Driveshaft or Axle U joint problem?

[drase]

I have a 2WD, 6 cyl, auto, 87 MJ. I have vibration above 40+ mph only why I'm accelerating. If I let off the gas the vibration stops. Does this sound like a driveshaft u joint problem more than axle?

 

On a 2WD truck how many axle u joints are there? Just 2, which are on the front?

[Dillithium]

Yes, 2 u joints. But in your driveshaft, not front axle. You have a front axle without axle shafts, so no u joints to worry about. How are your motor and tranny mounts?

[Blue XJ]

Sounds u-joint related to me, probably the one down by the rear axle, but I would replace both of them on the driveshaft.

[drase]

Yes, 2 u joints. But in your driveshaft, not front axle. You have a front axle without axle shafts, so no u joints to worry about. How are your motor and tranny mounts?

Awww, thanks for the info. I think the mounts are ok, I'll check them out.

[drase]

UPDATE: It was the driveshaft U-joints. Replaced both and no more vibration!! :banana:

[metrictonner]

Some manufacturers actually sell unbalanced brake drums that can cause rear axle vibration.  When you brake with these turkeys it vibrates more.

[gogmorgo]

An unbalanced brake drum would cause vibration all the time, like an unbalanced wheel or tire, would it not?

[Marine1Texas]

yes it would, however would be come worse during braking.