I had a vibration between 40-60 mph. I changed the u-joints and the needle bearing. When we went to put the shaft back on we noticed the pinon nut was a little loose (Ford 9") . My partner who is a big time mechanic said they are to be very tight . Sooo we torqued down the nut and installed locktite it took out some play that was in there. Then we reinstalled the driveshaft, and took it for a ride--- the vibration was worse, I check the tire pressure and lug nuts, and made sure no weights had fallen of the tires. I'm wondering if the pinon nut has to have some play or should I try to clock the drive shaft 180 like the manual says?

1986 Bronco
302
33X12.5X15
no lift

 

after reading vibration and bad handling I'm wondering if it isn't my radias arm bushings and ball joints?

 

You should try rotating the driveshaft 180 degrees. If that doesn't work you might want to have the shaft balanced. If you put it back together different after rebuilding it, it may not be balanced anymore. Hope this helps.

KJ

 

if your pinion nut was loose, you may have wiped the pinion bearings out - happened to me on my '88 with the 8.8 rear. Had odd noise coming from rear, checked u-joints like you did and found pinion nut loose, like you did. Tightened it and it got louder. Wound up doing pinion bearings, and while I had it apart, axle bearings and axle seals.

Mike

 

It *could* be the pinion bearings, esp since the problem got worse after messing w/the pinion nut.

The nut is supposed to be hella tight, but after you tighten it you're supposed to check pinion bearing preload w/an inch-lb torque wrench... if you've put too much preload on the bearings that could account for the additional noise.