Front brake slippage?

M

Matty8

Well-known member
Purchased a new bike recently (2007 ZZR600). Yesterday I noticed a very unstable bobble/shake feeling while braking (only tested at low speeds). The more I slow down the more pronounced it becomes.
Today I tested some more and I'm fairly certain that I'm feeling slippage in the brakes. At a constant brake pressure (at the lever) it will constantly slip then catch again, causing the bike to bobble up and down, quite severely at times, almost as if the road was wavy (I can see my headlights moving up and down on the pavement).

What could cause something like this?

Tomorrow I will throw it on the front stand and give it a visual inspection. I will also test braking at higher speeds, but I'm fairly certain that I won't feel anything at higher speeds.
 
Matty8 said:
Purchased a new bike recently (2007 ZZR600). Yesterday I noticed a very unstable bobble/shake feeling while braking (only tested at low speeds). The more I slow down the more pronounced it becomes.
Today I tested some more and I'm fairly certain that I'm feeling slippage in the brakes. At a constant brake pressure (at the lever) it will constantly slip then catch again, causing the bike to bobble up and down, quite severely at times, almost as if the road was wavy (I can see my headlights moving up and down on the pavement).

What could cause something like this?

Tomorrow I will throw it on the front stand and give it a visual inspection. I will also test braking at higher speeds, but I'm fairly certain that I won't feel anything at higher speeds.
Click to expand...
I had rotors like this, SWORE they were warped, but in the end it was uneven pad material buildup on the rotors. I had a shop hone them and then they were perfect.
 
^what he said.
 
Unfortunately it looks like the right rotor is bent/warped. I can visually see it move by about 1mm when I put a fixed reference beside the right rotor and spin the front wheel. And to confirm, I disconnected the right caliper and the front end stopped bouncing/slipping during my test ride.
Is there any chance that it is something other than a bent rotor? i.e. misalignment or something? I would hate to buy replacement rotors when I don't need to.

If I do need to replace the rotor, are new pads necessary as well? I'm thinking they may have worn unevenly, depending on how long this issue has been occurring for.
 
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