b'TECH TIP PAGE Tech Tip 21: If you draw a line through your upper & lower ball joints,to the ground, that is your cars steering axis. Your cars scrub radiusis the distance from the steering axis to tread centerline at ground level.If the steering axis intersects the center of your tread, that would be Zero Scrub Radius. The tire would literally PIVOT in the center of the tread as the car is steered, providing more grip when turning.Most production cars have 3-6 scrub radius & this causes the tirecontact patch to scrub as the car is steered. This is literally rippingthe tread around the steering axis further inboard, versus simplypivoting at the center of the tread. This dramatically reduces the tires grip on tight corners that require significant steering angle of the front tires. Long sweepers are less affected. Static scrub radius is measured with the car sitting still. Dynamic takes into account the tire distortion (sidewall roll under) when cornering, which requires data. We care most about the dynamic scrub radius in the tight corners. If the tires roll under .500 in an 80mph corner, thats our priority, not the .700 in a 140mph corner. Ideally, we want .500 static scrub radius. The scrub going past zero to -.200 doesnt affect us in the sweeping 140mph corner. All RSRT front suspensions are zero, or very low, scrub radius dynamically in tight corners for moreoverall front grip & easier steering!Tech Tip 4. As mentioned in other Tech Tips, the optimum amount of Ackerman is key to achieving additional grip (up to 25%) from the inside tire. All RSRT spindles, front or rear steer, have the desired Ackerman designed into the steering arms. Ron also designed in the desired Ackerman into the Speedtech ExtReme & Speedtech Tall spindles.B. The cool benefit of Slugged Spindles is you can adjust the steering quickness to suit the driver, or the track, in minutes. Loosen the tie rod boltsflip or swap the slugs & retighten the bolts. All RSRT spindles have slugged steering arms that allow up to 1 of steering arm length change in 1/4" increments. A lot of RSRT clients dial in more steering quickness to suit the autocross course and then flip/swap a lug to slow the steering for street or road courses.C. RSRT Front Steer Spindles have a steering arm length range of 4.25 to 5.25. The effective rate of most front steer spindles (OEM & RSRT) gain from 3/4 to 15/16 with the high caster we run. So, youll see the effective ratio higher on our dynamic software graphs.RSRT Rear Steer Spindles also have a steering arm length range of 4.25 to 5.25. BUT, the effective rate of most rear steer spindles (OEM & RSRT) loses about 3/4 to 15/16 with the high caster we run. So, youll see the effective ratio lower on our dynamic software graphs. D. Steering Box Ratios by themselves have clouded the steering rate issue for years. Steering box rate alone, is only helpful when running a known length, fixed steering arm. But doesnt equate from car to car with different OEM steering arm lengths. Your Steering Arm lengthcombined with steering box ratio is the key.887'