Ride Heights for NZ Saloon Racing

My name’s Codi Singer and we race a saloon car here in New Zealand. They are kind of like a cross between a Late Model and a Sprint Car. While we have been racing for 5 or 6 years and are doing all right, there are still some things that I don’t fully understand.

This off season we have completely rebuilt our car from last year and have improved it in many areas. So I’ve been reading a lot of past Circle Track articles regarding setup to help our team start the season in the right direction. I have a question regarding ride heights for dirt track racing and adjusting it. What heights are recommended for dirt track racing at each corner of the car? Last season our ride heights were about 8 inches on the LF, RF, and RR and 71/2 inches on the LR. The car looked far too high and had a lot of body roll in the corners.

To adjust the ride heights is it as simply as winding the adjusting nut on the coilovers on the front and the adjusting nut on the torsion bars on the rear to achieve the desired ride height. Will lowering the ride height effect other things like roll center and center of gravity?

Thanks for your response.

—Codi Singer

Codi,

Not knowing exactly what front end you have, I will offer some basic advice. Changing your ride height does change the moment (roll) centers, and if you change the basic rake of the chassis, it gets more involved.

Depending on whether the suspension is a straight axle (front or rear) or a double A-arm type, when the ride height changes, the arm angles change for an A-arm type and the chassis mount for the Panhard bar changes with a straight axle. Both of these scenarios mean that the moment arm changes, as does the handling with ride height changes.

Once you have designed the setup around both the geometry and the balance, you need to stay with that ride height set. If you need to change ride height for any reason, then you’ll need to reevaluate the geometry and balance for the new height.

There are other things that can change besides the moment center location and balance. The cambers and camber change is affected in an A-arm suspension and the lateral location of the straight axle as well as the axle steer are affected in a straight axle suspension.

I think you get the point that if you decide to make changes to the ride height, you’ll need to go over all of your other setup parameters so that things don’t get all messed up. And there are times when a ride height change is appropriate for many reasons. Just make sure you do it correctly and look at the other setup areas.

More Ride Height Discussion

I hate to do this to you, but I’m going to try to drag you into a debate that has been going on for several years between myself and my partner in a race car. We have both been at this for more than 20 years involving mostly stock cars including Street Stocks and Late Models. He also has several years of karting experience. We are now running an IMCA style conventional sprung Asphalt Modified on tracks ranging from 1/4- to 3/8-mile, with low to medium banking. The basic rules are 2,500 pounds, 58 percent left side weight, 3.5 inches minimum ride height, 8-inch Hoosier 700 tires.

The disagreement comes over setting the ride height. I was always taught you set the ride height to get the proper suspension A-arm angles that produce the proper roll center in the front, as well as camber gain. In the back, it’s for the correct trailing arm angles. I have also always understood that on asphalt, a low ride height is preferred to get a lower center of gravity.

The rules usually limit how low a car can be, typically 4 inches, and most builders design their cars to work in that range. I also understand dirt requires a higher center of gravity and are designed different. Most of the various brands of chassis I’ve worked with recommended 4 inches at the left front framerail and usually 1/2 higher on the right front, mainly due a taller tire at that position. The rears have always been recommended between 1/2 to 1 inch higher.

My partner sees himself as more of a “car whisperer.” Although he may set the left front to the recommended 33/4 he stands back and visually checks and adjusts to get “a good attitude. That is when the car significantly leans to the left, and has in the neighborhood of 11/2 to 2 inches more ride height on the right than the left. The control arm angles become unimportant in his method.

His insistence on the importance of a “good attitude” is bolstered by Darrell Waltrip doing stop motion of Cup cars going through the corner. Pointing out how a soft spring big bar car with the stiff right rear spring should look when the rest of the car is on the bumpstops. My question is, is there a speed advantage to running a significantly high right side ride height on a car with a conventional setup? If so, what would it be? I realize that this was part of an old-school set up, before scales were readily available. The car isn’t bottoming out or dragging on the track.

Hope you can help put this to rest. Thanks,

—Bryan

Brian,

Come on, you knew when you wrote that what I would say, didn’t you? If looks are important to your partner, you should set up the chassis correctly for geometry and balance and then hang the body so that the “look” is correct, not the other way around.

The look of a race car will never get it to handle correctly. If aero is considered important, and I don’t dissuade anyone from trying to improve in that area, then do it without undermining the setup and alignment of the chassis.

Stay on your program of correctly setting the moment centers, camber change, and alignment based on an agreed upon ride height and don’t forget to include balance and load distribution in all of that. Mechanical grip is the most important thing you can improve for short track performance.

I believe that in the past 10 years, many Cup teams have compromised the mechanical grip of the cars by concentrating too much on the car’s attitude and “look,” as your partner has. That is why we have strong teams and weak ones as to performance when they all look the same on the track. If looks were so important, they’d all be running up front, right?

Pure Stock Rules Problems

I like the info I get from Circle Track, but I have a question. Why do the rules at the dirt track give the Chevy boys an advantage? In the Pure Stocks it should be Chevy on Chevy and Ford on Ford and so on, right? Wrong, Chevys are allowed to run 9-inch Ford rearends, but a Ford with a Holley on it they say is not fair.

Did Fords not come with Holley carbs on them from the factory like the 780? I run a 351 Cleveland Ford and they make the rules for intake valves no bigger than 2.06. But the four-barrel heads on the Cleveland has 2.19 inch valves so I asked them what do they want me to do, run two-barrel heads and an aftermarket intake to match them with a four-barrel carb.?

I never heard from them again. What are they afraid of, fair competition? I ran into this problem at another track. They said show me the facts and you can run it and I did the next Friday. I was on the track and everyone was happy and the fans loved that there was more than just Chevys on the track.

Thanks for your time.

—Unsigned

Dear Unsigned,

We’re continually talking and writing about ambiguous rules packages and how many rules are either conflicting or do not seem practical. I think it is a good idea to look over the rules during the off season and make changes where appropriate.

We have spoken to several top sanctioning body leaders recently about this and they tend to agree that as time goes on, our racing changes and so should the rules. This way, we can allow the innovation that will always attract new racers while keeping the playing field equal.