lateral run-out can be caused by uneven torque, damaged studs, or a burr or rust between the hub and rotor. This variation can be tested with a dial indicator, and most times the variation can be more or less cancelled by reinstalling the disc in other position, so that the tolerances of both the hub and the disc tend to cancel each other. To reduce the run-out, the disc is mounted and torqued to half the specified torque (as there is no wheel to distribute stresses) then a dial Indicator is placed against the braking surface and the face of the dial is centered, the disc is slowly rotated by hand and the maximum deviation is noted. If the maximum run-out is within the maximum allowed run-out specified in the manual, the disc can be installed at that position, but if the technician wants to minimize the total lateral run-out, other around the clock positions can be tried. Excessive run-out can rapidly ruin the disc if it exceeds the specified tolerance (typically up to but most discs can attain less than or less if installed at the optimum position). Probe indicator Probe indicators typically consist of a graduated dial and needle driven by a clockwork (thus the clock terminology) to record the minor increments, with a smaller embedded clock face and needle to record the number of needle rotations on the main dial. The dial has fine gradations for precise measurement. The spring-loaded probe (or plunger) moves perpendicularly to the object being tested by either retracting or extending from the indicator's body. The dial face can be rotated to any position, this is used to orient the face towards the user as well as set the zero point, there will also be some means of incorporating limit indicators (the two metallic tabs visible in the right image, at 90 and 10 respectively), these limit tabs may be rotated around the dial face to any required position. There may also be a lever arm available that will allow the indicator's probe to be retracted easily. Mounting the indicator may be done several ways. Many indicators have a mounting lug with a hole for a bolt as part of the back plate. Alternately, the device can be held by the cylindrical stem that guides the plunger using a collet or special clamp, which is the method generally used by tools designed to