Flat mount caliper alignment and caliper bolts tightening

I’m facing this for the first time and test snug-ups have revealed that unsurprisingly, simply starting to wind on bolt torque creeps perfect alignment out of alignment.
Just thought I’d throw this out there, you guys (and gals) got any tips/tricks to make this easier/more straight forward?

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Copper washers, apparently!

I’ve never done it, but I’m sure someone has! :}

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I just did this the other day and discovered what you are talking about. It took me a couple tries, but I found making sure I kept the brake lever firmly pulled until the bolt was fully tightened solved the Issue.

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Gun sight method is still the best in my book. Place bike atop a high contrast surface or illuminate the floor beneath the brake with a white light (like an led headlight). Close one eye, center up the rotor between the pads, gradually start torquing each bolt a little bit at a time whilst keeping the one eye closed and the rotor centered. Go very very gradual at first.

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I was taught using this tool and a small torque ratchet. Regularly changing wheels for cyclocross makes it a necessity.

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I don’t like relying on grabbing the brake lever to center; the pistons may not come out evenly and the rotor can bend. Second sighting it with your eyes.

Turn the bolts in very small increments, alternating bolts, while holding the caliper tightly in place with your hand.

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I used a similar tool from Birzman. All those years spent manually lining up calipers were a waste. This tool is as close to a holy grail as possible.

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I’ve got a Birzman alignment tool, do you utilize that while squeezing the brake lever or just let the tool set the gaps while not squeezing the lever? like MarkPgh said, he’s not a fan of grabbing brake lever and I can understand why. but then again, grabbing some lever would force things to square-up (pads on the same exact plane as the rotor surfaces). fk me, am I overthinking all this??
Thanks for all your replies.

I do a light squeeze with the tool in. I was so giddy at how easily and well it works.

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I’ll 2nd the Birzman tool, works like a charm (gently squeezing the brakes). If I’m out somewhere without it then a business card folded in half works as well.

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Agree, using a feeler gage is the way to go. I tried all kinds of other methods and it was never repeatable until I purchased the Hayes Feel’R Gage. I also squeeze the lever on the feel’r gage while torquing the bolts. It just works every time.

If your rotor is bent or you pistons are not functioning the same/properly, they need fixed. Not maintaining those will lead to other problems and annoyances.

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Definitely the purple Hayes tool.

Loosen bolts, stick the tool in, pull lever firmly (front) or velcro lever down (rear), alternate tightening the bolts but strongly lead with the trailing (bottom /back) bolt.

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works perfect… ‘till the caliper bolt tightening shoots the whole thing to shit. I reckon all these methods are ‘YMMV’ kinda’ deals (and the devil is in the details).

The bolt tightening always moves the caliper in the same direction (EG the rear will move anticlockwise when viewed from the top) so it isn’t very hard to account for that when aligning it.
YMMV,of course.

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my rear caliper (viewed from above) was bodily adamant on moving inboard, even while ‘braced’ by hand. I had to compensate for that before I started cinching down the bolts. ‘YMMV’

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If the pistons aren’t coming out even (often the case) then your method is going to cause the disc to bend every time you pull on the brakes, because those uneven pistons are going to hit your perfectly-centred-when-pads- retracted rotor at different times. And cheap single piston mechanical brakes rely on the rotor bending to engage with the fixed pad.

I’m working in a new store and built >50 bikes in the last couple of weeks and the pulling brakes on with bolts loose method worked 90% of the time, for more stubborn brakes using the Shimano Pro version of the Birzman tool, and giving the brakes a squeeze, solved it.

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so what do you do about uneven piston advancement? pull the pads out, clean and reset? and what does ‘reset’ mean exactly?

edit- never mind, guess ‘reset’ means resetting piston orientation to piston seals for proper advancement/retraction. lol, I want some direct-mount rim brakes instead.

Yeah that - try clean the pistons and then cycle them in and out a few times in case it’s due to dry/stiff seals - but sometimes it’s unfixable.

I own 9 bikes - my favorite one is the only one with rim brakes!

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One of the things that works to stop ‘V’ brake pad movement (and may be applicable in your case as well) is oiling or lightly greasing only the outer / upper surface of the washer that contacts the tightening bolt.
I’ve also had creep because the concave-convex washers have been installed incorrectly. Some concave-convex washers are rough / have burrs and sanding them, or replacement with smoother ones works.
Hopefully some of the above, along with all the other suggestions sort out the issue.

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