Front brake problems
Posted September 01, 2002 - 07:14 AM
Anyone had the same problem? I assume the solution is to get a braided steel hose, but just want to check I'm not overlooking anything.
Posted September 01, 2002 - 07:21 AM
[ September 01, 2002, 10:22 AM: Message edited by: Dan Lorenze ]
Posted September 01, 2002 - 08:51 AM
Thanks for the response, but this isn't the problem in my case. If the disk rotor was warped, you would expect that pumping of the lever would firm it back up again - only the rotation of the disk would push the pads back. This doesn't happen in my case - the lever comes back to the bars even after pumping it a few times.
It almost feels like there's air in the system, but I've bled it through a few times but to no avail.
Any other ideas?
Posted September 01, 2002 - 08:56 AM
I would also bleed your brakes>> both at the caliper and your reservoir (master cylinder).
I would recommend a stainless steel line, w/ fresh brake fluid (NOT DOT 5!!!!!!!!! ).
You should change your fluid ABSOLUTE MINIMUM ONCE/Year >> actually every 3 months or so. Brake fluid sucks up water like there is no tomorrow!!
If you want to go the CR style brake routing kit, the problem is your headlight. The YZF's brake line goes diagnolly across the front # plate. Your headlight has an issue w/ this.
I went w/ the replacement, WR routing, SS line. I could not be happier, unless I slapped on a Honda Master Cylinder.
Posted September 01, 2002 - 11:18 AM
Yeah, but that's not the way it works. Do this as a test. Go position a flatblade screwdriver between the front pad and the rotor. Gently, not scratching or dinging the rotor, spread the pad about 3/8". Your theory would have a 'firm' lever. Try it. The lever will be pure mush and push the pad in 1/8" or so. The next pull will do the same thing. The 3rd or 4th pull will get the pad back in range of the rotor and firm up.
This same thing, on a smaller scale (hopefully) is happening with a slightly dinged or warped rotor. I agree with Mr. Lorenze that is the most likely problem. After that, low fluid in the reservoir, leaking pistons, expanding brake line, etc. You can tell if the rotor is warped by raising the front wheel and spinning it. If it is warped or dinged, it will have visible side to side runout.
Posted September 01, 2002 - 02:18 PM
Posted September 01, 2002 - 02:24 PM
MXH, Are you totally sure that the wheel wasn't spinning at all??? Put your bike on a stand and try it again with the wheel locked to your fork with a tie-down so it won't move. If you've completely bled the system I can't imagine what else it could be... Get back to us.
Originally posted by MXH:
the lever comes back to the bars even after pumping it a few times.
Any other ideas?
Posted September 01, 2002 - 08:01 PM
Posted September 02, 2002 - 05:40 AM
Posted September 02, 2002 - 06:45 AM
When brake fluid gets OLD and burned from constant heating and cooling it looses it's viscosity...therefore giving a spongy pedal or lever. Brake fluid should be flushed often...The harder you ride/race the more often it should be changed.....I change mine when I change my oil...Brake fluid is cheap (DOT4 High Temp) and fast with a mighty vac (5 minutes).
Posted September 02, 2002 - 11:42 AM
I thought there were other reasons as well...but cannot recall. I do know, for all the trouble, it was not even worth considering.
I think the DOT 5 fluids were for EXTREME braking temperatures, NOT something any motocross/race bike would even come close to seeing.
Anyone feel free to correct me if I am wrong!
Posted September 03, 2002 - 02:12 AM
Maybe I'll purchase another quart of it next payday.
Posted September 03, 2002 - 03:49 AM
Therefore it's something else - I have tried bleeding the whole system through with new brake fluid but it's still the same. Suppose I'll just
have to get a braided hose and try that.
Posted September 03, 2002 - 01:21 PM
I'm not sure I understood your first sentence. I think you meant that if the wheel is still and you use a screwdriver the lever will firm up after a few pulls. But on your bike, when riding, the lever never firms up no matter how many times you pull it.
If that is what you meant, a warped rotor would not firm up the lever but instead push enough fluid back into the master cylinder's reservoir while the lever was released that pulling it would not reseat the pads. The lever would always be mush.
This is a long distance diagnosis. If you want to be sure, put your bike on a stand with the front wheel off the ground. Pump the lever a few times until the brake is firm, normal feeling. Release the lever, spin the front wheel rapidly for a few seconds. Now see if it the lever is still firm. If mushy or requires more than one pull, the warped rotor caused it.
(OK, long shot but a leak could also cause it, the double blind test would be to firm up the lever, release it, and let it sit the same amount of time you rotated before. If it was mushy after turning but not after sitting the same amount of time, it really is the rotor.)
You will probably also be able to see the side to side motion (a very little is acceptable), the runout spec is in the manual.
Posted September 03, 2002 - 02:43 PM
Posted September 03, 2002 - 09:50 PM
I was saying that I agree with the theory of your screwdriver test.
BUT the problem is that I cannot firm up the lever no matter how many times i pump it. The bike is stationary and I am pumping the lever but it does not firm up. I am not spinning the front wheel at all - that's why I'm saying it can't be a bent rotor.
Posted September 04, 2002 - 01:53 AM
I know Moose offers rebuild kits for Quads...