I have a 95 GT with a T5 tranny. From the time I bought it, when you get it around 4000-4500 rpm and higher, the shifter vibrates violently and you can hear a sort of rumbling or vibration coming from where the transmission is. I'm pretty sure its the original transmission, and it works fine when driving it around town in the lower rpms. When I rev the engine in neutral, it sounds and feels normal. It only happens in gear, and I had a new clutch put in not too long ago, but I remember having the problem before the clutch was fixed. Now that I put a supercharger in it and I'm thinking about taking it to a strip, I want to make sure I don't do any damage to it. Anyone have an idea as to what this could be?

 

Flywheel and possibly the trans mount is screwed to. I have the same problem with my auto. It didn't exist until I swapped out for another trans and had to get a smaller flexplate and I bought one off of ebay so now after 4g's it usually vibrates really bad.

 

im having the same proplem but at about 3500 to 4000 rpms. i know it need to replace the trans mount, the motor has a new flywheel, it does it in neutral with clutch in and out, could it be a bad input bearing

 

had the same problem tried u joints trans mount new flywheel, after the 5th time with tranny out i figured id try an pilot bearing
worked great

 

if you hear a rumble from the tranny ...might wanna pull the tranny and inspect countershaft bearings , input and output shaft bearings