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Discussion Starter · #1 ·
I recently purchased a bike (2002 ZX6R) and the front brake pads are dragging heavily on the rotors.

Here's what I've tried:
1) Removed the calipers, sprayed brake cleaner on the pistons and pushed the pistons back, re-assembed, pumped brake. No difference.
2) Removed the front tire and replaced it with another I had, re-assembled. No difference.

From what I can tell the outside pad on each caliper is rubbing against the rotor, and those pistons are pressing even more into the pad when the brake is pulled. I can't see any movement of the inside pistons.

Any ideas? The previous owner said he had the calipers off the rotors and accidentily pulled the brake and he had to put everything back together (spring/s came out, etc.) However, he'd also low-sided the bike before hand so it could have been from that. He told me he'd changed the fluid once and it made no difference.

The rotors are straight.
 

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it could be the master cylinder return pressure is clogged(not releasing pressure) .


remove the brake calipers....insert a piece of wood or metal between the brake pads and apply pressure....does the object slide back out? or is it stuck in it?.....

this will separate the problem from the brake assembly or a front end alignment issue....

J
 

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Discussion Starter · #3 · (Edited)
it could be the master cylinder return pressure is clogged(not releasing pressure) .


remove the brake calipers....insert a piece of wood or metal between the brake pads and apply pressure....does the object slide back out? or is it stuck in it?.....

this will separate the problem from the brake assembly or a front end alignment issue....

J
I removed each caliper seperately, placed the same metal bracket (slightly smaller than the rotor) between the pads and pumped the brake till it grabbed. After letting off the brake the metal was held between the pads. I could pull it out, but it wouldn't fall out on it's own.

Does this mean its the brake assembly? ..maybe master cylinder? I recall the previous owner told me he rebuilt the master cylinder... I've never taken apart the master cylinder before.
 

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hey man i know you say your rotors are straight, but i had a problem similar recently. i drained/refilled my brake lines with fresh fluid and afterwards i felt a pulsing in the brakes. changed the fluid like 3 times and still no help. someone mentioned bent rotor. at first, i discounted that theory because i didn't feel the pulsing before, but after running out of ideas, i got a set of used (straight) rotors, put them on, and there was no more pulsing. i looked at my rotors and tried to measure them in some way to tell if they were bent/warped but i just couldn't see it with the naked eye. if nothing else works, pick up a pair of cheap, used, straight rotors, slap them on, and go from there. or if you wanted to, buy some galfer wave rotors. i dont know about the 2002 rotors, but i priced my 2005 rotors at the stealership and they are more expensive than an aftermarket "high performance" set of galfer waves.

just consider it.
 

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Powerhungry
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I removed each caliper seperately, placed the same metal bracket (slightly smaller than the rotor) between the pads and pumped the brake till it grabbed. After letting off the brake the metal was held between the pads. I could pull it out, but it wouldn't fall out on it's own.

Does this mean its the brake assembly? ..maybe master cylinder? I recall the previous owner told me he rebuilt the master cylinder... I've never taken apart the master cylinder before.
lets be clear here..how badly are they dragging?
with the tire off the ground, can you turn it, while its dragging?
or do you just hear the noise?
the pads will always very lightly touch the rotors. this is, so when you pull the lever, it doesnt have to travel far, before the pads hit the rotor.
 

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Discussion Starter · #6 ·
lets be clear here..how badly are they dragging?
with the tire off the ground, can you turn it, while its dragging?
or do you just hear the noise?
the pads will always very lightly touch the rotors. this is, so when you pull the lever, it doesnt have to travel far, before the pads hit the rotor.
Bad. As in, with the tire off the ground I can turn it by hand, but if I try to spin the tire it maybe gets a ~6 inches of rotation. Where normally, I believe I should get 1 1/2 tire rotation? The pads are more than lightly touching the rotors. I have another ZX6R and the front tire spins far more freely.

I spoke with the previous owner again and he said he pulled the front brake when the calipers were off the bike and didn't have any pads on. He said one of the pistons came out, so maybe it's a dirty seal not releasing the piston?
 

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What pads do they have in....with an HH pad on there, a wheel won't spin far at all.

But, I can't rule out a mechanical problem from where I sit.
 

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Discussion Starter · #8 ·
What pads do they have in....with an HH pad on there, a wheel won't spin far at all.

But, I can't rule out a mechanical problem from where I sit.
They're HH pads. On my other ZX6R I run EBC Perf. pads (not HH) and the wheel freely spins. I can easily push that ZX6R around my garage. However, when I try to push the ZX6R with HH pads there is a lot of resistance.

I was told the front wheel should have at least a wheel spin of rotation, is this not correct for HH pads? The rotors are EBC's... not stock.
 

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Discussion Starter · #9 ·
hey man i know you say your rotors are straight, but i had a problem similar recently. i drained/refilled my brake lines with fresh fluid and afterwards i felt a pulsing in the brakes. changed the fluid like 3 times and still no help. someone mentioned bent rotor. at first, i discounted that theory because i didn't feel the pulsing before, but after running out of ideas, i got a set of used (straight) rotors, put them on, and there was no more pulsing. i looked at my rotors and tried to measure them in some way to tell if they were bent/warped but i just couldn't see it with the naked eye. if nothing else works, pick up a pair of cheap, used, straight rotors, slap them on, and go from there. or if you wanted to, buy some galfer wave rotors. i dont know about the 2002 rotors, but i priced my 2005 rotors at the stealership and they are more expensive than an aftermarket "high performance" set of galfer waves.

just consider it.

Thanks, but I think that'll be my last resort since I had a spare wheel (rim, tire, rotors) for the bike and it made no difference. In addition, the previous owner specifically told me he's had a mechanic take a look at it and they ensured him the rotors were straight.
 

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it is a huge difference pushing around a bike with standard pads versus HH. I'm working on a buddies bike and was astounded how easy it pushes with street pads.

my zx6r has one rotor with about .020" side to side wobble in it....while this eats up some lever travel, it doesn't cuase me any vibration issues at the track. I don't think I could spin it hard enough to get a full turn....maybe half a turn.
 

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i run HH+ and my front spins 1+ easily....

that piston that popped out might be a large reason....i use 400 grit wet/dry paper to clean each piston to remove the road grime and brake dust gunk ....

J
 

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Discussion Starter · #12 ·
i run HH+ and my front spins 1+ easily....

that piston that popped out might be a large reason....i use 400 grit wet/dry paper to clean each piston to remove the road grime and brake dust gunk ....

J
Is there anything special I should use to clean the pistons with besides the 400 grid? I just happen to have some laying around, along with brake cleaner. What other supplies? Can you give me any pointers as I've never taken calipers apart to clean them...
 

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you don't need to fully disassemble them ..pump the brake to expose the clean part of the piston....make a 4" x1/4" strip of sandpaper...loop this around the piston and work back and forth...the grime should come off easily....spray with brake cleaner....repeat this for each piston....

be aware, if you pump too much they will fall out and be a real bugger.

once done they will move alot easire and the negative pressure from the brake lever will pull the pistons back and make for free movement....

J
 

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Discussion Starter · #14 ·
you don't need to fully disassemble them ..pump the brake to expose the clean part of the piston....make a 4" x1/4" strip of sandpaper...loop this around the piston and work back and forth...the grime should come off easily....spray with brake cleaner....repeat this for each piston....

be aware, if you pump too much they will fall out and be a real bugger.

once done they will move alot easire and the negative pressure from the brake lever will pull the pistons back and make for free movement....

J
I pumped the brake with the pads on till the pads touched, removed the pads, and sanded off each piston with 400 sandpaper till they were clean. Used brake cleaner after, pushed the pistons in till they were flush with the caliper. Put pads back on, then reconnected calipers to forks.

Same problem.

I did notice there spacers on the outside of the pads where the pistons press against the pad was missing on all four pads. In the process above before putting the pads back on I attached the metal spacer piece to each pad.

No difference.

I did however notice something off about the brake lever. On my other ZX6R the brake measurements are as follows (when pulling the brake in, measured from the inside of the mid brake lever to the grip):
#1 setting ~1.5 inch
#5 setting ~1.25 inch

On the bike having the issue its:
#1 setting ~1 inch
#5 setting ~0.75 inch

What's causing the brake lever to pull nearly clear to then grip?
 

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I pumped the brake with the pads on till the pads touched, removed the pads, and sanded off each piston with 400 sandpaper till they were clean. Used brake cleaner after, pushed the pistons in till they were flush with the caliper. Put pads back on, then reconnected calipers to forks.

Same problem.

I did notice there spacers on the outside of the pads where the pistons press against the pad was missing on all four pads. In the process above before putting the pads back on I attached the metal spacer piece to each pad.

No difference.

I did however notice something off about the brake lever. On my other ZX6R the brake measurements are as follows (when pulling the brake in, measured from the inside of the mid brake lever to the grip):
#1 setting ~1.5 inch
#5 setting ~1.25 inch

On the bike having the issue its:
#1 setting ~1 inch
#5 setting ~0.75 inch

What's causing the brake lever to pull nearly clear to then grip?
he meant...to pump the lever with the pads OUT. so the piston extends. and clean the outer portion. but...if ur going to try that. you NEED to put something between the pistons, to keep them from SHOOTING out of the bore.

the "spacer" is an anti-rattle/anti-squeal shim. and makes no difference.


the lever positon is adjustable. were they adjusted to the same position?
 

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Discussion Starter · #16 · (Edited)
he meant...to pump the lever with the pads OUT. so the piston extends. and clean the outer portion. but...if ur going to try that. you NEED to put something between the pistons, to keep them from SHOOTING out of the bore.

the "spacer" is an anti-rattle/anti-squeal shim. and makes no difference.


the lever positon is adjustable. were they adjusted to the same position?
Damn! I thought having them stick out as far as they did would be good enough, how wide of an object should I put between the pistons to ensure they don't shoot out? Something the size of a rotor or two?

Is there any reason why the spacer would be removed?

Spoke to the previous owner, he said the brake lever problem (nearing pulling to the grip no matter what setting you have it on) started after he pulled the brake accidentily and shot one of the pistons out and he repacked it. I'd desribe the brake as feeling really squishy as you can pull it nearly to the grip...
 

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Still sounds like a master cylinder problem to me. There have been a couple other similar threads where the MC was the problem.
 

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yeh, double or triple the rotors would probably work.


wait...i guess i just ASSUMED(i know shame on me) that he BLED it out.
it may have AIR in there. would explain the soft lever. and with the HH pads in there creating more friction(heat) it would cause pressure to build up.

have you bled them?

should have been the FIRST thing you tried.


if not..ive got a GOOD set of calipers i can sell you:D
edit: n/m i just noticed the section....mine are 05 calipers...
 

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Discussion Starter · #19 ·
yeh, double or triple the rotors would probably work.


wait...i guess i just ASSUMED(i know shame on me) that he BLED it out.
it may have AIR in there. would explain the soft lever. and with the HH pads in there creating more friction(heat) it would cause pressure to build up.

have you bled them?

should have been the FIRST thing you tried.


if not..ive got a GOOD set of calipers i can sell you:D
edit: n/m i just noticed the section....mine are 05 calipers...
I would have bled them first thing, however, the previous owner told me he'd already bled them once (after this problem) and it made no difference. So I haven't bled them, but I was going on faith the previous owner bled them correctly...

I already have another set of EBC rotors on a wheel.. :)
 

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Discussion Starter · #20 ·
Still sounds like a master cylinder problem to me. There have been a couple other similar threads where the MC was the problem.
I've never taken the MC apart before, I can't find any good instructions off hand, I have the manual but I've found it leaves things out... Pointers? Or have I missed a how to-MC post on here?
 
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