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 justexchange 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 ?

 

When you swapped the rotors were they for new ones or some used ones off ebay, and did you swap the pads out as well. If they were not new the rotors might be warped and if the old ones were warped the pads might have worn funny and might not seat right in the new rotors.

 

the old disks was warped for some time
the new breakedisks where 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 ?

 

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 measurebrake disk'sbefore sending and they was 100% ok

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

 

2 things that ban be easily done are :
1)
- put your bike on front and rear stands
- un bolt your calipers
- make your fonrt wheel turn with your facing the tire
- look if they're not bent somewhere

2)
- don't put your bike down the stands
- with one hand on the tire to prevent it from turning, use your second hand (as a human beeing you should have 2) to tug the disk on a radial move (from the center of the wheel to the rim edge). In other words, make as if you whished to remove the external part (steel) of the disk from the internal part (the holder).
- turn the wheel a bit and try again. You should do this at every disk nut (the O ring between the steel and the holder).
If the external part of the disk moves, then it's fried and causes a vibration and even a nasty dribble ...
That 2nd step is often forgotten when checking disks.

Try these and let us know.
BTW, do you have braided lines ?

J

 

I've read your explanation a little late mate.
What you describe might also be caused by a bent front axle.

 

np m8
you think a forgotten disk lock when taking off on the bike cud bend the front axle ?

 

you'd be suprised how some parts are prone to bend ... a simple forgotten disc lock is usually however not that bad.

There are some other possibilities :
- have you fitted braided lines ?
- do you feel your "brake/release/brake/release" sensation in the brake lever ?

J

 

Have you also made sure the wheel is balanced and somewhere along the way you didn't drop a wheel weight?

 

That's a good idea too, even though he'd certainly feel it when not braking.

J