So here is the deal, my camaro transmission was rebuilt with alot of upgrades. I notice with my car in neutral at about 1700rpm i get a very noticeable vibration trough the whole car. I know the car has Poly Transmission mounts and maybe I am feeling the normal harmonics of the car? I am worried it could be something more, the vibration goes away with higher RPMs above 2K. As I said though at 1700rpm the whole car vibrates, steering wheel and all vibrates noticeably.

 

How many miles on the car? Never expect less vibrations with a poly tranny mount! Switch to rubber to reduce vibrations.

 

poly mounts will transfer vibrations way better than stock. is there a reason you used poly, breaking mounts? you could try moving the converter connection to the flywheel/flexplate by one bolt. take three converter bolts out and turn converter to next hole and put er back together. this can work to help with vibration but not always.

 

And while the torque converter/transmission-to-engine connection is unbolted, you could start your engine and see how it compares. If the vibrations are still there, it's with the engine. If the vibrations are gone, it's the transmission or converter causing it.

 

mark the flexplate and converter so you know where it was.

 

Another question for the OP -- what motor mounts are you using, stock rubber or...?

 

The previous owner stated they where Poly, I put it up on ramps and inspected the mounts and they look like stock rubber ones NOT poly. I than took the starter out unbolted the Torque converter and inspected the flexplate for cracks, none where found......I was unaware until reading this that I can unbolt the converter and start the car to feel where the vibration is. I did notice the Harmonic Balancer had a slight wobble so I replaced it and the wobble is gone but still the same heavy vibration.

The vibration was very noticeable at 1700rpm but is present all trough the RPM range. The motor has 148K miles on it and I am afraid that if the vibration is on the Crank then it is possible my Mains are starting to go?

 

lets see a picture of the trans mount. does it look like this rubber one

 

My car has a poly mount and I don't feel any vibrations. I wouldn't expect normal driveline vibrations would be bad enough to vibrate a steering wheel as mentioned, even if the mount was solid steel... I'd suspect the problem isn't your poly mount.

 

The first symptom of a main bearing going bad is a knocking under load. Even with bad main bearing you will not feel anything until the motor is under loan.