Vibrating noise at around 4000 rpm

[SmoothCustomer]

Whenever I get my car up to about 4000 rpm it starts making a loud vibrating noise. I'm thinking it may be the exhaust? My crappy o2 housing has some messed up threads and it may not be sealing properly because of it. Any ideas?

 

Have you had any timing belt work done recently? It sounds like the rear balance shaft is out of phase.

 

[SmoothCustomer]

Yeah I just replaced my timing belt, but I deleted my balance shafts. And that sprocket was actually left in time anyways so I doubt that's the issue.

 

So, are you saying that the rear balance shaft was completely removed from the motor, or not? /ubbthreads/images/graemlins/dunno.gif

 

[SmoothCustomer]

Yes, both balance shafts were completely removed.