On-Car Computerized Brake Lathes

Advantages of Hub-Mounted On-the-Car Brake Lathes Compared to Caliper-Mounted Designs

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Today’s sensitive vehicles, evolving brake components and the increase of hubbed rotors on Sport Utility Vehicles demand different service procedures and equipment. Although bench lathes will continue to serve a primary role, they are no longer the only lathe needed in today’s professional brake shop.

Why is the OCL the Perfect Addition to the Brake Shop?

• Some vehicles are very “sensitive” to rotor runout. If most of the runout is not in the rotor…but, is caused by mounting surfaces at the vehicle, abnormal noise/vibration and pedal pulsation may be the result. A bench lathe can not address mounting induced runout.
• The OCL machines the rotor in its “native environment”. Since the mating surface between the rotor and hub is not disturbed…this helps to ensure the friction surfaces are machined truly perpendicular to the wheel’s axis of rotation.
• Additional tear down time for sport utility vehicles, light trucks…and some passenger cars with “captured rotors…” are virtually eliminated!
• Rotor conditions will not improve over time. In fact, runout promotes thickness variations. On some vehicles, as little as .0005” thickness variation can lead to vibration and pedal pulsation complaints!
• Because of its intermittent tool feed design, a non-directional pattern of interrupted arcs is produced during resurfacing with the OCL. Many manufacturers prefer a non–directional finish.

To prevent customer complaints and comebacks due to pedal pulsation, brake shudder and noise/vibration…. Rotor machining must eliminate runout, thickness variation and friction surfaces that are not perpendicular to the wheels’ axis of rotation The addition of the OCL Hub mounted Rotor Lathe to your brake shop, is the best way to help guarantee the most complete coverage.

RUNOUT and THICKNESS VARIATION

Most rotors exhibit some amount of lateral runout. In some cases, the runout may exceed “normal” limitations and cause no problem…at least initially.

Combine rotor runout with mounting induced run out and the total runout when the rotor is combined with it’s hub may well exceed factory limitations. This “stacked” runout may lead to customer complaints, even if it is as little as 0.002” – 0.005”.

Stacked run out beyond factory limits induces thickness variation of the rotor of just .0002” – .0005”. This measurement specification is the limit allowed by most manufacturers and is not able to be measured by most shops. A rotor is service beyond this limit is risking the potential for brake system related vibration complaints.

Given the compounding effects of run-out of the rotor face, mounting induced runout, and thickness variation, some vehicles may exhibit noise/vibration and pedal pulsation immediately…or, just a few thousand miles later. Research indicates that a vehicle, which initially developed pulsation at 8,000 miles, will re-develop the same pulsating condition over the same miles if the rotor is replaced without matching it to the vehicle.

Matching the rotor to the vehicle hub is made possible by resurfacing it on the car.

Why Buy A Hub Mount Lathe Rather Than A Lesser Expensive Caliper Mounted Lathe?

As with all quality lathes, the Hunter OCL uses a “closed loop” self-contained arrangement with the hub of the vehicle. This integration supplies an extremely rigid set up between the work piece and the cutting tools. The “closed loop” helps insure the rotor is held in place securely, the cutting tools maintain a position perpendicular to the axis of the rotor rotation, and that the noise during the resurfacing process is greatly reduced resulting in a superior surface finish.

By attaching directly to the hub of the vehicle, then compensating for stacked tolerances of the vehicle hub and rotor, the Hunter OCL consistently eliminates run-out and leaves no taper. The result is a “matched” rotor that will allow the brake system to perform as designed.

Conceptual Flaws of the Caliper Mount Lathe

The caliper mount lathe is a two piece unit. One part is the cutting mechanism and the other rotates the rotor. A rigid loop design does not exist. This violates a fundamental principle for an automotive lathe. Have you ever seen a two piece bench lathe?

Since the rotor is typically linked to the drive mechanism through a flexible coupling, a rigid attachment to the work piece is not maintained. This permits the hub bearings, steering knuckle and “end-play” to influence the noise and chatter during the resurfacing.

Caliper mounts attach the cutting mechanism to the steering knuckle. This falsely assumes that these mounting points are exactly perpendicular to the rotor’s axis of rotation. In some cases, compensating for these mounting errors is offered, however the procedure may be difficult, time consuming and with less than desirable results.

Because of the numerous steering knuckle configurations, various attachment procedures are required. The technician may have difficulty determining the best possible setup.

Avoid all of these problems by using Hunter’s OCL “closed loop” self-contained hub mounted design. This helps ensure the rotor is held in place securely, the cutting tools maintain a position perpendicular to the axis of the rotor rotation and a reduction in noise during the re-surfacing process resulting in a superior surface finish.

If you want a COMPLETE brake shop equipped to handle today’s problems…ask for a demonstration of Hunter’s OCL today.

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Purchased On-Car Brake Technology?