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Author Topic:   fwd questions
Dirt Maniac

Total posts: 199
posted December 14, 2002 11:24 PM
Okay, I need some advice. I'm going to build a front wheel drive stockcar. I need some input on how to make one handle properly. I need generic info which could apply to any car. Weight distribution, front to rear, right to left, rear braking, some thoughts on springs, etc. All assistance will be appreciated. Thanks SLEEPY
Dirt Roller

Total posts: 10
posted December 15, 2002 10:58 PM
It is hard to give specifics on this without knowing what type of car it is, what your rules are, and the layout of the tracks you plan to compete at. I do not have practical experience with FWD racecars; but, as a motorsports engineering student, I have put a decent amount of thought into it the subject. FWD cars inherently want to understeer. Basically the front tires do not have as much traction in the lateral direction, because they are using some of there available traction in the longitudinal direction. For the same reason the rear tires have too much lateral traction. This is a problem that can be a bit difficult to overcome. I have some theories. First, use very stiff springs in the back. This keeps more weight on the front tires where it is needed. The more weight on a tire the more traction it has available. The next part of my theory might sound a little strange. I think that you should use poor tires in the back. In the corners, you want the rear tires not to get good traction so that the back will come around. This is a situation where I believe that a hard tire with a small patch on the ground would be effective. Weight placement is a situation that I am conflicted on. You want as much weight on the front tires, as I explained, but at the same time weight in the rear helps bring the car around in the corner. The best answer will be a compromise.

As I said this is all theory. With more details about the car andthe track configuration, I could provide better information. Unfortunately, I don't check this website very often. Feel free to e-mail me if you want. I have plans to write an article on Traction and Traction Circles for my website in the near future. It might help clear some of this up.

Nate Stevens

[This message has been edited by (edited December 15, 2002).]

Dirt Full Roller

Total posts: 69
posted December 16, 2002 08:10 PM
i ran a fwd car the looser the faster i used a chain to get car as loose as i could . put chain to floor above the left rear and weld or bolt on to the left rear at the spring bottom and make it tight on flat surface, stiff spring on right rear car will get loose win it hit role center waight is no good in fwd all the waight is on drive wheels . also if your car can ajust the toe on the rear make the car steer with the back toe out the r/r as much as poss. when fwd car is loose you only have to turn steer wheel a couple inches and you hold down the gas all the way around the track. i ran on a 1/4 mile and a 1/3 mile both the same result . very fast with small motor. hope this helps. good luck


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