Caliper not fully releasing??
Posted 23 March 2003 - 03:27 PM
I noticed this while giving my bike a thourough looking over after a pretty hairy crash. My first thought was a bent rotor, due to the crash. But, I don't feel like this is a bent rotor because it is equally dragging the entire rotation of the tire.
If the bike is on the stand, and I spin the front tire quickly, it will not make much more than 1 and 1/2 turns on its on.
I have removed the caliper and pushed the pistons in by hand, and the wheel spins fine. After I apply the brake, it never fully releases, and drags.
What could cause this?? I have heard of brake lines on cars partialy collapsing and not letting brakes fully release, but i have never run into this prob with my bike.
Just looking for suggestions before I go ripping my caliper apart.
Posted 23 March 2003 - 03:43 PM
Posted 23 March 2003 - 03:55 PM
Two things that I would check first off:
1. Pull the caliper pins out and ensure that there is no rust, residue on it. Buff and clean off if there is.
2. Check your front disc to ensure that it is not tweaked/bent. From your post, you said you were pushing pads out but once brake is applied, there is tension on the disc, it may be rubbing.
If none of these are the culprit, then not sure where to go but listen to other suggestions from fellow TT'ers.
Posted 23 March 2003 - 04:32 PM
Posted 23 March 2003 - 04:37 PM
If it's the piston side pad. You have a failing seal or dirty piston. The piston is sealed and return actuated, by the sqaure cut seal on the piston. If the seal is worn (edges rounded). It will not distort enough, to return the piston, when hydraulic pressure is released.
You could also have an obstructed hose. Which is not releasing the pressure, after the brake has been released. You can apply the brake and release it, immediatly open the bleeder to see if there's any residual pressure in the caliper. This would indicate an obstructed hose.
Posted 23 March 2003 - 05:10 PM
Excellent advice on cracking the bleeder to check for residual pressure. I did not think of that. I will also take a close look to see which pad is making contact.
I am not going to look at it tonight, but I will work on it tommorow. I will post back what I find.
Posted 23 March 2003 - 06:31 PM
Posted 24 March 2003 - 08:12 AM
Posted 24 March 2003 - 08:30 AM
How much did the caliper kit cost? If it is not too expensive, I may try it.
Did you see my post on the Philips racing Fuel? I know you use it. The name has changed.
I have not had a chance to look at my brake yet today, but i have to get it fixed. The dragging brake has to be glazing the pad and creating mucho heat in the brake caliper.
Posted 24 March 2003 - 09:20 AM
From time to time I have to remove the pads and clean things up in the calipers. I have noticed that the pins get some what corroded and full of dust and crap.
I clean these periodical with a wire brush, grease things up and put back together. I ride in a dusty area and just do the cleaning as general maint.
Posted 24 March 2003 - 04:05 PM
I took the caliper off again and really gave it a good going over. I cleaned and lubed the pins, and cleaned the bolt that goes through the pads. I also used brake cleaner and cleaned around the piston dust seals.
It does release better, but I am still not convinced that it is right yet. The funny thing is that i cannot remember how easy it turned before.
So, if someone is coon-fingering your bike the next time that you are at the track, don't worry, it is just me seeing how easy your front wheel will spin.
My next thing to do will be a caliper kit if I am not satisfied with how it is now.
Posted 25 March 2003 - 03:41 AM
Posted 25 March 2003 - 04:07 AM
At first I thought the rotor was bent, but placing it on a dial Gage proved it was in tolerance. I then though the Caliper itself was miss aligned or the bracket holding it was damaged or bent. Again all in tolerance.
I have noticed my sons 02 250 does not do this, is it the calipers or is it the floating brakes ? or a combo of both.
Personally I think it has more to do with the floating rotor design...
Posted 25 March 2003 - 04:55 AM
It has to be, as Fastest stated, a matter of the pistons not retracting properly. My wheel does not drag at specific points. It drags equally the entire wheel revolution.
Posted 25 March 2003 - 07:38 AM
Posted 25 March 2003 - 03:08 PM
So, if someone is coon-fingering your bike the next time that you are at the track ...
Pervert! Stay away from my wheels!
I heard that brakes do that if you ride too slow for too long.
Posted 25 March 2003 - 03:25 PM
Posted 25 March 2003 - 03:33 PM