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      06-08-2009, 08:28 PM   #1
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Talking *** Review - Bilstein B16/PSS10 Ride Control Coilover Suspension on E92 335i ***

As some of you will know, my car has been in a constant evolution over the last year and a half, with parts coming and going, new products being tried, tested, and more often than not rejected. For a long time I had lived quite happily with the standard SE suspension, having uprated the anti-rollbars (sway bars for our US cousins) to help prevent excessive body roll. I had also done some M3 upgrade bits to the front tension struts, wishbones, and rear subframe bushes, just to keep everything tighter and in better control when pressing on. The car drove really well, handled positively, and yet was still comfortable as an everyday car living as it does on the cracked and potholed roads of Central London

However over the last six months or so I've been deliberating over a wholesale upgrade of the suspension, debating on whether I should finish the car off properly and go for a full coilover setup. I had noticed it was still a little soft and wooly when really going hard around the 'Ring, and a trackday and Brands Hatch also showed up cornering deficiencies in terms of lateral grip and body control

I was going to consider either the KW V3 coilovers, or the top-end Bilstein PSS10 kit. I could have considered things like Ohlins or Moton, but the thought of spending in excess of 4000 on a suspension setup (or in the case of the Ohlins something closer to 8000) didn't really appeal

It was whilst talking to Sal & Imran @ Evolve that I got round to investigating and then considering the Bilstein B16/PSS10 Ride Control system. You'll find Bilstein's blurb on the system if you click the link, but essentially what it is is Bilstein's top-end PSS10 10-way manually adjustable coilover system, specially setup in two preset damper positions (out of the possible 10) for road use and sports use, with the control changing from a manual turned-knob to an electronic control unit mounted in the cockpit of the car.

Effectively, you lose the full adjustability of the standard manual PSS10 coilovers, but gain in-cabin electronically switchable control over two damping setups. In both modes, the spring height/ride height remains the same - it is only the damping rate that is adjusted. Ride height can be adjusted when installing the springs, as there is an adjustable spring perch which lowers the car between 30mm and 50mm from standard ride height.

The dampers themselves are an inverted monotube design, gas-pressured, and married to matching shortened springs. They are a direct replacement for the OEM BMW suspension setup, although the Ride Control system requires wiring into the cabin for both operation and power.

I had done a fair bit of research into this Bilstein kit, and discovered it was partially developed for the Nissan GTR. Bilstein also do a variation of the same suspension dedicated to the adjustable setup on Porsches (called Bilstein Damptronic). Coupled with the fact that Walter Rohrl had a hand in the damping setup of the Ride Control system as he did the testing and development work at the 'Ring, I had pretty much made up my mind to give this system a go.

Sal & Imran @ Evolve very kindly got in touch with Bilstein UK on my behalf and arranged a new set to be shipped over from Germany It wasn't the first set that Evolve had procured - Darren Weston's car on the cover of Performance BMW magazine had the system installed as well, although that was setup to be slammed to the deck, rather than for performance. Set duly arrived, I picked it up from Luton and headed off to my usual installer, Birds in Uxbridge, as they were the only people who knew my car inside and out.

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The mechanical installation of the suspension kit was like any other - actually very simple if taking a methodical approach, and took about four hours in all. Bilstein supplied new bump stops (secondary springs) and all necessary fixings and C-clamps for the adjustment. The kit was exceptionally comprehensive and installation manual well laid out. The box even contained all the necessary TUV certificates for when the car is in Germany.

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Whilst the mechanical installation was easy, the levelling of the car proved a little more tricky, in terms of balancing the car properly. This alone was an on-the-ramp/off-the-ramp/on-the-ramp-again affair that lasted a good hour to two. But then again the three of us, Kevin Bird, Dennis the tech, and myself, are extremely fussy and wanted things to be done right.

The headache came with the cabling for the internal control module and switch. Taking power to the unit was easy - however routing the control module through the existing grommets in the bulkhead, and then running the control cable behind the dashboard into the ashtray area was a real bugger. To make matters worse, each damper has a wire that must run to the central control module. Because this installation was done to OEM standards, virtually every interior trim panel came out so the wires could be routed inside the OEM channels - there is no excess or extraneous cabling anywhere unexpected within the cabin. Told you we're fussy people!!

Anyway, the control button was eventually installed in lieu of the normal cigarette lighter socket in the front ashtray. Incidentally, the On/Off button you can see in the pic is a separate component relating to the video camera system in the car - another story !!

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So, once installed and levelled, how does it look ?!

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Compared to DXBs 335d SE

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You can see it's monstrously low, although I haven't had any issue with the tyre rubbing against the wheel arch in normal driving. The suspension is set so that it has as much spring travel as possible - it is on the highest ride height setting (which doesn't seem very high at all!!) It's effectively a 30mm drop over standard at the front, and I've given it a nose-down stance by only lowering the rear by 20mm or so.

The most important bit then - what does it feel like ??

Well, the first impression we had when driving the car down the road for the first time was just how damn good the dampers were. The normal suspension would crash and bang over the ridges and cracks in the road - the Bilstein dampers in comparison did thud, but they did so in a very controlled and unobtrusive way. The damping is just in a totally different league, which is to be expected given the cost. Regardless, it was a total surprise to see how comfortable the car was, even when so low and on supposedly sports orientated suspension

Pushing on down the country roads with the suspension in "Normal" setting, we discovered the dampers really were working very well in smoothing away the unruly ruts and crests. However, we did find that there was a bit of body float when really pushing on - it felt like the springs were a little over-stiff for the setup, or the dampers weren't doing a good enough job of keeping vertical body movement in check when driving that bit faster

However, one press of the Bilstein button into "Sport" mode and the whole character changes. The damping prowess is still very much evident, but it appears that the rebound damping rates suddenly get a lot stiffer, and the whole body of the car is tied into the road, with very little vertical travel. It is stiffer, it is firmer, but even so it doesn't become uncomfortable. It really is quite uncanny how the car is firm yet well damped and well controlled, all at the same time

Body roll is miniscule in comparison to the stock suspension - the car really really does corner like it's on rails, and the tyre contact patch is always maximised, giving a big increase in noticeable grip. The front end is very pointy now, but not to the extent that it becomes tiring to drive. It's just the car is very keen to turn in, and responds quickly to the smallest of steering inputs. The tyres and the other components obviously play a large factor in this, but the suspension change itself is a marked improvement.

"Normal" mode is actually very well judged for inner-city driving, or where the roads are particularly poor. I have become used to the slight floatiness, as I prefer the extra compliance it gives when going over speed humps and the like. The minute I get out on to proper roads, I give the button a press into "Sport" and I can feel the whole car just come alive through the steering wheel and the base of the seat

We finished setting up the car literally the day before Northern Meet 2, and I had the pleasure of Viv's company in the car for the majority of that glorious weekend. Hammering through the Yorkshire Dales either hanging on to Helen's Porka or when trying to outrun her, Viv & I really put the suspension through its paces. I don't think I've ever given a suspension on a car such a hard workout, and it really was faultless. The body control over the severe humps and dips in the Dales was unbelievable, and the sheer cornering power and grip available was in a totally different league to before. I don't think Viv can quite believe what the car was doing, even now!!

Two months on from there, the car and the Bilstein kit has seen heavy use around the Nurburgring. Here it really showed how good the body control was, and how much grip there was to be had. I don't have any empirical data to show, but through the butt dyno I reckon I was a good 10-15% quicker through the majority of the corners, and I was hammering through the Fuchsrohre compression dip at speeds well in excess of 140mph, with the car handling all the demands with ease. There are many who will vouch for the performance of the suspension, not least Marcel (Alpina_B3_Lux) and Carsten who both travelled over to the 'Ring specifically to have a ride in my car with the new Bilstein kit

It's a long review I know, but I can't think of many ways of expressing just how good this kit is. I drive my car daily in London, and it just shrugs off the potholes that abound. Not once have I got out of the car thinking I need to be in something more comfortable or soothing.

Bilstein have finally got a suspension kit spot on - the two modes are perfectly set for fannying about town, or for full-on attack mode when the mood and environment is right

Would I recommend it? Absolutely, although there is a caveat - 2000 is a lot to pay for a suspension kit, and that doesn't include the installation and setup (which we did over two days in the end). If you are in the market for a set of coilovers, you might want to consider the standard PSS10 kit, which is manually adjustable on the damper, and forego the fancy electronic control unit... You'll save almost 800 I think !!!

Thanks to Sal & Imran @ Evolve for sorting everything with Bilstein and sourcing me the kit in a hurry!
Thanks to Kevin, Dennis & the rest of the crew at Birds for their tireless work as ever