If you own a 2010-2014 Ford Raptor, there are some things that are a given…
Rear wheel hop on hard acceleration is one of the horrible design flaws that can be easily solved with a flutter stack!
What is a flutter stack?
Let’s start with the shim stack. As you can see in this pic, the shock oil is forced by the shim stack (rebound shims in this illustration). So, as you might imagine, the size and thickness of these shims can radically effect the way your shock performs.
By replacing several of the large shims with a more flexible large shim or shims (depending on the stack) and adding in a smaller shim between the largest and next smallest shim, you create a “flutter stack”.
This more flexible large shim and much smaller second shim allows the large shim to open quicker, thus making the first 1″ or so of the shock softer and more able to absorb the small fast bumps. Originally designed to handle washboard roads better (and it works really well), we have also noticed that on the road (especially with the Raptors) it almost eliminates rear wheel hop and makes the front shocks much better at absorbing the small bumps on our rough roads.
Depending on the vehicle and the performance desired, we have several versions of the flutter stack that we use. Every set of shocks we have installed flutter stacks in have improved performance on and off road!
Raptors are not the only vehicles that benefit from flutter stacks, however, the flutter stack is the least expensive upgrade you can do for your Raptor!