1985-1998 [Subscribe to Daily Digest] |
The instructions with the SAS bars are very true. Increasing the size of the bar on one end adversely affects that end while positively affecting the other.
Image what is happening when you throw your Aero around a tight right-hand corner. Torsion occurs on both ends of the bar, and this torsion results in a downward pressure on the left wheel and upward on the right. As the suspension rolls downward on the right, that end of the bar is twisting upward causing it to try to force the wheel downward. The right side is just the opposite: The bar is twisting downward and the torsion of the bar is trying to pull that wheel upward.
Added pressure on the outside wheel does not help traction, nor does lifting the wheel on the inside. But while these adverse forces occur, it is keeping the *other* end of the car more neatly in place, and the synergistic effect of two bars acting together creates a better-handling car.
If you recall the old days, most American cars only had front bars fitted. Understeer was and is consider a much safer handling characteristic than oversteer, which can be very dangerous in the wrong hands. Understeering toward a tree will likely result in hitting the tree from the front, but oversteering into it might put the tree at the driver or passenger door, which is not a good thing. Ten or fifteen years ago Porsche was sued when some yoyo oversteered into another car while attempting to negotiate a corner at an outragious speed. If I recall, Porsche lost the case since their cars traditionally tended to oversteer and little or no attempt was made to educate the owner of this characteristic or insure that they could negotiate it competently. This is similar to the guy who shoved his hand into his mower's deck to clean it out, but forgot to turn the engine off first, costing him some fingers. He sued the company because they didn't warn him not to...well, you get it. He won the case and got a hefty settlement. Anyway, I digress. Basically, oversteer can be a favorable handling characteristic in the hands of an accomplished driver, but deadly when piloted by a careless idiot.
Cars with standard front-only bars often had optional suspensions (e.g., Chevrolet's famous F-41) with small rear bars to decrease understeer somewhat, though never totally. In the case of our Saabs with dramatic front weight bias, it can work with two bars of equal thickness, perhaps even a slightly thicker rear bar, as they will understeer anyway. Increasing the rear bar thickness without a like change in the front is a very risky proposition, however. An car that typically understeers at normal speeds may switch to oversteer at higher speeds, during quick transients, or other conditions--and entering that territory may spell disaster for the driver not acquainted with that behavior.
posted by 68.11.251...
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