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PFM Tests Raybestos Police Rotors
In the past, Raybestos “Advance Technology” drilled and slotted rotors have solved wear problems for law enforcement. This is an “Ultra Premium” rotor, machined to extremely tight limits of lateral runout, parallelism and thickness variation. However, the Raybestos “Performance Drilled & Slotted” rotor was not specifically developed for police. Instead, it was the company’s top of the line rotor for all severe use applications from tow vehicles to racing, including police.
The slots in the friction swept the area of the rotor and the holes drilled through the rotor were designed to give maximum cooling. These holes and slots kept the temperatures of the rotor, and the other parts of the brake system, lower under extreme use. Lower temps reduce brake fade from overheated friction materials or boiled brake fluid. These drilled and slotted rotors have definitely been performance solutions.
However, many police departments used the drilled and slotted rotors as a maintenance solution, specifically to prevent warped rotors. These rotors solved that problem, too, but not because the rotors ran cooler!
It is hard to convince fleet managers and shop superintendents of this, but police rotors do not warp from heat. Instead, they wear unevenly due to excessive lateral runout. Wide tolerances in rotor machining end up causing the brake pedal and steering wheel pulsations associated with “warped” rotors in as few as 3,000 miles.
Raybestos “Performance Drilled & Slotted” rotors solved police wear problems not because they dissipated heat better but because they were machined to closer tolerances in the beginning. Heat is not the problem for police use. The problem is cheaply made rotors. A high quality rotor solves the pedal pulsation problem.
Police Patrol/ Pursuit Rotors
Raybestos has now developed a brake rotor specifically for police use. To read more see the Jan-Feb 2010 issue of Police Fleet Manager or go to the Article Archives at www.hendonpub.com. They started with the same close tolerance Advanced Technology rotor. Instead of adding holes and slots, they developed a unique pattern of internal vanes. These vanes pull air through the rotor regardless of which way the rotor is spinning. This dissipates heat better than its ultra premium rotor but more importantly for police use, it is machined to the tightest tolerances in the industry.
As a sidebar to the 2010 police brake pad tests conducted by Police Fleet Manager magazine, one police package Charger was fitted with Raybestos police rotors, front and rear, in addition to Raybestos police pads, front and rear. This car was run with a group of other Dodge Chargers for a series of brake pad tests. This blind testing allowed a direct comparison between Raybestos Police Patrol/Pursuit pads over OE rotors versus Raybestos Police Patrol/Pursuit pads over Raybestos Police Patrol/Pursuit rotors. In other words, it was an objective and controlled test of the Raybestos police rotors.
Of course, these brakes tests were only a performance comparison and not a wear or “warp” avoidance comparison. However, it could prove one point Raybestos is trying to make. Raybestos is moving away from drilled rotors for a couple of reasons. First, under the most severe use cracks can propagate from the drilled hole. Second, with the complex internal vane designs, it is hard to drill a hole and not interfere in some way with a vane. The company’s point is that a rotor can be made to run cooler without resorting to expensive slotting and problematic drilling.
Brake Test Results
We would not expect to see any performance difference at all between the OE rotors and the Raybestos rotors in the “cold 60-mph stop,” or in any of the other suburban-speed or urban-speed testing. During these other tests, the temperature of the brakes were either specifically controlled, or not a part of, the tests. In the “cold 60-mph stop,” the Raybestos/Raybestos car stopped, to the inch, the same as the Raybestos pad/OE rotor car.
However, we would expect to see a difference between the OE rotors and the Raybestos rotors in the high-speed, 60 mph ABS stops. Specifically, we would expect to see the Raybestos rotor heat up at a slower rate and heat up to a lesser maximum level. As a result, we would expect that the stopping distances under harsh conditions were shorter. And that is exactly what happened.
When things got really hot during the high-speed, continuous series of twelve stops from 60 mph, the car with Raybestos rotors stopped an average of 1.3 feet shorter than the car with the OE rotors. And what about that brutal 12th stop in this long series? The Charger with the Raybestos rotors stopped 2 feet shorter than the Charger with the OE rotors.
Better Machined Equals Longer Life
Frankly, for most police departments, the biggest advantage of the Raybestos Police Patrol/Pursuit rotor is not high-speed heat dissipation. Instead, it is better long-term rotor life. Not because it runs cooler and is less likely to warp. Rotors do NOT warp from heat. Instead, the pedal pulsation attributed to warp is actually uneven rotor wear. Pedal pulsation comes from thickness variation, which in turn is caused by excessive lateral runout. The Raybestos Police Patrol/Pursuit rotors have virtually zero lateral runout and virtually perfect parallelism.
Cheaper rotors develop thickness variation sooner. Better machined rotors develop thickness variations later. If you change rotors or turn rotors, every brake pad change, or even every second brake pad change, you need to start off with better rotors. We recommend you test a complete set of Raybestos Police Patrol/ Pursuit rotors.
Published in Police Fleet Manager, Sep/Oct 2010
Rating : 8.0
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