ZX9R brake shudder

[simon limbrick]

i have a 01 zx9r that has bad front brake shudder. from what ive heard it is fairly common on the 9r's and also on a lot of other kwakas to. im a bit suss about geting them machined and i know if i buy genuine discs that they will probably only end up warped to. does anyone do a set of better non-genuine discs, if so, WHO?

[javaman]

Mine also shudder (is this is the vibration sensation?) but only when used long (maybe hot) and hard braking. After it is hot it also makes squeaking noises. WTH causing this ? Only have the bike for few weeks so not sure of pad/disc quality.

[omen_child]

Why are you suss about getting them machined? it's common practice.

[MadKaw]

I don't think its common, My 9 doesn't shudder neither did any of my other kwakas..
Check the pads, rough up the surface a little in case they have glazed up and bleed the fluid. If this doesn't fix it, try lightly sanding the disk surface to take out any irregularities and if that doesn't fix you will either need your disks machined or replaced... Good luck...

[ZX-10R_04]

Also check the wheel bearings & clean the pistons in calipers

[I-K]

(nods in ZX-10R_04's direction) Loose steering-head bearings would be my first guess, too.

Omen: Machining might be common on car and aircraft disks, which have up to a cm of metal on them, but modern bike discs are typically ~5mm thick and the service limit for them is less than a mm below that.

The manual for the ZX6 is in the garage atm, but the '96-'99 GSX-R one I have handy specifies nominal front disk thickness of 4.8-5.2mm with a 4.5mm service limit.

If the disks warp, they're probably going to deflect by more than the difference between the nominal thickness and the service limit.

I've heard of people claiming they can_flatten_warped discs, but I can't recall ever hearing about anyone machining them.

You sure about this?

[red_dave]

(nods in ZX-10R_04's direction) Loose steering-head bearings would be my first guess, too.

I'm no expert but my 636 used to do the same until Stu (Hammer) took it for a spin and mentioned the head bearings were a bit notchy. I got the bike shop to check them out not long after and they ended tightening them up - I haven't had an issue since...

[Nanna10r]

Could also be caused by your Wheel Balance being way outta whack &/or type pressure being too low. I have braided lines on the "Tiggr" n although Ive had Major Break Fade on 1 Occasion never had any dramas of a shuddering nature.
They tend to replace disc rotors not machine them as the buggers are so thin to begin with to save weight. HTH.
Cheers Brett

[simon limbrick]

i was suss about geting them machined coz i know how thin they are. thanx for ur advice guys!!!!! mite have to look into the other possibilities as to why they are shuddering. the same thing is happening to a mates "99 model also. off to the workshop then..........

[corbywan]

Simon
Don't forget to let us know if you find the solution to your problem.

Thanks & Good luck