Topic: Front brake dragging

[drumstyx]

Just put the front wheel and brake together, and I've found the caliper doesn't want to retract, no matter how the caliper arm is adjusted. When I rebuilt the master cylinder, the tiny return hole was completely blocked, so I used some very very tiny drill bits (on the order of a couple thousandths) to open it up a tiny bit.

The odd thing is, when I pulled the caliper off, and held onto the pad, the return works quite well. Holding the pad in position and pressing the lever, the pad returns easily to its starting position. It's possible that the spring in the arm doesn't provide as much pressure as my hand though.

So I'm assuming it's the return hole being not big enough; the biggest bit I've put through it is 0.0225". Is this big enough?

[scottly]

The size of the return hole isn't the issue. Sounds like another alignment problem:
http://forums.sohc4.net/index.php/topic,161197.0.html

[drumstyx]

Sounds like it! Just loosened the arm mounting bolts and it worked perfectly! Thanks, I'll read that thread

[scottly]

Pay close attention to reply #8.

[drumstyx]

I don't have the front fender installed right now, so that could be part of it.

[scottly]

No, not having the fender installed is not the problem, it's only a problem when the fender brace is incorrectly installed between the upper caliper mount and the fork leg. The other common alignment issue concerns the axle: the axle nut should be on the left side of the bike, with the hex on the inside of the fork leg.
BTW, it might help if you tell us what version of SOHC you are working on.

[drumstyx]

My current suspicion is bad brake pads. I reused the old ones, the outer one of which is worn on an angle such that the bottom is slightly thicker than the top. I didn't think it'd be a problem, since it was going into the same caliper, but it's possible it was missing installed before. New pads are on the way.

[BomberMann650]

My current suspicion is bad brake pads. I reused the old ones, the outer one of which is worn on an angle such that the bottom is slightly thicker than the top. I didn't think it'd be a problem, since it was going into the same caliper, but it's possible it was missing installed before. New pads are on the way.

That is most certainly a problem!  Check to make sure your brake disc isn't turning into a brake 'cone'.

Cone mufflers good, cone brakes bad.

[drumstyx]

Disc shows very very little wear...probably only had organic pads, which I prefer anyway, considering the cost of a new disc

[BomberMann650]

Disc shows very very little wear...probably only had organic pads, which I prefer anyway, considering the cost of a new disc

Make no assumption, put a straight edge to it and you can rule out a potential problem.

[drumstyx]

Update: with new brake pads it works much better. The old pad must've been cocked slightly somehow. Bike's been sitting for like 20 years so I guess I should've replaced them anyway.

[Stev-o]

Update: with new brake pads it works much better. The old pad must've been cocked slightly somehow. Bike's been sitting for like 20 years so I guess I should've replaced them anyway.

Did you remove the paint on the metal part of the new pads? That has been known to be an issue...

[kslrr]

When in operation, the piston does not move very Mitch.  It should retract only as far as the seal flexes. The idea is the both pads are always in slight contact with the disk.  Refer to the manual on how to adjust the spring.


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