good how-to...:)
http://www.installuniversity.com/install_university/installu_pages/donations/brake_caliper_rebuild.htm

[Oldblueaccord]

Well its just like that web site's pictures shows.

Did you hone out the cylinder and get the rust and junk out of it? The new piston may not go past the ridge or it maybe oversized some. Remember lube lube lube. Brake fluid only.


wp

[vongiese]

The old parts are in good condition- piston is shiny as a chrome bumper 9after a little cleaning). This caliper was hanging up a bit, but not enough to warp the rotor. But it wasn't rusted either....seems strange.
Lube = brake fluid OR brake grease.... i'll be trying again later today (after I get off work). I already tore a hole in one of my new boots.....:mad: :mad:
thanks
mike

[Soundy]

Yeah, that link covers it pretty well... I did at least a couple caliper rebuilds on my old GLC years ago (like, 20 years ago, pre-internet), it's pretty straightforward. Considering a cylinder hone can be had for $15-$20, I'd recommend using one just to be sure there's no crud inside - a rough surface will cause problems and may not even be noticeable.

A large C-clamp is cheap and handy for pushing the pistons in too, just make sure it's well-centered so they go in straight.

[vongiese]

Well - I had better luck today. Cleaned up the caliper real good and then - like the fig 15 from the site above shows - slide the boot down the piston, then stretch it out and squeeze the boot so you can insert the lip of the boot into the slot in the cylinder, then - this is the trick - spin the boot in order to seat it in the cylinder. That's when the lubrication comes in that is soooo important. I used silicone grease (brake grease) on the seals and cylinder and some brake fluid. We'll see how long it lasts...

My cylinder wasn't nearly as smooth as my piston...butt the seal makes contact on the piston - the wall of the cylinder doesn't actually do any sealing.


Next will be my master cylinder - occassionally the pedal will slowly go to the floor...not all the time.

[Soundy]

Properly bleeding the system will PROBABLY take care of that mushiness problem.

[vongiese]

I can't pump up the brakes tho - they are solid....except occassionally if I hold pressure on the pedal - it will creep to the floor. Pretty sure that's the Master Cylinder.
thanks
mike

[MessyHonda]

I can't pump up the brakes tho - they are solid....except occassionally if I hold pressure on the pedal - it will creep to the floor. Pretty sure that's the Master Cylinder.
thanks
mike



yup...or you have air in the system...after i changed all my lines i put some dot 4 fluid and it does not happen to me any more

[vongiese]

yup...or you have air in the system...after i changed all my lines i put some dot 4 fluid and it does not happen to me any more

What does not happen? pedal creep to floor?

[MessyHonda]

What does not happen? pedal creep to floor?


yeah.....the pedal is nice and firm now. it would sucks on like hills and stuff because i would have to pump the pedal....not anymore tho

[Soundy]

Yeah, but is that the DOT4 fluid, or the fact that all the lines had to be fully bled? :)

[MessyHonda]

Yeah, but is that the DOT4 fluid, or the fact that all the lines had to be fully bled? :)



i swapped to se-i brakes....and i got SS lines....i did not fully drain the whole system but when i was bleading it most of the fluid was new. i mean...17 year old fluid.....to get replaced with a newer one...made a huge diference

[Soundy]

Yeah, some air in the lines over that time wouldn't surprise me. Old fluid will break down as well, and of course with a major upgrade like that, the brakes will naturally feel different.

Point is, it's likely the full bleed that more of a difference in the firmness than just the different type of fluid. In other words, simply changing to a different type of brake fluid won't magically fix the problem :)

[vongiese]

I can't pump up the brakes tho - they are solid....except occassionally if I hold pressure on the pedal - it will creep to the floor. Pretty sure that's the Master Cylinder.
thanks
mike

Found out that it was my other caliper hanging up...slightly dragging and heating up the caliper and fluid allowing it to seep around the master cylinder seals. Discovered the cliper warming up while in Seattle for a funeral.....
Got a rebuilt caliper - 30 min job. No more creep.:)