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Q. We run Dirt modifieds and our ongoing argument is: "does the chassis go away after a couple of years of racing?" I am a welder by trade and I don't believe that the chassis could "go away" without showing signs of metal fatigue or significant cracks at the welds, but the driver believes it does. Your opinion? (Submitted by: Chris Casey from Plymouth, CT)
A. This is a good one! As with anything that goes through a constant pounding, metal fatigue will take place. Even without signs of cracks, the tendency of the base metal to become more flexible over time rises. We have done chassis deflection testing on new cars compaired to two year old cars and found it takes less force to deflect the old chassis. Whether or not the amount of force to deflect the old chassis will ever be realized in a race environment is questionable. The amount of triangulated bar placements will also affect this. We have even seen deflection changes in TIG welded chassis over MIG welded chassis. So I guess the only really good answer is, keep the driver happy. Some drivers don't mind a car with flex. Others want to be able to feel that extra 1/2 turn on the sway bar. I personally will run a car for a few years, but then again I don't have the funds to build three new cars each year. I would if I could. It would be more for the new bolt-on stuff rather than chassis flex though.
A. This is a good one! As with anything that goes through a constant pounding, metal fatigue will take place. Even without signs of cracks, the tendency of the base metal to become more flexible over time rises. We have done chassis deflection testing on new cars compaired to two year old cars and found it takes less force to deflect the old chassis. Whether or not the amount of force to deflect the old chassis will ever be realized in a race environment is questionable. The amount of triangulated bar placements will also affect this. We have even seen deflection changes in TIG welded chassis over MIG welded chassis. So I guess the only really good answer is, keep the driver happy. Some drivers don't mind a car with flex. Others want to be able to feel that extra 1/2 turn on the sway bar. I personally will run a car for a few years, but then again I don't have the funds to build three new cars each year. I would if I could. It would be more for the new bolt-on stuff rather than chassis flex though.