CBR 954RR 2002 - 2003 - CBR 954RR Forum

Excessive lever travel front brake.

  #1  
Old 07-20-2014, 09:29 PM
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Default Excessive lever travel front brake.

I have been having an issue for awhile with excessive lever travel in my front brakes. I have rebuilt the calipers and master cylinder. All new seals the pistons are clean and look good. No real wear on the pistons, new HH pads. steel braided lines and the system has been bled scrupulously.

I don't have mushy brakes it is just that the lever moves nearly half way to the throttle before really starting to engage the brakes. I have Googled the symptom and some have said that the seals occasionally can pull the pistons back too far, if they are sticking to the seal, and cause them to use up a lot of travel to reengage the pads with the disk. This is why I rebuilt the calipers and then the master cylinder but no change.

Has anyone else experienced this ?
 
  #2  
Old 07-20-2014, 10:59 PM
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What is your lever dial set at?
 
  #3  
Old 07-21-2014, 09:55 AM
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Where does the lever bottom out at?
 
  #4  
Old 07-21-2014, 11:02 AM
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Unfortunately it's not the lever position dial as it is set to the max. The lever doesn't bottom out but I come close to trapping my fingers against the throttle on medium braking entering corners. The bike will stop hard but the travel and feel suck. My ZRX 1200R and 2007 GSXR 600 both have one finger brakes that are instant on. I have rebuilt the calipers on the ZRX and the six piston calipers are notorious for being hard to bleed but they are perfect. Bleeding the Honda seems to have little effect. I have been riding, racing , wrenching since the late 60's and haven't had this sort of issue before.

Backin 1990 I race a GSXR 1100 that gave me fits with a somewhat similar issue because I had flipped the buttons on the discs to make them floaters. Of course they rattled and pushed the pads back on the straights etc. It was a bad idea. They even would move and cause a lever travel issue when stationary due to the disc being able to move slightly when gripped by the pads due to pads wearing at a slight angle.

The only thing I notice on the honda is that the front wheel spins with less drag than the other 2 bikes indicating to me that the pads are releasing maybe more than the others. I would normally consider that a good thing but now maybe not so much :>)
 
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Old 07-21-2014, 12:30 PM
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Originally Posted by STANJ2 View Post
Unfortunately it's not the lever position dial as it is set to the max. The lever doesn't bottom out but I come close to trapping my fingers against the throttle on medium braking entering corners. The bike will stop hard but the travel and feel suck.
That paragraph indicates a bleeding issue. I've rebuilt the '54 calipers before, and never had that issue. And like your other bikes, the OEM 954 brakes were always a one finger brake for me too, and I thought they felt great (tons of power and good feel).

Originally Posted by STANJ2 View Post
The only thing I notice on the honda is that the front wheel spins with less drag than the other 2 bikes indicating to me that the pads are releasing maybe more than the others. I would normally consider that a good thing but now maybe not so much :>)
Is the rotor still kissing the pads at all when you spin the wheel? Have you serviced your other bikes' brakes recently? You said in your first post:
"it is just that the lever moves nearly half way to the throttle before really starting to engage the brakes."
So, when the wheel is spinning freely off of the ground, the first bit of lever movement doesn't do ANYTHING??? Or was that an observation of when you were riding the bike?
 
  #6  
Old 07-21-2014, 05:17 PM
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Ok Conrice my son and I just checked it. There is some disc drag when the wheel is off the ground. If he turns the wheel and I pull the lever the ball end will move about 3/4 of an inch before he can't continue to turn the wheel. I don't get much lever resistance until that inch has been traveled. It may be a bleed issue but I have bled it 3 to 4 times , don't see any bubbles in the fluid when bleeding and haven't had this problem before with it. Done the overnight rubber band trick,Mighty Vac etc. I would swear that the master cylinder isn't moving the fluid enough at first but it is a new piston and seals also. kind of stumped i will admit.
 
  #7  
Old 07-22-2014, 02:33 AM
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Sounds like there could be air trapped behind some of the pistons. The air needs to compress before it pushes the fluid forward. You could try to push brake fluid whit syringe from the bleeders. That has worked for many whit brakes that haven't bleed properly any other way. It pushes the air from behind the pistons to the lines were it will come out much easier.
 
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Old 07-22-2014, 07:52 AM
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Originally Posted by mika_u View Post
Sounds like there could be air trapped behind some of the pistons. The air needs to compress before it pushes the fluid forward. You could try to push brake fluid whit syringe from the bleeders. That has worked for many whit brakes that haven't bleed properly any other way. It pushes the air from behind the pistons to the lines were it will come out much easier.
Ever since I started reverse bleeding brakes - I ONLY reverse bleed brakes. It only takes a few minutes and it's always resulted in a perfect bleed. There's no guess work.

Even if you want to get fancy and buy a "kit" (which I have), it's only $10-15.
 

Last edited by Conrice; 07-22-2014 at 08:39 AM.
  #9  
Old 07-22-2014, 10:11 AM
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Thanks guys I will try it. I reverse bled the ZRX and it worked well. Those calipers definitely have that issue. It looks like I will have to do it on the Honda as well. I should have done it this time but thought the normal way would be fine as it worked in the past. I agree the reverse bleed is the best Back to the garage...

Thanks for the input.
 
  #10  
Old 07-22-2014, 12:07 PM
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Originally Posted by STANJ2 View Post
Thanks guys I will try it. I reverse bled the ZRX and it worked well. Those calipers definitely have that issue. It looks like I will have to do it on the Honda as well. I should have done it this time but thought the normal way would be fine as it worked in the past. I agree the reverse bleed is the best Back to the garage...

Thanks for the input.
I hope it goes well!
 

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