Fun With Air Ride – Part 4

So, where were we?  Ah, yes, the best part – Results Time!

Ride Height:  The car rides at nearly any height I want, from too low to ridiculously high.  The lower limit is governed by the bump stops on the shock absorbers.  The upper limit is governed by the maximum extended length of the shock absorbers.  At the lowest levels, steering is definitely affected and severely limited.  This is to be expected, since the tires “tuck” inside the wheel arches, and it’s a close fit.  The preset ride height offers less than an inch of wheel gap front and rear.  The headlight aim is not much different from the factory setting, since the rake of the vehicle is the same as it was on the factory suspension.

Ride Quality:  On the freeway, SMOOTH.  Smooth as glass. Smooth, like riding on a pool table. Does not track the drainage grooves, tracks straight and true, even in the roughest lanes.  On the streets, imperfections can definitely be felt, but without undue harshness.  Not bad at all, especially since the wheel sizing is +2, and he sidewall is only a 35% aspect ratio. The drastic reduction in the unsprung weight (over 20 pounds at each corner) definitely helps here. Acceleration and braking are also aided by the reduced inertia from reducing the reciprocating mass.  There is very little squat on acceleration, and the car simply “hooks up” and launches forward. There is no sign of the tires losing traction (maybe thanks to the traction control system, or the vehicle stability program, but I haven’t detected either of these systems activating under any acceleration, either in a straight line or accelerating while negotiating a turn or curve.  The Incident Log also shows no indication that my traction has been electronically assisted.  The overall feel on the streets is extremely responsive, if slightly less controlled and a little more “nervous” than my E39 BMW 540i. I will continue to adjust the damping of the shock absorbers while enjoying the instant response to steering inputs.

Handling:  Radically different. The handling is very stable as the limits are approached. There is a slight oversteer, with no “snap” or sudden loss of control. Cornering is composed and confident, it changes direction very quickly, and it forgives moderate levels of driver error when cornering using improper technique. However, when using proper cornering technique, this car grips like its life depended on it. Body roll has been reduced by less than half, and the “seat-of-the-pants” feel is much more stable, even though the driver’s seat is not especially sporty or supportive for this kind of spirited driving. There is a drastic improvement in the available acceleration exiting a corner, but at this time I’m not able to determine if this is caused by the improved ability to “plant” the outside rear tire, or simply by the reduced reciprocating mass of the wheels, or by the ability to carry more speed through the corner, therefore operating in a more favorable part of the powerband.  It’s likely that all of these are contributing factors. There is a very endearing quality inherent in some cars, notably the larger Audi S-Line cars, where the car feels as if it “shrinks around the driver.” This gives the car the feel of a smaller, much more nimble and agile device when driven aggressively.  This Caddy is already fairly small, so when it “shrinks around the driver,” it feels like a slot car – a beautiful, confidence-inspiring feeling.

Was it all worth it? Definitely. My OCD can now move on to something else, as I hereby declare this project FINISHED. Of course there will be tinkering…

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