handling issue on dirt

[GoneDirt]

I'm fairly new to the legends car and i run 3/8 dirt track, I am having issue's with being loose out of the corners to the point i either spin out or bounce off the wall, I have tried a hard and soft spring on the rr but it didn't effect exiting. I at a loss of what the adjust.

[VMS Motorsports]

What are you running for tire pressures and spring rates?

[Racinjj]

Yep, what Jim asked.  Also what cross weight are you running, it makes a huge difference with these cars?  If you want consistent handling you must scale your car.

[VMS Motorsports]

P.M'ed,
Let me know if you need anything else,
Jim

[GoneDirt]

Thanks to every one  for the input,  made a few changes to the cross and tire pressures and had a good run, finished 4th out of 11.

[VMS Motorsports]

Sounds good, congratulations

[justfreaky]

Congratulations!!!
Keep up the good work!
I told you there were awesome people here on the site!!!

Steve

[justfreaky]

Can you guys share the info that you gave him?  Tire pressures for dirt?  RR with bead lock tire pressure?  Cross?  Can some one explain calculating bite?

Sent you a PM.

Calculating side bite:

The formula for lateral acceleration is LA=V2/32R
The formula for finding the amount of weight transfer is  Transfer=W x CGH x G
                                                                                                                                                        TW
What the hell does that mean! 
It has to with Lateral Acceleration and Weight Transfer.

Lateral acceleration is the sideways force which a car generates in a turn. It is a measurement of the maximum amount of cornering force a car will generate.
Lateral acceleration is dependant on two things: velocity (speed) and the radius of the turn.
Lateral Acceleration is the Velocity squared (expressed in feet per second) Divided by the Radius Of The Turn x (times) 32.

Example: 
 A race car is tested and found to corner at .85 G's. One G equals the weight of the car, so this means that the car's suspension system can corner hard enough to withstand a sideways force equaling 85% of the car's total weight and still maitain tire contact with the track. The more G's of lateral acceleration the car can produce under maximum cornering, the greater cornering power of the car.
 
 A reasonable lateral acceleration for a Legends (or Dwarf) Car would be .85-G to 1.0-G for a paved track car, and .75-G to .85-G for a dirt car.

 Once the later acceleration for a particular car set up is known, the actual pounds of weight a car is transferring from the inside wheels to the outside wheels during maximum cornering can be calculated.
 There are three major factors which affect weight transfer: The car's weight, center of gravity height and it's track width. (See formula for finding weight transfer.)
 
 In other words, the amount of weight transfer in pounds eqauls the car weight (expressed in pounds) times the center of gravity height (expressed in inches) times the lateral force coefficient (expressed in G's) all divided by the car's track width (expressed in inches).


 References used for the above information come from the "Automotive Math Handbook" by Forbes Aird and "Dwarf Car Technology" by Steve Smith.
Check them out... Both are excellent books. Obviously, there is more information in the books. The "Dwarf Car Technology" book is easier to understand, and gives some practical use information.
 You asked for the formula to calculate side bite.... So there you go. 

Have Fun!

Steve

[Racinjj]

Wow, so how is that going to be usefull?

If you use teh basic setup provided by Steve Smith in his Dwarf car book you should be fine.  I am not that far off his setup and am doing pretty good.  I think far to many people try to out think these cars, you have limited adjustments so get the basics down and drive it like you stole it. 

This is a setup that I posted in another post:

This setup worked for me at 1/4, 1/3, and 4/10 mile tracks flat and banked. 

Springs:
185    200
165    145

50.0 - 51.0% cross weight

Tire Pressures:
9psi    14psi
9psi    14psi

You can swap the rear springs rates if you prefer a looser car.

[JGRacing]

You can start between 50 and 51% cross weight and tire pressures around 9 on the left and 12 on the right.  I have not used a beadlock yet, so someone else can probably tell you how much you can drop the right rear pressure.  You can find good information on springs, rear offset, etc. by searching previous posts on here.  My setup is a combination of what I learned on this site along with advice from some other legends racers.  I only have one race in this car, so other people on this site can give you more detailed setup help based on their experience.  

Bite is the amount of left rear weight compared to right rear weight.  You want to get what you can to plant the left rear tire, but within the 52% left side weight rule.  

[JGRacing]

Jeff got to this before I did.  Go with what he said in his post.  He has a pretty good winning percentage this year. 

[justfreaky]

I think you are both right, most people tend to over think the whole situation. He wanted to know the formula, so I posted it (with a bit of explanation). 
The legends cars are a spec class... In that respect, as John stated, go with the basic set up that Jeff posted (He does have a good percentage of wins. Not only this year, but last year also). You can always adjust to your driving style and preferrence for the feel of the car. If you are building a car from the ground up (like I am), all those formulas come into play. I didn't start out with a pre-designed chassis. The info provided was meant as a "for what it's worth". Obviously, you can not modify the chassis of a Legends Car. John is also correct with his suggestions about rear percentages and cross weight. As for tire pressures; Start out with what Jeff suggested

Steve

[Racinjj]

I was not trying to undermine what you stated Steve but I have seen too many new or inexperienced racers get themselves off coarse.  As far as with the beadlock, you can lower air pressures all you want just remember that it will change the spring rate of your tire.  I personally haven't lowered my RR tire pressure much.

[justfreaky]

Jeff,

I didn't think you were trying to undermine what I posted. You are correct that sometimes people tend to get caught up in the math, or make it more complicated than it needs to be. Given that the Legends Cars are a factory spec chassis, the math is pretty much already done.
I think the set up that you posted would be a very good start for anyone. Thank You for sharing!

Steve

[RickyBobby]

Jeff, what ride heights would you use on a setup like that?  I run paved tracks but have always wanted to try dirt.