Alpina Roadster S Supercharged - Modifications

ESS Tuning is Europe's premier BMW supercharging specialist. The company is highly regarded for its supercharger kits for the M52 and M54 six cylinder engines, which used in BMW models between 1994 and 2005. No off the shelf supercharger kits for the Alpina Roadster S existed before the Roadster S Superchar...

Limited slip differentials have been exclusive to BMW M-cars since the late nineties. The Alpina Roadster S is based on the Z4 3.0i and comes with a regular open diffferential. An open differential supplies equal torque to each of the rear wheels, decreasing overall torque when one of the wheels reaches t...

The Drexler LSD was ordered with a new rear axle, creating the ideal opportunity to alter the final drive ratio. I decided to order the LSD with a rear axle from the E46 330i automatic, featuring a final drive ratio of 3.46:1. The new ratio provides a 7 percent shorter gearing compared to the standard 3.23:1 fin...

Alpina greatly improved the exterior styling and aerodynamics of the Z4 by adding a front spoiler lip with raised Alpina logo and a rear spoiler that improves down force at higher speeds. The Alpina changes give the front a flatter and more aggressive look. The styling of the Roadster S Supercharged was furt...

To add sportiness to the rear and to lower the visual stance of the car, the carbon fibre rear diffuser from the BMW aero kit was fitted alongside a custom made quad pipe exhaust. The exhaust mod and the upgrade to the facelift tail lights and rear bumper left me with the choice of the Z4M rear bumper, wh...

The standard Z4 bonnet looks kind of bland and fails to match the otherwise dramatic styling of the Z4. BMW made up for this when it introduced the more muscular looking Z4M. The bonnet of the Z4M features an accentuated power bulge, created by two sharp front-to-rear crease lines. The Z4M bonnet p...

The E85 Z4 received a successful mid-life update at the end of 2005. At the same time, Alpina ceased production of the Roadster S after building 373 units. Changes for the facelifted Z4 included a revised rear bumper, updated LED rear lights, bi-xenon head lights and a new front bumper. The tail lights ...

My Alpina Roadster S was originally painted sterling grey, a sort of mouse grey colour which I thought wasn't very distinctive. Since the bonnet, side skirts, bumpers and one of the rear fenders already had to repainted, I thought I could just as well do a full body repaint. I picked a darker shade metallic gre...

The factory Z4 antenna is an impressive showing that reminds of the radio equipment used by military vehicles. While technically a fine piece of hardware, its massive length distracts the eye from the fine styling of the car. Replacing it with a stubby antenna was one of the first mods I did to my car. The s...

Corona rings or angel eyes, as they are largely known, have become a BMW identifier since the launch of the E39 5-series facelift in 2001. As of 2007, the feature was available on all BMW models except the Z4. The facelifted Z4 featured a dimly lit single ring next to the low beam, but no double rings lik...

Reiger Suspension is a leading provider of high performance shock absorbers for use under extreme conditions in motor sport. Reiger shock absorbers are used by many well known rally and rally-raid teams - the Ford and Suzuki WRC rally teams and the BMW X-Raid team to name a few. The company is head...

One of the weaknesses of the Z4 suspension is the high level of flex in the stock suspension bushings. Turner Motorsport offers several affordable bushing upgrades that firm up the suspension while maintaining stock ride quality. The rear trailing arm bushing limiter kit reduces bushing deflection, increasing bushing life a...

The Turner Motorsport rear trailing arm ball joint reduces suspension movement and slop in the rear of the car for better and more precise handling. The upgrade is fairly inexpensive at 45 dollar per bushing. It's difficult to rate its effectiveness since most of the suspension upgrades on my car were fitted at the same time. The co...

The standard Z4 suspension is fitted with fairly soft bushings designed to absorb road bumps. Problem is they lose steering feel as well. After trying the uprated Meyle bushings and finding out they turned sloppy in a year, I upgraded to Powerflex urethane bushings. The Powerflex bushings gave an amazi...

One of the shortcomings of the E85 Z4 is the lack of steering feel and precision. The E85 was the first BMW to use electric power steering, reducing weight and parasitic losses. The downside of the first generation electrically assisted steering was a loss of steering feedback. For this reason, BMW revert...

The BMW Z4 Roadster features excellent chassis rigidity. Nonetheless, any improvement in structural rigidity is desirable for a roofless car. The StrongStrut Alloy Competition-Lightweight strut tower bar provides a noticeable improvement in steering precision. StrongStruts offering is not the most affordable solution on the market, ...

The Turner Motorsport front subframe reinforcement kit for the E46 and E85 reinforces the upper and lower tabs of the subframe where the motor mount is located. The kit requires welding. According to Turner Motorsport the kit is useful on E46s that get older and see more track-use, as they start to develop cracks and bends in places th...

Alpina made many refinements to the interior of the Z4, including a hand-stitched steering wheel, based on the pre-facelift sports steering wheel. The steering wheel features an Alpina emblem on the center hub and stitched diagnoal rhombs in the classic Alpina colours blue and green. Although the Alpin...

The standard rubber covers for the clutch, brake and gas pedals were replaced with custom aluminum pedals from Ultimate Pedals. Ultimate Pedals has several finishes available. I opted for the subtle looks of the brushed aluminum finish with rubber grip inserts and heel and toe extensions. The pedals are grippy in we...

Weight saving was one of the primary objectives of the Alpina Roadster S project. The best option to remove weight from the interior without sacrificing the interior finish is to replace the heavy power seats with light weight racing shells. Recaro Pole Position seats have been a popular upgrade in the M3 scene and feature an ex...

The standard three-point seat belts were replaced with Schroth ASM Autocontroll III safety harnesses to complement the Recaro racing shells. The ASM Autocontrol III features an auto-locking inertia-reel that allows for free movement in normal circumstances and locks up during abnormal movement, keeping the driver in place. The i...

To enhance the interior ambiance, LEDs were added to the interior door handles and the interior back panel below the rollbars. The LEDs we used are BMW part number 63 31 6 902 239. These are a perfect match for the other amber coloured LEDs in the interior. Unfortunately, the brightness of the LED...

While the E85 Z4 offers a unique and overall stunning interior design, especially with the Z4M and Alpina refinements, it has been notoriously lacking in build quality. The doors of the pre-facelift models sound tinny and the interior is full of squeaks and creaks. By applying cloth and rubber tape on the interi...

Alpina has tuned the Roadster S with a lovely exhaust note. Some people even find it V8-ish. With just two exhaust tips it looked a bit too understated for my supercharged car. To enhance the looks we modified the carbon fibre diffuser and added two Alpina-style oval shaped exhaust tips to the right side of...

Bigger brakes were on top of my wishlist the moment I started to think about modding my Alpina. With the possibility of a supercharger conversion in mind, I knew a big brake kit would be a necessary investment. Upgrading the brakes on the Roadster S turned into quite a challenging objective because of t...

To match the looks of the Mov'it front brakes, the rear brake discs were replaced with Sandtler-branded drilled brake rotors. The brake calipers were painted in high gloss black and the OEM brake pads were upgraded to Ferodo DS2500 for a bit of extra bite. Upgrading to a big brake kit would have been highly expe...

The very first modification that was performed on the Roadster S was the installation of a BMW iPod interface. Back in 2004, BMW was the first car manufacturer to offer iPod integration. The functionality of BMW's first generation iPod interface was extremely limited, however, as it only supported playback of tracks in a maxim...

To improve the car's stance and to compensate for the wider track in the front, custom made wheel spacers were added to the rear wheels. The front wheels do not use seperate spacers as they are integrated into the brake assembly. A wider track in the front was required to create space for the Mov'it bra...

With 445HP on the rear wheels, the ability of the rear tyres to transfer power to the road surface is critical. The Alpina Roadster S is factory fitted with 265/30ZR19 rear tyres with 275mm the widest you can go on a Z4 without widening the wheel arches. Obviously that would be no easy modification. The be...