Hi guys I'm new to the rotary world I just pulled a RX7 out of a garage that was stored for the last 15yrs. It runs good but when it gets in 3rd and 4th I get a vibration. I changed the drive staff with a new one, put in two new engine mounts, new tires and replaced a couple saggy exhaust mounts. It appears to be more of a noise from something grounding out than a mechanical noise. I have not replaced the trans mount yet and didn't know bout a possible tail shaft bushing. The trans is the automatic 4 speed (I know an auto in a rx7) but my thought was for bracket racing and consistency. I have taken the car on a two hundred mile road trip and the noise will fade in and out and even gets a little aggravated when you decel. I have put the car on jacks and removed tires ran it to 30 - 40 and vibration is still there. Any help would be appreciated.

 

until you change the tranny mount, try swapping wheels, front to rear. a bent wheel is the first thing that popped into my head.