RubeRad

This is the front brake on a Specialized Allez Sport Triple, and it's dragging the right pad. What is the tool/wrench that is designed to get into that tiny space and tighten that nut so it will stay centered?

branko_76 

maybe this, it will engage the flats on the front while you tighten the nut on the rear


https://www.parktool.com/product/off...e-wrench-obw-4

RubeRad

Also, I notice from that picture how diagonal that front arm is, that's from my attempt (and failure) to take the brake apart to get to the centering bolt. The rubbing was there before that

RubeRad

Yeah, that looks like it would hold it. Not sure about 'the rear' though, I looked in the hole on the back of the fork and couldn't find a bolt

branko_76 

Should be a recessed hex nut then

cyccommute 

If the nut on the back of the brake is loose, just hold the brake near center and tighten it. You should be able to keep it centered well enough. Then use a screw driver on the screw on top (red arrow in the picture below) to fine tune the centering. If the caliper isn’t loose, you should be able to just adjust the centering screw.

Before you pick up a screwdriver, however, check to see that the wheel is square in the dropouts.

cyccommute 

Yup. Should be a 5mm.

Andrew R Stewart 

This caliper, like many we see, would benefit from a take apart and reassembly with cleaning and lubing. The arm pivots can be adjusted (usually for the better) for slop/friction balance. This is simple stuff although patience and focus are abilities used Careful examining of the pivots and any locking nuts and set screws is a must first. Andy

Russ Roth

You don't really need a tool to center a dual pivot brakes, tighten down the nut that holds it to the frame so its snug, don't over tighten. Grab the pad of the side that's rubbing and pull it away from the rim. That's it. The little screw being pointed to is something that virtually never needs to be touched. I've spent way more time adjusting that screw from someone else playing with it then I ever did actually using it.
However the pivot bolt just to the left of that screw is clearly loose and unadjusted. You'll need to tighten that up which I find easier to do without the cable installed in the caliper. You'll need to loosen the nut slightly, and start tightening the bolt. As you tighten squeeze the pads to the rim and make sure they snap back open, at the point they don't back off 1/4-1/2 a turn and tighten up the nut. After tightening the nut double check the pads snap back open, sometimes tightening that up tightens the pivots and you may have to back the bolt off a touch more. Reinstall the cable and center. With old school single pivots you had to use tools but with duals they just pull to the side you want and you can easily futz with them.

RubeRad

OK the futzing screw was too good to be true. Screwed all the way in or all the way out, doesn't help. Screwed all the way in may be marginally better, but the whole brake wants to be rotated over to the side. It can be easily rotated by hand, but immediately rotates back. The rear brake cannot be rotated by hand. I think the answer must be in that locking nut.

I found the 5mm hex bolt in the back of the fork, it was already tight.

I got the front arm off, seems the reason it was all askew was from the previous time I halfway got it off, I wasn't able to get it back on right because of the protruding bottom of the futzing screw. With the screw backed out I could get the arm back on (with a little lube on the pivot).

When the arm was off, I could see a 5mm bolt on the front, that was also already tight.

So again, it seems like that locknut in the tight area has to be tightened down good, yes?

RubeRad

I believe the caliper is loose. (and the wheel is square in the dropouts)

cxwrench

^All of this^. If you hadn't tried to take the brake apart all you would have had to do was make sure the nut on back was snug, center the caliper by hand, and then tighten the nut. Now you've got a little more work to do. The adjuster screw is probably ignored by 99.999% of people w/ tools.

cyccommute 

You are making this way harder than it needs to be. The centering screw is there to “center” the brake. Why work harder than needed.

RubeRad

The nut on the back (behind the fork) is beyond snug. I switched to the leverage position of the PW-5 and cranked it down a little more, but it is not loose, yet the whole brake swings back and forth with very little hand effort

RubeRad

Tried to get in there with 13mm cone wrench, it almost seemed like it was grabbing, but then mushed off

branko_76 

I never regret taking a well used bike component apart. In addition to having a freshly cleaned, lubed and adjusted part, I usually learn something in the process.

RubeRad

What if that screw doesn't get the job done?

The caliper should not be able to rotate back and forth by hand, should it? The rear one is quite firmly in place

branko_76 

That is correct. You'll need to snug up the bolt that holds the arms. This is independent of the nut that holds the caliper to the bike. Removing the caliper from the bike may help you to figure out how to do it.

RubeRad

It sounds like you're talking about the bolt that holds two arms down. When I had the outside arm off, I checked that and it was quite tight.

So the only thing left would be the bolt behind the 3 arms, betwee the serrated thing and the spring. That I can't grab, so I guess I have to buy that Park OBW-4 to get at it.

blamester

You have to now remove the brake to adjust it correctly. A set of allen keys is nessecary. It's not difficult. There are likely grub screws and ball bearings in there so be careful..

AeroGut

I don’t know exactly what model that is, but here’s a diagram of a dura-ace caliper that’s probably similar. Might be helpful if you take it apart:

https://www.flickr.com/photos/stronglight/4042079326

Russ Roth

Finding a screwdriver on my repair stand is harder then just grab a side and pull over. The rest of that is due to the fact his brake caliper is visibly falling apart. You mentioned having him check his wheel was straight in the drops but its noticeably obvious that it is straight to the main body of the brake, the outer pivot arm is coming unbolted, hence the other directions.

RubeRad

That's fixed. That was because I had previously tried to take it apart, but gave up and tried to screw it back together. The outer arm didn't neatly slide into place because the protruding centering screw was in the way. You can see in the photo the little stainless backstop that that screw is supposed to press against, not being where it belongs under the screw.

When I started this whole thing, the arm was not all akimbo like that, it just looked normal like the back brake, but the whole thing was loose and the right pad riding the rim.

Now I'm back to nominal assembly, I just haven't posted another picture.

RubeRad

FYI this is the bike, I don't know if 'Light Dual Pivot brakes' means off-brand or not
https://www.specialized.com/us/en/al...Text=9000-7949

Iride01 

The little screw to help you center the brake pads on the rim only controls movement in one direction. So you have to balance that with the adjustment from the barrel adjuster. If you've gotten the screw too loose or too tight, then you might need to turn the screw to put it in the middle of it's adjustment range, then put the barrel adjuster in the middle of it's adjustment range and then assess if you need to put the cable in a different position in the hold fast.