What is dirt late model yaw?

What’s going on with this East Bay thing? This has been the place to be in years past for some of the best racing in the country. This year; no lift speeds, but no passing either. Over priced food, with pizza a shopping mall food court would be ashamed to serve. Car counts down, with some of the best in the country choosing to skip it. Admission fees are up, well at lest they will be able to send their kids to Ivy League colleges. It doesn’t appear to be the place to be in February any more. Let’s just put all that past us and talk about what is going on tech wise down here.

After hearing from many the end of the swing arm era at East Bay, there were several Rayburns that did quite well on opening night. Mike Marlar won on a hammer down limited passing track. The swing arm is just a consistent smooth driving car and he didn’t bobble too much. The other notable sight is that Bloomquist racing, after never really running well here is coming to life. His cars are smooth and controllable even on some of the roughest parts of the track.

Tire traction and traction circle

For a while now I have been talking about traction circles, camber, and steering yaw angles and really bare bone basic principles like that. It appears that these basic principles are separating the fast car from the slow cars down here. Even though Dan Schlieper isn’t driving our cars anymore we have been hanging out with him, lending a hand down here. Dan struggled a little bit the opening night and into the first part of last night. Scott pretty much mopped up the field last night with what is supposedly the same set up Dan has in his car. So, what is the difference? Steering angles and car yaw angle. Scott’s car last night would go into the corner; get a quick snap turn and his front tires would be pointing straight off the corner. The roll steer he had set into his car matched what he needed the car angle to be as it turned the middle of the corner. Exiting the corner both front tires where pointed straight ahead. If you go back to the traction circle theory, with both tires pointed straight, he had more of the rear tires he could use for forward traction.

Roll steer

On the other hand Dan struggled with a car that was too tight for him. His car would yaw more than the roll steer he had in it. He had to turn it with the gas, or with the brake to get it to yaw the way he was comfortable with. After that he had to counter steer the front tires to ‘catch’ the car. Now we again go back to the traction circle and see that if the front tires are turned you are in essence either looking for side bite or have side bite already loaded into the car. There will be less of the tire available for forward traction. This is what it looked to me to be the problem with Dan’s car. From the center off his tires were turned and the car just didn’t have the traction he needed off the corner. Just a little more roll steer in the rear axle may do the trick to get the car to roll the corner and allow his front tires to be straighter off the corner. This would, of course, allow him to use as much available traction in his tires for forward traction, making his center off speed much higher.

Now as I sit here and analyze it, it all seems pretty simple. But, we all know when you’re scrambling in the pits trying to get something to go, it is rarely that simple. These cars are so adjustable now; one little change affects so many different things. Hitting that exact adjustment that cures all of the cars problems can be a daunting task. Sometimes it takes a couple of days of racing to figure it out. I still believe if you whittle things down to basics it will make the task just a little bit easier.

Til next time,

Kevin