Latest Trick
Current NASCAR
Using the suspension rubber bushing for fore/aft movement has been around for years. The use of an expensiveBithermic Rubber isn't necessary.
The auto companies having been using "Voided " bushings for at least 30+ years in front/rear suspensions. I got involved with this during my work assignment in the vehicle suspension study lab at Michelin Tire in the late 70's.
To improve comfort levels, the suspension bushings are frequently made with an internal "void" in the rubber (meaning no rubber, just a vacant space with no rubber) in the 3 and 9 o'clock positions to allow more suspension compliance (controlled movement) in the fore/aft directions).
The more void, the more movement. The same trick could be used inrear trailing bushings to accomplish a rear steer effect under application or releaseof torque on the rear suspension.
Igot involved with some work with Ford shortly after the 5.0L Ford Mustang went to market to fix a rear axle tramp problem. They used voided bushings in the rear arms which allowed fore/aft movement under standing start torque application. I filled the bushing voids with plasticand the problem was solved, but at the expense of reduced comfort levels, which Ford couldn't live with.
Ford eventually went to a horizontal mounted small torque damper (shock absorber) on each side to cure the problem. The '90 5.0L Mustang I have in my garage has those pieces on it. So, it was used for years.
With comfort levels not being in the equation, this voided bushing could be a great racing chassis "tuning" device while still remaining within the truck arm rear suspension rules. No need to go with 4-links, which I don't think isNASCAR legal.