Tips for Aligning Disc Brake Calipers?

[jtakeda]

Originally Posted by joevers

Also, a surprising amount of bikes of all materials at all price points would brake *substantially* better if the brake mounts were faced. They rarely rarely are.

This has never even occurred to me.

OP. Can you explain the rubbing in the rear?

If you have the bike in a stand can you see where it’s rubbing? If so I’d just loosen one bolt and manually move the caliper over and tighten.

Also, flat mount? Post? Iso?

[davidb]

As mentioned above the frame/fork more than likely needs faced. If the caliper is sitting perpendicular to the axle it is never going to work right. Find a shop or buy the tools. A file is terrible and will just make things worse. As will sandpaper or a knife cutting off the paint.

[joosttx]

Have you pushed the caliper pistons all the way back?

[indy.cyclist]

Originally Posted by lavi

Yes. This certainly frustrating. I had a buddy (Clean39T, shocker) tell me about the Hayes Feel'r alignment tool. It worked.

I would try this or the Birzman before anything else.
Sounds like your pistons are not retracting all the way.

[John H.]

I see you are running Hope calipers.
Since I have a Bingham with Hope Calipers I will chime in.

I found that I needed to center these calipers by hand/eye. It seems like the hose will easily move/change the angle of the caliper (especially on the rear).

I go through cycles of leaving the caliper fully loose to find the spot where the rotor 100% clears, then gradually tighten the caliper down. I may need to do this several times to sneak up on the spot where I have clearance and also have a fully tightened down caliper.

[chrisroph]

Is there a reasonably priced flat mount facing tool available? I know of the VAR and the Park but they are priced a bit out of range of the garage mechanic.

[dddd]

It's important to have the pads forced against the disc so as to avoid any twist along the bolt axis direction, since it takes too many repeated attempts to balance this tilt with the left/right caliper positioning at the same time.

So with the lever held applied with a rubber band, two hands are free to push the caliper to the left or right while the other hand tightens the bolts, which should find a good center within just 1-3 tries (give yourself five it's the first time).

It was mentioned that the caliper can walk as the bolts are tightened. so it's best to lubricate the bolt head and washer seating surfaces with a delicately-applied drop of oil before lightly tightening the bolts in alternating increments (just don't use an aerosol can or get any oil near any pad/rotor surfaces).

It's important also to be able to examine not only the evenness of the left and right gaps, but also whether they have uniform thickness instead of wedge-shaped, which would reduce needed clearance and force the rotor into bending mode.
So it's best to put the bike over a sun-lit sidewalk to allow clear sighting of the gaps as the pads move in and out, AND to observe the nature of any bending/twisting of the rotor. This last item proves very instructional for those seeking near-perfection, and also saves time.

Sometimes the oval-shaped bolt holes in the caliper mounting can fail to allow centering over the rotor, but that is rare. And most mounting surfaces won't need any additional facing, that's pretty rare unless it's a super low-end bike.

On well-used calipers, sometimes I will have to loosen up gunked-up piston seals by spraying the area with rubbing alcohol (usually this is needed only after pads have been replaced and there seems to be insufficient retraction on one side).

When the rotor doesn't move visibly at all (either in front of or behind the caliper!), is when and only when the centering can be called good (the only exception is on mechanical calipers with just one moving piston, where there has to be at least some clearance between the rotor and the stationary pad).

[davidb]

Originally Posted by chrisroph

Is there a reasonably priced flat mount facing tool available? I know of the VAR and the Park but they are priced a bit out of range of the garage mechanic.

If there is I can not find one. Also if anyone does find one please let us know. I was using the Park at work. Just decided the VAR will pay for itself. Having used the VAR it is the best tool for the job.

[Old School]

Hope is the only company I know of that sells shims by the bundle. I wonder if you have Hope rotors, and the caliper needs shimmed out a mm or so, to keep the pads from the rivets

[joosttx]

Originally Posted by John H.

I see you are running Hope calipers.
Since I have a Bingham with Hope Calipers I will chime in.

I found that I needed to center these calipers by hand/eye. It seems like the hose will easily move/change the angle of the caliper (especially on the rear).

I go through cycles of leaving the caliper fully loose to find the spot where the rotor 100% clears, then gradually tighten the caliper down. I may need to do this several times to sneak up on the spot where I have clearance and also have a fully tightened down caliper.

Same thing with my Hope's and my Bingham gravel bike. The hose will mis-align your brake-lever-squeeze alignment. Like you I keep the bolts barely loose enough. I loosen, squeeze the levers, and repeat until when the caliper barely moves when I squeeze the brake. I also have my daughter engage the brake as I tighten the caliper bolts.

[teleguy57]

Originally Posted by Old School

Hope is the only company I know of that sells shims by the bundle. I wonder if you have Hope rotors, and the caliper needs shimmed out a mm or so, to keep the pads from the rivets

Not sure how many you are thinking, but I've had good success with November Cycle rotor shims.