Progressive rate atv suspension linkage

Abstract

A progressive rear suspension linkage is used in the rear suspension of an ATV to aid in ride quality and safety by changing leverage ratio thru the travel of the rear suspension. The rear shock attaches to it as well as to the frame. The linkage system attaches to the frame at one end and to the rear suspension arm at the other end and changes leverage as the mounting point on the frame and the rear suspension arm come closer together or further apart as the rear suspension arms moves thru its travel. This in turn lets some linkages move in a scissors type movement with the rear shock bolted to it at a given point. This invention provides an improvement to the OEM designs, making for improved handling and safer control of ATVs.

1 . A method of retrofitting a rear suspension of an off-road vehicle having at least three wheels to provide a rear suspension having a progression ratio through the off-road vehicle's rear wheel or wheels' travel range of suspension, the method comprising:
 measuring the progression ratio when a distance between the frame of the off-road vehicle and the ground is between 1.5 inches and 12.0 inches; and   modifying an original equipment manufacturer rear suspension of the off-road vehicle to provide a rear suspension having a progression ratio of between approximately 24% and 69% when the distance between the off-road vehicle frame and the ground is between approximately 1.5 inches and approximately 12.0 inches.   
   
   
       2 . The method of  claim 1 , wherein modifying the rear suspension comprises installing a rear suspension comprising a first link and a second link, the method comprising
 mounting the first opening in the first link to the off-road vehicle's frame and the second opening to the second link,   mounting the first opening in the second link to the off-road vehicle's swing arm, and   mounting the off-road vehicle's rear shock absorber to the shock mount opening in one of the first link and the second link.   
   
   
       3 . The method of  claim 1 , wherein retrofitting comprises mounting a linkage in conjunction with an original equipment manufactured (OEM) linkage. 
   
   
       4 . The method of  claim 1 , wherein retrofitting comprises mounting a linkage in conjunction with an after market linkage. 
   
   
       5 . The method of  claim 1 , wherein the rear suspension linkage progression ratio of 24% to 69% is calculated according to the formula:
   (1.00−((1/B)/(1/A)))×100, wherein   A comprises a leverage ratio at an off-road vehicle frame height of 1.5 inches off the ground, and   B comprises a leverage ratio at an off-road vehicle frame height of 12 inches off the ground.   
   
   
       6 . The method of  claim 2 , wherein the first link comprises the shock mount opening for mounting to the off-road vehicle rear shock absorber. 
   
   
       7 . The method of  claim 2 , wherein the second link comprises the shock mount opening for mounting to the off-road vehicle rear shock absorber. 
   
   
       8 . The method of  claim 1 , wherein an up travel of the off-road vehicle rear suspension is equal to the distance between the rear shock mounts as measured at the center point of a shock mount on the off-road vehicle and the shock mount opening on the rear suspension linkage when the distance between the ground and the off-road vehicle frame is 1.5 inches and the rear shock absorber is compressed. 
   
   
       9 . The method of  claim 1 , wherein a down travel of the off-road vehicle rear suspension is equal to the distance between the rear shock mounts as measured at the center point of a shock mount on the off-road vehicle and the shock mount opening on the rear suspension linkage when the distance between the ground and the off-road vehicle frame is 12 inches and the rear shock absorber is extended. 
   
   
       10 . The method of  claim 1 , wherein the rear suspension linkage consists of the first link and the second link. 
   
   
       11 . The method of  claim 1 , wherein installing the rear suspension linkage comprising installing the rear suspension linkage in a four-wheeled off-road vehicle. 
   
   
       12 . The method of  claim 1 , wherein installing the rear suspension linkage comprising installing the rear suspension linkage in a three-wheeled off-road vehicle. 
   
   
       13 . The method of  claim 1 , wherein for purposes of measuring the distance between the off-road vehicle frame and the ground, the measurement on the off-road vehicle frame is measured at one of the off-road vehicle foot peg area and the rear of the off-road vehicle frame. 
   
   
       14 . The method of  claim 1 , wherein for purposes of measuring the distance between the off-road vehicle frame and the ground, an off-road vehicle frame lower flat area is level with the ground on off-road vehicle frames having a rake similar to a front end of a 2004 Honda YFZ450 and the off-road vehicle frame is raised 0.5 inches in the front at a point approximately 22 inches forward of the foot pegs for an off-road vehicle frame with less rake than the 2004 Honda YFZ450. 
   
   
       15 . The method of  claim 1 , wherein the progression ratio of the rear linkage increases a shock shaft speed through the up travel. 
   
   
       16 . An off-road vehicle having at least three wheels, wherein the off-road vehicle has been retrofit with a rear suspension according to the method of claim  21 . 
   
   
       17 . The off-road vehicle of  claim 16 , wherein the rear suspension has a progression ratio through the off-road vehicle's rear wheel or wheels' travel range of suspension of between approximately 24% and 69% when the distance between the off-road vehicle frame and the ground is between approximately 1.5 inches and approximately 12.0 inches. 
   
   
       18 . The off-road vehicle of  claim 16 , wherein the progression ratio of the rear linkage increases a shock shaft speed through the up travel. 
   
   
       19 . The off-road vehicle of  claim 16 , wherein the off-road vehicle comprises a four-wheeled off-road vehicle. 
   
   
       20 . The off-road vehicle of  claim 16 , wherein the off-road vehicle comprises a three-wheeled off-road vehicle.