How to align (center) a 4 piston brake caliper over a rotor (Magura MT7 - Will probably work with others as well)

[Rip]

With 4 piston brake calipers you want to make sure the actual caliper body is centered over the rotor rather than the brake pads and simply loosening the caliper bolts, pulling the brake lever on and tightening the bolts again doesn't do the job well enough.

This may be common knowledge already or more than likely there is a better way but I came up with this and it's worked perfectly for me so far. By all means if you know of a better/easier way then please post it below.

This was done on my Inspired Fourplay with Magura MT7 calipers but the same logic could be applied to other makes and models.

 

Step 1

Remove the wheel, remove the brake pads (important), gently push back all of the pistons all the way back (important) with something like a plastic tyre lever and measure the gap in your caliper body, mine is 3.50mm

Step 2

Measure the thickness of the rotor, mine is 2.00mm

Step 3

Take the size of your caliper gap (3.50mm) and subtract the thickness of your rotor (2.00mm) = 1.50mm. Then divide that by 2, which is 0.75mm (remember this number)

Step 4

Put your wheel back in but without the brake pads

Step 5

Find a clean piece of paper and measure it, mine is 0.10mm

Cut, stack and fold your paper so it is as close to your number from Step 3 as possible, mine worked out at about 0.72mm, do this twice so you have 2 stacks (only 1 stack is pictured below)

Step 7

Remove your brake caliper, trim your paper as required and fold the stacks over your rotor

Step 8

Carefully lower your caliper over the paper and on to your rotor

Step 9 

Slowly and gradually tighten your caliper bolts

Step 10

Remove your wheel and put your brake pads back in

 

Proof that this method works, a few tugs on the brake lever and the wheel spins freely with no pad rubbing, yes I accidentally filmed myself pumping the front brake lever then spinning the rear wheel because I'm an idiot lol so until I re-film the clip you'll have to trust me that both my wheels spin freely now after using this method. And no my bike isn't pink.

 

 

 

Edited January 22, 2021 by Rip

[AdamR28]

Clever technique, I like it!

[Rip]

Just now, Adam@TartyBikes said:

Clever technique, I like it!

Thanks :-)

[Maintenance Justice]

Probably the most precise approach to brake adjustment I've seen. This would work great for flat mount where calliper alignment is a bit more tricky to get right the 'normal' way

[Rip]

2 minutes ago, Maintenance Justice said:

Probably the most precise approach to brake adjustment I've seen. This would work great for flat mount where calliper alignment is a bit more tricky to get right the 'normal' way

Haha, I'm a CNC machinist by trade so I kind of have that precise approach ingrained into me. 

[Swoofty]

The OCD is strong with this one! I've never had a problem with just eyeballing it in the caliper, but yes, the key is to center the caliper to the rotor, not the brake pads to the rotor. Make sure the pads/pistons are pushed all the way in before alignment because Maguras will self center to the rotor and it needs to be centered for best actuation. Of course rotors only stay true for a day or two...

[Rip]

1 hour ago, Swoofty said:

The OCD is strong with this one! I've never had a problem with just eyeballing it in the caliper, but yes, the key is to center the caliper to the rotor, not the brake pads to the rotor. Make sure the pads/pistons are pushed all the way in before alignment because Maguras will self center to the rotor and it needs to be centered for best actuation. Of course rotors only stay true for a day or two...

I'll add a bit about pushing the pistons back.

[AdamR28]

Plastic tyre lever works well for this...

[Rip]

4 hours ago, Adam@TartyBikes said:

Plastic tyre lever works well for this...

Perfect! Added to OP.

Edited October 5, 2020 by Rip

[Rip]

5 months of riding (when I can, around the weather) and my calipers are still perfectly centered and my wheels still spin freely. All I've done is periodically checked the torque on the caliper mounting bolts.