Brake Issue - Wrist Twisters
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post #1 of 8 Old 11-21-2016, 07:30 PM Thread Starter
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Brake Issue

I had a car just barely clip the front left of my bike. I was stopped at the time, and looked down and didn't see any damage. But, the first stop that I made, I had no front brakes, until I pumped the brake lever a few times. This gives me brake pressure for a few seconds, but then I have to pump for the next stop.

I wasn't sure where to start tracking it down, so I started by flushing/bleeding. Same problem. I'm suspicious that something is messed up with the left caliper. I just ordered some G&J brake lines and banjo bolts - since this seemed like a nice option anyway. I'm planning on replacing the lines when they come in - and hoping this'll fix things.

I guess I don't really have a particular question - just tossing out my situation in case anybody has any thoughts. I'll update with progress (hopefully) as I go.

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post #2 of 8 Old 11-21-2016, 08:20 PM
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Quote:
Originally Posted by abclark8011 View Post
I had a car just barely clip the front left of my bike. I was stopped at the time, and looked down and didn't see any damage. But, the first stop that I made, I had no front brakes, until I pumped the brake lever a few times. This gives me brake pressure for a few seconds, but then I have to pump for the next stop.

I wasn't sure where to start tracking it down, so I started by flushing/bleeding. Same problem. I'm suspicious that something is messed up with the left caliper. I just ordered some G&J brake lines and banjo bolts - since this seemed like a nice option anyway. I'm planning on replacing the lines when they come in - and hoping this'll fix things.

I guess I don't really have a particular question - just tossing out my situation in case anybody has any thoughts. I'll update with progress (hopefully) as I go.
Definitely sounds like a leak somewhere. Do you see any fluid leaking anywhere? Chances of the caliper actually failing is small. Maybe check the bleeder screw to be safe. Good news is that its a pretty simple system. I would start with replacing the lines, which you're doing anyway, and if that doesn't work, rebuild the MC or get a new one. Depending on your skill level and budget.

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post #3 of 8 Old 11-21-2016, 09:01 PM Thread Starter
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I'll clean everything up well and see if I can track down the leak. I might order some new bleeder screws as it looks like they were rounded off a little by PO (and now would be the time).

Also - anyone know what #5 ("PROTECTOR 45512-MA6-006") actually does, or how it connects? I noticed it was loose when the fluid was drained, and I stuck it back down on the orifice where it looked like it went.

Thanks for the help.
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post #4 of 8 Old 11-22-2016, 04:15 AM
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Could be a warped rotor pushing your pistons back into the caliper. Check runout.
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post #5 of 8 Old 11-22-2016, 07:20 AM
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Quote:
Originally Posted by SPYDER View Post
Could be a warped rotor pushing your pistons back into the caliper. Check runout.
Along this line of thought. If the wheel was pushed to the side maybe it is out of alignment and is causing one or both rotors to run in a misaligned orientation. This could also push the pistons back into the caliper. The solution could be as simple as re-setting the fork (& wheel) alignment.

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post #6 of 8 Old 11-22-2016, 07:38 AM
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Did you get the drivers license and insurance information from the car driver? If not you may be screwed as regards getting your bike back into working condition.

Forget trying to bleed the brakes. If you did not have the problem before the encounter with the car and did afterward logic dictates the cause is the impact. It certainly sounds like the left rotor has a significant bend, undoubtedly due to the impact. The bend will drive the pistons in the caliper back, requiring pumping up until they stay in contact with the rotor. While the impact may not have hit the rotor directly it is likely the caliper was hit, bending the rotor and possibly bending the mounts on the fork and / or the caliper.

To test for this, support the front wheel off the ground and give it a good spin. If the left rotor is bent it will be pretty obvious. Unfortunately the only cure is to replace the rotor, and preferably both to balance braking forces.

A thorough inspection is absolutely necessary! Don't mess around with questionable brakes!

Rob

If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
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post #7 of 8 Old 11-22-2016, 09:24 AM Thread Starter
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Wow. Great info. I never would've thought about the rotor. I'll do some investigation. And I'm definitely not driving the bike right now. :-( Having to fall back on the wife's FZ6.

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post #8 of 8 Old 03-23-2017, 07:43 PM Thread Starter
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SOLVED!

Having found no time to look into it all winter, I finally took the bike to the shop. A warped rotor was the problem (as suggested by the wise ones here). Had them replace the rotors and install the G&J lines at the same time. The 919 is back!! I was getting used to the FZ6, and had almost forgotten how much fun the 919 is.

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