98 Rx Axle buzzing/grumbling

[joachimf]

Dear @all,

drove a friends '98 Ex 4x4 4.0 A/T yesterday because he told me about an axle buzzing/grumbling noise that has developed louder over the last weeks. Vehicle has 8.5x15 wheels with 31er tires, 105k mls:

Noise starts around 20 mph and really get loud at 40 mph with peak at 55 mph, then it becomes less prominent. Could feel a slight vibration in my left foot resting on the fender well and in my right foot on the loud pedal.

Tried some turns, sharp circles and different loads. No diff chatter from the rear, tranny shifts are normal and smooth. Noise does not depend on engine speed. 4x4 works as it should, and does not change the noise.

Raised the front end and turned the front wheels with hand. Wheels turn freely with slight brake pad noise. Right wheel developed a deep howl when you turn it faster. To rule the tires out he changed the big wheels for the original 7x16 wheels with 255/70 tires. Same scenario as described.

Any ideas from your side what that loud buzzing/grumbling noise could cause?

Thanks for your help guys!!!

 

[drdoom]

Maybe it is the front hub assembly going out.

 

[joachimf]

@drdoom,

well, yes, that was my first idea. To get a confirmation we put the Ex on a chassis hoist yesterday with a guy in the truck. Started up the 245 and put the shifter in 'D' and accelerated. Drivetrain sounds smooth, no abnormal noise.

Then we switched to 4x4 high. This caused some noise coming from the front right side.

My feeling is it could be the right front hub or something in the drive shaft area. You know the front diff is on the left side and the pumpkin has a short axle tube with an axle shaft to the right side. Maybe a bearing in this area could be the noisy one, too.

We will replace the hub first because of its easy access and price. Will keep you informed about the results.