Sprinter Van and RV Suspension 101

We get many calls and questions about the Sprinter's suspension. The Sprinter van is used in many different applications and often in heavy duty work conditions. It is a versatile vehicle. They can be outfitted as fully loaded RV's, work vans, mobile offices, limousines, passenger vans, and many other uses. Because the Sprinter chassis is used for so many different applications, people will call to ask about suspension upgrades and ways to fine tune their suspension, to reduce bounce, sway, sag, or side to side wobble when navigating driveways. While this article won’t cover the many aftermarket products that can help improve the ride of your Sprinter, it will hopefully clear up some basic facts on the Sprinter van and Sprinter cab chassis suspension components and what they actually do.

The three major components of the Sprinter suspension system are springs, shocks and struts, and anti-sway bars. The springs hold the vehicle’s weight and allow for “travel,” which is the up and down movement of the spring. Shocks and struts dampen spring movement and oscillation. Anti-sway bars control body roll which is when the vehicle wants to lean while cornering, and when entering or exiting uneven surfaces. Let’s take a closer look at each of these three.

Springs:

When you hit a dip in the road and the back of the van moves down, it compresses the spring; then the van unloads the compressed spring load and comes back up fast. This is called “rebound,” and excessive rebound can be uncomfortable for rear passengers. However, if you did not have springs, it would feel like you were driving a brick. You would be jarred by every tiny bump.

The Sprinter’s rear springs are a pair of typical semi-elliptical (curved) leaf springs, similar to Ford, Chevy or Dodge trucks from the 50’s to current. The springs run parallel to the length of the vehicle on each side and hold the weight of the vehicle. If you jump up and down on the bumper, the movement you are getting is in the spring. This is your cushion between you and the road. When the body of the vehicle dips downward, the spring compresses; this movement is referred to as “jounce” or “compression.” The upward movement of the body when the spring unloads is “rebound.”

On each end of the rear Sprinter springs you have a spring “eye.” This is a single loop or “wrap” in the steel which provides a mounting point. It has rubber bushings and steel sleeves installed in the eye. This eliminates metal to metal contact at the attachment points and reduces vibration and road noise that could transfer into the cab. A large bolt passes through the bushing sleeve and attaches the spring to the frame of the vehicle. Each spring is attached solidly to the chassis frame on one end, and to a swinging shackle on the other end. The shackle is bolted to the spring eye; a bolt passes through the bushing and sleeve, just as it does on the fixed end. The other end of the shackle is then mounted to the frame in the same manor. There will be similar rubber bushings inserted into the frame at the shackle attachment.  As a curved spring compresses, it will flatten out and become longer; the lengthening of the spring is taken up by the swinging shackle which moves like a pendulum.

The rear leaf springs sit on top of the rear straight axle tube via welded spring perches, and are attached with u-bolts. To keep the spring from over flexing, or hitting metal during compression / jounce, there is a right and left rubber bump stop mounted to the frame, also called a “jounce bumper.” The axle will hit the rubber stop before you have any metal on metal contact or over flexing.

The Sprinter front suspension consists of a single semi-elliptical transverse leaf spring. Transverse in this case refers to the fact that the front leaf spring runs side to side at a right angle to the length of the van, where a traditional leaf spring runs front to back. The Sprinter front spring runs from the lower control arm on the right side to the lower control arm on the left side and also attaches to the front cradle near the center point. The Sprinter also uses a series of rubber blocks that work in combination with the front transverse spring. There are also rubber bump stops on each side to limit compression travel and bottoming out.

Struts and shocks:

The term “shock” is typically used to identify a shock absorber that has a fixed mount on each end. This is typical on most straight axle vehicles. The struts and shocks on any vehicle are designed to dampen spring movement, dampen spring oscillation and absorb shock.

The rear of the Sprinter has a basic shock absorber attaching to the frame on the top and to a shock mount welded to the axle tube at the bottom. They bolt to the frame mount and bottom shock mount using a similar bolt and bushing system as the spring eye. This is a similar set up to most trucks on the road today.

 Struts are used on the front of the Sprinter and are a fancy name for a shock that also has some structural purpose. Some struts can incorporate a spring into their design, but not so with the Sprinter. The Sprinter front strut does not hold any weight, nor will they provide any lift – again, the transverse front spring does that. The front struts attach to the body of the van at the top and to the front hub assembly on the bottom.

The front strut on a Sprinter acts as an upper control arm and ball joint. The strut is still a shock absorber but also acts as a structural part of the suspension and steering system. The strut actually holds the tire and wheel in place. The lower portion of the hub is attached to the lower control arm with a ball joint; the lower control arm is also where the front spring attaches.

There are two lower mounting bolts on the front strut and the second bolt up from the bottom is a camber adjustment bolt. It is oval or cam shaped and allows you to reposition the bottom of the strut by turning it; this moves the top of the wheel in or out, thus changing the camber alignment on the front wheel.

Sway bars:

Sway bars are implemented to reduce body roll or lean while cornering or driving over road irregularities. They are also known as “anti-sway bars,” “anti-roll bars” and “stabilizer bars.”

There is a front sway bar on your Sprinter and - if lucky - a rear sway bar, too. The front sway bar is semi-integrated into the sub frame of the Sprinter and is difficult to replace. There are no aftermarket front sway bars available. It attaches the body and frame to the cradle where the suspension attaches.

The Sprinter rear sway bar attaches to the frame on the top and the axle tube on the bottom. Many 2007 and up 2500 Sprinter vans were ordered by dealers as “sway bar delete,” meaning no sway bar. This was done possibly to save space for RV items. Most Sprinters will take an aftermarket sway bar without interference issues, even the ones that came without a sway bar.

We could go into a lot more detail and really bore people, but this covers the basics. We get a lot of questions on the front spring because it is hard to see. We also get many questions on the function of the front struts and rear shocks. We will cover a few more items like chassis, steering, and model identification in other articles. If you have further questions about your Sprinter van suspension, feel free to call us at 971-678-5940 or SprinterUpgrades.com. We hope this helps, and like always, we hope to see you on the road!