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Matt, Engineer
Category: BMW
Satisfied Customers: 21854
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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BMW 135i coupe (2012). Caliper retaining bolt head (4/axle)

Customer Question

BMW 135i coupe (2012). Caliper retaining bolt head (4/axle) broke off leaving only bolt shaft in caliper and leaving me with an incredible headache. Conventional screw/bolt extractors do not work as the material is a very hard metal alloy thus almost impossible to pilot drill into. Any advice would be truly appreciated. Thank you for your time.
Ryan ***@******.***
Submitted: 1 year ago.
Category: BMW
Expert:  Matt replied 1 year ago.

Hello Ryan

there's a couple of methods to try

if you have access to a welder then its possible to try and weld a tab or bar onto it so you can undo the stub You can simply take a washer and a bolt of a slightly larger size and tack weld it to the bolt body. Once you have it tack welded, I like to fill the nut with weld and run a bead around the base of where it meets the bolt body. This allows you to put a socket on the bolt again, as well as puts heat into the bolt that will allow it to expand and contract, breaking some of the corrosion. I prefer to use a MIG welder to do this job as it allows for a little more control than with a stick welder.

if thats not an option then if you can try to use a small chisel to tap the edge of the bolt to try and unwind it as often once the bolt head is removed then there's no tension in the remains of the bolt

soaking everything in penetrating oil for at least 20 minutes beforehand will also help

Expert:  Matt replied 1 year ago.


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