Does anyone know the torque specs for the bolts with a front brake caliper?
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Joined: Sep 2016
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From: NY
2010 C63 2019 GLA45
Originally Posted by BLKROKT
Hey guys, just a reminder. If you’ve ever touched these bolts (I’m talking about the big M12 caliper to caliper bracket bolts), do yourself a favor and look at them every once in a while.
My car is finally going back together after my disaster of a track day in March. I was inspecting my brakes before putting the wheels back on, and found one of these bolts had backed out about 1/8”. Scary! Took the bolt out, cleaned the threads, chased the hole, applied a little antiseize because I noticed some galvanic corrosion, and torqued to 90ft/lbs.
Don’t know if I missed torquing it down or what, but will keep a close watch on it. Gotta keep an eye on absolutely everything you modify because you never know.
My car is finally going back together after my disaster of a track day in March. I was inspecting my brakes before putting the wheels back on, and found one of these bolts had backed out about 1/8”. Scary! Took the bolt out, cleaned the threads, chased the hole, applied a little antiseize because I noticed some galvanic corrosion, and torqued to 90ft/lbs.
Don’t know if I missed torquing it down or what, but will keep a close watch on it. Gotta keep an eye on absolutely everything you modify because you never know.
Lubricant (such as anti seize), modifies the assembly torque.
If say they spec calls out 90 Ft Lb and you did "lubricated" 90 ft Lb, the twist stress that you've put on those bolts, is consistent with a assembly torque well into the 100's.
Chasing the threads on such a safety important bolt, I would only do with another bolt, that has had channels cut across its threads.
Now, vibrations;
You should have inspected the threads when you removed the bolt initially, for leftovers of threadlocker. If it had that, and if the WIS calls for that, then that's what should go there.
The thing even with that, is that if Mercedes specified threadlocker on those, must be one that takes high temperatures.
Now if currently you have antiseize there, even with the assembly torque in place, vibrations may loosen it.
I recommend going back, degreasing that antiseize out of there and maybe applying a threadlocker instead. Like a Loctite Blue, for now. Also your use of the car is different than what these people designed for the car and temperatures higher.
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I also made the same mistake while replacing the rotors and pads on my car. Instead of removing the knuckles, I took out the hex caliper bolts. I didn't over-torque them, keeping them at 120NM/88ft-lbs. However, after the replacement, I noticed that the wheel is now pointing slightly to the right (about 2-3 degrees). There are no vibrations or judders while braking. This misalignment issue only surfaced after the rotor and pad change, whereas I had an alignment done just 4 months ago. Could these two events be related?
Last edited by vinnan; Jul 29, 2023 at 05:42 PM.
