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Discussion Starter · #1 · (Edited)
Hey guys, I am experiencing problems with my CBR.
When under heavy braking I am suffering vibrations through the front end, and am not sure what the cause is. Has anyone experienced this, and if so, what is the solution?

I have tried the following:
1. Tire pressure and new tyres (currently riding on supercorsa sc1/sc2) and have tried pressures from 25psi to 36psi.
2. Disassembling and inspecting head stem bearings- bearings have been replaced with new aftermarket items and are fitted correctly.
3. Fitting new brake pads, flushing lines (aftermarket braided ones) with fresh fluid and testing trueness of discs. All seem fine.
4. Making sure suspension is set up correctly and not bottoming out under braking.

Perhaps it has something to do with the electronic steering dampener or suspension internals needing freshening up, but any advice would be greatly appreciated.

Thanks!
 

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Hey guys, I am experiencing problems with my CBR.
When under heavy braking I am suffering vibrations through the front end, and am not sure what the cause is. Has anyone experienced this, and if so, what is the solution?

I have tried the following:
1. Tire pressure and new tyres (currently riding on supercorsa sc1/sc2) and have tried pressures from 25psi to 36psi.
2. Disassembling and inspecting head stem bearings- bearings have been replaced with new aftermarket items and are fitted correctly.
3. Fitting new brake pads, flushing lines (aftermarket braided ones) with fresh fluid and testing trueness of discs. All seem fine.
4. Making sure suspension is set up correctly and not bottoming out under braking.

Perhaps it has something to do with the electronic steering dampener or suspension internals needing freshening up, but any advice would be greatly appreciated.

Thanks!
Where are you feeling the vibration?
Any blue or black areas on the rotor indicating heat or warping?
Any odd wear indications on the tyre?
 

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Discussion Starter · #3 ·
Hey man,

No there are no problems with discs or tyres- feeling vibration through 'bars. talked to suspension specialist today- he said that forks are bottoming out (most probably) and springs need to be replaced. will save up and get it done!

going up to 1kg springs from stock- i had fiddled with preload and pads/bearings etc. but to no avail.
 

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Hey man,

No there are no problems with discs or tyres- feeling vibration through 'bars. talked to suspension specialist today- he said that forks are bottoming out (most probably) and springs need to be replaced. will save up and get it done!

going up to 1kg springs from stock- i had fiddled with preload and pads/bearings etc. but to no avail.
Probably?
Put a cable-tie around a fork leg and confirm it.
 

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Discussion Starter · #5 ·
sorry- when i say probably i mean:
I have used rubber rings around the fork leg and been monitoring them for ages, they are consistently 20mm from the bottom after a track session or quick road fang. originally i thought that unless the rubbers were at the bottom then they had plenty of play remaining, unfortunately 20mm (give or take 3-5mm) is the point where the internals bottom out. will be replacing with new springs- keep you posted! servicing forks and rear shocks at same time of course!
 

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sorry- when i say probably i mean:
I have used rubber rings around the fork leg and been monitoring them for ages, they are consistently 20mm from the bottom after a track session or quick road fang. originally i thought that unless the rubbers were at the bottom then they had plenty of play remaining, unfortunately 20mm (give or take 3-5mm) is the point where the internals bottom out. will be replacing with new springs- keep you posted! servicing forks and rear shocks at same time of course!
Yes, they are definately bottoming then :)
Have you tried increasing preload and/or increasing the oil level?
 

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Discussion Starter · #7 ·
have played with preload a bit, and fresh fork oil was used when fork seals were replaced middle last year. new springs have been ordered and both front and rear will receive service. will have to change a few settings to suit but i will let the pros handle that- suspension is hard to get perfect. can't wait to ride it after though!
 

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have played with preload a bit, and fresh fork oil was used when fork seals were replaced middle last year. new springs have been ordered and both front and rear will receive service. will have to change a few settings to suit but i will let the pros handle that- suspension is hard to get perfect. can't wait to ride it after though!
I didn't say fresh oil, I said _more_ oil.
Raising the oil level reduces the volume of air in the fork.
The air is a progressive spring that augments your coil spring.
Try 20mm more oil in each fork and see if that feels any better.
 
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