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Discussion Starter · #1 · (Edited)
This brake issue doesn't only happen on ED's - it is the bane of all lightly-used cars with aluminum wheels in winter-salt areas, but it is probably worse in the ED's because if driven for economy, 80 percent of the braking is regen.

The picture below (right) shows the rather deteriorated brake rotor condition on my 2015 451ED after 41K miles. An annoying scraping sound had developed on the left front wheel. I replaced the pads once maybe 10K miles ago - not because the old ones wore out but because I changed to ceramic pads to stop that annoying black dust problem.

The pads were still like new, but of course needed replacement anyway with the installation of new rotors.

This is a problem with my other car too because I only put 4-5K miles in a year on it - mostly in winter.

My attempted solution to the problem is on the left - paint all parts of the rotor with high temperature paint except the friction surfaces. "Coated" rotors may also be available.

The job went easily without problems - penetrating oil and hammer whacks got the old discs off and the hub flanges needed some sanding to remove rust blisters.

But upon installation I think I stripped the threads on one of the wheel bolt holes. Without thinking, I set the torque wrench to 85 ft-lbs - the same as used on my Subaru Outback. (just checked - that is close to the specs for a 451 - 110 N-m or 81 ft-lb). Two bolts tightened, one didn't. After a third-to half-turn of no torque increase, I stopped before things got worse at about 75-80 ft-lbs. It's fine for now, while I shop for a heli-coil kit and new bolt before the wheel needs to be removed again for the state inspection in September.

66812
 

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Discussion Starter · #3 · (Edited)
I don't see how 85 rather than 81 ft.lbs. could strip a bolt. Maybe you cross-threaded?
I don't see either - I finger-turned the bolts most of the way in - they were not cross threaded. There is a chance that I was just experiencing the compression of a thicker than expected layer of paint on the rotor plus a thin coating of grease on the hub flange and the bolt/hole is not stripped at all. But it sure felt like that sinking feeling you get when a bolt does not snug up.

I'll try loosening/re-tightening the bolts in a few days.
 

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Check the threads in the wheel hubs. I’ve seen damaged female threads make a mess of bolts. Run a tap trough them if in doubt.
 
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