Brock's Performance president, Brock Davidson, an avid performance enthusiast and past national championship winning rider as well as tuner, explains how to adjust the rear suspension on his BMW S1000RR 'Christine' for drag race use. Follow along as he explains how the rebound dampening functions as it relates to the launch and down track acceleration between himself and his lighter 'jockeys'.
Note: At 9/16th sag using a 95 Newton (542 lb.) spring with a 150 lb. rider in the saddle, a rear tire pressure of 12 psi is used. Brock's weight of around 210 lbs. suited brings the sag to 1" and a tire pressure of 18 psi is used. The bike squats a bit more than optimum, which means the spring preload should be increased a bit, or the spring rate might need to be increased -- BUT, the object is for this bike to be as fast as possible with the smaller riders--not tuned for him--so only tire pressure adjustments are made.
How to adjust rider sag: • Brock's Performance Dr...
Slick track = more rebound dampening added, more squat for more traction. Less tire pressure, if possible.
Sticky Track = more spring preload, less squat, more tire pressure... although light riders tend to spin, so lower pressure is generally used. (see Jeremy's run at beginning of video, it is very close to perfect.)
Bumpy Track = If the racing surface is exceptionally bumpy, the rebound dampening must be reduced (example adjust from -15 clicks to -20 clicks) to prevent high speed 'oscillation'.
Stock or Short Wheelbase Applications = Stock/Short wheelbase bikes do not require as much 'squat', because they are not as prone to spinning. Since more squat leads to additional traction, this can also cause stock wheelbase bikes to wheelie. As a result, we would have a bit more static spring pressure dialed in, with more compression dampening and less rebound dampening (to force the front end back down as the rear rises).
Special thanks to www.dragbikelive.com for the video coverage.
Also note: This advice applies to all makes and models. The BMW S1000RR shown was simply used as a handy example for this particular video. Spring rates will differ between makes/models.
Visit www.BrocksPerformance.com for additional information, installation instructions, information forums, and FAQ sections.
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Please watch: "2017 GSX-R1K S2B: Episode 4 - Exhaust Installation and Theory (Part 3): Full Exhaust Systems"
• 2017 GSX-R1000 S2B: Ep...
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