I’ve been looking around for some info on if i need to make setup changes when our races go from qualifying in the evening to racing into the night. Does the track change kinda like a drag strip where once the sun goes down the track starts to grip up? Any help would be greatly appreciated.
In my experience the track will free up as the sun goes down and track temperature drops. However this can be counteracted by more rubber getting laid down. Kinda depends on the race.
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Rick is right. Compared to a day race, the track will have less grip than usual in the race. You will also notice that it takes tires longer to “come in” than in day races. Adjust your tire pressures a little and let her rip.
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It kind of depends on your track and where its located. At my last night race here in North Texas, the temps went from the high 90’s during the first Heat down to the low 80’s for the Final. Racing finished up around Midnight. Its an Asphalt surface, so it retained heat for a little while, but as the groups progressed it certainly fell off.
You could reverse your setup changes from early morning to late afternoon and get similar results. Just like in the morning it takes a while for the track to start coming in, in the evening it will take a while to start falling off. Tracks are a Living thing. Depending on your ambient temp changes and humidity levels, you may have to make more extreme changes.
For me, it was narrow the rear slightly, raise starting pressures slightly and maybe add a little caster if I was in one of the last sessions.
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Here in the humid Midwest, I’ve seen a few night races where the track got dewy once the sun went down, and made it super slick. There were puddles on our sidepods pushing up the grid.
Generally it will get slippery for a night race and track temp will be much cooler, so tire pressure changes and some chassis adjustments to get the kart some sidebite again would be normally what I do.
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Definitely depends on the track and the ambient temp range. The two tracks I’ve raced at night (NCMP and Trackhouse) have been polar opposites in terms of how the track developed.
NCMP gets pretty slick so going up on tire pressure and adding caster is important.
Trackhouse was getting greasy during the late afternoon since ambient temps were high that weekend, so the grip level went up slightly in the early evening as the track cooled off. Later at night the grip came down only slightly, but was still at a level comparable to earlier in the day. Chassis and tire pressure changes were minimal.
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Absolutely, I remember nights at RA where we kept a rag in our pocket on grid to keep wiping the visor off. It would look like a rain race 
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The best is T1 right after the dew sets in. If it is a junior class, you might lose the whole field into the grass!
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I do wish I could still post the video of all the Euro pros flying out of t1, pure wet understeer, all of them into barriers. Pretty much whole field. I think it was taken down though.
That was my concern with location and humidity. Dewy T1 is No Fun!
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