Bent Axle? [Video]

[Cody Rodgers]

Hey guys,

I've owned a 1998 K2500 6.5L suburban for about 3 years now. Since I purchased it, I've had what I'd describe as a drive line vibration (seat of the pants, not in steering wheel, resonating) noise that I can't quite pin-point. I've replaced the u-joints, had the driveshafts balanced, and have installed a new transfer case tail-housing. That took care of some up-down slop from the tail shaft bushing. But the vibration persists.

Now I'm looking at the rear axle's/ hubs as the potential culprit. I don't know much about trucks, but I know I have the 14 bolt full floating rear end. From what I've read, it's unlikely the axle shafts would have been bent since they arn't loaded as much as compared to a semi-float. I've taken a video of the hubs spinning and can see a little wobble in them. Here's a youtube link:

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What do you guys's think?

 

[evilunclegrimace]

The right side appears to be fine, the hub is running true.Watch the hub and sight at the hole in the sheet metal in the back ground.The throw at the edge of the drum is due to casting tolerances or the drum might not be flush on the hub. The left side is inconclusive as far as the hub is concerned, the tire has some throw in it and could be part of your problem,try swapping different tires and see if any thing changes. To get very precise clean the face and out side diameter of the hubs and use a dial indicator to see if you have any lateral or radial run out. Make sure that the bearing are properly adjusted before you make any measurements.

 

[evilunclegrimace]

There is another thing to check and that is to make sure that your differential pinion is not bent.Pinion shafts are soft and if any one hammered on it for any reason there is the possibility that it could be running with a wobble.

There are specialty tools to make checking run out on a pinion. It is a "U" joint that is precision machined with a circular race in the center to allow a dial indicator to measure run out with. It will check both radial and axial run out.

 

[evilunclegrimace]

You must be registered for see images attach

 

[someotherguy]

I'm with you on the right side looking fine and the left a little sketchy. Of course we didn't get to see the right side tire rolling since it's removed.

That left side tire looks like the tread may not be square on the carcass, might be a belt separating. Hard to tell from the vid. Wheel may also be bent.

If you don't have another set of tires to try, just try rotating front/rear and see if you feel the vibration in the steering.

Richard

 

[Cody Rodgers]

Thanks for the replies guys. All great points.

Some more info:

I've removed the drums and assoc. brake hdwr to replace the brake cylinders. With all this stuff off, including both rear wheels I put the truck back in gear and ran it in place up to about 55 mph. Even at idle there's a noticeable pulsating vibration. On the road, the vibration is worst at around 50mph. I've included a link below of the vibration in the cab. You might need to turn up your subwoofers top hear the full extent of it. Otherwise keep an ear out for the stuff rattling in the cab.

This rules out the tires being the culprit. I'll check the run out at both hubs, but I'm leaning towards the pinion at this point. Both hubs look pretty straight when turning with the wheels off. Thanks again for the tips guys.

With the driveshafts, u joints, and transfer case ruled out. Any other common areas for a vibration like this to originate from? (Aside from the pinion). ex. transmission output shaft bearing, etc

Link:

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[Cody Rodgers]

Not discounting "someotherguys" comment about the tire tread. Definitely something wonky going on with those. I can see the wobble in the side mirrors on the road lol. I would agree that the belt is perhaps separating.

 

[Markgyver]

Have you had the drive shaft balanced?
Also make sure the drive shaft has its correct phasing.

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