Project S4: Bilstein B16 Coilovers

As a motoring Editor, journalist and road tester, I’ve been lucky enough to be taken around a number of suspension manufacturers’ factories to see how their different engineering approaches develop (and affect) their end product. And I have tested a huge range of suspension kits – on road, race and rally cars. But, without a shadow of doubt, it’s my own, long term road and track testing on my project cars that has been the most revealing – following the kit from arrival, through fitment and into proper testing. With my project cars, extensive long term testing for ride quality, handling ability, safety, durability and wear rates has revealed whether an aftermarket suspension kit is worth investing in, or not. After all, despite them being by far one of the best modifications to make if you want to go faster, they are not cheap – costing anywhere between £500 to 10 times that, or indeed whatever you want to pay. You need to make the right choice: Pick right, fit once, set-up properly and enjoy quality handling.

The most amazing suspension factory I have had the pleasure of visiting was the Bilstein factory, in Ennepetal, Germany. Not only was its scale incredible (being part of the huge ThyssenKrupp), but the equipment they had for research & development, and construction was mind-blowing – as was their product philosophy, and knowledge. It was an incredible experience, watching a kit go from the drawing board, through R&D, into construction, then testing, and finally, production, marketing and packaging. And I also had a close look at tiny motorsport dampers, being hand built, for use on great circuits like the Nordschleife – where the Bilstein brand is key, being on every kilometre board of the legendary track, and having a box at the Grune Hole entrance. Bilstein even have a driving god ambassador of the brand, Walter Röhrl, who tests with them at the Green Hell and their epic test centre in Papenburg, north Germany. Mr Röhrl says: “The car needs to become one with me, part of my body, where I alone decide what it has to do. I’m working with BILSTEIN to ensure that this applies to every car.” If its good enough for Walter…

Having been around the Bilstein factory, I traveled north to Papenburg, to test a NISMO 350Z special I’d brought on test against a standard 350Z, with Bilstein coil-overs fitted. It was mind-blowing how much better the Bilstein car was, even over a NISMO-tuned 350Z – offering more grip, control and fun, and substantially better ride quality and advanced handling prowess. I was a convert there and then, and my drives around the Nurburgring in various Bilstein-equipped cars since have done nothing but re-enforce my belief in the Bilstein brand and their unique take on suspension engineering.

Bilstein are pioneers and promoters of mono-tube, gas damping technology. They say: “Over time, the mono-tube gas pressure technology developed by BILSTEIN has established itself as a standard in automotive construction. This technology involves keeping the oil in the absorber under pressure, which prevents it from foaming when temperatures and loads are increasing. As a result, full damping power is retained even when the system is placed under extreme stress, a feature that can be observed in the self-lowering piston. Our mono-tube gas pressure technology:

  • Ensures a high level of traction and more precise handling.
  • Is a must-have for powerful sport suspensions &
  • Adds safety in all dynamic driving situations.

They continue: “It’s the original and best: BILSTEIN’s mono-tube technology is the number-one choice in motorsports and series-production sports cars: no other type gives engineers the same freedom to choose the perfect installation location or position (e.g. Upside-Down technology). It gives:

  • A large effective surface on the working piston creating increased damping power and better handling.
  • Improved dissipation of thermal energy outwards enables a consistently high level of absorber performance.
  • Sturdy structure for added safety in Upside-Down Technology.”

Bilstein offer a huge range of kits for a huge range of cars – from universal spares (B1-B4), through high performance shocks (B6, B6 off-road and B8), sport & threaded ride height adjustable kits (B10, B12, B14, B16 & B16; with remote dampers), electronic dampers (B16 damptronic® and Bilstein ridecontrol®), to bespoke motorsport kits.

For the Project S4, I wanted a kit that would be both comfortable on the road and highly capable on track, so, with expert advise from Bilstein, I went for the B16 Sport & Threaded ride height “coil-over” suspension kit, built to fit my 1998 B5 Audi S4. It’s key benefits are:

  • 9/10 characteristic curve pairs can be selected by the adjustment wheel while installed, offering easy damping adjustment, ranging from extreme sportiness for track use right up to the highest level of driving comfort.
  • Threaded body adjustable range of 20mm at both axles while installed, offering easy ride height adjustment.
  • Lowering of approx. 30-50 mm at front and rear.
  • Road-tested by BILSTEIN under motor sports conditions and fine-tuned.
  • Spring plates and lock nuts made from a special aluminium alloy.
  • Surface coating using Triple-C-Technology® for long-lasting corrosion resistance.
  • Round threads for perfect handling.
  • Quality sport springs made from highly durable material.
  • Gas pressure technology.
  • BILSTEIN mono-tube/Upside-Down technology, made in Germany.
  • German TÜV certificate.

The quality of the Bilstein B16 kit is obvious, even to an engineering layman like me – from a design and manufacturing point of view… and is far superior to kits I have seen costing a whole lot more, ostensibly built for motorsport. And the Bilstein-Technology – tested on the Nurburgring Nordschleife sticker proudly attached to each leg just instills the right feeling: You know it’s going to be good stuff.

Dave at did the greasing up and fitting, and said, whilst the Audi’s suspension design requires a lot of messing about to get new suspension on, the Bilstein’s were faultless in their design, lining up and slotting in a treat.

I’ve yet to do a proper laser wheel alignment, to maximise the effectiveness of the Bilstein B16 kit (read here very soon, with further road and track testing), but first impressions are utterly incredible.

The S4’s standard suspension was good – comfortable, capable, fairly neutral and grippy, if with a little too much understeer-bias and loathe to turn in for ultimate perfection: It’s a compromise kit, built mainly for comfort, than handling. The Bilsteins are a very different matter: Built for BOTH comfort AND handling.

Set down 30mm over standard ride height, the S4 now looks mean and purposeful, with its Bilsteins in tow. With 6/10 clicks on the damping (so, on the sporty side of ride comfort), I was expecting a bit of bone shaking. And, whilst there is a noticeable (unintrusive) little jiggle at very low speeds compared with the standard set-up (only to be expected, with the harder spring rates), the ride quality is amazingly comfortable, thanks to the outstanding damping ability. Bilstein don’t do bone-shaking spring rates – they let their gas pressure mono-tube dampers do the work, which is spot on. And, as the speed increases, so the amazing damping influence gets more and more and better and better. The Bilsteins are quick to react to every surface imperfection, keeping the tyres in contact with the ground as long as possible, without intruding on the ride quality. There’s a perfect relationship between spring and damper, giving you a feeling of immense confidence behind the wheel.

The damping is deeply, deeply impressive, but it’s the turn-in and change of direction that’s the most radical improvement. The S4 is now razor sharp on first turn-in, hunting out any spot you wish to aim at without fuss and staying totally stable and accurate. And the S4’s now utterly amazing at directional changes, handling flatter, faster and better… critically, with minimal moments of inertia, allowing you to place the car just where you want it. This is going to be outstanding on track! Amazingly, the Bilstein B16 kit has somehow made the relatively (nose) heavy S4 seem lightweight, agile, safe and exciting all at once. It’s neutral, accurate, sharp and fleet-footed. Utterly jaw-dropping stuff. And that’s before I’ve optimised it with a wheel alignment.

I’ve had a lot of average, some pretty dire, some utterly diabolical and a couple of good experiences fitting suspension kits. I’ve made cars better, and a lot of cars worse. As such, I was worried I was going to ruin a pretty good all-round suspension set-up taking off the S4’s standard stuff. What a fool! I shouldn’t have worried… I was fitting Bilsteins! And I can’t praise them enough. God only knows how good they will be after a decent alignment, and on track later this Summer, with the dampers cranked to the max, with their easy one-click adjustability. They’re certainly going to push the Dunlops to the limit, that’s for sure…

Amazing! Thank you Bilstein engineers!

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