intermittant vibration-pulling my hair out!

[MarkMrtnFan2]

I've got a '99 f350 crewcab long bed with a 4" lift and have been experiencing an intermittant vibration in the drive train. It doesn't matter what speed, high or low, but it comes and goes when I hit a small bump. It will start with a bump and stop when I hit another one. So far I've rebuilt the rear end completely, had the driveshaft balanced and new ends put on, new Spicer u-joints, new carrier bearing, swapped transfer cases, eliminated the stock springs and add-a-leafs and had custom springs built to do away with the lift blocks, checked the tranny pressures and shift points ( it was rebuilt about 40,000 miles ago), checked the driveline angles, and replaced the rear yoke. Does anyone have any other ideas?? One thing I have found is that if it does start to vibrate, just switch to 4WD and it'll stop instantly even though the hubs are unlocked or I can leave the hubs locked in and in 2WD and it's ok...

[f350crew/long]

Hey I have the same problem. Ever figure out what the reason for this is?

[MarkMrtnFan2]

I haven't figured it out yet, but the next thing I'm going to try is swapping out the drive shaft, just to make sure that's not what's causing it.( I had it balanced back when this all started and I just want to be sure they didin't screw something up). I've found out that if I run with the hubs unlocked but in 4 wheel drive, it still vibrates but it doesn't get real bad. It's usually around 65-70 MPH when it's the worst. I'll get back with a post as soon as I get some time and ck it out...:

[f350crew/long]

After posting I went out to the truck and checked the oil levels in my front and rear differentials. The rear was almost dry and took a whole quart to fill. The front was very low and took about half a quart. Drove the truck today for about I'd say 30 miles and I haven't experienced the vibration yet. Yesterday I experienced it alot, and it seem to get more frequent. I'll let everyone know if it works, but so far it seems to have improved.

[bmodel]

I had this problem, it ended up being a $10.00 needle bearing on the front hubs, where the axle shaft for the front diff goes through the center of the hub. The needle bearing does not get any lube, so when it dries out it causes that horrible vibration and will wear out the axle stub if it is not taken care of!

[GoFastPadre]

Originally Posted by bmodel

I had this problem, it ended up being a $10.00 needle bearing on the front hubs, where the axle shaft for the front diff goes through the center of the hub. The needle bearing does not get any lube, so when it dries out it causes that horrible vibration and will wear out the axle stub if it is not taken care of!

Good Info I was going to suggest tire balance.

[f350crew/long]

Originally Posted by bmodel

I had this problem, it ended up being a $10.00 needle bearing on the front hubs, where the axle shaft for the front diff goes through the center of the hub. The needle bearing does not get any lube, so when it dries out it causes that horrible vibration and will wear out the axle stub if it is not taken care of!

I do suspect it being the hubs. If I unlock them and put some miles on it, I can count on it happening. Once I lock the hubs and drive the truck, It will not happen. I thought that maybe my hubs are locking partially, while driving, causing this vibration. If I replace the hubs with warns,then it should go away? or is it easier to replace this needle bearing?

[bmodel]

The needle bearing are located inside the bearing hub, not the locking hub assembly. To replace the needle bearings you would have to pull the 4 nuts on the rear of the hub assembly remove the whole hub and R&R the needle bearings in the center of the hub, this is the faulty bearing, check your axle stub too while you have it apart. Don't replace the whole hub this will cost $350.00 to $400.00 a side.