Driveshaft help

[B-Co Kid]

It's me again...so I got a few extra buck to throw at the

B-Co and I need more expertise. When I get around 40 mph, I hear a rumbling vibrating sound. And when I get of the gas it goes away. From my limited expertise, I would say check u-joint or driveshaft. The shop told me the

U-joints were good, and driveshaft won't give problems with 6" lift. I think it's the driveshaft. My question is should I install a longer driveshaft or could something else be the problem??? By the way I have 6" pro comp stage II lift with 3" body lift.

 

[Rons beast]

A longer driveshaft won't help with a vibration. However if the truck is lifted that high you should be sure you have an angle wedge in the spring mounts to adjust the pinion angle to match the driveshaft.

The other possibility if the U-joints are good, is that the rear end is getting worn and the bearings are needing replaced. Check the gear **** first.

Good Luck

 

[Bully Bob]

Also; check the big pinion ****** nut, (under/behind the rear u-joint). Even though they're a lock-style nut..., they've been known to come loose.

 

[Krafty]

my old 81 bronco before I sold it, I noticed the yoke/ pinion nut on the rear end was loose, I just put some lock tight on it and cranked it tight in my inexperienced youth, it was behaving similarly to yours except after a while if you nailed the throttle it would act like the clutch was slipping (which is what I thought it was when I sold it)before "catching" and accelerating if you let off a bit. turns out the pinion was slipping on the ring gear and pretty much blew up on the guy I sold it to. I felt really bad after I found out, and even offered to buy it back. to this day I still consider tracking him down to see what happened to it.

the point of the story was the slop in the pinion/ ring gear was causing my vibration under load, and progressively got worse.

 

[lynchsg]

My 82 with just a 2" lift had rear drive shaft vibration. 1st I tried wedging the rear end Pinion shaft angle to match the transfer case angle but the U-joints were binding with the short Bronco drive shaft. It has the dual Cardone type (CV) U-joint assembly at the transfer case end of the drive shaft. After some Off-Road magazine research I found an article that suggested wedging the rear end housing so that the Pinion shaft ****** points almost directly at the transfer case ******...vibration gone!