[T_Bone]

Hey guys,

Can you confirm (or correct) the information I have that the torque spec for the rear caliper bracket bolt is 30 Nm (22 ft-lbs)? This seems very low--it was more than twice that on my E46!

This was my source, on page 22... http://f30.bimmerpost.com/forums/att...6&d=1476916748

Appears legit, but again, seems really low...

Thanks in advance.

[_bdiddyb_]

That is correct. My Bentley manual also states 30 +- 2Nm

[Bimmer_pnoy]

Here you go. I hope this helps.

[T_Bone]

Thanks, guys, for the confirmation... Much appreciated!

[Briman]

My first post on the forum.... The 30 Nm torque is the first step in the tightening sequence. The bolt is then tightened an additional 90 degrees (1/4 turn). There is no calculation to determine the final resultant tightening force, but it is more than 30 Nm. Dealers do not replace these bolts so I assume that they are not torque to yield.

[FaRKle!]

The rear caliper bolts (M12x1.5x32mm) are similar to the front bolts (M12x1.5x43mm). The front bolt spec is about 80-81ft-lbs. I would just do the rear the same if reusing a bolt. If using a new bolt, then do the 30Nm + 90deg.

[herrbrahms]

Having just done this job, I was also puzzled by the 22 ft-lb torque figure. I did my front brakes a month ago, (standard F30 single piston brakes) and those bolts were much easier to break loose. At the rears, it probably took me on the order of 120 ft-lbs to crack these bolts loose, but the strange part is that it required around 40 ft-lbs to keep working them out until almost the very end. It was a ratchet job all the way, none of the usual hand spinning.

I replaced the bolts not so much because it was recommended, but because the insane torque combined with poor recessed access caused me to round off the 16mm heads a bit, and the last thing I want is trouble in another 5 years when I have to do this again. The replacement bolts come with preinstalled threadlocker as expected. I lightly cleaned the threads in the caliper bracket to make sure the residue was removed, and finished with canned air.

When I reinstalled these bolts, it took far more than 22 ft-lbs merely to work the bolts down. I probably used upwards of 60 ft-lbs once they were more than halfway home. I even had to switch to the bulky 1/2 inch ratchet that I had used to break the old bolts loose in order to set final torque, which was between 80 and 100 ft-lbs.

Understand, I had no intention of setting such extreme torque, but I was cranking hard only to still see daylight between the bottom bolt's flange and the rear knuckle. It wasn't home yet. (It also wasn't cross-threaded, in case anyone's thinking that.) I'm just glad that I was working with steel and cast iron. If these had been aluminum assemblies, I would have had serious worries about stripping the threads out.

I should also mention that I'm in temperate Seattle and rust wasn't significant. The machined surfaces sealing bracket to knuckle were shiny when separated.

[cleaver]

So I replaced my front and rear rotors and pads about 5000 miles ago, but forgot to torque the additional 90 degrees on the rear caliper bracket bolts. I used the old bolts but I think I did use threadlocker. Should I just torque the additional 90 degrees or remove and re-torque them, or just leave them be?

[FaRKle!]

Originally Posted by cleaver

So I replaced my front and rear rotors and pads about 5000 miles ago, but forgot to torque the additional 90 degrees on the rear caliper bracket bolts. I used the old bolts but I think I did use threadlocker. Should I just torque the additional 90 degrees or remove and re-torque them, or just leave them be?

If you reused your old bolts absolutely don't add an additional 90deg. That 90deg is to stretch the bolt. Once it's been stretched once, stretching it again will cause issues. Just set it to the fastening torque. If you set it to fastening torque and added threadlocker it should be fine.

[cleaver]

Thanks FarKLe!

[Logicoeur]

Originally Posted by FaRKle!

If you reused your old bolts absolutely don't add an additional 90deg. That 90deg is to stretch the bolt. Once it's been stretched once, stretching it again will cause issues. Just set it to the fastening torque. If you set it to fastening torque and added threadlocker it should be fine.

Is this a situation for blue or red?

[FaRKle!]

Originally Posted by Logicoeur

Is this a situation for blue or red?

Blue 242 should be fine.