Front break sticking?

[theswede]

Hi all,

It's been a while since I stuck my head in here last time, glad to see the board is still alive and healthy!
I have run into a bit of an issue with my scoot lately which I'd appreciate some feedback on to help resolve.
Last couple of times I have been out riding I have noticed a strange grinding noise from the front wheel, changing in pitch and in intensity with the speed I ride. It's not constantly there though, it sort of comes and goes....
First I was afraid it was the bearings going, I have had trouble with them before and swapped them out once but today I tore it down and I can't find anything wrong with the bearings, they feel as good as new.
I wonder if the sound could be coming from the break pads sticking to the rotor, and what to do about that?
Is there a spring in there or something that retracts the piston that could have broken, or is it just sticking because of built-up grime?
How would I clean it best if it's just grime?

Thanks guys,

Otto

[shiftless]

There is no spring... the caliper floats, and a little pad contact on the rotor is normal
Yours may need cleaning
I use ordinary brake cleaner, just take it apart and clean it up
Make sure your pads are not worn

[jmkjr72]

sounds like worn or improperly seated brake pads
what kind of shape is you rotor in are there rough spots or ridges on the rotor

[Rebel]

The brake pads will normally be just off the surface of the disk, if they are not coming off the disk I'd check the master cylinder on the handle bar to see if it has a problem not letting the brake fluid come back into it when you let off the lever. Another culprit could be the ABS valve on these, they are not really an ABS like in a car, but a flow limiter that if plugged can keep the brakes from letting off. You can actually remove the ABS valve and the brakes will work pretty well.

[theswede]

Ok, thanks for the input guys!
I'll get some break cleaner and use it and pull the pads to check them too.
The rotor is ok, no rough spots or ridges.

Might as well change out the break fluid while I am at it i suppose, the original Chinese junk is still in the system.
Rebel has an interesting point, it might be that there is too much brake fluid in the system... I can't see any air bubble in the reservoir.

/Otto

[zedooo]

I have the same problem...but I think I just have to clean the brake system...will do

[theswede]

Ok, break fluid replaced and the whole assembly cleaned using half a can of break cleaner. The original chinese snake oil looked horrid, glad to have replaced it.
As far as I can tell the break seems to have stopped sticking, need to go out on a long ride to be sure...

/Otto

[Rebel]

Otto,

Keep us up on if the cleaning fixed it.

Zedoo,

Did you get yours cleaned? Did ti seem to help?

Doug

[theswede]

Cleaning and break fluid change didn't fix this issue it turns out. After a couple of km's of riding today the sound was back...
It turns out the problem wasn't even the break system but the speedo gear.
The drive wheel (inside the speedo gear) had sized up almost completely against the axle, the wearing surfaces where bone dry and there was a strip of exposed metal where the anodizing (or whatever it was) had been worn off.
Cleaning and oiling it all seems to have removed the problem, hope the damage wasn't too bad and that it will stay working. If the problem comes back I will at least know which part to replace...

/Otto