Drivetrain Vibes

[tleed]

1996 Suburban K2500 6.5L diesel, 224k miles: I have an annoying drivetrain vibration at 65-75 mph. New tires on the front and just re-balanced old tires on the rear. Vibration's still there. Mechanic suggests balancing the driveshaft next. The u-joints seems tight, no slack there.

 

I might be having a problem with my torque converter. The engine will drop about 700 rpm when I let off the gas on the highway. The motor does no rev up when I touch the brakes on the highway (as if the torque converter is unlocking). I got 17.8 mpg on my last tank highway driving, unloaded.

 

Is there any possibility the vibration is in the torque converter and it's related to a failure to lock up properly? Or should I keep looking for the vibration elsewhere?

 

Thomas

[Boogity3]

If the drivetrain vibrates its probably the driveshaft out of round, unbalanced or the slip yoke could be damaged. Get under there and see if you have any dents on the drive shaft. When you get to higher speeds and you get a vibe it's usually because the driveshaft is "whipping" like a jump rope. You can find good ones for cheap prices (about $150) at a junk yard or spend about $800 for a new one.