Enlarged Bolt Holes in Rear Brake Rotors

[BarryD]

I just bought a Rear Brake Restoration Kit from Classic Garage. After I installed the new rotors I noticed that the holes in the rotor are significantly larger than the lug bolts (the holes are 15.2 mm; the bolts are 11.4 mm). I then measured the holes in the old rotors and they were just large enough for the lug bolt to pass through them. I'm guessing that the enlarged holes would cause the rotors to erode the lug bolts thereby making them unusable. The markings on the box showed the correct (I checked EPC) part number: 126 423 00 12.

Check out the photo. Am I missing something or should I tell the vendor that these rotors are unacceptable?

A quick update on the car: My mother gave it to me last October after it had sat for over ten years. I went through the "it sat for ten years " procedures and was able to take her for a ride at Christmas (though a caliper stuck and the brakes overheated!). In the process I've hooked up with Jon B, Alfred, Franz, and the other owners in Northern San Diego County. It's been a great experience so far - everything I fix makes it a bit more enjoyable to own. It's a beautiful original car, and I'm doing what's needed to make it safe and driveable. If you need pictures of "what's original" just ask.  We lost my mother last month; at least she knew her car is being cared for.

[twistedtree]

It will need to be resolved and shouldn't be driven like that.  If the box and EPC agree on the part number, then is seems that either the rotors and the box don't go together, or perhaps you have a different rear end in your car.  Have you checked the rear end serial number to see if it matches the data card?  That would tell you if it's original to the car or not.

Hopefully one of the more experience guys here will recognized big holes versus little holes and know what each goes with.

[Jonny B]

I am also in the process of getting new rear rotors on my 280 SL. I have the rotors (from MB, Dave Gallon) and they are the same part number as Barry indicates. The bolt holes (just checked are just at or slightly under 15mm. Not able to check versus the rotors on the car now, but should be able to tomorrow.

[BarryD]

When you check your old rotors could you please measure your lug bolts also?

[BarryD]

I ordered a set of rotors from MBZ and they also have the enlarged holes. I guess the pressure from the lug bolts and surface friction keeps the rotor from rotating with respect to the axle. Though it still bothers me that the old rotors seemed to have the correct hole diameter (barely larger than the lug bolts), I'll put the car together, torque the lug bolts, and check things in a few thousand miles.

[Benz Dr.]

These rotors fit many different cars from about 1967 to about 1989 and may have been modified to help fit the later cars better.  The larger holes won't cause any problems.

 I think the disc is hub centered as are the rims so the holes are only a place for the screws to go through. The typered seat on the screws pulls them into position anyway so you have nothing to worry about.