[mweisdorfer]

I'm looking for a DIY for a brake caliper piston boot. It has a metal ring inside the boot that's supposed to snap in place when you apply enough "even" pressure to it.

I'm wondering if any has seen a DIY either here or I. YouTube etc.

[bluewater328]

This is for the F30 Msports, but its the same theory.

[juld0zer]

Any popular car with ATE calipers will have a DIY that someone has written up. eg. Mazda3, Golf..

They are really easy but i wouldn't call it a 'snapping' sound. I've only done boots as part of a piston seal replacement. I usually fit the inner section of the seal onto the groove of the piston, lube up the outer ring and push the piston home with an object wider than the piston and (collapsed) boot like wood, jar lid, even bare hands. The metal part is in the side which goes into the groove in the caliper (if there is any. I haven't done an E90 personally but the Mazda3 had a metal core in the outer section)

[mweisdorfer]

Originally Posted by juld0zer

Any popular car with ATE calipers will have a DIY that someone has written up. eg. Mazda3, Golf..

They are really easy but i wouldn't call it a 'snapping' sound. I've only done boots as part of a piston seal replacement. I usually fit the inner section of the seal onto the groove of the piston, lube up the outer ring and push the piston home with an object wider than the piston and (collapsed) boot like wood, jar lid, even bare hands. The metal part is in the side which goes into the groove in the caliper (if there is any. I haven't done an E90 personally but the Mazda3 had a metal core in the outer section)

I'm 99% sure that there is a lip on the caliper in which the metal ring in the boot must snap over for it to be installed correctly

[juld0zer]

https://www.m3post.com/forums/showthread.php?t=1377763 This might give you an insight.

Here is an article about a Golf R32 which uses a very similae caliper to the 335i: https://www.thebeardeddetailer.com/blog/2019/7/18/mk5-volkswagen-r32-brake-caliper-rebuild?format=amp

It's not something we do every day but the last time, I managed with a block of wood and rubber grease or rubber care spray