As a whole, a suspension system consists of three parts:

  1.   A MASS (the vehicle)
  2.   A SPRING (see Choosing the Right Vanagon Spring)
  3.   A DAMPER (the shock)

The spring suspends the vehicle while the shock controls the oscillation (the motion) of the vehicle.

Depending on your application, shocks serve various purposes.  But a shock’s main purpose is to “dampen” the energy it encounters.  At its core, damper technology is about transferring energy by way of guiding and controlling the flow of fluid.  A shock is a hydraulic pressure relief valve, and it is the internal transferring of fluid within the shock’s piston and the individual valves that gives the damper its resistance force. The fluid transfer is the displacement of energy received from the “inputs,” or variances in terrain.

On the streets, a shocks main purpose is to utilize dampening to keep your tire in as much contact with the street as possible.  You want your tire to “grip” tightly on turns and when traveling along the freeways.  More contact with the road means more control over the vehicle. 

In off-road applications you are still looking for grip, but dissipating the energy from the various off-road impediments is also very important.  Off-road ditches, rocks and hazards create a tremendous amount of energy, and the damper’s job is to absorb and dissipate that energy, creating a smoother overall ride. If you have ever watched a trophy truck run over the desert at 100+ mph, you see that the wheels bounce up and down very rapidly while the body of the vehicle sits pretty flat.  Good shocks make a world of difference. 

As for the shock itself, all dampers have three basic parts:

  1.   A BODY
  2.   A SHAFT
  3.   A PISTON (however, a reservoir can be added to enhance the shock)

The Shock Body and Shaft

The shock body is the housing that keeps everything together and guides the piston and shaft through its travel. The shaft is what connects the actual suspension component (ie; a control arm or trailing arm) to the chassis. Different lengths of shafts provide for more or less suspension travel, and the thickness of the shaft has a great impact on not only the durability of a shock, but the performance as well.

Rear Radflo Piggyback Reservoir




As a gas, nitrogen is compressible whereas fluid is not; therefore, the displaced fluid has to go somewhere when the shock compresses. Some shocks have internal reservoirs that are housed inside the shock body while others have piggyback or completely remote reservoirs. 

We enhanced our rear Radflo 2WD Vanagon shocks with a piggyback reservoir. 

Emulsion vs. Internal Floating Piston (IFP)

Inside the shock body is the reservoir which consists of fluid.  Some shocks combine oil and nitrogen gas into a single mixture, which is not separated by an internal piston; this describes an emulsion shock. Under aggressive use in an emulsion shock, foam is generated and the oil cavitates, thus reducing the shocks dampening ability, resulting in more wear and tear on the vehicle, not to mention a distressing, disagreeable ride if you are off road.  Our competitors sell this emulsion-type shock. 

We designed our front Radflo 2WD Vanagon shock with an IFP.

In Reality, Two Pistons…

 In a shock with an IFP, there are actually two pistons.  One is the IFP that separates the oil from nitrogen; the other is the piston that is part of the valving that is attached to the shock shaft inside the shock body. 

It’s important to remember that fluid is not compressible.  That’s why shocks are charged with nitrogen gas.  Inside the reservoir is a nitrogen chamber. 

Front Radflo Internal Floating Piston

The chamber is separated by a small round disc called a floating piston.  As the shock compresses, the valving piston (attached to the end of the shaft) pushes fluid up and into the reservoir, compressing the nitrogen and slowing the velocity of the shaft as it’s ingested into the body.  It is in the valving piston where the shock actually gets its damping capabilities. This displaced fluid puts pressure on the floating piston, compressing the nitrogen gas behind it and providing an internal spring rate.

shim stack


At each end of each valving piston is a shim stack, kind of like washers layered on top of one another to form a Christmas tree shape. As the shaft is ingested into the body at a given velocity, there is a buildup of pressure due to the compressing of the nitrogen gas. The valving piston acts as a sort of pressure relief valve so that when the pressure builds up from compressing the nitrogen behind the floating piston, it then overcomes the force of the shims, and it opens up the shim stack, allowing the fluid to pass.



The stiffer the shim stack, the more pressure it takes for that fluid to open up the shim stack and allow the fluid to pass. The same thing happens when the shock rebounds. There is a rebound shim stack on the opposite side of the piston and as the spring rebounds, or pushes back against the mass, it forces fluid through the rebound ports in the piston.                               

As a shock moves up and down, fluid flows through the valving piston controlling how fast the shock moves through its travel. Some shocks have external adjustments that can change how fast or slow the fluid flows within the shock, but it is the piston with the shim stack valving that controls how the fluid moves and how well a shock dampens the force it encounters. 

Joining Again with Off-Road Experts Radflo Suspension Technologies for Our 2WD Shock System


Burley Motorsports 2WD Radflo Shocks

Like all Burley Motorsports products, our Radflo shock absorbers are deliberately overbuilt.  They are manufactured using SSID steel tubing to ensure strength, longevity and superior wear resistance.  In addition, the tube is enhanced with a clear cadmium finish to provide the highest level of corrosion resistance.  Engineered to the correct size and length for a 2WD Vanagon, both front and rear shocks are tailor-made in a joint effort between Burley Motorsports and Radflo Suspension Technologies to bring out the very best from your Volkwagen 2WD Vanagon and yet remain within all VW specs to fit properly!  

Designed for the harshest off-road racing conditions with a Nitro Steel® rod and slippery, bronze rod guide, these shocks provide unyielding performance in the roughest terrain and offer the smoothest ride on the streets. A multi-direction, triple lip sealing system prevents oil contamination while ensuring excellent gas and oil retention.  Even the oil itself is an exclusive foam-resistant Radflo product produced to withstand the highest temperatures.

These shocks come with self-adjusting, velocity-sensitive valving, which automatically adjust to terrain for improved control, handling and comfort. Radflo’s exclusive Freeflo™ racing piston utilizes adaptive damping technology to automatically match shock performance to surface conditions with multi-stage compression and rebound damping.

The front shock boasts a nitrogen-charged internal floating piston (IFP).  These shocks use the IFP to separate the nitrogen and oil, allowing the piston to be in pure oil which allows for better performance all around.  The other shocks offered on the market for Vanagon owners are usually emulsion shocks which combine the oil and the nitrogen.  Shocks with an IFP put a preload on the oil to eliminate cavitation and foaming, which completely degrade a shock. 

Even more hardcore, the rear shock adds a nitrogen-charged piggyback reservoir onto the monotube.  This increases heat dissipation which allows for more compression and rebound dampening, which translate to a more controlled ride both on and off the road.  There is a dramatic enhancement in internal operating pressure caused by adding additional reservoir space onto a shock.  Comfort, enhanced control and predictability, and a noticeable upgrade in dampening quality can all be expected when purchasing this shock.

Our proprietary shock absorbers are engineered to outlast and outperform the competition. All components are manufactured from the highest quality materials and machined to exacting tolerances right here in the United States.  Every shock is manufactured entirely in-house at Radflo Suspension Technologies, under strict quality control.

We went with the best.