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Old 01-11-2006, 02:36 PM
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xntrik xntrik is offline
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Quote:
Originally Posted by Triaged
I take it you are talking about anti-dive in the front end?...or are you talking about anti-lift at the back end?

Care to explain any of this to me? Why would the nose diving cause the rear tires to slide? How much anti-dive are we talking about?

I apologize for the delay in answering. I will try to keep it short and simple.

BOTH,

Think how it would be if there were no springs but solid bars. No lift, no dive, no squat. But we must compromise.

If you ever have the opportunity to see pictures of a Fox or SN-95 Mustang doing a maximum effort stop (in lots of magazines) and then the new BMW video ad showing the Beemer stopping..... you will see that the Mustang pitches nose down 3-4 inches and the rear rises 3-4 inches and the Beemer stays almost level to maybe an inch.

Front and rear geometry are fixed by design, and by nature are a compromise of the lift and dive (squat) by their design. What works very well for drag launches is poor for stopping ability, etc.

When a front end nose dives the weight of the vehicle is being removed from the wheels on each end. Actually if the front end did not dive, the center of gravity would stay higher and there would be more downforce on the front tires. If during a stop the front springs were suddenly solid... there would be more downforce on the tires.

When the rear squats on launch, the weight bias is being removed from the rear wheels. Either way a stiffer spring or better geometry would improve the traction.

Suprisingly shorter ladder bars are are good for the rear. They lift the rear on launch, planting the rear tires, and when stopping, they are short enough to try to "pull" the rear of the vehicle downward when braking. But ladder bars are not the best for either situation and have other handling deficiencies.

When the front end drops and the rear rises during a stop, the rear tires are especially unloaded and traction suffers. Even with sticky rubber there is not enough weight on the contact patch to maintain reasonable traction.

Most stopping ability is determined by the tires themselves, by contact patch size and rubber compound. Skinny front runners are poor stoppers. If you have ever driven a drag race car on the street you could appreciate the deficiencies of the suspension settings.

Me? I drive a 5 series Beemer every day.
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