Drivetrain and Backfire position bug

[ic6x]

I've got the problem back after downgrading only suspension to stock because race suspension is bouncy, I got the testing car performance loading screen, Disconnected when it stuck at 58% (like what whiteseed said).

when I logged in back, I got the same loading screen but it hop from 58% directly to 100% and I still have 3 gears, upgrading the car suspension to street level won't fix the bug.