VW Tech Tip VW Suspension Technical Article Tech Tip: by Charles Adams The following is a technical THE TRUTH ABOUT SUSPENSIONS MYTH: Lowering or raising my car will give it greater performance than I article written for better If you want a smooth ride and not just looks, there is more than meets could expect at stock height. For ex- understanding of the rear the eye at a quick glance. Anyone ample if I simply lower my car it will corner better than my friend’s car that air-cooled VW suspension can lower or raise a vehicle and call it good, but just like any good en- is not lowered. Alternatively, if I raise as well as our products. For gine build, if you seek performance, my car it will perform better off road, absorbing bumps and jumps, than my the majority of people, the everything should be prepared in advance and every component’s friend’s car that is not raised. rear VW suspension is little function should be understood. It understood and more is more than just ordering the most FACT: Every suspension rides at its costly parts, assembling them, and greatest potential when it is riding often misunderstood. blowing away the competition. Yet within the parameters that it was suspensions are not a mystery and designed for. This means that facto- they certainly are not rocket science. ry suspensions perform the greatest The truth is that they are simply and when the ride at factory height and easily understood if they are ex- the geometry is not tampered with. plained simply. Unfortunately there Therefore it is of upmost importance is a seemingly infi nite amount of that any part that is purchased is misinformation, which is unneces- actually designed to operate with- sarily complicated, leaving the reader in the altered region, rewriting the bewildered about how to approach chalkboard so to speak. But doing this their own car’s suspension. This is is like hitting the factory reset button, not how we roll, so we encourage as the car is either lowered or raised. you to read on and come to your own It also means that there is not a “one conclusions to piece together the size fi ts all” suspension. If you seek suspension that is just right for you. true performance, safety, and han- It is our hope that you will fi nd the dling then you will carefully need to material easy to read and to grasp. select the parts that are designed to operate at the ride height that you are most often going to drive. Raise Plates and Drop Plate Drop or raise the rear of your air- cooled VW without loosing ride quality! It seems that there are 101 different things that you can do to the front suspension, but when it comes to the rear, VW owners have been given little choice until now. Figure 1 Benefi ts It is now possible to have a full suspension performance vehicle! Our Drop Plates have been engineered to drop the rear of your VW yet allow your car to ride and feel as the factory intended. While the math and engi- neering may be extensive, the concept is simple: Drop Plates locate the axle up higher, but maintain factory spring plate travel in the lower region (fac- Figure 2 tory articulation region) and maintain torsion in the system. This idea is similar to Drop Spindles in that sense. However with Atomwerk Drop Plates the upward range of travel is extend- ed, which means that you will be able to roll over even taller bumps (assum- ing that your upper stopper has not been cut off). Figure 3 Can’t I just lower or raise my VW with factory plates? plate only has a limited distance that it resistance that is found in the tor- Of course you can lower/raise your was designed to articulate (travel) in be- sion bar. The further up you push the vehicle using your stock spring plates. tween. This space that limits the spring spring plate the more torsion you are People have been doing this for de- plate travel is often referred to as the loading in the system, kind of like a cades. Atomwerk Drop Plates were torsion housing. The travel is limited by heavy duty rat trap! not created so that you can just lower/ a lower stopper and an upper stopper, When you lower your VW’s rear sus- raise your vehicle; they were created in addition to the factory rubber bump pension with factory plates you have as an alternative to a bad, clunky, and stop. When you lower or raise your ve- made it impossible for the spring squirrely ride that you are bound to hicle you literally force your spring plate plate to articulate correctly, and that get when you lower/raise your vehicle to operate outside of its designed travel is why it will smash into the upper with stock plates. range. There are three specifi c factors stopper when going over bumps. Not that affect your ride quality: good! In general, the spring plate should be able to articulate down- Why does my ride quality 1) The spring plate articulation ward about 25% of the total travel change when I lower or raise 2) Torsion in the system range and should be able to articulate with factory spring plates? 3) Toe-in on swing axles about 75% upward, respectively. There are several reasons for this. Torsion in the system changes when The easiest way to think about this is The spring plate articulation is the you lower a VW and the initial torsion that a lowered stock VW is operating factory travel range. It is the angular (pre-load) changes drastically and this outside of the factory geometry in the distance between the lower stopper signifi cantly changes your car’s ride torsion housing. You see, the spring and the upper stopper. Torsion is the characteristics, as we will see later. Mechanics of per. When the vehicle is lowered the think that it is better described as Lowered and Raised spring plates tend to pull the axles, and “bump toe-in” since it is toe-in that thus the wheels, toward the vehicle. is induced. Regardless, this is an inev- Swing Axle Suspensions The dangerous thing is that bad toe-in itable effect of the swing axle suspen- will manifest itself when a person least sion - including stock VWs. However, if Toe-in expects it. This is not something that it can be felt at all - it would only be Toe-in is the effect of the rear wheels I personally like experiencing at high while absorbing very tall bumps. Every turning into the vehicle as a result of speeds, on slippery roads, or with my one of us who has ever driven a swing the rear axles being pulled forward. family in the car. Have you ever driven axle VW has experienced thousands of When using factory plates, toe-in will over a wet surface on one side of the negligible bump steering on practically occur any time the spring plate is at road and felt the rear dart to one side? every trip. any angle other than horizontal, as can Toe-in becomes dangerous, and literally be seen in the adjacent drawings. In a steers the rear of the vehicle when each lowered or raised VW the vehicle’s toe- Why Shouldn’t I Notch my Plate? wheel experiences a different kinetic Figures 4 and 6 demonstrate the in on each rear tire will normally cancel coeffi cient of friction (grip to the road) position of a stock spring plate in a out the other, assuming that the vehicle in respect to each other and at the vehicle that has been both lowered has been lowered evenly and there has same moment in time. The tire that and raised about 2.5 inches. You can been no frame damage. In the adja- has the greatest grip to the road will see how close a factory spring plate cent drawings it is demonstrated by win the grip battle and quite literally rides to the stoppers when a vehicle’s the horizontal (x) distance between the steer the rear end of the vehicle in one height is changed. In extreme cases it center of the torsion bar and the factory direction. NOT GOOD! There have been takes “Notching” (removal of mate- axle location. It is represented by the several documented cases where drivers rial) of a stock spring plate to fi t into vertical line (y). Figure 6 demonstrates have totaled their VWs due to bad toe- these positions. Atomwerk Engineer- the position of a stock spring plate that in surprising them unexpectedly. In ing Inc. does not recommend anyone has been re-indexed to lower a vehicle addition, it should be noted that since to notch a factory spring plate (either about 2.5 inches (note that this is not the spring plates still need to travel in top or bottom) because this creates the distance that an actual spring plate an arc, the toe-in can only drastically a stress concentration in a plate that has been dropped, as they are separate increase as the vehicle absorbs bumps was engineered for economy. calculations). One can see how close it in the road. It can also be seen from rides to the upper stopper. It doesn’t the adjacent fi gures that toe-in also take much of a bump to make the happens in raised applications.