I have a *whomp-whomping* sound coming from the back of my rig...the sound doesnt seem to affect the driveablity of the truck..so far.

The noise is deffinitley noticeable more over 20km/hr.

I checked all my lug nuts, checked the oil in my diff, nothing seems loose under the truck. I did just install my downey springs, but i think the sound started just before the install...(i dont think the angle of the drivetrain changed too much)

I dont appear to be missing any weights on the sides of my wheels, but i havent had my wheels rotated or balanced in over a year.

Tonight im going to put the spare tire on one side, then the other and see if that makes the sound go away...

ANyone else have any suggestions... i really hope nothing is wrong with my Rear Differential.

 

Sounds like a tire issue to me. You should be able to visually inspect the tire and find the problem.

 

THats the crazy part.... for all i can tell the tire looks fine...

 

i dont think it is a tire problem. you feel tire issues before you hear them.

 

just rotate your tires...or throw a spare on the one you think it coming from...if it continues then put the spare on the other one and the one you took off back on....thats a sure fire way to find out if its one of the tires....

did you skid to a stop somewhere?....this can make a flat spot on a really long slide...

 

Rub your hand around the tread area of all the tires.
Sometimes you can feel imperfections in the tread better than you can see them.

 

i think its the bearing. you should get it checked out

 

Put the axle up on jackstands and let the tire spin with the engine idling. Hold a pointer up to the tread and see if there is any radial runout (in and out motion) of the tread face. I had some Swampers that had a 3/8" flat spot along the tread. And also run your hand along the spinning tire to feel for bulges, etc. and look for the tread for wavy spots. I've had tires where belts broke and there would be a section of tread where it would jog back and forth then straight the rest of the circumference.

 

You may also want to check the inner face of the tire too. Sometimes when people check for imperfections on wheels etc... they only look at the outer face of the tire... be sure to check the inner face too. Those are harder to spot.

 

THanks for the suggestions.... i rotated the spare tire in with both rear wheels and noticed nothing different... my neighboor thought it might be a U-Joint...but a bearing is also a possibility.

I think i could figure out how to replace the U-Joint myself...but not very confident with bearings...

any other advice?

 

The true way to test for the tire imperfections is to do a roadforce balance on each, but seeing as you swapped on the spare for each of your other tires and still no change I would highly doubt the tire was at fault here. Sometimes as the tread wears down the tire can also get louder so you need to take that into consideration as well. Other areas could definately be the u-joints, diffs, wheel bearings, tranny, transfer case (if 4wd), etc. If you can hear the problem, then you will be able to track it down with a little work.

 

It is possible that the tire could have a broken steel belt. You can't see the steel belts because they are beneath the layers of rubber. I would take it to a shop and let them inspect it.

 

Usually when a belt breaks or separates there will be an obvious shifting in the tread also.(Makes the tread look wavy)

 

seriously.. its the bearing..

 

Scotty Bean..... So if its the bearing do I have to take it into a shop?

 

you would have to replace the bearing. im not sure but i think you have to get it pressed out and pressed in.. and i think only a shop can do that unless you have a press.

 

could be a tire, an untrained eye can easily look over things... i used to work in a place that did tires, and i was a tire technician, so i can easily spot something most people would never see

 

two things to do here...

In a parking lot. Drive in a figure-8 listening for your noise. Which way are you turning if the sound disappears. Bearings will produce more of a growling noise that will disappear when you unload the inside tire while turning.

Tires tend to produce more of a "whomping" sound than a bearing will. If it is a low speed (25-35MPH) sound or a vibration that feels like the vehicle is shaking, you most likely will have broken a belt. The only way to fix it is to replace the tire.

Balance issues start to show up at around 55-65 MPH. Running big tires and aluminum wheels, I had big issues with weights wanting to be thrown all the time. To fix this, I went with a product called Equal wheel balancing powder. You can find this stuff at truck tire shops.

To confirm a broken belt, I have always put the suspected tire onto a tire balancer and with a paint stick, light mark the face of the tire. The high spots will jump out at you like nothing you have seen before. This little trick will also bring out other little things like toe-in/out being off as well as a bad shock or a ball joint.

Couple of places to start.

 

End result.... blown wheel bearing....$250 incl labour and tax

Good eye Scotty Bean