Rumbling noise loud at one speed , quiet at another

[WNY964x4]

ok , this is really getting to me , on my 97 4x4 with a 5spd and Elec. T-case. When i am going 40 - 50 MPH regardless of the gear or tires. I get a very loud rumbling/humming sound. Then once i get past 50 it quiets down but is still there. It almost sounds as if it is coming from the front but i cannot tell.


for further info
1.the front auto hubs have grenaded themselves
2.the trans was running kinda hot ( i was pulling some big hills in 4th at 70 with about 1200#'s in the bed )
3.and it fells as thought i the vibration can be felt through the shifter
4.it is bad enough that it is causing my driverside mirror to vibrate

any help is greatly appreciated

 

[WNY964x4]

somebody has to have an idea of what is causing this , it is really getting on my nerves , everytime i post a question i really need answered noone answers

more info on the truck
Year : 97
Gears : 3.73
Miles : 131 , 068

 

[scotts90ranger]

is it extended cab? if so I say carrier bearing

if not, or you know it's not the carrier bearing, get underneath and grab the rear drive shaft at the front and back and wiggle around, how much play is there?

if nothing stands out, does it change whether you are coasting or under power? my explorer does that when coasting at 60 or above and I think it's the carrier bearing

 

[WNY964x4]

is it extended cab? if so I say carrier bearing

if not, or you know it's not the carrier bearing, get underneath and grab the rear drive shaft at the front and back and wiggle around, how much play is there?

if nothing stands out, does it change whether you are coasting or under power? my explorer does that when coasting at 60 or above and I think it's the carrier bearing

it is an extended cab , and the noise stays consistent wether under power or coasting

 

[4x4junkie]

If it's coming from the front, I'd suspect wheel bearings. Nothing else should be turning up there if you're in 2WD.

 

[WNY964x4]

i am thinking it is more coming from the back , and i was coasting down a hill in neutral last night at ~50 mph and the noise was there , but very quiet

 

[skippy]

How old is the universal joint?

 

[WNY964x4]

i am only the second owner of the truck and have no service records for the first 12 years of its life , all of which have been in ny , and the u-joints are non greaseable

 

[maroon ranger]

Guaranteed driveshaft and or carrier/center support bearing! Take it to a driveline shop and have your drive shaft balanced if your carrier bearing isn't the problem.

 

[oldfordman]

I agree with the others. Truck is 12 yr old. Check and/or replace the u-joints and carrier bearing. I once had a u-joint go dry in only one cup. Made a lot of weird noises and vibrations, but felt tight when I crawled underneath to check it out. Since the thing had over 150K on it at the time, I replaced all the u-joints and the carrier bearing. Do it once, then forget about it. Get the balance checked by a GOOD shop- the 2 piece shafts can be tricky to properly balance. One last thing- make sure both of the front hubs have completely disengaged. (I hate those auto hubs)

 

[sittenHIGHon35s]

I also agree with the others u joint or possiably ur trany but unlikly