DL racing questions

[Lukus]

Yet another newbie to this forum, i've always been an enthusiast of DL racing. I have a few questions in regards to the cars that run in these events.

First question is, what sort of suspension do the cars run? Is a conventional circuit set-up (low and stiff) and alignment sufficient? (obviously without the negative camber) Or is there a black art to getting it all right?

Second question is, what is done to stop the salt from getting into every crevice of the car and rusting it out? Is there a special process to treat the body or is it a case of thoroughly cleaning before and after the runs?

Third question is, what are the most important things to consider when building 1 of these high speed weapons? Aero is obviously the top of the list or very close, but is power essential? What about weight? Is a light car an advantage? Or does it make high speed stability difficult?

I appreciate input from anyone who cares to respond!

Cheers,

Lukus

[DON NOBLE ... DLRA # 281]

i race a nissan skyline station wagon , totally standard suspension , been up to 140 mph , no probs perfectly stable .

yep rust can be a prob only way to stop the salt being a prob is to clean it off the best way you can

[DLRA]

First question is, what sort of suspension do the cars run? Is a conventional circuit set-up (low and stiff) and alignment sufficient? (obviously without the negative camber) Or is there a black art to getting it all right?

The salt in Oz is a lot smoother than that at Bonneville (or so I'm told) but it's still pretty rough and can be undulating. You gotta remember this is a lake and the "lay" salt is greatly effected by the evaporation of the water and the wind. It's not uncommon to have high and low points along the track. So you need some travel and not real stiff.

Second question is, what is done to stop the salt from getting into every crevice of the car and rusting it out? Is there a special process to treat the body or is it a case of thoroughly cleaning before and after the runs?

No one really bothers during the event. There is a a chemical that you can apply to the underbody prior to going on the salt which is supposed to protect the car and make removal easier, but it is expensive. Some guys use diesel, other just wash everything down when they get home and soak on WD40 or similar. But you can't stop it. A lot of the guys spend extra during preparation and assembly to get parts coated to help protect them and this delays the corrosion process a bit. But eventually you have to just face the inevitable.

Third question is, what are the most important things to consider when building 1 of these high speed weapons? Aero is obviously the top of the list or very close, but is power essential? What about weight? Is a light car an advantage? Or does it make high speed stability difficult?

The frontal area of the vehicle is probably most important, as this is what the vehicle has to push through the air. Not just the actual front of the car, but the siloette of the whole vehicle if you like. The less frontal area the easier it is to cut through the air.
Then aerodynamics begin to play a role. Many roadster owners will atest to their cars wanting to spin at high speed, this is because of the frontal area of the grill pushing against the air, much like trying to push a brick wall, something has to give. Once the vehicles attain certain speeds they must fit certain aerodynamic aids to ensure their stability.
Power is important, but so is gearing and tire diameter, it's being able to get the power down at the right time and every car or bike is diferent. It has to compliement the charactistics of the motor.
Weight is the DL racers friend and many cars run ballast to help them handle better.

Hope some of this helps.

[weezilco]

Hey Greg, thanks for the thorough treatise.

One query- The rulebook sez roof rails are required for cars going over 200mph. What function do they accomplish?

thanky.

-Brian

[John Broughan]

Brian, the roof rails aid directional stability to production based cars at high speeds. My car ran 200 MPH with no suspension, and runs fine. Up to about 70 MPH it is quite rough, but over that is no problem. I have thought that on a production car, either run it on the bump rubbers, or very close. The salt is flat, but not perfectly smooth. It is a bit hard to describe, but it is flatter than the best road, but rougher.
The lower the car, the less air underneath, wich will also cut drag, as the underneath of a car is not very smooth at all.
Weight is important, because it gives you downforce, without drag. Wings also give downforce, but create drag. You need to carefully consider the rules for the class you want to enter, and make sure that what you want to modify is within the class limits. This applies mostly to production car based entries.