Disc Conditions:

^ Thickness - Do not replace discs unless they are BELOW the minimum thickness. DO NOT attempt to predict the disc wear rate between services.

^ Scoring - Disc surface scoring is normal and does not affect braking performance.

^ Runout - Maximum run-out is .004" (this must be checked relative to the spindle). Make sure the hub bearing clearances are correct, the hub to disc mating surfaces are completely clean and that the disc is clamped in place using slave wheel nuts with washers (not applicable to Series III and XJ-S rear discs). Torque to 65-75 ft. lbs.

^ Discoloration of Discs - The blue corrosion protective coating will not affect brake performance. This blue coating turns black and eventually will wear off.

^ Heat Spotting/Pad Material Deposits - Vehicles equipped with Ferrodo 3401 pads may show heat spotting or radial black lines of pad material on the front discs, in-line with the ventilation webs of ventilated discs.

Installing Jurid 518 pads will usually resolve this problem. only change the discs if judder still occurs after bedding-in the new pads.

^ Disc Corrosion - After the protective bags are removed from the discs during PDI, disc surface corrosion will occur if the vehicle is allowed to stand for an extended period of time in humid conditions. This surface corrosion will wear off with brake use, although some initial brake noise may occur. If necessary, clean the discs and pads using fine sand paper.