Jack the vehicle and CHOCK safely to avoid any possible chance of vehicle falling on the mechanic, do NOT attempt this procedure unless you are a qualified technician.

Remove one wheel and the old brake rotor which sometimes needs to be hammered off from behind quite aggressively and may even crack or fracture at this point,take care not to damage surrounding parts especially hydraulic lines. The harder it is to remove the rotor the more work you are going to need to do to clean up the vehicle hub which will be covered with rust and scale if the rotor was seized upon it.


1) Clean the hub by scraping off all scale until you see clear grey cast iron, sand gently around the studs or holes and wipe clean or airline clean (normal procedures to be used, mask and goggles of course for your safety) , do NOT apply any lubricant.Hand fit one rotor taking care not to get any dirt dust or grit behind the mount up face

2) Check runout as follows. The fact that our rotor has three slots makes no difference, you apply the magnetic dial gauge base to a heavy suspension part or metallic work item that will not move nearby and after fitting the rotor to a rust and dirt free hub you FIT THREE OF THE LUG NUTS and tighten them to 50 Ft lbs just to nip the rotor up firm (without of course the wheel being re-fitted at this stage) . Reverse the lug nuts if of a tapered front type as the rotor does not have the corresponding tapers in its front face ( so as not to damage the new rotor) and if need be use a spacer to allow the nuts to clamp the rotor up firmly to the hub.

3) Set the dial gauge to zero and mark on the rotor itself.....the number "0" where the pointer first contacts, rotate the rotor carefully and each time the gauge pointer comes to a slot retract the pointer just enough to allow it to pass over the slot without the pointer dropping into the slot and release gently once it has passed the slot. At the mid point between each slot (see diagram below) mark the dial gauge readings (with a felt pen or sharpie) in thousandths and inch or tenths of a mm depending on whether you work in inches or the metric system ON THE ROTOR

4) If total reading is more than 0.004 inches or 0.1mm MARK A LINE on any stud and the rotor at that same point, remove the rotor and rotate one quarter of a turn (that will be one stud for a four bolt set up, two studs on a 6/7/8 lug set up very roughly) and perform the measuring process again.

If you cannot get the dial gauge to read below 0.004 inches or 0.1mm you have a problem on the vehicle that needs to be solved before you drive the vehicle. Failure to do this will result in vibration setting in the first 3000 miles of driving as the pads contact the high spot on the rotor and wear a thin spot (this is called disc thickness variation) and that is not a warranty item.

Get me your address KC and the rotor numbers again and I will replace them by UPS.

You CAN by the way turn slotted rotors, I have done it many times on a Pro Cut lathe and almost all workshops have these.

If they tell you they cant they are simply trying to sell you new rotors and rip you off.