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Discussion Starter #1
hellow, got a 1999 mod cbr900rr with only 24.000km on the clock :)
but i got vibration in the front brakes, the wheel is ok and i just exchange the front brakedisks
but still vibrate when breaking, first owner did forget a lock on the breake disk when trying to drive off, can that have hurt the breake calipper/shock-absorber ?

eny ideas what to do ?
 

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i would change the wheel bearings as they are reasonably cheep to do , and also make sure the head bearing is ok and doesnt need tightening , he shouldnt have been going fast enough to cause any real damage the the caliper
 

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I had a vibration when applying the front brake on my RRW, but it didn't seem too bad so i just ignored it. I didn't ignore the looseness in the front end, though, and the shop I brought it to confirmed my fork bushes and seals were shot and steering head bearing should be changed.

I'm waiting for the ... darn... parts to be delivered (they tell me it will take 3 weeks!!) but I'm thinking I will lose the vibration when the front end is rebuilt. I'll let you know if it proves successful.
 

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Discussion Starter #5
the old disks was warped for some time
bought new breakedisks "used ones", but did buy them from a mc dealer, he told me they was NOT warped, no did not buy new pads as they are almost new
wont the pads "asjust" them selvs to a new set of disks ?

if not can i sand them down my selv so they become even ?
 

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Easy way to check if the discs are warped is to get a piece of card, tape it to the fork leg so that it just clears the disc, get the front wheel off the ground & spin it slowly, if the disc is warped you should see the gap changing as you spin the wheel.

If the gap changes either the disc is warped or it is not fitted correctly.
 

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What vibrates when you are braking? Is it the brake lever, the bars, the front wheel?

Does it only happen for a second or two or does it continue all the way to a stop?

Here are some candidates for your issue:
Wheel out of balance
Wheel bearings worn
Head bearings loose or worn
Rotors warped
Caliper or mounting bent

Answering the above questions will help us target the offending parts.
 

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Discussion Starter #8
the brake lever is pulsing a bit but it feels that it is the caliper or the brake disk that makes the vibrate
it goes from all the way to full stopp

what makes a rotor get warped and can it get fixed ?
 

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the brake lever is pulsing a bit but it feels that it is the caliper or the brake disk that makes the vibrate
it goes from all the way to full stopp

what makes a rotor get warped and can it get fixed ?
That sounds like a warped or bent rotor. Is the vibration the same as with the old rotors? If so then its probably not the rotors because it would be near impossible for different rotors to be warped the same.

To eliminate the rotors for sure you need to measure the run out.

Mount a pencil on the fork leg so the point touches the disk. spin the wheel and make sure the pencil touches all the way around. then do the same on the other rotor.

If the pencil does not stay in contact with the rotor then the rotor is warped or bent. If it does stay in contact then something else is wrong.

Have you looked at your caliber mounting bolts to ensure they are not bent?

It is critical that all braking components are straight, I am concerned about the disk lock hitting the caliper.

The idea here is to eliminate what is good so we can isolate what is bad.
 

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Discussion Starter #10
what is the reasen for a rotor to get warped if you drive "normal" ?
the vibration is smaler with new (used) rotors, but same type of vibration

did the pencil trix today, as far as i can see it touches all the way around
did take out the brake pads and all 4 looks the same

by "caliber mounting bolts" do you meen the bolt that fasten the caliber to the shock ?

i cant see enything wrong with : wheel,caliber,shock,pads,rotor:idunno:

eny idea's ??
 

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When you have the front wheel off the ground, spin the wheel & gradually apply the front brake, does the brake bite & release, bite & release, if it does you may have a high spot on one of the discs.

I had this problem 3 years ago on my 929. To cure the problem I used a small very fine abrasive stone to rub the high spot down.
 

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Discussion Starter #12
i have taken all apart and change the front damper oil becouse of a bad oil-ring
front wheel bearing,stearing bearing,caliber,damper looks fine
pads looks almost alike, but not 100% even
with the front brake half inn at slow speed i can feel : brake-relese-brake-relese
feels like when the wheel har gone one time around the brake "takes" harder at "one" point

is this still typical for a bad brake disk ?
talked to the mc-shop again and he said he did measure brake disk's before sending and they was 100% ok

plz help me, going to tae track soon and got to get this sorted!!
 

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daft question but has it got to much brake fluid in the reservoir . as i know someone on another forum that had a similar problem and took out some brake fluid cos it was over full and problem went away
 

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Discussion Starter #14
daft question but has it got to much brake fluid in the reservoir . as i know someone on another forum that had a similar problem and took out some brake fluid cos it was over full and problem went away

why cud a over full resevoir make a problem like mine ?

you think a forgotten disk lock when taking off on the bike cud bend the front axle ?
 

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i would change the wheel bearings as they are reasonably cheep to do , and also make sure the head bearing is ok and doesnt need tightening , he shouldnt have been going fast enough to cause any real damage the the caliper
I agree - I had head shake on mine at about 25000kms and it felt like vibration from the breaks.
 

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... also make sure the head bearing is ok and doesnt need tightening
My shop tells me that the shake in MY bike was because of the steering head bearings and the bad fork bushings. You said your seals needed changing. So there is at least one fork issue.What about the bushings? And head bearings?

Sadly it will still be another couple of weeks before I can find out if the pulsing has gone away on my bike, but if my shop can be believed then you should focus on the forks and steering head bearings.
 

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Discussion Starter #17
bearings feels ok, oil seal was jus leaking
but if it was wheel/stearing bearings,shoud not the bike feels funny in hi speed then ? (with no braking)

sins the first owner forget the disk lock i still belive the problem is "down" in the front area, it shure feels like "hi spot" brake related...

bike only 23.000km, no wheely/track driving so far
 

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If you can spin the wheel and feel high spots with the brake lever then you know where the porblem is. There are only a few parts involved down there, the disk (replaced already), the Caliper, the fork leg, the axel. the wheel. Figure out which is bent and replace it.

Suggested test: Remove one caliper and place something hard between the pads. IF you dont put something between the pads you will be very sorry when you apply the brake......

with that caliper out of the way spin the wheel and lightly apply the brake. Does it pulsate? if so its not the caliper thats removed put it back on and remove the other caliper.

Spin wheel and apply light brake does it pulsate if it does not pulsate then you have located which side has the problem.

The point is to be methodical in troubleshooting take stuff away and see if the problem goes with it.

I am still betting on the rotors being bent.

If it does pulsate then perhaps both sides have the problem.

If both sides pulsate individually I would suspect something common like the wheel bearings (not likely from what you described so far) or maybe the wheel or axel is bent

If only one side pulsates then you have a bad disc or caliper.
 

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One stupid question, have take your bike to the nearest Honda dealer.
It seems as though you are doing to much guesing here - your life depends on those breaks working properly.
 

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Discussion Starter #20
problem here is that the honda dealer has no mechanic for the moment so i have to try to fix this my self...

i did check the "disk nut's" and the all are lose,the steel of the disk can "float freely"
the vibration is ONLY there when i apply the front brakes (200km/h with no brakes and its fine)
with hi speed braking it is a big vibration, but the slower the speed, it goes over to be pulsing or brake/release/brake/release sensation
i did mont a pencil to the shock-leg and both the disk and the rim seems fine when turning the wheel
but if i hold light on the brake and turn the wheel,i can feel brake/release/brake/release
this is on the right side (did remove caliper in left side, no problems there)
did take the front axel out and it is fine

starting to think my new "used" rotors realy are bent or the caliper must have taken a "hit" when the disklock did stop the bike when he did try to take off, but i cant se eny damage on the caliper or the fork

what do you think ?
 
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