new brakes

[patrick]

Thought you guys might like this. I was helping someone with their GS. Issue was front brake didn't cut it. So, we fixed it...

Made a bracket.



Glass beaded the rotor.



Bolted things back together with an F4 caliper.



Hooked the line back up, bled the system, bedded in the sintered pads. It's all spiffy now.

A braided line and GSXR750 adjustable brake lever are on the way...

[what?!]

let us know how it works out!

[BOSS500]

seriously that looks like a nice job  

[RVertigo]

Glass beaded the rotor.

OK... What does that do for ya'?

[Alphamazing]

Glass beaded the rotor.

OK... What does that do for ya'?

I'm pretty sure it creates more firction between the rotor and pads, thus increasing stopping power.

How did you make that bracket? SolidWorks modeling followed by CNC machining? Or what? I really really like that.

[patrick]

I'm pretty sure it creates more firction between the rotor and pads, thus increasing stopping power.

How did you make that bracket? SolidWorks modeling followed by CNC machining? Or what? I really really like that.

Some brake pads leave a deposit on the rotor. Not all brake pads are compatible with each others' deposits. It is good practice, when switching pad types, to clean the rotor by glass bead blasting it. This prevents the new pads from essentially having a hissy fit over what's already on the rotor. To be perfectly honest, I can't recall if it's necessary when switching from resin pads to sintered, or the other way around, or if it's just when switching from sintered to carbon, or what. In a past life, I worked as a mechanic on a roadracing team, and the brake pad guys told us to glass bead blast rotors before using their carbon pads. So, just to be safe, I cleaned the rotor. It sure doesn't hurt.

I didn't use a computer program or CNC mill to make the adapter bracket. I set the caliper up where I wanted it, measured all the mounting points with a dial caliper, made a full size drawing with a pencil, paper, straight edge, compass, and the dial calipers, scribed reference marks onto a billet of 6061 aluminum, then milled it on a Bridgeport vertical mill. No CNC, NC, or even DRO. Old school.

This is how I clamped the caliper to the rotor while measuring everything.

You'll see a couple of R6/R1 monoblock calipers there too. But the 1/2" bore (12.7mm) GS master cylinder will work better with the F4/929 style caliper because of the piston sizes. Those YZF calipers use 27/30mm pistons, and the CBR calipers use 32/34. The stock GS caliper uses 27/34, which gives a 11.69:1 hydraulic advantage with the 12.7mm master cylinder bore. Going to the YZF calipers would cause a decrease in hydraulic advantage ratio to 10:1. That would be bad. The lever would be hard as a rock, but you'd have to yank on it with all four fingers to get the bike to slow down. Going to the CBR caliper gives an increase in hydraulic advantage ratio to 13.52:1. That is good. 2 finger brakes. You could actually accomplish largely the same thing by switching to a 12mm master cylinder. With the stock GS caliper, you'd get a 13.09:1 hydraulic advantage ratio. 12mm master cylinders are kind of hard to come by though. 11mm master cylinders are more plentiful. You'll find them on XR650Ls and I think XR250Ls, which also have a mirror mount and a brake light switch on their master cylinders. If you didn't care about either of those features because you're using it on a club racer with no lights, pretty much any current Japanese motocross bike's master cylinder will work. I think the vast majority of them use an 11mm bore. But you'd be giving up the mirror mount and brake light switch.

With an 11mm master cylinder, you'd get a 15.58:1 hydraulic advantage, which would basically mean you'd have the front tire locking with one finger on the lever. But you'd definitely need a braided line to help reduce lever throw. With the stock rubber line, you'd almost certainly either be trapping your other fingers against the grip, or have the lever all the way to the grip when slowing quickly.

Here's a good source of info on machining metals, if you don't know what a vertical mill is: http://www-me.mit.edu/Lectures/MachineTools/outline.html

[RVertigo]

You MUST be an engineer.

[werase643]

what didn't cut it
a GS will stand on it's nose with stock brake


reality.... hella kewl job

[Alphamazing]

I'm an ME, and I want to learn how to do that stuff. I'm getting trained in CAD so I like to use it when I can, but I have no problems drawing stuff out, either. All the same, that's some nice work.