Control to Match Our Grip

Update by Per Schroeder to the BMW 325it project car
Sep 27, 2011

The car has been lowered about one inch, front and rear.
The entire suspension swap took about three hours. (and yes, there are jack stands under the car.)
The front suspension uses 325 lb./in. springs.
The rear suspension uses Ground Control's proprietary rear spring and perch design.

We’re going to put some serious miles on this combination and see how it lasts for the long haul.

With the addition of the nice large (and grippy) Yokohamas, our BMW wagon gained a slightly odd feeling at the limit of adhesion. The aging stock suspension (not even BMW’s sport option) was simply not up to the task of controlling the motions of the wheel and tire package, especially at higher speeds.

Of course, we could bolt on a stupidly-stiff suspension package that would be totally at home on the track—but our ride to work would simply suck as a result. We decided to find the best of both worlds.

Koni’s ( line of FSD shock absorbers are designed for stock and mild aftermarket springs and their special valving works to improve comfort over high shock speed impacts (like expansion joints) while giving better control during normal transitional maneuvers. They’re not designed for stiff or really short springs as the valving is not designed to handle the rates.

Instead of a basic “sport” spring, we paired them with a matched set of Ground Control ( coilovers, camber plates and rear upper shock mounts. Surprisingly—we’re getting our cake and eating it too by being very careful with the spring rates. We chose 325 lb./in. front springs and for the rear, Ground Control has BMW-specific rear springs that are wound to fit in the stock control arm location. Ours had a rate of 430 lbs.-in, which is a nice balance of comfort and handling with the FSD shock absorbers.

Coupled with Ground Control’s optional urethane-isolated camber plates and upper shock mounts, the ride comfort is actually better than stock. We’re noticing huge improvements over expansion joints and lane marking dots, while still giving great roll and dive control during hard cornering.

We’re going to put some serious miles on this combination and see how it lasts for the long haul. We’re in love so far though!

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View comments on the GRM forums
spritedriver28 New Reader
9/27/11 11:53 a.m.

I've always thought these BMW wagons looked frumpy if not downright ugly, but between the wheels and the lowering this one looks great! Well done!

Shaun GRM+ Memberand HalfDork
9/28/11 11:42 a.m.

I love wagons, and like spritedriver28, this era of 3 series have never done anything for me (unlike the 5 series wagons). That just looks mean!

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