Dinan Stage 1 - Stage 2 - Front sway bar

[kitw]

I long resisted getting the Dinan front sway bar, since I figured it would make my car understeer. For those of you that don't know, a sway bar resists body roll by connecting the two sides of the suspension together, without compromising ride quality, like stiffer springs could. When a bump hits both wheels, the sway bar rotates, not resisting suspension movement at all, given that it is properly designed. When the car rolls and one side compresses and the other extends due to body roll, the sway bar is twisted, giving an effectively stiffer spring rate for that side of the car. By increasing weight transfer to the outside, body roll is reduced. The M3 has sway bars front and rear.

The E93 M3 uses a 28mm bar, but it is only the arms that are 28mm, the center section is 26mm, just like the E90/E92 bar. Both are lightweight hollow sway bars.

The Dinan front sway bar is 28.5mm. It doesn't sound like much more thickness (less than 10%) but it is significantly stiffer because it's solid. It's a big beefy piece. Installation is easy and Dinan even uses OEM BMW mounts from another car. I was wary of the solid bushings, I hate that most poly bushing squeak, but Dinan uses a self lubricating poly bushing, so hopefully it won't squeak. (They also include a high quality waterproof grease.)

I went one step further, and wrapped the bar in teflon tape (like you'd use to seal a plumbing fixture). Between that, the grease and the self lubricating bushing, hopefully it won't squeak.

Installation was very straight forward, drop the aluminum underpanel, (8mm screws, 10mm nuts and 16mm nuts), undo the endlinks (16mm nuts/17mm on the other) and then drop the stock brackets containing the rubber bushings (13mm nut and 10mm nut on driver's side). Installation is the reverse. Took about an hour, a good shop can do it in 1/2 that. Note that the rear sway bar is a huge pain and Dinan doesn't make one for that reason.

So, I thought that this bar was going to be a compromise and that the car would end up understeering a lot. I am running a decent amount of negative camber up front, -1.8 / -1.9 with the pins out and Dinan Stage 1 springs, which lower about 0.6" front and rear.

I was very pleasantly surprised. Body roll is reduced quite a bit, turn in feels more sure and the car takes a set more quickly. It is slightly less tolerant of mid corner bumps, but not hugely so. I was very surprised to find that there is very little additional understeer on the street. It makes high speed corners feel more stable and there is still ample power to kick the tail out around slow speed corners, in which the m3 feels like a big heavy pig anyway. (remember, I also own a Lotus Elise, which is just over half the weight of the M3)

I'm sure on a race track or in an AutoX setting, you're going to get more push, as the M3 is a little bit pushy from the factory. But, on the street, it makes the car feel more confident with better, more crisp turn in. I definitely like it and don't see any downside, other than the cost. (and the weight of the bar, but at less than 10 lbs it's not a huge difference either way)

In comparison to the RD sport sway bars, the RD Sport bars are a decent amount larger, 30.5mm, although they are also hollow, so lighter. I suspect the front is pretty similar in stiffness to the Dinan bar, since the Dinan bar is solid. The Dinan bar is the price of both RD Sport sway bars, although it's easy to DIY, (most shops charge $300+ for a rear sway bar on an E9x car!)

I've very pleased with the bar and since I haven't seen many reviews of people who've gone to through the stages of Dinan's suspension offerings separately, I thought I'd share. The Camber plates are going in soon.

[mexicanmike]

Nice review and short explanations!!! Good stuff.

[klammer]

Nice review and a good explanation of the swaybars pros and cons. Have to completely agree with the assessments and with the camber plates, understeer is still there but better at the track. I did stg. 3 all at once so like to hear how each individual piece affects handling. Looking forward to the review on the plates.