08 w/ABS,Just replaced my front rotors-Now I can't get a firm lever to stay

[ZRX631]

It will pump up firm but the next time you pull it you have no brakes. I removed the front wheel and might have moved the pistons some during removal but I did not open the system so I don't see how any air could get in.

I have done it this way many times on other bikes but this is my first with ABS.

Any ideas or recommendations? I'll bleed it as a last resort but I want to understand what happened first.

Thanks in advance.

[VirginiaJim]

There's nothing special with bleeding an 08 ABS....so no worries there.  If you pump it up (appropriate German accent of course) and it stays pumped without moving the bike...then ok.  If you lose the lever after you move the front wheel/bike, you've done something when you replaced the rotors.  So which is it?  You lose the lever while standing still or after the bike moves?

[ZRX631]

Standing still or moving it loses the lever.

Went out and rechecked my work. Found the interupter ring making slight contact with the pick up. Pulled the calipers and found the right side inner pistons pushed in all the way. Pulled right disk and found that the hub was bent. (I took a chance on some low mileage used ones) Replaced this with original disk and all is well. Took it for a short ride and the pulsing at low speed seems to be gone and the lever is rock solid again.


Thanks for your assistance Jim.

[VirginiaJim]

That shouldn't be happening standing still unless you've got some sort of leak at the pistons.  I've never had an issue with that and I've replaced both of my rotors as well.  Did you loosen any brake lines?

[Daytona_Mike]

hmm..something is pushing the pads back into the calipers. When you squeeze the lever and you look at the rotors do they move (or just one rotor, it doesn't matter) .The rotor will act like a spring and push back against one pad on one side.
I will try saying it another way. One or two pistons on one side of the caliper  are stuck when you pushed them in or stuck out.

[Glennn]

Certainly sounds like you have introduced an air bubble somehow. 

• Did you leave the calipers mounted, or remove them during the process
• Did one of the pistons fall out of the calipers, or appear loose when you had the rotors off
• Did you force the pistons back into the calipers without loosening the bleed screw
• Did you see ANY sign of brake fluid around the calipers when you had the rotors out

[ZRX631]

I was editing while you guys posted :Went out and rechecked my work. Found the interupter ring making slight contact with the pick up. Pulled the calipers and found the right side inner pistons pushed in all the way. Pulled right disk and found that the hub was bent. (I took a chance on some low mileage used ones) Replaced this with original disk and all is well. Took it for a short ride and the pulsing at low speed seems to be gone and the lever is rock solid again.

Thanks
Gary

[Conrad]

Gary,

As Jim said there's nothing special about bleeding the brakes on these bikes. You can do the entire bike in less than 15 mins with one of these.


Motion Pro 08-0143 Hydraulic Brake Bleeder

[VirginiaJim]

It's not like some ABS on cars where it can get complex to bleed.  The clutch side on the other hand...

[Daytona_Mike]

I was editing while you guys posted :Went out and rechecked my work. Found the interrupter ring making slight contact with the pick up. Pulled the calipers and found the right side inner pistons pushed in all the way. Pulled right disk and found that the hub was bent. (I took a chance on some low mileage used ones) Replaced this with original disk and all is well. Took it for a short ride and the pulsing at low speed seems to be gone and the lever is rock solid again.

Thanks Gary for letting us know what the issue was. I knew it had nothing to do with bleeding since you originally stated you had not opened the system.
I was trying to find the parts you described on Ron Ayers microfiche but cannot. I wanted to know what happened so I dont end up creating the same problem.
the interrupter ring?   The pick up could be the encoder sensor I assume. How did the inner pistons get pushed all the way in?
Thanks

[ZRX631]

Thanks Gary for letting us know what the issue was. I knew it had nothing to do with bleeding since you originally stated you had not opened the system.
I was trying to find the parts you described on Ron Ayers microfiche but cannot. I wanted to know what happened so I dont end up creating the same problem.
the interrupter ring?   The pick up could be the encoder sensor I assume. How did the inner pistons get pushed all the way in?
Thanks

I have been working out of town, sorry I missed your reply.  I was using terms I'm familiar with as the rotor sensor is what I called the interrupter ring  and the mag pick up is what senses the speed of the interrupter ring.(couldn't find that in Ron Ayers quickly) I work with helicopters and this is a similar system to what we use to sense rotor speed.

As far as the pistons pushing back: I originally felt a little pulsing in the front brake but didn't want to buy new rotors just yet to check it out so I took a chance on some ZX14 rotors on ebay. One was terribly warped and in my rush to get them on I missed it. The warped rotor was pushing the pistons back on both sides as it rolled. As soon as I put an original rotor back on that side the problem went away. I knew it wasn't a brake problem as I never opened it up. As I tell people when troubleshooting at work, 9 times out of 10 the new problem is related to what you just fixed.

Anyway all is good now and I have a 14 front end in the garage for my ZRX so soon both bikes will have all the same front suspension and brakes.

Sorry for the long post, don't want to leave anything out.

Gary

[VirginiaJim]

The ZX-14s are/were having the same issues with warping that we are/were.