Originally Posted by Malek@MRF
Most companies that you are referring to are machining new bushings to improve feel and performance of the car, not for component failure.
Yes, machine solid mounts will help the problem and minimize it through reducing bushing deflection. However, this does not solve the problem, it alleviates it for the reason just mentioned.
Just a little fact about R&D in regards to this matter, creating the solid differential bushings through Solidworks and having them machined is an easier task than making new hardware. Now if we are talking about the actual sub-frame bushings, that's a different ballgame, however, hardware failure for the sub-frame is non-existent.
The companies I have in mind are racing these cars ..they are going far beyond just improving the feel..by unitizing the diff to the rear subframe you have all but eliminated the inherent "flex" in the rubber mounts..if you were to use solid mounts here there would be no need to use partially threaded bolts..
Maybe there is some credibilty to swapping the bolts if using the OEM mounts...but this is treating the casuality and not the underlying cause which are the mounts themselves.