Front Suspension

Discussion in '2005 - 2009 Specific Tech' started by Mr44666, Jan 5, 2004.

  1. A nose heavy car will understeer while a tail heavy car will over steer. Toyota MR2s, Acura NSXs, and early Porches are know for this tail happy dynamic.

    To explain it, think of the car a pendulum with the front of the car hanging from the ceiling.

    If the rear of the car is heavy, then the car will tend to rotate easily about the front axis. Think of it as a string with a weight on the end of it.

    If the front of the car is heavy, then the car will resist rotation about its front axis. Think of a string with no weight attached.

    An easy way to check this out is with a hammer. Take the hammer by the handle and hold if horzontal to the floor. It will tend to rotate downward quite easily. Now take the opposite end of it and do the same thing. It will be easier to hold it horizontal.

    When a car goes into a turn at speed the car is rotating around the center between the front wheels. If the force produced by this change in accelerationis greater that the frictional force of the rear, tires then the car spins out. If the car is balanced to the rear this lateral force can easily overcome the frictional force of the tire. The frictional force is the weight on the tire multiplied by the coefficient of friction. The coefficient is variable depending on the type of tire, the road, temperature, etc and is always less than 1.

    Hope this helps.
  2. Hmm, Hot Rod seems to take a somewhat oversimplistic take on weight distribution, handling balance and rear tire needs.

    For pure handling purposes, something around 50/50 is in fact an ideal balance, maybe even a bit of rearward bias. In terms of pure straight line traction, you basically want the most weight over the driven wheels, where ever they might be. Thus for a RWD car like the Mustang, the more relative mass pressing the driven rear tires down onto the tarmac, the better. That's one reason why Porche 911s with their distinct rear weight bias can be so quick off the line, they waste little energy creating tire smoke, simply hunkering down, digging in and shooting off. Yes, they do have bigger rear tires, but more on that later. And anyways, overall, steady state cornering balanced is far more influenced by suspension design and tuning anyway, particularly sway bar relative sizing.

    Where larger tires do start making sense is when the cumulative forces, be they cornering, accelerating or braking, start overwhelming a tire's contact patch adhesion capabilities, i.e., high-torque Mustang. But the stock and optional tires aren't wimpy here by any means and what small gain might be realized through wider rear tires has to be balanced by increased cost and complexities of fielding different wheel/tire sizes, especially for a car at Mustang's price point.

    I suspect that instead, Ford will dial in the sway bars towards a bit of understeer, enough to keep the ham footed from spinning themselves off into the woods backwards while not too much to make the Mustang a plowing pig for those more adept at wheel and pedal.

    But vehicle handling dynamics is an excedingly complex interplay of a huge number of variables (suspension design, tuning, weight and balance, tires size and design, road surface quality and conditions, etc.), far more so than the relatively simple interplay for dragstrip action, which is what the Hot Rod folks basically specialize in.
  3. rhumbline
    I agree, 50/50 is perfect for the enthusiasts, and I expect the SVT version will probably hit that mark with ease.
  4. Hmmm, as an example, the Ferrari 575 Maranello (front engine, rear drive) has a "perfect" 50/50 weigth distribution, but wears 225/40 ZR18 in the front and 295/35 ZR18 in the rear--ie much wider tires on the rear.

    But the Mustang wears P255/45R18 on 18x9 wheels ON ALL FOURS.

    Keep in mind, again, that the quote comes from Ford, not Hot Rod. The people at Hot Rod are not total idiots, either.
  5. how much better is the 05 supposed to handle as compared to the 99-04's? my dads getting an 05, and selling his 89, and was wondering how it woudl handle compared to other stangs.
  6. It would seem, based on the engineer's targets and the type of hardware being used, that the new one should blow the old one out of the water. If it doesn't, Ford is going to look pretty dumb.