[bthomas518]

I've looked up part # for rear brake pad carrier bolts (34-20-6-850-536), it is a M12 x 1.5, 32mm. Was wondering if anyone knows if these are supposed to be replaced after removal?

The torque spec of 30Nm + additional 90 degrees turn makes me think these are one time use "stretch" bolts, but not sure.

Can anyone chime in?

Thanks,
Bryan

[bthomas518]

Page 22 of this .pdf suggests that they need to be replaced. http://f30.bimmerpost.com/forums/att...6&d=1476916748

I think they are under $5 each, probably wise to just buy new ones and toss the old.

If anyone knows for sure, would still like to hear from you.

[John in VA]

This isn't a project I've had to do on the F30 or F22 yet, but on the 2002s, E28s, E30, E39 & E46s I've not replaced the bolts. Maybe use some blue threadlocker.

[aerobod]

Definitely a stretch bolt that should be replaced. The TIS specifies 50Nm +60 degrees for the 228i rear caliper carrier here: https://www.newtis.info/tisv2/a/en/f...rakes/GfyH0Hrd that would likely be close to 30Nm +90 degrees, though.

[bthomas518]

Thank you, sir!

[dradernh]

Originally Posted by aerobod

Definitely a stretch bolt that should be replaced. The TIS specifies 50Nm +60 degrees for the 228i rear caliper carrier here: https://www.newtis.info/tisv2/a/en/f...rakes/GfyH0Hrd that would likely be close to 30Nm +90 degrees, though.

I'm curious...when reinstalling the front caliper bolts, would you recommend replacing them as well?

Oddly, the bolt is listed as a Torx while a hex is shown in the parts image:

[aerobod]

Originally Posted by dradernh

I'm curious...when reinstalling the front caliper bolts, would you recommend replacing them as well?

Oddly, the bolt is listed as a Torx while a hex is shown in the parts image:

The TIS shows them as requiring replacement, but not a stretch bolt due to no angular specification in the tightening torque, so the replacement may be a precaution due to thread locker or other reasons, but shouldn’t be due to the elongation of the bolt making it unsuitable for reuse: https://www.newtis.info/tisv2/a/en/f...rakes/GfqyNpyB

M12x1.5 at 110Nm for a 10.9 or 12.9 bolt is below it’s plastic range, so strain in the bolt shouldn’t be an issue for reuse. The picture in realoem showing a hex bolt may just be a generic image, the descriptions are usually more accurate.

[pbedrosi]

Doing rear brakes now, called dealer for bolt replacement and they reuse them unless seriously corroded....and the torque is "pad carrier to knuckle" torque. It was a bitch to remove, definitely not 22 ft-lbs, these are the 110Nm/81 ft-lb bolts.