Sprinter Frame (Chassis), Steering, and Basic Model ID
In the world of full size vans and utility vans, Mercedes is the clear front runner with several variations on the Sprinter van and new models coming out every year. This article covers a few facts about the Sprinter chassis, steering, and basic model identification.
The definition of a chassis (pronounced “chass-see”) varies per source, but in automotive will usually refer to the frame of the vehicle. The body sits on top of the chassis and the engine and transmission attach to it.
The Sprinter vans are a unibody vehicle which means the frame is integrated with the body as opposed to body-on-frame vehicles which have a separate boxed frame that the body sits on. “Unibody” is short for unitized body or unitary construction design. They are built by welding preformed body panels to preformed frame sections. The frame sections are usually open at the top and once welded to the body floor panel become closed and integrated. The preformed body panels such as the floor pan are designed in a structural way and once welded to the frame channels they both become part of the structural framework. The frame acts as the skeleton for the vehicle, and all suspension components, body, engine and transmission, mount to the frame in some way. Unibody vehicles will generally use a sub frame or engine cradle to attach the engine to the unibody frame work.
The Sprinter cab chassis is a van cab (body) and rear framework with no rear van body. These are used to mount flatbed, utility box, or Class C RV coaches to (think Winnebago View or Pleasure Way’s Class C options). The cab chasses are still unibody, but they’re sort of a hybrid in the rear portion since the framework has almost a mirror image open channel unibody frame welded on top of the lower frame. This creates more of body-on-frame type boxed system and allows you to then mount your utility box or RV coach body to this framework. Unibody construction is used in all modern cars, some trucks and some vans; it is strong, lightweight, and efficient. Note: A body on frame vehicle will use rubber bushings (body bushings) between the body and frame and the body will attach using body bolts. Unibody does not need these bushings, although many unibody vehicles will use a similar bushing set up on the engine sub frame or cradle.
The Sprinters have a power rack and pinion style steering system. We are not going to go too far into defining a rack and pinion system, as it is really a bit too techy for this article. Essentially, it is a round gear (pinion gear) that rotates on a track style gear (rack gear). When the pinion rotates via the steering wheel and steering shaft, it moves the track gear right or left. On the rack and pinion system you have tie rods on the inside and outside that are pushed out or pulled in via the rack gear. These tie rods attach to your hub (wheel area) and basically push one wheel out while drawing the other in, giving you steering. If you read our suspension 101 article, you will remember that there is no upper control arm on a Sprinter, so the front strut shaft will rotate as you turn from right to left. Most older vehicles had a steering gear box that was frame mounted and attached to steering arms, drag links, pitman arms, and tie rods to accomplish the same thing. Rack and Pinion is a cleaner design which eliminates much of the old steering linkages that were needed.
Sprinter Model Identification
The 2500 Sprinter is a single rear wheel vehicle (not dual). It is a lighter duty vehicle and has a smaller load carrying capacity than the 3500.
The 3500 van is a dual rear wheel vehicle, aka “a dually,” and has either a two leaf (or blade) or three leaf spring pack in the rear. The 3500 has a much heavier spring system, rear axle, and bearings than the 2500, giving it a higher load carrying capacity. Brakes and other items are also sized accordingly.
The 3500 cab and chassis is similar to the van but as already mentioned, it comes as just a cab and frame (chassis). Again, these are the units that are built into the Class C RV’s and utility box trucks. There is also a Sprinter F50 chassis that is a 3500 unit that comes without the cab body, just the front inner structural body panels and rear frame. To our knowledge this unit is used mainly by Winnebago and Navion for their Class A RV’s, the Via and Reyo.
Mercedes is the only manufacturer to offer a four-wheel drive option for their full size van. The Sprinter 4x4 model is available in both 2500 and 3500 van chassis and is similar in most respects to their 2wd counterparts. The front and rear of the Sprinter 4wd van sit slightly higher to accommodate the transfer case and front differential. Note that most after-market suspension parts are not compatible between the 2wd Sprinter and the 4wd Sprinter.
We are not going to get into actual numbers for GVWR and axle ratings, etc. Please see your inner door tag on the driver side door jamb to check your gross vehicle weight rating, axle rating, tire pressures and other information. To identify year, please see our article on how to determine the correct year of your Sprinter or Sprinter based RV. For more information on basic suspension information see our Sprinter Suspension 101 article.
We hope this offers you a little more understanding of the construction of your Sprinter. We learn new things about the Sprinter vans every day, and our best insights come from customer feedback and photos. If you have observations or questions, please post them in the comments or e-mail us directly. firstname.lastname@example.org
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