Date: Mon, 01 Mar 1999 07:55:56 -0500
From: "Steve D'Gerolamo" <steved3_at_idt.net>
Subject: [E36M3] Warped Rotors
From: "htown8"<HTOWN8_at_EARTHLINK.NET Subject: [E36M3] Warped Roters My car
started to experience bad vibration while breaking from above 80mph when brakes are hot. I have european M3's lightweight rotors with PF Z-Rated pads. I checked both front rotors, and my right one seems slightly warped. It can be turned by hand, but there is a resistance at one point then turn freely again. Since I don't get any vibration when not breaking, it cannot be off-balanced wheels. I was thinking to take them to Pepboys to be turned. But I want to make sure one thing before doing that. Can rotors be warped slightly? or do they have to be perfectly true? Thanks in advance. TOSHI p.s. Pepboys are OK for turning rotors, aren't they?

The best way to determine if you've got excessive runout is with a dial indicator attached to a magnetic base which can be affixed to the strut. Remove the wheels and run 5 DIN 961 M12x1.5x30 bolts with 12mm washers (you can probably use the lug nuts with stacks of 12mm washers) through the rotors into the hubs to secure them properly. Position the dial indicator against the rotor and zero out the scale. Rotate the rotor one full turn and note the variation in runout. Anything greater than .008" or .03mm is out of spec and needs to be replaced. I would not cut the rotors if they are warped, despite what the experts at Pep Boys say. SD

Date: Mon, 01 Mar 1999 07:55:56 -0500
From: "Steve D'Gerolamo" <steved3_at_idt.net>
Subject: [E36M3] Warped Rotors
From: "htown8"<HTOWN8_at_EARTHLINK.NET Subject: [E36M3] Warped Roters My car
started to experience bad vibration while breaking from above 80mph when brakes are hot. I have european M3's lightweight rotors with PF Z-Rated pads. I checked both front rotors, and my right one seems slightly warped. It can be turned by hand, but there is a resistance at one point then turn freely again. Since I don't get any vibration when not breaking, it cannot be off-balanced wheels. I was thinking to take them to Pepboys to be turned. But I want to make sure one thing before doing that. Can rotors be warped slightly? or do they have to be perfectly true? Thanks in advance. TOSHI p.s. Pepboys are OK for turning rotors, aren't they?

The best way to determine if you've got excessive runout is with a dial indicator attached to a magnetic base which can be affixed to the strut. Remove the wheels and run 5 DIN 961 M12x1.5x30 bolts with 12mm washers (you can probably use the lug nuts with stacks of 12mm washers) through the rotors into the hubs to secure them properly. Position the dial indicator against the rotor and zero out the scale. Rotate the rotor one full turn and note the variation in runout. Anything greater than .008" or .03mm is out of spec and needs to be replaced. I would not cut the rotors if they are warped, despite what the experts at Pep Boys say. SD