1994-2002 [Subscribe to Daily Digest] |
Braking hard from 100 mph is a _very_ stressful thing and many small imbalances that would not show up at lower speeds will be found at higher speeds.
One thing to note is that Saab brake system allows unequal brake forces at different wheels. Under a very hard stop, I am pretty sure the algorithum will increase the brake force to the limit of traction at each wheel, but this will not necessarily be balanced from left to right. If you have more braking force on the left than the right, the vehicle will yaw in that direction. That could be your issue. Also if the let and right wheels are seeing unequal braking forces , the compliant steering effects willnot be equal and opposite and the car will pull in one direction or another. If this effect adds or subtracts from the imbalance of brake forces depends on the suspension designers philosophy for split mu surfaces. Some feel teh car should naturally want to go straight when braking on split mu, some argue it should pull to the higher mu side. Mot sure about the 9-3, but I know the 9-5 was designed using the former. The imbalance could be due to small differences in the road, or suspension geometry/compliance.
If your abs sensors were wired backwards, which I have never seen, you would be more likely to lock a wheel. Since you did not mention this I assume it was not the case.
More likely though you experienced some oversteer while braking hard. Under hard braking forces the front tires will be loaded much more than the rear tires. This will increase the cornering stiffness of the front tires. The cornering stiffness of the rear tires will decrease as well since they are lightly loaded. That combination starts you heading in the oversteer direction. If you brake hard enough at a high enough speed and your vehicle is dynamically oversteer, you can exceed the critical speed of the vehicle for the conditions and it will get a bit scary to drive. My bet is on that, but I wasn't there.
A word to the wise, stay away from large disturbances at high speeds. (don't brake / steer harder than you have to.) It is just plain safer.
-Joe
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