Bronco Driveshaft

[firemanmichael]

I am new to your group and wanted to thank you for letting me sign up. I am hoping some one could help me out. I have a 1990 Ford Bronco that I have had many years. I now have a very bad vibration from 45-75 mph. My tires are well balanced, wheel bearings are good. I have had to tighten the bolts on the rear driveshaft as they come loose often. I cannot move the rear driveshaft by hand, however, I can move the front driveshaft by hand (turn it from left to right, not up and down). What are the symptoms of a bad drive shaft? Thanks for your time.

 

[JLasvegas]

its possible that the driveshaft could be out of balance, if the bolts are coming loose often

you should be able to pull it out and take it to a shop and have them check to see if its out of round

is there a lift on the vehicle? could be the pinion angle causing too much stress on the bolts and they come loose.

its also possible something in the road could have struck the shaft while driving and threw it off balance

 

[BroncoJoe19]

You may want to consider getting new bolts.

IT is my understanding that the threads of a bolt are like a spring, and that it is possible to over torque the bolt, and fatigue the spring effect of the bolts. If they are not holding... they may be fatigued, and need to be replaced.

 

[Seabronc]

Something else to check is your U-joints. They may be worn, chances are that the drive shaft and U-joints haven't been lubed in years. That unfortunately may have caused the U-joints to wear, which shows it's self as vibration which may be more noticeable at specific speeds. Look for rust or rusty looking grease around the U-joint bearing cups.

Good luck,

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