HUMMING NOISE ??????

[MTN4X4]

i have a 91 with 260,000 miles on it.
4.5 inch of lift. i have a humming noise when driving from the ft
may be left ft. it will go away when i put it into 4-wheel drive.
but as soon i step on the brakes it comes back. release the brakes and
the noise is gone.
take it out of 4-wheel drive and the noise is back.
any ideas would be nice..............

 

[winterbeater]

Left front wheel bearing? Loading is changing with 4WD and braking.

 

[MTN4X4]

are you sure...
the noise doesnt change when turning.

 

[winterbeater]

No, not sure. Just a WAG. And not changing when turning IS a clue that leads away from that hypothesis.

 

[89xj]

ideas would be to test/check the hubs, axle u-joints, and check the brake components for wear. ive heard that the caliper can wear a groove into the knuckle and cause a strange noise.

is the front d30 on the 91 still a disconnect axle?

 

[MTN4X4]

its a non vac disconnect
if was the knuckles it would make it all the time ?
the u joints a less then a year old.
how about carrier bearing ?

 

[Combatcm]

I just had some vibes in the general front area drivers side. I thoughbt it was the hub, i changed it out. It was still there so i took out the front driveshaft. It was the driveshaft, im currently changing the u joints.

 

[MTN4X4]

did it change when you went into 4 wheel dr?

 

[jeepman121]

Front carrier bearings...??? My dads went bad on his 99. The humming/groaning sounded like he had knobby mud tires at times especially when braking.

 

[CharlesS]

With the symptoms you are posting....IF you have a non axle disconnect front differential; I would check the front driveshaft U joints.....
Putting the transfercase in 4WD applies torque to the U joints and when applying the brakes the torque changes....

 

[MAY POP]

It is humming because it doesnt know the words!

 

[latenights]

It is humming because it doesnt know the words!

:laugh: