I've noticed when I have my 2006 SC430 on jackstands and only 3 of the 4 jackstands are in contact with the car (my driveway sucks) when I go to close the drivers/passenger door sometimes the window glass won't seal and sticks out. I have to really slam it to get the glass to seal. Anyone notice that issue with their cars?

In general what's the opinion of how ridged the chassis is? Mine has lived a rough life (salvage title due to some minor floor and lower control arm damage), wondering if the accident "loosened up" the chassis. I'm planning to spend time/money with some mods, trying to decide if it's better to find a nicer one to start with or what. My other convertible was a 2016 MX-5 and that felt more or less the same rigidity-wise (but so much lighter!)

 

The chassis does flex a fair amount. I've learned to always lower the windows BEFORE jacking up the car.

 

Well, I answered this once but for some reason the response didn't post so I will try again. The SC is a very heavy car. 4700 lbs. It should never be supported on an uneven surface as you describe. The underbody bracing to reduce body flex is designed to prevent side to side flex, improve stiffening in corners etc. It was NEVER designed to work for body TWIST. By putting the car up on an uneven surface as you describe, you run the risk of doing damage to the frame. The risk is admittedly minimal. But that risk is there none the less. There are other improvements that can be made to increase rigidity, but again, those improvements are meant to reduce chassis role with heavier sway bars, additional stiffening cross members for the front and rear and some have even gone so far as to use thicker designed pieces for the door latches to improve overall body stiffness. Hope this helps.

Paul