Front Brakes Apply Lightly When Wheel is Turned

[ZacharyB]

What de dilly yo?

In earnest, my front brakes apply when turning the front wheel. I recently had the calipers and master cylinder off the bike, where I cleaned both, including a stopped-up relief orifice.

Now not three hours of riding time later the brakes are starting to drag again. On the highway it will make a very high pitched, oscillating whine at certain speeds. It increases in intensity when I turn a certain direction. I find it strange that turning the front wheel would have this kind of effect.

The rear brake has been cleaned as well, but it does not drag or whine. In fact it was all I used to get home (worked pretty well too). My reservoir on the front master cylinder is not overfilled.

What can I do?

[cbxchris]

Are your rotors warped?? Do you have the proper pads? Are the pistons and seals in good shape in the calipers?? How is the bore in the caliper body?? Just throwing some things out there for thought.

[Anonymous]

Are your brake hoses routed properly? Could they possibly be kinking or being otherwise squeezed somewhere?

If this is truly an action of brakes being applied, rather than warped rotors or something, it would happen at all speeds. Is there any way to observe the problem at low/no speed?

Off the wall: Do you have the anti-dive hooked up?

[Anonymous]

just a guess

But I think the change in pitch is probably the rotor moving slightly with the different directional forces acting on the wheel. It probably wouldn't have to move much to make a change in sound, on the same note how's the front wheel bearings?....Mike

[HiSPL]

Did you thouroughly grease the two pins that the caliper slides on? These pins dry up over time and cause the caliper to stay in one position on the rotor after releasing the brakes. Remember these are floating calipers. they have to slide around to work properly. The pins I'm refering to are the ones under the rubber accordion boots where the caliper bolts to the fork.

Good luck,
-=Tim=-

[ZacharyB]

1. Rotors might be warped slightly but not to an extreme degree. If this is the problem I have no money to correct it now, so -> end

2. Proper pads=yes

3. All seals look good. Pistons squeaky clean. Pistons slide in and out of caliper piston bores ok with rubber seal in place.

4. The brake hose from master cylinder to routing tube under the front fork cover is "pulled", I'll try to loosen it

5. In fact, the squealing occurs at low speeds. It is actually random and relative to the front brakes sticking at various speeds after I have used the front brakes. It takes time for the fluid to move past what may be a clogged (again) relief hole. I want to bore this hole out with a drill, is it absolutely necessary it remains so small in diameter?

6. No anti-dive on this bike, it is a '78 750

7. Front wheel bearings are okay, no play and wheel turns freely with no noise when brakes are not applied

8. I did NOT grease the sliding pins that the brake pad plate slides on. Looks like that's next. That and attention to that *$#@) relief hole

Thanks everyone

[sv650]

O-ring

Also, check & be certain that the o-ring in the caliper is sitting in a clean groove. Brake fluid salts build up behind the o-ring, preventing full retraction of the piston. Clean the groove with an appropriate tool and the problem is usually resolved.

Check:

http://www.thegsresources.com/_forum/viewtopic.php?t=14178&highlight=brake

SV

[Anonymous]

I would be most suspect of the hose that is tight. I put my tank on one day and accidentally snagged one of my throttle cables, so every time I would move the handlebars to the left it would open the bike wide open - figured that out in about 2 milliseconds of making a left turn at full throttle.

[ZacharyB]

Hello, the problem has been figured out, it was the relief hole. It had clogged again and a few pokes of wire brush wire had me bonking the bottom of the master cylinder again. The thing I am concerned about is that it clogged again in such a short period of time. I really want to take a drill to this thing.

Can I bore out the relief hole to twice its size? (Arguably no bigger than 1 mm.) Is this possible? Will someone answer me or will that someone wait for me to become a human tangle after I find out I suddenly have no brakes at 50 MPH?

Does it retain pressure on the system for the hole to be that small?

I should also add I greased the sliding pad pins for good measure.

[ZacharyB]

This is my last entreaty for any precautions before I take the thinnest drill bit I can find and drill out the relief hole a bit!

All in all, if anything goes wrong of this operation I'll be the guinea pig for this hot topic