Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/125736
DiffBrake stops quicker than experts .... N > :; ..., ~ w Z W ...J U >- U By Cycle News East Staff For the past week we've been trying out a new device called DiffBrake which, in effect, makes its user into an expert rider as far as stopping is concerned. The DiffBrake is the brainchild of aerospace engineer Russ Shreve of Michigan and, as its name implies, it is a differential connection activated by the rear brake pedal that applies the front brake at just the right pressure to slow or stop a speeding motorcycle quicker than all but a few experts can achieve with conventional controls. What is more, the DiffBrake is operated by the foot brake pedal alone, leaving the rider's right hand firmly clutching the throttle-grip for better control over bumpy terrain. Inventor Shreve brought us a Yamaha 125, kindly loaned for our test by Bloomfield Sport Cycle in Pontiac, Michigan. He explained that the DiffBrake has been tested and developed for eigh t months on ice. I snow, mud and pavement (wet and dry) in both competition and everyday use. Thirty-seven test units are now in use by such racing stars as Dick Robbins who nms it on his motocross-winning Ossa, and brother Jim Robbins has a unit fitted to his Husqvarna. Both men swear by the device, claiming it stops them in about half the distance of the conventional hand-and-toe metnod. Barry Mayo, famed Michigan dirt racer, claims he ""ins about two seconds in II!: .' DiffBrak.e installation is easy. It compensates automatically for wear. We taught a beginner to ride on this installation. Kit comes with special striated cable and complete instructions. 51.1 Yall., M.C. & OIlarli Sports festival PRESENTS SUNDAY, ..·--SI 8, 1971 each tum over the cOmpetitIOn, just because he runs a DiffBrake. Two seconds per turn, multiplied by, say, ten turns per lap, equals a 20~econd gain over the opposition each lap. That may help explain why DiffBrakes are selling so rapidly in Michigan, where Mayo and the Robbines run. Another factor that will help make them popular is the price. You can buy a DiffBrake kit and install it in 15 to 20 minutes for $21.95. The principle that DiffBrake uses to give its advantage is that the front brake provides 70% of the stopping power on a motorcycle. By linking the rear and front binders in series, Shreve's invention applies first the rear brake, as pressure is increased, then the front brake is applied by the same pedal, at a differential pressure compared to the rear, determined by an adjustment preloaded on the DiffBrake's spring, which interrupts the rear braking operation rod. (Cable-operated rear brakes have to be modified to rod-operated when the unit is installed.) As proof of the pudding, we flung Bloomfield's cycle around our test track, diving into the turns 30 feet deeper than usual and hitting the brake pedal hard. The machine squatted on its suspension and tracked around the tum with amazing control. We aimed for the only mud-puddle on the course, trying to lock the front brake independently of the rear, but it just didn't happen. All the time the right hand was tightly wrapped around the throttle grip and we've never felt in better control. It was possible, by toeing the brake lightly, to lock the rear wheel to set up a slide, while allowing the front one to free·wheel, maintaining control. I t seemed to work too good to be true. We 'offered the Yamaha to Bob Grodzinski, local motocross expert and factory tester for John Penton, and Bob com£irmed our findings. "It's real nice," he admitted. But he'd like to have tried it on a bigger motor, like his 360 Husky, on a wetter course. The staff and several guest testers agreed that the DiffBrake works "like power brakes." It sh ould be a terrific safety advantage for road riders as well as that universally desired "unfair advantage" for racers. The only drawback we could find is one that Russ Snreve pointed out often happens to enduro riders using the DiffBrake: "other bikes keep running into you from the rear." Kits are available to fit most any machine (specify make, model and year) from DiffBrake, Inc., Box 94, Troy, Michigan 48084. Price is $21.95. The number there is (313) 689-3230 and dealer inquiries are invited. MX SCHOOL CONTINUES With a good turnout of riders having attended the first John Rice Motocross school at Indian Dunes Park in Valencia, Ca., Walt James, who is the general manager at the "Old Reservation," announced today that the school program will continue "every Monday from 9:00 a.m. - noon until further notice.'" The school is free except for the usual weekday Dunes admission price. And after the riders have received their instructions, they are welcome to remain for the balance of the day practicing what they've learned. AMA WELSH JOINS OF COORDINATOR PROFESSIONAL RACING Dave Welsh, 33, of Tacoma, Wash., has accepted the position of Coordinator of Professional Racing for the AMA, a position which, with Director of Professional Racing Bill Boyce, manages all professional motorcycle competition sanctioned by theAMA. Welsh was chosen for his new position based on his extensive background in motorcycle race managemen t and his experience in working with the AMA. He has served in the field as AMA Western Regional Referee for three yean, and prior to that he was referee for the district including Washington and Oregon. DIRT BIKE magazine the first and only of its kind• Actual dyno readings on test bikes! 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