I have had my car for about a month and I don't get on it too much, but today after I replaced the tranny mount I was testing it out and I notice a vibration when the rpm's get up there. It's almost like a pulsating vibration that starts at about 5k and goes all the way up to the shift point around 6k. It gets about 3 pulses in before it shifts. Without trying to make myself sound like an idiot, it sounds like if you were to make a "car noise" by going - "vrooom-vrooom-vroooom" then it shifts... lol.

I put the ES poly mount in, and I'm sure that it makes it more noticeable. But it was there before too. Does anyone know what might be causing this or has had this happen to them?

I think it's fairly stock, with a K&N FIPK and De-screened and polished MAF. But it should be untouched internally.

 

unbalanced driveshaft maybe?

 

Thanks. Maybe I'll look into getting a used aluminum shaft off an LS1 car. Maybe that will help. Any other ideas?

 

Driveshaft, brake rotors, or tires.