I ordered and received from Fastlane a pair of front rotors for my car. I ordered the ATE rotors. When I pulled them out of the box, first I noticed these things are very heavy, then I noticed they both had notches/grooves, if you will, cut into the outer edge. One rotor has a larger "notch" than the other. It looks like they remove some material. I am making a guess that this was done for balancing purposes. If so, then WOW!!. I have never heard of balancing brake rotors. German engineering strikes again. Anyone heard of or seen this before?

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

Since most shops balance the wheels and tires off of the cars, all of the rotating components have to be balanced before installation and all do come that way.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

So, even a set of "Motorcraft" rotors for a Ford for example, would be balanced in the same manner?

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1999 MB SL500 (110,000 mi)
2004 Volvo V70 2.5T (220,000 mi)
2014 Tesla Model S 85 (136,000 mi)
MBCA member

In my father's auto repair garage years ago, My father used to balance a lot of wheels with his weaver spin balancer. he sold the customer on his wheel balance job because he balanced the wheel, hub, and drum all togather as one unit. It did make a diffrence. I still have his old weaver balancer. I recently had to balance the drums on my 98 Izuzu SUV. They had not balanced them at the factory, and it did make a driffrence. everything that turns at a high rpm, should be balanced. Boyd