Vibration/humming consistant with speed.

[PANTERA]

My 92 Ranger 4X4 just started doing this vibration and humming that's consistent with vehicle speed. I jacked the vehicle up and checked the wheels for play, drive shaft U-joints for play and checked the steering as well. All seem good. I replaced the ball joints and axle shaft u-joints this summer. Could the wheel bearings be shot even if there is no play in the wheels? I'm at a loss. Any advice would be greatly appreciated. Thanks,
Jason

 

[adsm08]

Yes, the wheel bearings can be noisy with no play. In fact in your setup if they are over-tightened it can make them make noise.

 

[RonD]

Balance weights can fall off or be knocked off wheels, tires can even get a bad spot

 

[PANTERA]

Thought of wheel weights too, didn't notice any missing. Would a missing weight cause the noise and vibration up until the truck is almost stopped? I'm looking at replacing the bearings this week and PRAYING that fixes the problem. BTW, what are the chances that the problem could be caused from the bearings in the back? The noise/vibration seems like it's coming from the front, but not 100% certain.

 

[RonD]

I would think a bad tire or missing weight would be a higher speed only

Can you jack up the rear end of the truck?
and run the truck, in 2wd, no noise = front end

 

[Andy D]

Just for grins, check the fluid levels in the pumpkins and TC . Just to eliminate easy stuff. I check that stuff before I head for the PITA stuff.

 

[exbass94]

Does the vibration only happen with the hubs locked in, or does it do it regardless?

 

[FritzTKatt]

Trans fluid. Had a higher pitch whining once, only noticeable when coasting though. Worth a shot, and if not it could likely use a bit of fluid anyway

 

[PANTERA]

Thanks for the reply guys. Ron, I'm jacking it up tomorrow to do just that. Had the window rolled down in 20 degree weather tonight coming home from work to try to locate the noise. No luck. Will check the fluids as well. I engaged and disengaged the hubs with equal results.
I was helping my in-laws haul bags of wood pellets from store to home and had the truck loaded down pretty good. On the way home is when this crap started, so that got me wondering if that extra weight put too much stress on the rear axle and screwed up the rear bearings? Gotta win that lottery to get me a new Ranger!!! Lol

 

[PANTERA]

Well, jacked up the rear end and ran the truck to 25mph when the vibration occurred and pin pointed the noise to the rear axle passenger side, sooooo it looks like I'm in for a project this weekend! BTW, anyone know how much lube the 8.8" takes? And can I drive this thing short distances up until this weekend? Thanks for all your advice guys, I really appreciate it!

 

[RonD]

Here are the rear axle specs for Rangers, and other Ford models
http://www.therangerstation.com/tech_library/Axles.html

Not sure oil capacity is in there, I would get 3 quarts, should take 2.5 quarts, if completely drained.

You never know about slight noises and if running will cause more damage or strand you, but you have been driving it and "so far so good", so.......IMO I don't think a few more miles will matter one way or the other.
But notice I am not including my home phone number with that opinion

 

[tmcalavy]

Just top off the diff until it starts to ooze out of the plug hole when the truck is on level ground...a 7.5 diff supposedly takes 2.5 quarts, but don't know about an 8.8 diff. My 7.5 will only take a little over 2 before it starts dripping out of the plug hole...just don't get your head/hair/face too close or you'll get that rank lube-smell on you.

 

[PANTERA]

Just top off the diff until it starts to ooze out of the plug hole when the truck is on level ground...a 7.5 diff supposedly takes 2.5 quarts, but don't know about an 8.8 diff. My 7.5 will only take a little over 2 before it starts dripping out of the plug hole...just don't get your head/hair/face too close or you'll get that rank lube-smell on you.

C'mon, I hear chicks dig the "differential cologne"! Lol.
Thanks guys!

 

[FritzTKatt]

Just buy a gallon jug. Cheaper... Makes life easier.

If you have a posi don't forget the friction modifier.