Sticking, Squeaking Front Brakes

When I am pushing my bike, or riding at very slow speeds, my front brakes make a horrible squeaking noise. When I put my bike up on the center stand, lift up the front, and try to spin the wheel, it only turns a few inches and stops.

Is there supposed to be constant brake pad pressure on the discs? If so, how much is "normal". Shouldn't I be able to spin the front wheel and have it go for a while before stopping? Is there a way to adjust the "brake off pressure"?

I already replaced the fluid and bled the lines. Situation didn't improve.

FYI, my bike has dual discs. And the wheel spins freely and noise-free with the calipers off.

Any suggestions? Thanks.

Sounds like your pistons are sticking in your caliper(s). Have you tried using a C-clamp to push your pistons back into the calipers a little bit
and then see if the problem reoccurs?

I did push the pads back in when I took them off and put them back on. But after the brakes are applied for the first time, the pressure on the discs comes back.

If the pistons are sticking, is there a way to lube them, or do I need to rebuild them?

If they've never been apart, the return hole could be full of GUNK. I know some I have taken apart were full of gunk that kept them from working right. But once I cleaned them up and blew out all the passages the worked fine.
The piston just slides back and forth with a rubber seal against the walls to keep the fluid in. There is really not much to it.
That's just me though. I'm sure if somebody else has an idea, they will chime in.

mariozappa wrote:

If they've never been apart, the return hole could be full of GUNK. I know some I have taken apart were full of gunk that kept them from working right. But once I cleaned them up and blew out all the passages the worked fine.
The piston just slides back and forth with a rubber seal against the walls to keep the fluid in. There is really not much to it.
That's just me though. I'm sure if somebody else has an idea, they will chime in.

I assume the return hole is in the M/C, not the caliper, correct? Is it a "big deal" to take apart and put back together? Anything I need to be wary of?

Yes, sorry...the return holes is in the MC.
The calipers come apart pretty easy.
Search the archives, there are some pretty good directions from other members there on what to do.

the best fix is to rebuild both the master and wheel cyls, I would also replace the fliud with dot 5

Brake Seal Grease. Like this. tinyurl.com/3ae4jg
I've just bought some:woohoo:

The seal on the piston is designed to deform into a relief-clearance in the seal groove as the piston moves forward. When the pressure is released, the seal is supposed to retract slightly back to its normal shape. This retracts the piston. If there is corrosion in the relief-clearance, the seal doesn't ever move. So it never "retracts" the piston.

A rebuild and cleaning of the groove should fix it.

DON'T DO IT! That is, don't use DOT 5 brake fluid! It is silicone and it is NOT hygroscopic. Meaning: instead of moisture that penetrates the brake system being absorbed and evenly distributed throughout the brake fluid, the moisture will collect into "puddles" in the brake system and create serious problems. Silicone is sometimes used for racing applications, but only when the racer is going to change the brake fluid every couple of weeks or so. Nobody is going to do that with a street bike, and nobody I know with a 30 year old KZ (even if in mint condition) with street tires is ever going to brake so hard and so frequently on the street that they will need the extra "boiling point" margin of DOT5. Also, it is not compatible with DOT3 or DOT4, so unless one plans to change a bunch of brake components switching back and forth is a bad idea. Use DOT3 or DOT4. I'm sure some may disagree, but thems the facts. (Can I climb down off this soap box now?) Ed

Hey Skyman,
Seems like a lot of good advice here. I'd lean toward the corrosion in the calipers, or at least gelled brake fluid in the calipers along with an accumulation of gunk. I've had luck with just pumping a bunch of clean fluid through the system. If that doesn't work and you decide to try to rebuild the calipers you'll soon realize that getting the pistons out isn't really easy, once they're removed from the system.

Quick solution Pressurized Air! Be Frikking careful! Put several layers of terry cloth between the piston and the backing and with your precious digits out of the way use an air nozzle with a rubber cone on the end to pump air into the caliper. The piston will be expressed with enough force to crush your finger if it's in harms way.

Don't be discouraged by minor pitting. Clean it up with some 600 emery cloth. If you can't smooth out the corrosion, a different caliper is probably cheaper than a new piston.

KZCSI

650ed wrote:

DON'T DO IT! That is, don't use DOT 5 brake fluid! It is silicone and it is NOT hygroscopic. Meaning: instead of moisture that penetrates the brake system being absorbed and evenly distributed throughout the brake fluid, the moisture will collect into "puddles" in the brake system and create serious problems. Silicone is sometimes used for racing applications, but only when the racer is going to change the brake fluid every couple of weeks or so. Nobody is going to do that with a street bike, and nobody I know with a 30 year old KZ (even if in mint condition) with street tires is ever going to brake so hard and so frequently on the street that they will need the extra "boiling point" margin of DOT5. Also, it is not compatible with DOT3 or DOT4, so unless one plans to change a bunch of brake components switching back and forth is a bad idea. Use DOT3 or DOT4. I'm sure some may disagree, but thems the facts. (Can I climb down off this soap box now?) Ed

ive used dot5 for years in everything from dumptrucks to motorcycles,have NEVER had any kind of braking problems.ive never heard of anybody changing brake fluid every couple of weeks:whistle: any kind of brake fluid should be changed every couple of years,especially dot3-4 because it turns to trash;)