The 2024 Season 4 build features a simple update to the Xfinity cars to eliminate coil-binding from the front suspension: The adjustment for the Main Spring Rate has been removed and the rate locked at a constant 250lb/in as well as the spring being lengthened slightly to allow for more travel. This both corrects the issue of hard-binding the front springs and makes the front of the car easier to keep down.
The adjustment itself was removed due to the vast majority of setups using the lowest available values for main spring (300 or 325), meaning a variable setting wasn't necessary, and keeps the car in-line with the system currently in use for the NASCAR Trucks. Unlike the Trucks, however, the Xfinity car will still use a separate bump spring option as in the past which will still operate differently than the Truck's dual-rate progressive spring.
Other aspects of the car have gone unchanged for ovals, however small tweaks have been made to the Road Course package to alleviate rear tire overheating and reduce the tire's long-term "memory" to sliding. We discovered situations where the car could be driving completely normally yet overheat the rear tires without major slides or wheelspin events, a condition that could remain and even worsen through the tire set's life. Small changes to the tire parameters, as well as some adjustments to how far forward the aerodynamic center of pressure can move, have been made to the Road Course cars only to reduce the chance of this happening and, if it does happen, reduce the likelihood of the issue building and building as the run goes on. Many will perceive these changes as a slight increase in rear-end grip on Road Courses.
The manual for the Xfinity cars has been updated to reflect the suspension changes and can be found here: https://s100.iracing.com/wp-content/upl…y-Manual-V5.pdf