Front End Intermittant Vibe 4x4

[HH65AM1]

'01 F-250 SD XLT 7.3ℓ 4x4
While in 2WD and slow speeds, Drive over a bump and a vibe starts coming from the front end.
The ways I have found to stop the vibe is to:
Engage 4HI, stop, or hitting another bump works sometimes.
This does not happen while in 4HI.
Could this be the 4WD driveshaft turning while not engaged?
If so, how is the shaft kept from turning while in 2WD?
Am I on track here?

Thanks for helping! -Keith

FYI: Tires, Shocks, and steering Stabilizer have been eliminated at the possible cause. As they are all new and/or balanced, thanks!

[NoRalPh]

Nope, I can almost GUARANTEE you, your needle bearings are shot in the front hub.

It's a cheap and fairly easy fix depending on your tools & skill level.

The reason it doesn't happen in 4WD is because those little bearings aren't turning when engaged. In 2wd they have to support the stationary stub axle.

Welcome to guzzle's 4x4 Needle Bearing Maintenance Web Page

[jm03powerstroke]

Yup i would go with u axle bearings in the front hub bearing too. had the same problem. its a cheap and easy fix if u dont need a new outter alxe shaft. i would recommend replace the axle shaft bearing and the axle shaft seal too. just make sure the shaft is ok with no damage or u will be doing the same fix with in six months.

[NoRalPh]

Originally Posted by jm03powerstroke

i would recommend replace the axle shaft bearing and the axle shaft seal too. just make sure the shaft is ok with no damage or u will be doing the same fix with in six months.

I don't know what these seals & bearings are you're talking about, But, you don't have to do Any of that. You certainly would NOT want to replace the, $60, Knuckle Seal and the only "axle" brg you could be describing I'd think would be the ft. Hub Assemble and No, you can just put in the $8 needles.

Also, even if your stub axle is pitted where the needles ride and they wear-out prematurely, I'd rather change them often (takes 30mins once you do 'em a couple times) then spend the hundreds of dollars you would on a new axle/seal/ & U-Joint!

[HH65AM1]

@NoRalPh...So you are saying it is the 4wd driveshaft turning while in 2wd? The solution is to replace the needle bearing in the Front Hub?
I still have to drive the truck 1,500 miles to get back home to perform the maintenance.
If it becomes undriveable... Remove the front driveshaft?
Thanks for the help.
I have already replaced the starter outside in 21° on this trip already. (10 minutes to get it off and 10 minutes to get the new one on!)

[03_Turbo7.3]

Originally Posted by HH65AM1

@NoRalPh...So you are saying it is the 4wd driveshaft turning while in 2wd? The solution is to replace the needle bearing in the Front Hub?
I still have to drive the truck 1,500 miles to get back home to perform the maintenance.
If it becomes undriveable... Remove the front driveshaft?
Thanks for the help.
I have already replaced the starter outside in 21° on this trip already. (10 minutes to get it off and 10 minutes to get the new one on!)

Just engage your front hubs manually, youll be fine for the drive home, if i was home id take a pic of a failed one for you have a few kicken around. The needle bearings inside the hub have prob not been serviced in a very long time. there in the service manual but lots of ppl have no idea what they are, once you replace the little bearing youll be back on the rd in no time, pack them well with bearing grease.

The seals hes talking about are the 3 seals, i replaced mine due to old and was in there anyways, theres the dust seal on teh axle, hub seal and a yellow oring for the hub which id replace no matter what..its cheap

[jm03powerstroke]

i am talking about the nice big $60 seal. when that bearing goes bad an start dont the intermitting vibration the sale is also bad it loosing up and will cause a problem down the road with the auto locking hubs not wotking right and water getting in trust me.. i have had this problem, i would just do it right the first time and replace the needle bearing inside the hub bearing and the axle seal. make sure the outta axle shaft is not worn down were the bearing rides because it will do it agian and again till u replace it. the fix was around 250 bucks
axle shaft outta $120 new
axle shaft seal $60
axle shaft bearing $10
u joint because u have it aprat $40

[NoRalPh]

Originally Posted by HH65AM1

@NoRalPh...So you are saying it is the 4wd driveshaft turning while in 2wd? The solution is to replace the needle bearing in the Front Hub?
I still have to drive the truck 1,500 miles to get back home to perform the maintenance.
If it becomes undriveable... Remove the front driveshaft?
Thanks for the help.
I have already replaced the starter outside in 21° on this trip already. (10 minutes to get it off and 10 minutes to get the new one on!)

I don't believe it has anything to do with the driveshaft. The noise would be coming from the ft hubs alone and locking them will not only eliminate the noise but prevent further damage to the stub axle. You can drive with the ft diff spinning without hurting anything but a little bit of fuel mileage (but still in 2WD)

You can choose for yourself weather to do the $10/30min fix or the $250/3hr fix once when you get home