BMW markets its cars as the Ultimate Driving Machines, and the 3 series is the model that has probably made the largest contribution to that claim. Most reviewers agree that the e90 is the last best of the 3-series drivers’ cars, and more than a few refer to the 335d as the “diesel M3.” The 335d certainly is unique: fast and frugal. And, with the right upgrades, it is a great driver’s car.
However, 335ds are all over 10 years old, and many have over 100K miles on them. Suspension components wear, causing ride and handling to deteriorate. In this article we’ll review what you might consider replacing in your 335d to bring the ride and handling back to, or better than, new.
Background
The e90 platform retained some great features from earlier cars that help create an excellent driving experience: most important, hydraulic steering. The F30 successor to the e90 has been criticized for its numb steering. The e90 steering, although heavy, transmits a lot of road feel to the steering wheel.
Unfortunately, one “feature” that was added with the launch of the e90 platform were run flat tires. These tires present a dilemma to enthusiasts: live with the weight, harsher ride, and short tread life, or take a risk with non-run flats and sacrifice most of your trunk space to a spare tire. Neither seem to be good options. Our project BMW has retained the run flats (for now) but the suspension upgrades we’ve made has helped minimize the tires’ disadvantages. More on that in a moment. First, let’s look at replacing control arms.
Control Arms
BMWs are notorious for wearing out control arms. Some maintenance experts recommend changing them every 40K miles. Although that may seem excessive, they do wear out faster than control arms on other cars. Why? Big, heavy wheels and run flat tires don’t help; they transmit a lot of shock and road irregularities to the control arm bushings. And bushings may be softer to compensate for the hard tires.
Fortunately, replacement kits are not prohibitively expensive. Front kits cost less than $300, rear less than $200.
Replacing sway bar links while you’re at it is a good idea, as those bushings wear quickly, and make noise when they do. And they’re inexpensive.
The M3 Upgrade
A fortunate quirk of e90 platform cars with RWD like the 335d is that you can upgrade your suspension with M3 control arms. These arms cost about $100 more than the stock arms (front and rear) and in the rear replace stamped steel arms with aluminum. They also replace rubber bushings with spherical bearings in some locations, dramatically improving steering response and feel. Bearings don’t deflect under hard cornering loads, keeping geometry intact.
Alignment
BMWs are both sensitive to alignment, and also can be difficult to align because there are so many adjustments. But getting it right is a good idea. Here’s our project car’s report.
This car could use a couple tweaks to equalize the front left and right camber and perhaps reduce the rear camber a bit, even though it is within spec.
Here is our project car Alignment Report.
Dampers
BMWs stock dampers are from ZF/Sachs. They don’t provide great ride control and tend to wear fairly quickly. By 60K miles they’re usually pretty much done. Bilsteins, either HDs or sports) are the preferred upgrade for many BMW drivers. However, on our project car we went with Koni Special Actives. These dampers have Konis’s Frequency Selective Damping, making them softer over bumps and potholes, firmer in cornering. They do an excellent job of managing the heavier wheel/tire setups common to these cars, and still provide dramatically improved handling.
The Result
When we purchased our project car with 48K miles on it the ride and handling were disappointing. Noise from worn sway bar bushings, floaty ride, crashing over large bumps. BMW techs often comment that there are lots of cars out there riding around on worn arms and suspension. Since the wear happens over time they don’t realize how much the ride and handling has deteriorated.
The new arms and bushings along with the Koni Special Actives have transformed the car into the Ultimate Driving Machine as advertised. Turn-in is far improved, understeer is reduced, and the car handles our poor New England roads much better than before. The overall investment is significant, but worth it if you want to keep your 335d driving like new well into its second decade.
