[Closed] How to stop Calipers rolling inwards when you tighten them up?

I've often though of drilling and tapping the sides of the bolt slots and adding grub screws to fine tune the position.

I believe Hayes might actually have stolen my idea. Lot of faff though.

If this happens, I tend to tighten up the bolts a little whilst holding the brake on, then tap gently on the caliper to align it, then each bolt tightened a smidge in turn.

But I feel your pain, it's annoying!

Before some smart arse says “just hold it as you tighten it up”, I have tried this but its hard to get the caliper aligned vertically.

Ah, that's how I've always setup disc brakes. Pulling the lever and tightening the bolts rarely gets the caliper central.

I hold the caliper in place while tightening the bolts - alternately.

But one of these might help you.

https://www.wiggle.co.uk/lifeline-pro-disc-brake-caliper-alignment-tool

Do it by eye rather than the squeeze the lever method, hold the caliper between your thumb and finger and nip up the bolt so that you can see daylight either side of the pad at that end, repeat at the bottom, tighten the other end checking to make sure it doesn't move, repeat until tight.

Takes a few more minutes to do but guarantees quieter brakes IME.

+1 for tinas

Same here. Align by eye, hold in place and nip up bolts then tighten each bolt 1/8 to 1/4 a turn at a time until tight.

Pack the gap between pads and disk with cardboard so that the caliper is firmly centred (the IceToolz tool above does the same thing), then use TWO Allen keys to slowly nip up the bolts simultaneously. Doing the bolts up one by one can twist the caliper out of alignment.

Another one here for aligning by eye

To do it properly you need to remove the pads, push back the pistons and align the caliper by eye over the disc so its sitting centrally, once you have it central nip up the bolts slightly so the caliper doesn't move once let go

Next to stop the caliper from moving when you fully tighten the bolts i use a large adjustable spanner and a thin rag (stops any marks) to hold the caliper body in place whilst i tighten up the bolts fully

Refit the pads and pump the lever to push the pads out and you should have a nice central caliper with a free running disc

@ecsrs has it. It's how Hope recommend aligning their calipers. Slightly more faffage but it works. Also once the bolts begin to give some resistance then only tighten each one by a quarter turn then do the other, similar to how you'd tighten a headset/stem (as @drewd says).

When I've had this I've held a finger against the inside of the caliper whilst tightening. Only really needed for a half a turn.

There's these things called fingers in coordination with eyes

By eye, after nip the caliper bolts up a bit so you can just about move them, line them up, gradually tighten.

Thanks for all the suggestions.

I have discovered some small washers with sharp edges have worked well on the back.

I got to the point on the front where even if I held it as solidly as I could, I still couldn't stop the caliper sliding inwards with the rotation of the bolt. Then I replaced the bolts with ones that weren't slightly bent and things went better.

What's the width of the gap in most calipers? Imagine a rotor so thick it would just fit in the caliper with pads removed. Then you could tighten the caliper, swap back to the proper rotor and add the pads. Perfect balance and alignment every time.

Onzadog you read my mind

Initial squeeze to get it in place, then 1/4 turn each end and constantly eye-up and adjust. I also found if you're using an adaptor then the cup/cone washers seem to remove the issue of the caliper moving.

Hayes has it sussed. They've used thicker mounts and put a grub screw into the side of it. The grub screw acts against the mounting bolt so centers it perfectly. Shame other makers dont do the same, it would make set up very easy.

I use the mostly tighten, then tap each side with the handle of a pin hammer(and long thing would do) and judge it by eye looking at any deflection in the disc as the pads begin to contact the rotor. Just a back and forward, tap, tap, tap and fully tighten and check for zero deflection or start again. A faff about, but works for me.

Just a thought, you do have washers under the bolt heads don't you?
I find that adding grease to the washer & underside of bolt head helps enormously, so the bolt, washer, calliper all slide against each other, rather than bind & twist as you tighten.
Not had a problem with alignment since.

What’s the width of the gap in most calipers? Imagine a rotor so thick it would just fit in the caliper with pads removed. Then you could tighten the caliper, swap back to the proper rotor and add the pads. Perfect balance and alignment every time.

Wouldn't that be a useful thing to have if you were doing mg maintenance... Say like bleeding the caliper, too?

... Maybe you should patent it?

They twist because the caliper mounts aren't perfectly faced and aligned.

Some are better than others. Avid, like all sram stuff, is made to very poor tolerances (don't get me started on GXP) - so they just insist you use cup washers.

By eye with the pads removed is generally best. If this doesn't work it usually means you have a sticky piston and could do with working the pistons in and out whilst lubing with red rubber grease.

Is that lifeline alignment tool any good?

I do exactly as TINAS recommends. The hold-the-brake-lever-and-tighten-the-bolts approach gets you about 80% of the way there but leads to uneven pad wear and squealing brakes in my experience.

You can get a handy spacer thing to help you set up the position perfectly. I find taking the pads out and shining a torch from behind makes it much easier.

CNC adapters instead of cast ones and cup n cone washers on the top of caliper, the adapter or the caliper body could be slightly off.
Badly painted calipers can have this issue.

I must add caliper alignment to adjusting front mech and fitting tubeless tyres.