Weird Question

This Friday at our local circle track, the tech "officials" decided to test front track width post race(?!), and most of the cars that came off the track failed, this resulted in some DQ's and some seriously pissed off racers.
Most of the cars were about 1/8" too wide, that ain't much if you ask me, and all of them were saying the tires were heated and grew in diameter. I figured, well duh, of course the tires are gonna swell up, but after thinking more, the whole front end is gonna heat up, the tubing, A-arms, it's all metal, and it's hot.
I know there are some pretty smart folks on this board, how much would a front clip expand from 70 degrees F to 200? They were thinking tires, but I'm thinking the whole deal is gonna expand.

My best friend is a left turn racer and he goes to national event races. I went with him to Iowa one year and we knew they teched post race so we made sure everything measured correctly while hot. I am not sure how much everything expanded but it was a learning experience to think that way. I would guess that with tires and metal that it could be close to a half inch.

The coefficient of expansion of steel is .00000073 in/in/*F. So if the width of the frame is 5' and the temp was raised 130*. 60"X130*X,00000073=.005694" no where near .125. Add in the rims at a higher coefficient of .000000123 and rubber at .000000428 and you will never get close to .125."

bs ..... there are more variables then just heat involved !!!! there is more force (stretch )involved then heat

How much do the tires grow due to air pressure changes on a circle track car?

Well, that's the other part of it, they are running on different tires than last season.
Last year they were on Hoosier Comanches, it's a race tire but it's treaded, hard, and not very "racy", this year they're on actual racing slicks, Hoosier 980's, their bias plies, so I would imagine there is more heat built up during the feature this season, and I would bet they grow quite a bit.
From Schmitty's reply I'm guessing the actual chassis expansion would be inconsequential, so that theory goes away.
The track reversed it's decision, though, partly due to the tremendous amount of bad comments on the local racing forum,
and the fact that most of the racers weren't coming back.

on a smaller scale, when we ran Quarter Midgets...dirt. We run ten laps on a 1/10 mile oval and gain about 3 pounds of air pressure. The handling would go to shit. So we switched to nitrogen, problem solved for short races. 30 laps we would gain on average about 1/2 pound...nothing to worry about.

I would hope that the racers would be upset, it's not like an 1/8" is that big of a deal. It it was an inch or more, I may see some guys crying foul, but they were cutting some really fine hairs there.

FYI:



Have a good day!
Michael

That's cool, thanx!