I'm getting some pulsating coming from my rear vented rotors, and the thickness is right at 19mm, so I might as well replace them. I measured the runout this weekend, and it is coming in at .015" - that's a small number but it's still causing pulsating under braking once the brakes get heated up. Plus, I can hear the occassional squeek coming from the rears under braking in a pulsating sound. So again, I'm replacing the rotors.

My struggle comes with identifying what kind of rotors these are off of. I removed one of them this weekend and could not find a part number anywhere. The measure in at 285mm diameter (11.25 inches) with a current thickness of 19mm. That tells me they probably started life as 20mm. I also believe my rear calipers are M's.

So, I either have 69-73 vented rears or 74-77 / 78-83 vented rears, but I don't know if there are diameter differences between these options. Can someone help me figure out what I have so I can order new ones?

Thanks,

Dion

I'm not positive, but I'd guess that the rotor is the 69 to 83 variety that was cut down to the 285mm dia. The 911 uses a 290mm, and the 914/6 uses a 286mm. The 911 needs to be reduced to fit properly.

Thanks, unfortunately, that makes sense. Any idea if I can buy them modified like this, or do I need to take them somewhere to get turned down?

Dion

what calipers are you running over them?

I believe they are front M calipers.

Dion

Eric Shea offers them as an option. I do them also, but stick to selling in Canada.
Could have had a set delivered on Sunday. A friend from Medina met me in Erie so I could return a dog to them.
I do that run often enough the car knows its own way now. Anyone from Erie PA?

Thanks. No need to go out of your way as the car isn't going to get on the road much any longer this season. I can probably get up to Erie, PA durin the offseason sometime as well.

Send me a PM with the details, cost etc. and we can make arrangements.

Thanks,

Dion