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      09-25-2011, 10:21 AM   #112
Alpina_B3_Lux
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Drives: Audi R8 V10, BMW 330d E91 LCI
Join Date: Feb 2008
Location: Germany

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2009 335i  [4.39]
REVIEW: Bilstein PSS10 / B16 Ride Control coilover (long!)

20. Bilstein B16 Ride Control coilover on E90 335i LCI

Why?

As you may have read in my review about various M3 suspension pieces that can be installed in a 335i as well as the Quaife differential (see here: REVIEW: M3 suspension parts & Quaife limited slip differential ), I've been in the game for improving the suspension of my 335i for some time. The M3 pieces that have been installed so far have already had a considerable positive effect on the steering response, manoeuverability and decrease of body-roll, as well as provided me with a much more direct feedback from the road.

However, that was only the first step - I always intended to replace the core parts of the suspension (i.e. the springs and dampers) with something more sophisticated. I was never interested in just lowering the car, which is why there never was the question of just installing different springs and be done with it (although this could have already improved the suspension as well, at least somewhat). As a consequence, the only serious solution lay in a complete sports suspension or coilover kit, with matched springs and dampers.

Another factor that influenced my decision making process was that I needed a suspension that was approved by the German TÜV (the technical inspection), as my car is registered in Germany and a different suspension would immediately be visible. Therefor, some kits that for example HP Autowerks offers were no viable option, as it would be very difficult to get them TÜV approved. I did some research and found that, in general, people were quite positive about Bilstein suspensions which also have a very good name in Germany (where they are part of the big steel company Thyssen Krupp). There are also other really excellent kits out there now, such as the KW V3 coilover or the Öhlins Road & Track, but at the time I could not find any extensive reviews for the E90 platform of them and therefor excluded them.

Also, another important element was (and still is) that the suspension needed to be compliant and comfortable enough for me to allow me to drive it on a daily basis. My car is not a dedicated track car, and the roads in Europe are not always in a very good state; I therefor needed something that did not make me lose my fillings each time I went over a pothole or elicited screams of protest from various (in particular female) passengers.

In the end, there was one coilover that seemed to fit all those requirements: the Bilstein B16 Ride Control. It is based on their latest high-end coilover PSS10 with the difference that you cannot manually change the compression/rebound settings but it is specially setup in two preset damper positions for road use and sports use, with the control by way of 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.

Bilstein developed this kit partially for the Nissan GTR, but also offers similar kits for Porsches (called Damptronic in that case) and apparently tested this extensively on the Nürburgring Nordschleife.

It seemed to me a great compromise between having sufficient ride comfort and being able to enjoy the car on the track. Something else that convinced me were two positive reviews of two of my friends here on the forum, as well as test drives I did with both their cars:

*** Review - Bilstein B16/PSS10 Ride Control Coilover Suspension on E92 335i
Teaser: Bilstein Ride Control Suspension installed

I would like to take the opportunity here to thank both of them for their availability and the opportunity to test the suspension extensively. Thanks guys!!

How?

I got my kit used from a forum member who did not need it any more; if you're in the market for it, you can for example order it from Turner Motorsport: Turner Motorsport / Bilstein B16 Ride Control. The retail price is 3400 USD (!), although you can now get it for 2600 USD. In Europe you pay around 2000 EUR for a new set.

I had it installed at my usual garage, Daum Motorsport. The mechanical installation is rather straightforward, and the kit comes with a very comprehensive installation manual as well as all the parts you need to install it. Also, annexed to the manual is a TÜV certificate should you need it (such as in my case). Very methodical and practical!

The more difficult part of the installation is the cabling for the internal control module and switch, in particular as you have to run wires from each damper to the control unit in the cabin and install the control knob so that you can use it while driving. In the two above mentioned reviews, both had the knob installed in the ashtray, which I found a perfect solution. Taking power to the unit is simple - 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 pain - in particular as virtually every interior trim panel had to come out so the wires could be routed inside the OEM channels.

A few photos of the various parts of the complete suspension (front assembly, rear assembly, cabling etc.):

Before the installation - parts photos (1):


Before the installation - parts photos (2):


Before the installation - parts photos (3):


Before the installation - parts photos (4):


Before the installation - parts photos (5):


And here are some photos of how it looks installed (sorry for the dirt but they were taken quite some time after the installation…):

Front strut assembly:


Front strut assembly - a closer look:


Rear axle:


Rear axle (2):


Suspension button - behind the ashtray lid:


How the car looks (1):


How the car looks (2):


As you can see, it sits extremely low - although the Bilstein manual mentions a drop of 30mm over stock, it looks quite a bit more to my eyes. And bear in mind that the suspension is set to the highest ride setting possible.

Improvements?

When I first sat in the car and started to drive, I had the impression I was sitting in another car. So big was the difference! Not only you're sitting closer to the road itself (due to the lowering of the car), but you feel much more connected to it. The car feels much more settled, it only shrugs nonchalantly at normal turns and even if pushing it, there is very little body roll as compared to the stock suspension. The dampers also worked quite well at smoothing out ruts and crests; the only problem they had was with short ridges / bumps which were quite noticeable to the passengers. Still, for a considerably lower coilover, the ride comfort was still very much in evidence, even on less-than-ideal back roads.

When pressing the Bilstein button into "Sport" mode, the rebound damping rates seem to become noticeably stiffer, and you have the feeling it is even more glued to the road than before, with vertical movements of the car being even more reduced. During normal traffic conditions on public roads, even very fast corners leave the car totally unperturbed, so high is the mechanical grip. Actually, when first approaching a corner at high speed I kept thinking about what the car would do - but it just sailed around it like on rails, as if it was saying "well, if that's all, I can go to sleep again". I do not use the "Sport" mode so much during normal driving, however, as it makes the car slightly more nervous and a little too reactive to my taste.

The real test came when I took the car to the Nordschleife of the Nürburgring. Since its installation, I have done in total roundabout 100 laps with the Bilstein suspension in it. In summary it is far, far better than the OEM suspension, in that it gives you more confidence in the reaction of the car, its grip and the predictability, as well as making you more aware of weight transfer in corners as you're much more connected to the car. Gone is the often floaty sensation and the rather indirect body control of the stock suspension. In particular difficult sections like the Fuchsröhre that are a test for any suspension are far easier to negotiate, or the twists and turns of Hatzenbach.

Problems / disadvantages?

I have used the Bilstein suspension now for over a year, and there were unfortunately several problems with it.

Problem no. 1: Steering wheel sensor

After having the suspension installed and starting the car for the first time, a storm of warning lights popped up on the dash: DSC malfunction, active steering malfunction and several others that I do not remember right now. Also, the steering wheel was half-turned when the car drove straight, and the power steering was completely off.

What happened?

From what I understand after doing some research on the forums and speaking to BMW mechanics, the steering wheel sensor thought that the considerable lowering of the car was the sign of a serious malfunction of the car itself, and could not compensate for the difference in height. It apparently needs to be calibrated to the car's height (there is some margin, of course, but the monstrous lowering exceeded such margin) in order to be able to send its data on to the electronic assistance systems, power steering (or active steering in my case) included. As the signals were out of whack, the car shut down all those systems as they would otherwise rely on corrupted data.

What to do?

My shop could not solve the problem, as they did not have the necessary BMW systems in order to properly recalibrate the steering sensor. I therefor had to have it done at a BMW dealership, which set me back almost 600 EUR. Ouch!

Problem no. 2: Ride height

The car is just too low, even on the highest settings. Of course I did want it to be lower than the stock suspension (I did not even have the M suspension which is already 10mm lower), but it should not look totally slammed as it does now. Of course, optics are only one consideration (and are very subjective), but the practical disadvantages of the present ride height are considerable:
• Any entrance to a parking lot is problematic, as when going down a steep slope the front spoiler often gets into contact with the floor.
• If having to get towed away (which unfortunately happened to me a few weeks ago due to an oil leak), it can be very tricky to get it up on a tow truck as the front spoiler will be too low to negotiate the slope of the tow truck's trailer bed.
• The spring travel is so reduced that when driving faster over harsh bumps or potholes, the wheel often strikes through the spring travel and connects directly with the strut assembly and chassis. In the long run, that is good neither for the tires themselves (in particular 19" ones with their reduced diameter), nor for the car as a whole.

Here are a few photos in order to illustrate the ride height:

On the Nürburgring / entrance to the Karussell (1):


On the Nürburgring / in the Karussell (2):

On the Nürburgring / in the Karussell (3):


It seems to me - and my garage confirmed this - that the springs are far too weak for the car, resulting in the weight of the car compressing the springs so much that even at the highest setting it sits far too low, and has too little spring travel left. Most likely this is a result of Bilstein offering the identical kit for all 3 series, be it a 316i E90 or a 335i E93 - which all differ greatly in weight. In the German car forums I encountered a few other people with the same problem.

I tried to partially solve this problem by installing the "bad roads package" for the front axle (the rear will not fit due to the Bilstein coilover).

Bad Roads Package (front axle):


However, the problem remains as now I can set the car a bit higher (not much, though) on the front, but the rear end remains too low - which does not look well at all. I therefor left it more or less on the same setting as before.

Problem no. 3: Dampers / build quality

After a few months of driving the car, the front dampers started to make clunking noises which were in particular audible at low speeds. They also seemed to get worse when the car was driven hard (e.g. on the Nürburgring). A search in other BMW forums revealed that this was not an isolated case but actually a systematic problem with this suspension. However, Bilstein seemed to be aware of this, replacing the dampers without costs.

Unfortunately and to my disappointment, after running for a few months with new dampers, the same problem recurred and these new dampers also started making the same noises again. Not really what I expected of a so-called high-end suspension system; and even though Bilstein may again replace the faulty dampers, the removal and re-installation always costs a few hundred EUR, which I am reluctant to incur again and again.

Summary

The suspension is indeed quite good and a noticeable improvement over the stock suspension. I still enjoy it quite a lot, and (at least if you like your suspension on the sportive side) there is no problem driving it on a daily basis. Unfortunately these positive points are counterbalanced by the two above mentioned - and to me, serious - problems that I am unwilling to accept from a suspension at that price. Also, I have driven the PSS10 (i.e. the same suspension but with the possibility of manual adjustment of compression+rebound in 10 steps) and it seemed firmer to me.

It is likely that next spring I will replace the Bilstein with the Road & Track coilover from Öhlins, which a few people of this forum are also running (two of them being in England, which is great to have additional feedback) and that should not have the drawbacks of my current setup.

Alpina_B3_Lux
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Audi R8 V10; sold: BMW 335i