Front brake problem

[DLaw]

I have an 09 C14 with ABS, 45,000 miles. Just got done doing tires, rear brakes, spark plugs, etc. The whole process took about a week for lack of free time. When I got it all back together last night, I rolled her out of the garage and hit the front brakes and nothing at first, but then a pump or two and the lever was back. At first, I thought I'd just forgotten to pump it up after putting the front wheel back on, it was a couple days ago. So I didn't think anything of it until I rolled to the end of the driveway and it happened again. Rode her around the block a bit, (thankfully the rear brakes I just installed are working perfectly), and every time I went to stop I had nothing at the front lever until a pump or two. The lines are not twisted or kinked at all, and I removed the front calipers to make sure there wasn't anything stuck in there, or something goofy of the like. Also made sure the pads are in there straight.

Being that it's not a power brake set-up, I don't think I would've knocked anything loose while doing the spark plugs like a vacuum line. Anyone heard of something like this, or of master cyliner/caliper/line failure at or around 45k? Thanks.

[curly]

Sounds like they need bleeding, but I've never heard of air getting in the system without taking brake lines loose or running the master cylinder dry. Good luck.

[DLaw]

I was thinking the exact same thing...sigh. Weird, too. If you just roll the bike a couple feet, it loses its prime. Don't even have to make it to the end of the block.

[Conrad]

Bleeding the brakes, and the clutch, is pretty darn easy on the C14. I use a Motion Pro brake bleeder and I can do the whole bike in about 15 mins. 20 if I have to get my own beer.

Just do it.

[DLaw]

I've done it before, have the Motion Pro myself. Just seems odd that, like Curly said, it'd get air in there without breaking lines or bleeders. Well, we'll give that a shot first, I guess.

[Conrad]

You're right, it is odd. My clutch was like that once in a while before I bled it for the the first time. Twice I had to pump it up, seemingly for no reason. After the bleed it was perfect and the issue hasn't come back. 

[DLaw]

Ok, well, its certainly cheap/easy enough to do...let's see how this goes.

[lather]

I was thinking the exact same thing...sigh. Weird, too. If you just roll the bike a couple feet, it loses its prime. Don't even have to make it to the end of the block.

That sounds like the axle is not properly seated and the rotors are pushing the pads away. Try loosening the pich bolts, blocking the front wheel and pumping the forks several times and retorque.

[Steve Bell]

Sounds like a bent rotor. If you can check this yourself I would start there.

[VirginiaJim]

Could be or not.  Could be the carrier itself (more likely).  The key word is tires, as the wheel has been removed from the bike.  If the op took it to a tire place and didn't remove the rotors it's possible the carrier was bent during the installation.   We had another member with exactly the same symptom sometime back.   I'll have to look for that one.  Course it could have been in Forum I.  My memory isn't exactly a steel trap.

I had the same thing happen to my bike and the front brake did exactly the same thing as the OP's.  I was stupid and layed it in the back of the truck without thinking about the rotors.

I would still do what Lather suggested but I would get a dial indicator and check for runout.  If it's bad enough to affect the lever like that it should be obvious.  Take the calipers off the wheel and spin it and see what shows.   If it's that bad you should be able to see a warp.  You may be able to form it back if you're lucky.

[lt1]

Have you both actually ridden the bike (ie - at least half and hour of stop & go, not just around the block) and checked the fluid level in both resevoirs?  Sometimes after a brake pad change, it takes a bit of riding for the brakes to stay firm.  It's not common, but I've had it happen a few times.  If nothing else, you may need to pump both brakes up longer than first firmness, the tie off the front lever and weight the rear pedal overnight.

[Breaker19]

Most likely bad/dirty fluid, causing the pressure to bypass the master cylinder pistons. Common problem in older bikes, because of the lack of flushing of the fluid mainly. Junk gets built up from fluid contamination with moisture, etc. Bleed the brakes with fresh fluid. If that doesn't fix it, yank off the master cylinder and take it apart. Bet it's got some crap in it. Hard to think that a 3 year old bike has bad piston material in the MC but stranger things have happened. Worst case scenario is you have to rebuild the MC. No biggie.

[VirginiaJim]

I rode with mine quite a bit until I started hearing scraping noises when the front brakes were applied.   Upon examination some pads had abnormal wear and were down to the metal.  I changed one side rotor (I think it was the left side that had the abnormal wear) and the brake lever issue went away.  I think I still have that rotor.

This was sometime back and was the first tire change on the bike.  Never had it since, as I am extremely careful with handling wheels with rotors still on.  In fact, I take them both off when I get the tires changed now.

[DLaw]

Yeah, could be all of the above. I always drop my wheels myself and take them to get new tires at the dealer. I rode the bike a fair bit today around town (30 miles or so) using the rear brake which works fine primarily and then pumping the lever until I got pressure back. I tend to doubt a rotor got warped in the process; figure it would pulse a bit once pressure did come back and it doesn't. The fluid is relatively new; flushed it with the last front pad change in March. The system has not been opened since then.

I'm waiting for the sun to go down a bit and then I'll flush it again to see if anything comes of it; and I'll try loosening the pinch bolts-jouncing-retorquing and see where that gets me. Hopefully, it straightens out after one of those things. Otherwise, I have two weeks to do a master rebuild or whatever before the Ramapo 500. I've never rebuilt a radial MC....any different from the normal style?

[motospec]

If you lose the front brake pressure every time the front wheel is rotated one or two turns it is definitely a bent rotor. If the pressure stays up fine when the wheel is not rotated that is telling you the rotor is bent and pushing the pistons in when it wobbles and will take a couple of pumps to move them enough to regain brakes. I've seen a number of rotors on many different bikes straightened with a plastic mallet while checking runout with a dial indicator. It doesn't make them perfect but will make them usable with no problems. It doesn't take much to straighten them.

[VirginiaJim]

What he said...

Your first post...Congratulations.  Welcome to the nut house.

[Cheesecake]

If you lose the front brake pressure every time the front wheel is rotated one or two turns it is definitely a bent rotor. If the pressure stays up fine when the wheel is not rotated that is telling you the rotor is bent and pushing the pistons in when it wobbles and will take a couple of pumps to move them enough to regain brakes. I've seen a number of rotors on many different bikes straightened with a plastic mallet while checking runout with a dial indicator. It doesn't make them perfect but will make them usable with no problems. It doesn't take much to straighten them.

I experienced a mech hold a sharpie in his hand while wrapping his hand around the front fork, and spin the wheel, the sharpie marked the rotor where it was bent, then he smacked the rotor with a brass punch about 30 times in various locations. Made it better but I had to replace the rotors to get it back right. The rotors float on those metal donuts, and it doesn't take much to mess that little fragile system up. Welcome to the bleeding edge of motorcycling!

[Fretka]

You did check the fluid level in the reservoir......right?

[Fearless]

I am experiencing the same problem after changing front tire. What ended up fixing your problem?

[VirginiaJim]

Sounds like the rotor carrier got bent during the tire change....  Happened to me on my first tire change.