putting my cb360 caliper back together?

jonwright

jonwright

surfing and motorcycles.... yup
ok so after the long and painful battle with my what seemed to be a siezed piston... I WON. so now i have a empty clean caliper body, a shiny looking piston, and the rubber washer/seal looks lightly warn but seems to be in pretty good shape. i dont really want to fork out 8 bucks for a new seal, so i figured i would just put it back together with the seal i have and see if it works.
now, the piston drops in freely with out the seal in place, and comes out freely so long as i dont have my finger over the hole for the brake line (good sign i think) but when i try to put it back in with the seal in place it is almost impossible to get it in there. what is the correct method of re assembling my caliper? do i want to grease anything up for assembly? so i can slide the piston in? do i want to push the piston all the way in before filling my master cylinder and bleeding? it looked like the brake pad was like glued some how to the piston at some point. is it normaly just supposed to sit on top of the piston? i guess what i need here is a caliper re assembly for dummies, since i havnt ever done this before. so any of your previous knowledge would be super helpful.
DSCN1784.jpg
 
Use some brake fluid and lube the piston, set it all the way down in the caliper, once u add the fluid it will pressurize the system back after u bleed it, once thats done spin ur wheel and check to see how the brakes are working.
 
fatherjon said:
ok so after the long and painful battle with my what seemed to be a siezed piston... I WON. so now i have a empty clean caliper body, a shiny looking piston, and the rubber washer/seal looks lightly warn but seems to be in pretty good shape. i dont really want to fork out 8 bucks for a new seal, so i figured i would just put it back together with the seal i have and see if it works.
now, the piston drops in freely with out the seal in place, and comes out freely so long as i dont have my finger over the hole for the brake line (good sign i think) but when i try to put it back in with the seal in place it is almost impossible to get it in there. what is the correct method of re assembling my caliper? do i want to grease anything up for assembly? so i can slide the piston in? do i want to push the piston all the way in before filling my master cylinder and bleeding? it looked like the brake pad was like glued some how to the piston at some point. is it normaly just supposed to sit on top of the piston? i guess what i need here is a caliper re assembly for dummies, since i havnt ever done this before. so any of your previous knowledge would be super helpful.
DSCN1784.jpg
Click to expand...

Seriously? You can't spend a lousy $8.00 to rebuild your caliper properly? This is your brakes, man! You don't mess around with half-assed work on your brakes!

Don't use brake fluid to lubricate the piston. Brake fluid is hydroscopic, and remains of it outside of the piston will attract moisture, and could cause corrosion.

Get some silicone grease made for caliper assembly. DO NOT use a petroleum grease. Petroleum and brake fluid, (a glycol fluid, not oil,) ar incompatible.

http://www.amazon.com/Permatex-24110-Caliper-Brush-Top-Bottle/dp/B000HBNV6W

This is not the same black moly stuff often used to grease brake caliper pins.
 
[quote author=AlphaDogChoppers]
Seriously? You can't spend a lousy $8.00 to rebuild your caliper properly? This is your brakes, man! You don't mess around with half-assed work on your brakes!
[/quote]

+1

And make damn sure that every bit of crap and crud is out of that grove the seal sits in as well. Else it will cause the piston to bind and the brakes to not release.
 
I only kinda agree with spending the $8...if there are no cracks or problems, the seal will hold up just fine.
Whenever I flush(replace old brake fluid with new) a brake system, I always take apart the caliper like shown here in his post, and clean clean clean.
IF the seal is in working order, I jst clean it up an put it back in.
I also Always use brake fluid to lubricate the piston, might stop that if you can convince me but in theory, as the piston moves out and in with typical braking,
and as the pads wear down, I believe that brake fluid would be lubricating that seal naturally>am I wrong?
 
Frogman,
You raise an important issue that is worth mentioning which I will explain for the benefit of the OP and anyone else reading this thread.

Disk brakes have no mechanism for making the brakes release. All there is is the square profile O-ring seal. The seal's resilience is what withdraws the piston a few thousandths of an inch to reduce brake drag when pressure on the piston is released. VERY important, that any time a caliper is taken apart, that all new rubber parts are installed. Also, when changing pads, the pistons should be cleaned very well before being pushed back into the calipers. Many motorcycle calipers have no dust boot on on the outside of the pistion, so the piston will be covered with crud. You don't want to be pushing that crud through the seal into the caliper.

Lydall Racing Brakes has an excellent tutorial on how to clean calipers.
http://www.lyndallracingbrakes.com/service_tech.htm
 
Fatherjon,
I also forgot to mention... The "glue" you mentioned is probably some sort of material to prevent disk brake noise. On every brake job I do, I coat the back of the pad with "Disk Brake Quiet." I use a body filler spreader to put an even coat on the back of the pads. I like to do it well ahead of time so that it has time to dry before I have to do the job.

http://www.amazon.com/CRC-Disc-Brake-Quiet-05016/dp/B000CINV88
 
<<I believe that brake fluid would be lubricating that seal naturally>am I wrong?>>

Yes, you are wrong. Here is why...
The brake fluid is on the inside of the seal. When you lubricate the piston with brake fluid before assembly, the brake fluid is on the outside of the seal, exposed to air and moisture.

The seal isn't just a seal. Whether it is working properly or not is not determined by whether fluid is leaking past it or not. It also has the function of pulling the piston back when pressure is released. That is not to say that you can't continue to use the seal from a perfectly functioning caliper that you pulled the piston just to clean. Personally, I would never pull the piston without changing the seal. Just good practice. It's not necessary to pull the piston to clean it. I will give the brake a couple strokes to bring the piston further out, then I will clean it and lube with a little of the silicone caliper grease. I never open a brake system unnecessarily.
 
hey guys i appreciate it. this is my first time doing all this so i need the help i can get. i probably will go a head an order it any way, your right, brakes really isnt something i want to skimp on. really this was great info and im glad i asked. thanks again
 
as said i would put a new seal in, over here in the UK we use red rubber grease for the seals, i swear by the
stuff, makes rebuilt brakes last twice as long and gives your brake fluid a nice pink effect (oooh eerrrr)
 
hey alphadog, so, once i get the grease and the new seal, is there any place i want to make sure i do or dont get grease? im guessing the piston obviously needs it, but as far as the seal goes, do i want to dry fit the seal into the groove and then apply the grease to the piston and just slide it in? or can i/should i be alittle more libral with it? i would rather do it right the first time ya know... i appreciate you answering all my dumb questions, you really are helping me out a lot
 
I put a little grease in the groove, put the seal in, then wipe out the caliper bore. Then I put a thin film of the grease on the outside of the piston, and put it into the caliper. After the piston is fully seated into the caliper, I wipe off any grease.
 
awesome. looks like i can get just a little packet of that grease so between that and the seal i should be a little less than 15 bucks on my calipr rebuild. i know i am a cheap skate, but brakes really isnt something i want to skimp on. my old seal really does look fine to me but better safe than sorry. thanks again for your help.
 
Thanks for all the advice. I did all this to my cb360 and its much better since it was completely stuck before. Its still not totally releasing on its own after I apply the brake. The pads can move off the disc but you have to push it. What actually pulls the caliper back in after you apply brakes and what could my problem be. Its very clean in there.
 
keeleydavis said:
What actually pulls the caliper back in after you apply brakes and what could my problem be.
Click to expand...

Nothing. The only thing that makes the brakes release is slight distortion of the piston seal when the brakes are applied. When you release the brakes, the seal pulls the piston back only a few thousandths of an inch. Disk brakes usually drag just a little.
 
AlphaDogChoppers said:
Nothing. The only thing that makes the brakes release is slight distortion of the piston seal when the brakes are applied. When you release the brakes, the seal pulls the piston back only a few thousandths of an inch. Disk brakes usually drag just a little.
Click to expand...
Gotcha. I also noticed I may need to bleed the brakes a bit more since the hand brake is not as firm as before. Would that help with suction?
 
It might help.
Try this trick for getting the last little bubbles out:

The problem with bleeding motorcycle brakes is that you are trying to get bubbles to go down a tube to get them out at the caliper. Trouble is, between pumps, they float back up. You can loosen the banjo bolt at the master cylinder, and burp the bubble out there where they gather. Before you try that, though, try pulling in the brake lever, and tie it there with a bungie for a few minutes. Tap the lines with your fingers or a screwdriver handle to shake loose any bubbles that might be clinging to the walls of the tubes. After a few minutes, release the lever, and bubbles trapped at the top might be pulled into the master cylinder. I have cured many a spongy brake that way.
 
AlphaDogChoppers said:
It might help.
Try this trick for getting the last little bubbles out:

The problem with bleeding motorcycle brakes is that you are trying to get bubbles to go down a tube to get them out at the caliper. Trouble is, between pumps, they float back up. You can loosen the banjo bolt at the master cylinder, and burp the bubble out there where they gather. Before you try that, though, try pulling in the brake lever, and tie it there with a bungie for a few minutes. Tap the lines with your fingers or a screwdriver handle to shake loose any bubbles that might be clinging to the walls of the tubes. After a few minutes, release the lever, and bubbles trapped at the top might be pulled into the master cylinder. I have cured many a spongy brake that way.
Click to expand...

Wow, that method of holding the lever and tapping really did the trick. Thanks so much for the suggestion!!!
 
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