Front brake conversion problem.
Thread Starter
WERA #44
Superstock
Joined: Jul 2007
Posts: 265
From: About 57 miles south of VIR
Front brake conversion problem.
2002 Superhawk meets 2001 GSXR 1000 calipers and master cylinder.
Calipers bolt directly on with new Kevlar composite pads, No problem.
Pair of braided lines from OEM Hawk brakes, And Gsxr Master Cylinder,
bleed and ready.
Bike waits in shed for nice weather to bed brakes and try out.
Roll bike out with big grin on pretty day! Why so hard to push? Brake lever has no play and appears to be holding pressure on the system?!?!?
8mm to blead port while static (no pull on lever)---spurt--
pump and bleed, all checks OK. Put bike up 'cause don't know how long it will ride before binding.
2 days later, same pressure issue.
Master cylinder got full rebuild with a kit before installation, Ebay item, unknown history, I rebuilt it.
I have dealt with this issue before on a hydraulic GSXR clutch, But have any of you seen this and what causes it?
Calipers bolt directly on with new Kevlar composite pads, No problem.
Pair of braided lines from OEM Hawk brakes, And Gsxr Master Cylinder,
bleed and ready.
Bike waits in shed for nice weather to bed brakes and try out.
Roll bike out with big grin on pretty day! Why so hard to push? Brake lever has no play and appears to be holding pressure on the system?!?!?
8mm to blead port while static (no pull on lever)---spurt--
pump and bleed, all checks OK. Put bike up 'cause don't know how long it will ride before binding.
2 days later, same pressure issue.
Master cylinder got full rebuild with a kit before installation, Ebay item, unknown history, I rebuilt it.
I have dealt with this issue before on a hydraulic GSXR clutch, But have any of you seen this and what causes it?
Moderator
MotoGP
Joined: Dec 2004
Posts: 2,553
From: South Texas
Calipers aren't centered on the rotors. Look again. The inside pistons are probably pushed all the way in now and can't move (stiff lever feel). You'll need to shim the calipers away from the fork mounts with a couple of thin washers to give the inside pistons some "free play" room. I used stainless steel ones from the local home hardware store.
Hope this makes sense.
Hope this makes sense.
Senior Member
SuperBike
Joined: Jul 2004
Posts: 1,015
Calipers aren't centered on the rotors. Look again. The inside pistons are probably pushed all the way in now and can't move (stiff lever feel). You'll need to shim the calipers away from the fork mounts with a couple of thin washers to give the inside pistons some "free play" room. I used stainless steel ones from the local home hardware store.
Hope this makes sense.
Hope this makes sense.
Thread Starter
WERA #44
Superstock
Joined: Jul 2007
Posts: 265
From: About 57 miles south of VIR
Pistons and seals looked good on the calipers, nice movement, no complaints when not pressurized.
The system just seems to build pressure when static for a day or two.
When my GSXR clutch did this, a rebuild of the master cylinder cured it.
I just wonder what specifically does this.
Got a 954 master cylinder on the way, maybe the Honda is just rejecting the Suzuki part. But I'm keeping the 6 pots cause they are it.
The system just seems to build pressure when static for a day or two.
When my GSXR clutch did this, a rebuild of the master cylinder cured it.
I just wonder what specifically does this.
Got a 954 master cylinder on the way, maybe the Honda is just rejecting the Suzuki part. But I'm keeping the 6 pots cause they are it.
Administrator
World Champion
Joined: Dec 2004
Posts: 105,287
From: Fulton, MO
So, the pressure is just building up inside the brake system?? It's spring so it's obviously getting warmer. The expansion of the fluid would explain this phenomenon, but only with another problem. That problem would be that the master cylinder is not venting to the reservoir correctly. There is a tiny hole between the master cylinder piston and where the tube goes to the reservoir. If that's clogged on the inside then it won't vent. Also, if the piston doesn't return all the way to it's normal free position then it won't vent. Being as it is a Gixxer m/c, check the lever clearances and ensure everything moves as it should.
Senior Member
SuperBike
Joined: Jul 2004
Posts: 1,015
Hawkrider is correct, make sure the lever is able to travel all the way to the grip and not hit the Stock VTR throttle housing. I have the same calipers with a 06 GSXR 1000 Radial Master Cylinder and i had to move some things around to prevent the lever from hitting my throttle assembly.
Senior Member
SuperBike
Joined: Jul 2004
Posts: 1,015
Yes, but i also had to rotate the throttle assembly a little as well to keep the lever from hitting the throttle cable housing. This will require you drilling a new throttle postion hole in the clip-on to allow the housing located pin to be moved forward. Notice I run my lever much further down than the stock position. I like to be able to pull my fingers off the grip and as they move forward they just clear the top of the lever.
As well make sure the part of the lever closest to the triple tree mount (nearest center of bike) isn't hitting the brake lines.
Don't know if these will help or not, but here are a few pics of my completed setup
As well make sure the part of the lever closest to the triple tree mount (nearest center of bike) isn't hitting the brake lines.
Don't know if these will help or not, but here are a few pics of my completed setup
Last edited by Thumper; Apr 7, 2008 at 06:46 PM.
Thread Starter
WERA #44
Superstock
Joined: Jul 2007
Posts: 265
From: About 57 miles south of VIR
So, the pressure is just building up inside the brake system?? It's spring so it's obviously getting warmer. The expansion of the fluid would explain this phenomenon, but only with another problem. That problem would be that the master cylinder is not venting to the reservoir correctly. There is a tiny hole between the master cylinder piston and where the tube goes to the reservoir. If that's clogged on the inside then it won't vent. Also, if the piston doesn't return all the way to it's normal free position then it won't vent. Being as it is a Gixxer m/c, check the lever clearances and ensure everything moves as it should.
Moderator
MotoGP
Joined: Dec 2004
Posts: 2,553
From: South Texas
It's been too long since I had them on the stock forks. I know I had to shim them when I moved them over to F4i forks which uses different axle spacers, etc., so that's probably what I'm thinking about. Sorry for the confusion.
Happy,
Sounds like a stuck piston or two or three or........
Happy,
Sounds like a stuck piston or two or three or........
Senior Member
SuperBike
Joined: Jul 2004
Posts: 1,015
I did an Ed Bargy Racing school a few years ago and as part of the school you got a race package of goodies valued at about a third of the Race class. The race package included all kinds of Motul race lubricants and the RBF600 brake fliud you see was included. I have since used the free bottle and bought more and installed on my other rides.
I am no lubricant expert, so free is free and if it works, i'll buy more as i did.
Here is a link to the product detail on Motospotstore.com site. Stuff is not cheap, which i guess means it is GOOD.......lol
Along with Vesrah pads you have a great combo...
Oh the color you see is the actual color. Kind of unusual......
http://www.motorspotstore.com/rbf600radot4.html
How could you go wrong with this logo.......
Last edited by Thumper; Apr 8, 2008 at 08:09 PM.
Senior Member
SuperSport
Joined: Nov 2005
Posts: 547
Isn't the simplest solution supposed to be the correct one. Maybe the right answer here isn't in the brake system at all, it could be a bad lever.
Usually, if something is sticking, or not returning to its original state, the pressure either wasn't correct to begin with, or it's being dissipated in an unwanted location, anywhere from the bleed valve at the bottom to a seal at the top of the lever.
Thread Starter
WERA #44
Superstock
Joined: Jul 2007
Posts: 265
From: About 57 miles south of VIR
Problem solved, 954 master cylinder installed, fit like a honda part, not much trouble.
Bled to perfection in about 10 minuets
Works very well with the GSXR 6 pots.
The GSXR master cylinder has some issues. Greg was right about the non-venting issue.
Bled to perfection in about 10 minuets
Works very well with the GSXR 6 pots.
The GSXR master cylinder has some issues. Greg was right about the non-venting issue.
Senior Member
SuperBike
Joined: Jul 2004
Posts: 1,015
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