Tech Analysis: VW

Neuspeed Suspension Tuning

From the February, 2009 issue of European Car

By EC Staff

It wouldn't be completely accurate to say that Bill Neumann invented watercooled Volkswagen performance tuning, but Neuspeed is certainly among the oldest and most respected Volkswagen and Audi tuners in North America. european car recently spent some time with Aaron Neumann, the company's technical authority, learning about Neuspeed's suspension modification program for the MkIV platform, the GTI 1.8T in particular.

Neuspeed's overall objective is highly satisfied customers who drive their cars on the streets. That means high levels of fit and finish and attention to detail, simple, straightforward installation and good day-to-day performance, taking into account the wide range of enthusiasts' commitment and budget.

With the smooth highways in Europe, many European tuners like to use stiff springs to control roll, but Neuspeed prefers to use moderate spring rates that will be compatible with healthy original-equipment dampers and still provide a smooth ride on much rougher U.S. roads. When spring rates are set, the cornering balance is dialed in with anti-roll bars.

On the MkIV Golf and New Beetle, the front spring rate is approximately 150 lb/in. and the rear is about 140 lb/in. The Jetta, perhaps because it is considered a more sedate vehicle, uses a front spring rate of less than 110 lb/in. but the same rate to support the trunk. Motion ratio, the relationship between wheel movement and spring movement, is very close to 1:1 on both the front and rear of the car. Neuspeed knows not every customer will also buy performance dampers to go with its springs, so Neuspeed's first step, the Sport springs, are designed to lower the car about 1 1/2-in. and work with the stock dampers.

The rear spring rate is 170 lb/in., because that's all the damper will handle. The front spring rate is increased to 220 lb/in. Aaron stated that making the front springs too soft will allow the car to get into the front bumpstop more often, leading to a "porpoising" oscillation. Even though Neuspeed's Sport springs are designed to work with a stop damper, installation of aftermarket sport dampers such as Bilstein or Koni (both are available from Neuspeed) is highly recommended for best performance.

Neuspeed's Race springs are more aggressive, with 220 lb/in. in the rear and 285 lb/in. in the front. They also lower the car another 1/2 in, which brings the long-travel, foamy bumpstops (sometimes called "supplemental springs") into play, effectively adding even more spring rate with a highly progressive curve. For this reason, high-performance dampers are required with race springs.

Handling balance is dialed in with anti-roll bars. Stock MkIV front anti-roll bars range from 21- to 23mm, depending on year. The stock rear "anti-roll bar" consists of the beam itself, fortified with a welded-in, 17mm tubular reinforcement. Volkswagen's MacPherson strut front suspension has little camber gain with compression, so eliminating as much body roll as possible is required for maximum grip. Neuspeed states that 25mm is the largest diameter front bar that will fit, and suggests a 25mm hollow bar may not be much stiffer than a 23mm solid bar. Neuspeed's 25mm bar provides the maximum benefit possible.

In the rear, a three-way adjustable 28mm bar is provided (such a bar can actually be adjusted five ways by setting the spherical-bearing end links in different holes on each side of the bar, splitting the three standard adjustments). The roll-resisting rate added by the bar is 190 lb/in. on the soft setting and 225 lb/in. on the firmest setting. For a 1.8t owner on a serious budget, adding just Neuspeed's rear anti-roll bar will go a long way toward eliminating the factory-tuned understeer, but VR6 cars always need the added stiffness of the 25mm front bar as well.

Neuspeed's rear anti-roll bar mounts to the beam with polyurethane bushings retained by steel straps that hook around the beam and are fastened with a bolt. No drilling is required. The end links are spherical bearings to allow adjustment. MkIV Volkswagens have had many problems with the front anti-roll bar contacting the driveshaft under compression. Aaron reported the contact occurs near the end of the bar as it swings up and the movement becomes horizontal, rather than on the main part of the arm. Neuspeed's bar provides a revised bend radius to clear the front driveshaft on lowered vehicles. Enthusiasts doing violent burnouts with powerful 1.8t cars often have greater problems, because the lower control arm just bounces all over the place due to its soft bushings. The situation can be significantly improved by installing urethane or, better yet, Volkswagen factory motorsport control arm mounts. They are sold for the MkIII but also fit the MkIV. Although the MkIV Volkswagen is much, much stronger than the sardine-can early cars, you really can't have a chassis that is too stiff. To that end, Neuspeed added its upper strut tower brace and front subframe brace to its MkIV chassis product lineup. The strut tower brace is made from 1-in. outside diameter mild steel with 0.063-in. (1/16-in.) wall thickness. It is available chrome-plated or powdercoated. It mounts to the strut tower using four Nutsert fasteners, a method Neuspeed has used since the introduction of the MkII chassis. A Nutsert is an aluminum sleeve with a flange at one end and a thin-walled center section. Tightening a screw collapses the center section, similar to how a pop rivet works, leaving a solid set of threads in a thin material. Unlike a nut and washer, a Nutsert requires access on only one side of the panel. It is simple and elegant, with high pullout strength. The only problems, Aaron said, have been with customers who drilled a hole larger than specified or were otherwise sloppy in their installation.

Neuspeed's front lower tie bar was demanded by many customers. It is designed to stiffen the lower subframe by connecting the cantilevered forward ends. It is made from billet 6061 T6 aluminum with anodized ends and a polished center section. Motorsport control arm bushings may be required to obtain the maximum benefit from this part.

For maximum street performance, Neuspeed recommends Bilstein's PSS9 coilover kit, with adjustable ride height and damping. These use 60mm inside-diameter race springs, available in a range of rates for custom tuning, which also provide greater inboard clearance for wider wheels and tires. The dampers uses a single external knob to adjust rebound and compression simultaneously, with nine adjustment positions indicated by detents. Bilstein PSS9 eliminates several of the compromises inherent in the factory suspension design. The long-travel bump stops are gone, and the weak stock struts are replaced with very high-quality dampers, shorter to maintain travel at lower ride heights. The dampers are tuned to control high spring rates, which Aaron stated are 450 lb/in. in front and 285 lb/in. in the rear.

Extracting ultimate handling performance from the car will require adding camber. Even when lowered, the MkIV car has only about 0.5-degree negative camber, when 1.5 to 2.0 degrees would be preferred for serious street use. Unfortunately, Volkswagen's pinch-bolt-style lower strut mounting can't even be modified to provide adjustment. Extending the lower control arm can cause problems with driveshaft geometry and fender clearance, and adding real camber plates will require some fairly invasive surgery to the top of the strut tower.

Scheduling didn't allow us to spend much time behind the wheel of Neuspeed's GTI, but our photographer captured an impressive demonstration of the improvements to the car's cornering behavior. Check out the accompanying photos for more details.