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Is there a simple test for determining if there is a bent rear axle shaft? I would think that some sort of contraption that could run very close to the rear flange with the axle turning might measure any run-out. I guess you would have to remove the shoes etc.
Any ideas or tips would be appreciated.

Bill,
How about putting some kind of pointer that is just touching the tire at the sidewall and rotate to see if there's deviation. A dial indicator on the flange face would work too. Good luck.

Curt B.

A magnetic dial indicator would be the contraption to which you refer. The farther out you can get from the bearing would be most effective, as a bent axle won't be apparent right at the bearing. If you brake drum is concentric, you could just adjust the brakes until they just drag and listen as the wheel is turned slowly to determine if it drags more at one point than 180 degress from that point. Why do you suspect a bent axle?

I have had a constant mild jumping/hopping in the rear end of the truck. I suspected a left tire as it was hopping quite a bit when run with the wheels elevated. I did not try that wheel on the right side.
I did a rear brake reline and did not turn the drums. When I adjusted the shoes I could not get a constant drag on the drums when I turned the wheel by hand. It would drag and run smooth and so on.
I thought that either the drum is out of round or the axle might be bent. And seeing how I had a bouncy tire I started to think the whole problem might be an axle.
There is no sign of seal problems on that side and when I tried to balance the wheels that particular tire was way out of balance and would have taken too much weight to rectify.
I thought when I posted that perhaps if I could check the axle with some type of indicator then I could hopefully rule that out as a cause of my hopping.

A dial indicator at the flange will tell you if the flange is bent. Im not so sure you will be able to check for bent axle with out removal and a long enough machined straight edge and feeler gauges. Tire hop= possible bad tires:broken belts. Or suspension components:shocks,bad spring. Drum could be bad. My guess is bent flange and get the drums measured and turned. I think if the axle was bent you would have bearing noise also or soon enough. Just my guess.

I have never encountered a bent axle but have seen bent flanges from :Curb checking after sliding on ice or big pot holes while carrying a load or someone backs into your truck and the bumper just pushes the wheel. All can bend a flange or wheel or deform the drum. If you realy think its the axle use a long enough machined straight edge and feeler gauges, the gap wont lie. If its bent be concerned about the axle tube and stress on the differential.

From your description of tire balance problems and a 'bouncy tire' I would bet on that being the source of your 'mild jumping or hopping'. Axles do bend, but it takes a lot of force and the wheel usually gets bent a lot worse.

Balance the tire first. Check runnout at the wheel bead seat area. About .040 or less runout is the norm. That way you check the wheel and axle. If you have a problem, swap sides with the rear wheels to determine if it axle or wheel runout.

Before I did anything I'd move the rear tire to a front axle....set up a block of wood, spin and determine that the tire is not out-of-round or that the rim is bent. Also can check rim runout with just some simple blocks and a pointer. Once you've determined that the rim is not bent and that the tire is round, you can move on to the more complicated stuff. Place the "confirmed" rim/tire back on the rear axle in question.....if it's bent you'll be able to see it....you know the rim/tire is true. I've seen rust/road gunk on the wheel mounting surface throw off a rim. It takes a pretty good whack to bend an axle.....rims and tires are much more often the ones getting the beating.

I always try to do the least complicated troubleshooting first.....getting a firm baseline more often than not...leads to a simple fix. Hope this helps.

Dave

I have tested and tried to balance the tire. On the balancing machine it has a runout of much more than .040, more like .375. The rim is okay as it was checked without the tire. Tried to balance the tire but it would have taken quite a few ounces of lead to make it right. Even rotated the tire on the rim 180 degrees. BTW this is a bias-ply tire.

A quick and accurate check to find an axle bent enough to be noticeable is to pull the wheel, make sure the drum is seated tight to the axle flange, pick a spot on the backing plate to watch the gap between it and the drum, spin the axle and look for any deviation in the gap, (wobble of the drum). How much is too much? I don't have a number, but it should run true without any noticeable wobble. Spend seven years in a body shop and you will see lots of bent axles.

John