Some questions.

[Kraven868]

I starting to design a car so naturally I have a lot of questions. I am planning on using 5 inches of ground clearance but I don’t know if there are any regulations pertaining to how much clearance is required. I will use a unequal length double a-arm design for the front and rear with coilovers. I am planning on a 100 inch wheelbase with an overall width of 75 inches. I want to use 13 inch wide wheels in rear with 10 inch wide wheels in front.
Is 5 inches of ground clearance sufficient for daily driving around town sometimes over bad roads? How much jounce and bounce is required because I currently don’t have much room between my tires and my wheel wells. I want the car to have tight handling even if I must sacrifice some ride quality. I was also wondering if anyone knew of some companies that supply universal knuckles?

 

[GregLocock]

I starting to design a car so naturally I have a lot of questions. I am planning on using 5 inches of ground clearance but I don’t know if there are any regulations pertaining to how much clearance is required.

That depends on your jurisdiction. 5 inches sounds a bit marginal, 6 is safer.

Is 5 inches of ground clearance sufficient for daily driving around town sometimes over bad roads?

Depends what you mean by bad roads. You need to consider ramp angles as well, especially if you have an air dam at the front.

How much jounce and bounce is required because I currently don’t have much room between my tires and my wheel wells.

For normal road use at least 2 inches, and preferably 3 inches of jounce and at least 1 inch and preferably 4 inches of rebound, from the normal driving load.

The more wheel travel you have the less compromised your shock and spring tuning will be, but your suspesnion geoetry will have to be more accurate as well. As Colin Chapman said, any suspension can be made to work if you don't let it move.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Kraven868]

What I mean by bad roads is paved roads that are somewhat bumpy with an occasional pothole, basic city driving. I will be using an air dam in front and have considered what angles of ramps would cause the front end to rub. How steep of inclines should I take into consideration to safely traverse town. I am looking for handling almost comparable to that of something like a Ferrari and realize that the ride will be compromised as well as having to take some driveways carefully and at angles to avoid drag the front end up the concrete. I wanted to use 5 inches of ground clearance as long as 5 inches is sufficient to make it over speed bumps without getting high centered. I wanted to keep the clearance between the wheel wells and the tires at a minimum to keep an aggressive look by having the wheel wells look full. Currently my design has only 2 inches between the top of the tire and the bottom of the wheel well, will I have to increase this distance to allow for more travel or could I keep ride quality to at least that of a corvette with less than 2 inches of travel? How much jounce and bounce would be found on a Ferrari or even a small high performance import? I am also having difficulty finding accurate dimensions of ford engines and other parts to determine fit in my design.