Emergency brake bleeding advice needed!

[donkason]

I am getting ready to hit Mid Ohio tomorrow and need some help. I wrecked my Gixxer last year and the bike went on its side and I believe sucked air into the front brake lines. All the fluid pushed to one side and left the air pocket where the fluid is pulled from. No big deal, I thought.

So I bleed my brakes about a month ago and everything feels great. Bubbles came out, and the lever got a nice feel to it. I let it sit for awhile and jumped on it to move it and again the lever fell right to the grip and no front brakes. I bled them again thinking I missed something. Last night they were fine. I jump on it today and it feels great. I roll it out of my garage backwards and the second it hit the drive way slope the lever went right to the grip again and no front brakes.

I'm perplexed here. I've run a pint of fluid and bled the reservoir and both calipers repeatedly.

Any ideas or is there something I'm missing?

The reservoir is not damaged from the wreck nor are the brake lines.

[ZxHooligan]

Air is somewhere. Maybe the plunger in the handle is damaged. Can you pump them up and it gets hard without bleeding them?

[conn-e-rot]

And no leaks?

[gixxie750]

rotors are bent?

[conn-e-rot]

I have read where guys have had trouble bleeding brakes on other bikes and they zip tied the lever to grip overnight and that helped to let the air work up into the master cylinder. Never tried it though

[donkason]

Rotors are straight, no leaks anywhere, and yes when I pump it up it gets harder. I go from 0 brakes to about half with a few pumps.

Idk how I can run that much fluid and there is still air somewhere though. I'm going to try again.

I would do the zip tie but I need to roll early on the morning and want to get it resolved tonight.

[r1crusher]

You probably have air in the MC. Did you bleed it as well?

[ZxHooligan]

If there is no leaks then I would probably swap out the master cylinder that's the only thing I can think of could be a tiny hole in it. This is how every master cylinder that I have had to replace in cars start to go

[Gixxus Christ!]

Remove calipers, turn upside down, bleed again.

This is a common issue with some brakes on zooks, I think the nissin 4 pot ones. Air gets trapped in the bottom pot.

[donkason]

I was wrong. The drivers left rotor looks bent when I spin it. The right is fine. I marked where the lever goes in relation to the rotor and there is a spot where I hit it when it wrecked.

Would that cause it.

Edited May 14, 2013 by donkason

[Gixxus Christ!]

Only if you lose brake feel after ROLLING the bike. If it happens over night without moving it, you have air someplace.

[donkason]

Only if you lose brake feel after ROLLING the bike. If it happens over night without moving it, you have air someplace.

That's it. I roll it and lose it. I thought it was overnight at first but when I was backing it out of the garage I noticed it lost all feel, then rolling to a different spot brought it back.

Well, I learned something new today and time to go buy some new rotors. If any of you have rotors for a 2007 GSXR 750 PM me.

Track day was scheduled and paid for too

[Gixxus Christ!]

That sucks dude, rotors and track days aren't cheap. You may be able to find a used set at a bike salvage lot if any are close to you, just measure the thickness and make sure they're not bent.

[Helmutt]

Shoot an email or call Cory, he has tons of used/salvage OEM parts for most jap sportbikes at decent prices. Hopefully he has what you need. I use him for all my new/mint ZX14 parts, he's a quick shipper

www.402bike.com

[ohdaho]

Your kind of SOL unless someone on the board can help you out with a 310 rotor.

[Gixxus Christ!]

Wish I could help but at least you know the problem now. Good luck dude.

[donkason]

Corey has a rotor on the way. That place is legit. He measures it for me and double checked it for straightness before he shipped it. It'll be here in a day or two. He's my new parts guy!

Thanks for your help guys.

[redkow97]

Should have tried to borrow a front wheel for the day.

Sucks that you missed th track time

[yotaman88210]

I highly doubt a slightly bent rotor would cause your lever to fall all the way to the grip. Just doesnt sound right. Sucks you missed a track day man. Sucks a lot!

[yotaman88210]

Should have tried to borrow a front wheel for the day.

Sucks that you missed th track time

I would of just gone to the day and hoped someone had a spare wheel or rotor.

[Gixxus Christ!]

Not that far fetched when you consider the ratio of movement between the lever and the piston. The pistons only have to move maybe .060 to start applying brake pressure, meanwhile at the lever you've moved as much as 3/4". If the rotor is bent bad enough it could push a piston in as much as 1/8", now you have to make up that travel and get resistance on that piston before the hydraulic pressure will act on the rest.

[yotaman88210]

I just assumed if it was bent enough to cause this then he would of noticed sooner it was the rotor

[bshultz0930]

I just assumed if it was bent enough to cause this then he would of noticed sooner it was the rotor

not if he hadnt rode the bike. the calipers on a bike are not free floating like a car. a car caliper has slides which in the case of a warped or bent rotor the caliper will shift with the rotor. but on bikes its a solid mount, so the bent part of the rotor, as it passes through the pads it pushes on the pads pushing the pistons in, in turn having to pump up the lever again.

[r1crusher]

Floating rotors FTW. You can actually mod stock gsxr rotors to make them "semi-floating".

I have this done on my race bike.

[yotaman88210]

not if he hadnt rode the bike. the calipers on a bike are not free floating like a car. a car caliper has slides which in the case of a warped or bent rotor the caliper will shift with the rotor. but on bikes its a solid mount, so the bent part of the rotor, as it passes through the pads it pushes on the pads pushing the pistons in, in turn having to pump up the lever again.

Thanks for the lesson. Im so relieved I finally know how brakes work on a motorcycle vs. a car. Glad we got that cleared up.