b'TECH TIP PAGETech 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 achassis 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 changesandhas 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 hisexperiences, Designing a car with the optimum rigidity is a balancing act. We all have seenrace 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 tuningchanges are made.The worst is when the chassis is so flexi-flyer the suspension and/orsteering 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 throughswitchbacks (chicanes). If the chassis has the correct amount of rigidity in the right places, thecar accelerates better & brakes better too.A well designed chassis is confidence inspiring.Achassis 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.Ifirst 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, theywould launch & 60 quicker with additional frame structure. Some called it a double frame rail.We call it a backbone connecting the rear half of thechassis to the front in the trans tunnel area.When the short stroke 500 NHRA Pro/StockRacers tried this, they slowed down. The additional stiffness actually hurt grip on launch & itshowed in the 60 times. Decades later when I got into USAC Midget racing, I bought a used race car.I could see itwas a more rigid design than others.Man that thing was fast!For 10 laps.It was TOOSENSITIVE.As the track would rubber up on a 30-50 lap race, this cars handling wouldchange 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.Icould see the difference between his House Car & his customer cars.His cars hadadditional 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, thecar is less sensitive. It works OK at most tracks & track changes dont affect it as much.Imake 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 & noextra 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 laptime & 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. 544'