Suspension For The Real WorldI'm in the process of buying a suspension for my '99 EK9 Civic hatchback. I've done a full Type-R swap (subframe, five-lug, blah, blah) and am looking at Progress. I remember you used this suspension on your original Civic Si project car, but couldn't find the suspension installment in my piles of old magazines. I'm hoping you'll share your memories of that car and suspension. Ed at Progress has been very helpful, but I am slightly skeptical about the spring rates he is quoting (450lb/in. front, 650lb/in. rear), even though the Series-1 coilover set-up will have custom valving for those springs.
I have a pretty high tolerance for a firm ride, but my VW background has given me a good idea of the difference between too much, not enough, track, autocross, street, and-most importantly-fun (the latter sorely lacking recently).
Reading your column has a lot to do with where I spend my money. I stopped listening to 'experts' (read salespeople, e-gurus, and 'that guy'). My local SCCA chapter has also been helpful, but your background in this unique situation would be really appreciated. I'm looking for a car biased toward aggressive street driving with some autocross thrown in for good measure. I also have an 80-mile commute to consider, though. It will be primarily street driving and I do want to retain some of the 'slop' that seems to be needed in a street car. It seems to me that too much suspension on a street car not only loosens fillings (especially on the roads here in PA) but also hurts handling on rough pavement.Bob FowlerSomewhere near Philly
The first concern with making a street car handle well is simply firming up the springs and dampers to keep body motions under control when you start throwing big speeds and big cornering loads at it. Second, with a front-drive car, you also want to reduce the car's natural understeer. That means shifting cornering loads to the rear tires by making the rear proportionally stiffer than the front (with some combination of springs, dampers and anti-roll bars). Lowering the car to get the center of gravity down is a distant third in importance. Lowering will only help if you've done the first two things well enough that the suspension doesn't bottom out with the lowered car's reduced travel. Keep these priorities in mind when making your suspension mods.
Your concerns about balancing street and track performance are well founded, but don't assume your VW experience will translate directly into the Honda world without a little math. The fundamental difference between the strut suspension on your VW and the double wishbones on your Civic is the motion ratio between the spring and the wheel. On a strut, the spring acts directly on the hub, so it moves with the wheel in a nearly perfect 1:1 relationship. For every inch the wheel moves, the spring will compress about an inch. That means a 300lb/in spring acts like a 300lb/in spring. How nice.
On the Civic, and most double-wishbone cars, the spring acts on the lower control arm somewhere between the outer ball joint (which moves with the wheel) and the inner control arm bushing (which doesn't). On the front of your Civic, one inch of wheel motion causes only 0.7 inches of spring travel (according to Ed at Progress, who has already measured this, unlike me). The spring rate obeys this same 0.7:1 relationship, so a 300lb/in spring only acts like a 210lb/in spring at the wheel.
Back in the November '99 issue (have you checked behind the toilet?), we installed the first-generation Progress coilover suspension. At the time, they were running 350lb/in. springs up front and 250lb/in. in the rear and we marveled at the smooth ride. In retrospect, we shouldn't have been surprised. With about a 0.7 motion ratio in the front, and around 0.75 in the rear, the actual wheel rates were only 245 front and 188 rear. It's no mystery why the ride was so smooth.