03/04/2024
So I just saw a Facebook video from a very respected bracket racer who was talking about the starting line. Most of his talk centered around top bulb, but he touched upon bottom, too. It's a great video, very informative, but one thing that struck me was his assertion that (and I'm paraphrasing here) cutting a light on the bottom should be easy to do just by making some changes to tire size and the launch RPM.
Wrong. It takes preparation and testing to know where you are before even getting in the car. Here's what I've done: I take my practice tree (if you don't have one, get one. Tabletop or handheld will do) and set it to .500 Pro. Get used to reacting consistently, and it doesn't matter what the reaction time are. You're trying for the tightest window of reactions. Make ten hits, average them, write the number down. Walk away. Come back later, do it again. And again. And again. You want to see the averages be very close.
Once the averages from all these hits are close, it's time to take your car to the track and test. The goal is to react with the same consistency when you're on the starting line. To do this, you'll want to test on a .500 Pro tree. Again, don't worry about the reaction time. If possible, tell the track to turn off the boards and have a friend get your time slip so you won't know the reaction time. Make three hits like this. Then look at the time slips to see your RTs. The times don't matter; the grouping does. You want the grouping to be tight. If the group is tight and the numbers are late, then it's time to start adjusting the car to react quicker (smaller front tires, raise the tire pressure in the fronts--and more importantly in the slicks if you're running non-radial slicks, raise your RPM).
Once the changes are made, do it again. Once you've gotten the car to react as best as you can on a Pro tree, switch to a .500 Full tree and focus on that bottom bulb. If you're reacting to it the same as on a Pro tree, congratulations. That's the hard part. If you're coming up late, thanks to your prep work you'll know you're sitting on it. If you're coming up red, you're jumping.
I hope this helps any of you who need it. Good luck at the track