So ive had my 1jz swap running in my sc300 for almost two weeks now, but theres one thing that's bothering me. The motor runs perfect, compression tested the same for all the cylinders, and all that, but there seems to be a slight vibration at about 1300 rpms. Idle seems perfectly smooth, and any rpm higher than 1300 or 1400 the vibration gets less and less evident until about 1800-2000, where you can barely even tell its there. At any rpm's higher than that its smooth. I tested this with the car not moving...just in neutral. I dont think its a vacuum issue, and it isn't the clutch fan or any of the accessories on the front of the motor, as i tested it without the belt on for a few seconds.

I'm thinking its an imbalance, either in the harmonic balancer, or maybe in the flywheel or pressure plate. By the way, i put in an ACT modified street clutch and heavy duty pressure plate. I had the flywheel resurfaced, but i didnt think to balance that and i figured the pressure plate was balanced already, so i just put it together like that.

Is there anything else i should be considering?...anybody else had this vibration? I'd like to get some opinions before i drop the transmission again..

 

it could be your motor mounts. that might be it.

 

both motor mounts are new.... the old ones broke when i took the ge motor out. the bottom bolts for em werent completely tight though, i checked them yesterday and tightened them. still has the vibration. tomorrow i'll check the top bolts for the motor mounts, but im pretty sure theyre tight too.

 

ok....motor mounts are both good...and theyre tight....im pretty sure its an imbalance in the flywheel/pressure plate. anybody agree?

 

I'll agree.......And circle gets the square!