Car vibration Need help in determining emination

[xxtrizz]

I own a Nissan 1990 240sx I have replaced everything on the vehicle and I mean practically everything save the driveline and suspension. The engine is newer totally rebuilt

Forged pistonspauter rodsSI SS valvesceramic coats in the headspec stage 3 clutchFidanza flywheelASP pulley all new accesories nismo thermonismo mounts invluding transmissionBRM exhaust system

The thing has had a complete overhaul and I mean full. However when I drive in gear and deaccelearate there is a built up vibration in the vehicle. Sounds almost like a transmission grind but apparently from a few mechanics ive been with including my father they say the Transmission is fine and that its actually a vibration being built up in the car somewhere. Im unable as of now to ascertain specifically where the vibration is eminating from. I have been told by nissan several times its the exhaust system. However, I jacked the vehicle up to see if I could simulate the noise while in gear put it in 2, 3 , 4 , 5 there seems to be a noise coming from the driveline system somewhere.... in fifth gear its very loud as though the system is loose and shifting as if it were off balance somewhere. I took it into Nissan and explained that that noise could be heard while in gear when the car is off the ground. They told me that its just simple driveline noise and the vehicle is older and would not affect it in the sense im experiencing... im at wits end here trying to figure this thing out. ANy ideas ??? ITs causing my car to fall apart here... the vibration has set up some sort of irregularity here in my idle and now the engine function weird and after my nice rebuild... I think im gonna cry... HELP!!!

[1991S13]

Is it coming from the driveshaft?

Pull the back half of the driveshaft off and see if it goes away. If not, pull the other half of the shaft off and see if that eliminates it. If so, I would either try balancing the driveshaft, or changing the carrier bearing.

If the vibration still happens, atleast you eliminated the driveshaft being a possibility. It could either be in the transmission or rear.

I fought with this same thing for a couple of days. Turns out it was the carrier bearing.

[Nismo_Freak]

You can always upgrade the driveshaft if you have to replace it as well, but I suggest a driveshaft halo if you are going to a single piece.

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