I have a vibration in my 94 351w, Tremec TKO, 3.90 gear ratio equipped mustang that I can not narrow down. The vibration starts at about 70-75 mph and gets worse the faster I go. I have heard that the TKO swap could cause problems because of the size of the tranny doesnt allow for the unit to set high enough in the tunnel causing the tranny to face downward inturn causing bad drive line angles. So Im leaning towards the angles being the problem but cant seem to fix it no matter what I adjust. So far I am sure its not the motor because it doesnt change with rpm and is still there when the clutch is in or the car is in neutral at speed. I replaced the rear tires and rebalanced the fronts. Also jacked the car up and ran it w/o tires and the vibration is still there. I replaced the driveshaft with a new aluminum FMS unit and then again with a new balanced steel unit. The tranny was remove and checked for a bent output shaft, all looked good. The ring and pinion have been change from a 3.55 to a 3.90 which only caused the vibration to come on sooner plus I verifed the pinion was true and round...it was. I also installed adjustable upper control arms and have played with all sorts of different angles from equal to the tranny to extreme opposite. This does change the vibration but doesnt eliminate it. I also lowered my motor down, which helped the some, but created too many other clearance problems so I put the stock motor mount back in. I have verified that my output shaft and pinion angles are equal but opposite and they are. The angles are equal but the working angle of the driveshaft seems more then stock which is expected but could an above stock working angle cause a vibration like this? Im leaning towards just replacing the TKO with a world class T5 in hopes that the angle is the problem but I hate to spend all the money to find out its something simple that I overlooked.
Any help is greatly appreciated because I am stuck and out of ideas.
Any help is greatly appreciated because I am stuck and out of ideas.