Vibration, Vibration at certain RPM's Options

[rapid36]

Hey guys I have a 94 celica st automatic transmission, I brought this car back to life after 3 years of sitting, The car ran fine and everything but when i was doing exhaust work i put everything back together and now all of a sudden I have a vibration at 900 and below rpm and anything over 3500 rpm it makes the vibration. I ruled out the exhaust since I just got done redoing the entire system, for good measure though i will be double checking this. It sounds like its coming from the back of the motor and on the driver side, I suspected a transmission problem? So I flushed the whole system and put in brand new fluid and filter as well. I can drive the car around just fine and never over heats and the vibration only comes at certain rpm NOT SPEED. So I thought what the heck why not take out the starter and see whats going on with that. So I took out the starter and it looks fine, no chipping of gears or anything. The engine is very stable and has no idling problems so i ruled out being an engine performance problem, I also replaced all of the engine mounts and still no luck. Anyone have an idea of what this could be?????

[Langing]

Hey guys I have a 94 celica st automatic transmission, I brought this car back to life after 3 years of sitting, The car ran fine and everything but when i was doing exhaust work i put everything back together and now all of a sudden I have a vibration at 900 and below rpm and anything over 3500 rpm it makes the vibration. I ruled out the exhaust since I just got done redoing the entire system, for good measure though i will be double checking this. It sounds like its coming from the back of the motor and on the driver side, I suspected a transmission problem? So I flushed the whole system and put in brand new fluid and filter as well. I can drive the car around just fine and never over heats and the vibration only comes at certain rpm NOT SPEED. So I thought what the heck why not take out the starter and see whats going on with that. So I took out the starter and it looks fine, no chipping of gears or anything. The engine is very stable and has no idling problems so i ruled out being an engine performance problem, I also replaced all of the engine mounts and still no luck. Anyone have an idea of what this could be?????

Specifically, what did you do to your exhaust? What parts, other than strictly exhaust parts did you r and r in order to do the exhaust work?