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All,
My experience
Out of the box, the car was fine. Even wear on the tires, handled nicely, rode well ('02 Aero Wagon). Then I installed the rolling out load floor. Then I piled on, from time to time, with pavers and floor tiles. Like gently driving at or near the bump stops.
Fast forward to end-of-warranty: Car was an inch low, camber was at 2 1/2 degrees, and the tire wear was an issue. Had the SAAAB Store in Tampa install shims (I gave 'em 4 thick, 2 thin, and they used 'em all), where they brought the car to mid-Aero spec (about 1 1/2 degrees camber). All was well enough, except that the car was low. And with the towing dolly (and 9-3SCV) attached and the birds in the wagon, it looked *really low*. And the shocks were at the age (75K) that folks begin to have problems.
I got excited about load-leveling rear suspension, but in the end cheaped out and vowed to move bricks and tiles on a trailer instead, and fit in new shocks and springs (and all the rubber parts that touch the shock).
Car is now an inch higher in the back, and the camber brought itself to middle setting, standard suspension (0.9 degrees). Car handles fine. The diminished camber setting hasn't changed the handling (it still plows through corners as compared to the 9-3 ;-)).
Now it may be that the standard springs don't take a set when fully compressed, but the Aero springs definitely do. This is bad design, plain and simple.
Spring design 101: add coils until it doesn't take a set, fully compressed, increase the wire guage and spring diameter to get the right spring constant. (increasing wire gauge decreases the total deflection necessary to cause a set, increasing the number of coils decreases the spring constant, so yeah, the two requirements work against each other).
One more trick: Build the spring "too long" and compress it to prestrain the coils. If you do it right, the spring won't set further. What happens is the first time the spring takes a set, when it relaxes there's a residual stress that is built into the spring. Then, when you compress it back, it doesn't cause further permanent deflection.
Anyway, GM/Saab didn't attend the Spring 101 course, or if they did, they chose to ignore the lessons. Inexplicable, but then we also have snapping 9-3 springs, so ach du lieber, der Opelwagenschpringgemacher must have a bug in their program.
To answer the question: the best solution is the self leveling suspension. Second best is to have new springs made, if you can. A good spring designer can take a caliper to your existing spring and build one that has the same stiffness, the proper rest length to restore the suspension to the nominal height.
Now the current WIS seems not to have the suspension settings. I have a page from an earlier version that someone sent me, which puts the "nominal height" at 610 mm (24"). I've never seen that. I get 23" with new springs. The WIS doesn't always have correct dimensions. and (Just try getting your hands on a 28mm thick front brake rotor. And if you do, good luck getting the pads over it. 25mm is the correct dimension. Pisses me off b/c I scrapped a set of rotors that had 23.something thickness - more than half the life left in them if you are counting down from 25 to 22, but next to nothing if you count down from 28... but I digress)
Anyway, if you're at 22, judging from my experience, new springs will give you an extra inch of wheel travel, and according to my table, bring the camber down by 0.2 to 0.3 degrees. More than that, and you need shims. And you probably will need shims.
And don't neglect the front camber. The SAAAB Store brings that into spec by slightly grinding on the upper strut mounting hole. That way they can rotate the steering knuckle to bring camber into spec. They prefer this to "camber bolts" which are essentially undersized bolts with an eccentric, fattened center part, which allows the steering knuckle to be rotated slightly. They say they don't get adequate clamping force from the smaller threaded portion of the bolt.
posted by 24.165.154...
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