What is a Clutch Mod?
Brock’s Performance clutch mods are designed to either lock or completely replace the OEM back-torque limiter (also known as a slipper-clutch) in modern sportbike applications to provide a much smoother/quicker dead stop launch.
Example 1: The Brock’s Performance Hayabusa Ultra Clutch Mod (or Ultra Mod for short) #270461 completely replaces the stock two-piece back-torque limiter. While a slipper clutch is a very useful tool when road racing, it creates problems when trying to launch smoothly from a dead stop. The stock back-torque limiter is responsible for jerking and chattering when launching a powerful Suzuki Hayabusa from a dead stop. This buck/jerk not only hampers quick launches at the drag strip, but can eventually damage components: inner clutch basket, outer clutch hub and even lead to premature drive chain failure (even broken cases!). The Ultra Mod is one piece billet aluminum construction that eliminates jerking and chattering for a much smoother launch. The spring spacers included in the kit are designed to increase the OEM spring pressure by a precise amount as determined necessary by our engineering team for use in 90% of applications. The Ultra Mod is also 60% lighter than the steel components it replaces, for quicker engine acceleration and throttle response. Brock’s Performance offers several Ultra Mods, which completely replace the OEM two-piece unit, Primarily in Suzuki applications.
Example 2: A clutch mod designed to lock (disable) the existing back-torque limiter can be found in Brock’s Performance store for many Kawasaki applications as well as Yamaha and BMW’s. In each application, a locking ring (AKA Clutch Mod) is provided to disable the functioning of the OEM slipper clutch. Aftermarket springs and or shims are included in the kit to promote longer clutch life and enhance drag racing performance. If these springs are not used as directed, premature clutch failure can result. In some cases, this failure can occur on the very first drag strip run.
Can I run Brock’s clutch springs, but keep my OEM back-torque limiter?
CAN YOU? Yes….SHOULD YOU? Probably not…. Brock’s Performance clutch mods and springs are matched to the application. If different springs than stock are used, the amount of ‘slip’ when downshifting will be altered. This could lead to a potentially hazardous situation as the rear wheel can slip MORE or LESS than the engineers designed into your bike/application.
In the video below. Notice how the rider tries to ‘lubricate’ the clutch plates by leaning the bike hard right…it’s a fruitless attempt. This bike is in need of a clutch mod (at a minimum) but more likely a clutch mod and cushion would make the largest improvements (assuming any/all worn-out clutch components are replaced). The chatter/grab associated with this bike is also indicative in larger displacement/higher torque applications.
This is an example of a large displacement/ultra-powerful machine using a Brock’s Performance clutch mod and cushion properly (far lane):
This video shows what happens when the stock back-torque limiter is used in stock wheelbase applications. In this example, the entire clutch had to be converted from an assist (or ramp assist) to a unit that uses an ultra-mod: