b'TECH TIP PAGE Tech Tip 19: When you think about it, all chassis are rigid or flexible to some degree. Nochassis is 100% with zero flex, and if it is, you built it waaaaaaay too heavy. Rigidity in a chassis makes the car more responsive to driver input & tuning changes & creates more grip. Flexibility in a chassis makes the car less responsive to driver input & tuning changesand has less grip. Most production cars are limp noodles & flex way too much.You can build a chassis too rigid for optimum performance. Ron Sutton shared his experiences, Designing a car with the optimum rigidity is a balancing act. We all have seen race cars too soft. Too flexible under race loads. These cars are sluggish & slow. They are lazy to respond to Driver input & the handling doesnt change much when significant tuning changes are made. The worst is when the chassis is so flexi-flyer the suspension and/or steering move around. These cars are not consistent & teach the Driver bad habits.We know a more rigid chassis is quick & responsive to driver input. Especially in the suspension & steering area. The car turns in better. It is quick & responsive through switchbacks (chicanes). If the chassis has the correct amount of rigidity in the right places, the car accelerates better & brakes better too. A well designed chassis is confidence inspiring. A chassis that is too flexibleor too stiffcan be scary as hell to drive.Yes, a chassis can be too rigid. I have seen a LOT of race cars overbuilt for the application. I first learned this in the 80s while we were building drag race doorslammers. The long stroke, 600-700 cubic inch Mountain Motor Pro/Stock cars of that era created so much torque, they would launch & 60 quicker with additional frame structure.Some called it a double frame rail.We call it a backbone connecting the rear half of the chassis to the front in the trans tunnel area. When the short stroke 500 NHRA Pro/Stock Racers tried this, they slowed down. The additional stiffness actually hurt grip on launch & it showed in the 60 times.Decades later when I got into USAC Midget racing, I bought a used race car. I could see it was a more rigid design than others. Man that thing was fast!For 10 laps. It was TOO SENSITIVE. As the track would rubber up on a 30-50 lap race, this cars handling would change significantly. We had to decide which 10 laps we wanted that car fastest. LOLOur biggest competitor in the USAC Midget chassis business had a little trick up his sleeve. I could see the difference between his House Car & his customer cars. His cars had additional bracing to be more rigid. When I asked him about it, he grinned & said My customers are not constant tuners like you & I are. By making my customer cars softer, the car is less sensitive. It works OK at most tracks & track changes dont affect it as much. I make mine stiffer, which requires being more spot on the setup, but our car is faster.I design all our race car chassis knowing exactly where the loads are, and are not, as well as how much G-loads that car & suspension package can create. There are no wasted bars & no extra weight. Ive designed the Track-Pro, Star, Hero & Warriors a little softer than our Race-Pro, Star, Hero & Warriors. Our Track Car clients are less concerned with a few tenths in lap time & want to have a fun, easy day. Our Race Car clients want every ounce of performance & are willing to do the constant tuning it takes to win races & championships. Your choice.350'