If the rear end is on jackstands, with tires off and drums on, and i can see the drum wobble in and out when looking at the distance between the drum and the backing plate, what would this be?

Bent axle? Bearings?

I have been trying to find a vibration for quite a while now. Took the drum to auto parts store and they put it on the lathe and it did not wobble....

So, what next?

Thanks

 

if the hub assy is moving in and out the bearing is either not adj properly or its faulty. if you grab the hub assy and try to push/pull and it moves, try adjusting the bearing,
typically a failed bearing wont give you a vibration, it would have lots of noise(that you would feel)

inpect your U-joints, they might feel tight when checking them by hand, but if you see any rust/rust dust near the cups, that u-joint would be 100% failed!, some times you have to remove the drv shaft and manually rotate the joint thru its range, if it binds it would need to be replaced

check all u-joints that includes front U-joints and front drv shaft, they can and will cause vibration issues.
as for the wobble your seeing the external casting may not true, but that no indication of balance or trueness, Highly doubt that is any cause of vibration, especially since you had them turned on a lathe

 

Bent axle sounds logical, remove it and check it

 

What truck is this? If this is a 3/4 to 1 ton. should have floating axles. take the drum off and take a look at them I"ll in motion. I would put an inductor on them to check. If you run them with the truck engine, don't step on the brake with the drums off.

Foating axle shouldn't get bent. they don't carry any wieght, they just drive the wheel.

 

It's a 3/4 ton with the Dana 80. They did not turn the drum, just put it on and let it spin.

I have been noticing a loud "whine/roar" upon strong acceleration. Not sure exactly where it is coming from, but I will pull the axles tonight and check the bearings also.

Thanks

 

Only thing that will give you runout would be a bad hub/bearings. A bent axle shaft, you'll never know unless you remove to to do a runout check on V-blocks. Bent axle housing, your hub will still spin true.

 

I would put some lugs on the to hold the drum tight to the hub, then recheck it. If still has runout. Pull drum off. Run it again and watch the hub. If you can't see the hub runout. should put an inductor on it to make sure. If that all runs good. Then the drum is messed up. Chould take the drum to a place that turns drums, have them put it on the machine, They could tell you how bad the drum is.

 

Ok, so bearings look good, axle looks good, but OMG, I cannot find a replacement wheel seal that fits. Most auto parts places show a Timken 4250, but I got home and too small. Anyone have a valid part number for the seal?

Thanks

 

Here is the video? Ideas?

http://www.youtube.com/watch?v=btywakS8r3E

 

to me that proves nothing, you have no machined edge there to compare, now if the face (front) was walking like that I'd have concerns.. does the other side do this ? if not rotate drums and compare, I doubt its anything, to confirm try installing the wheel and see if the wheel walks like the hub did.

again if you have a vibration, I'd be looking somewhere else, U-joints/hanger bearing

 

I'll get a dial indicator today. My concern is on jackstands WITH the wheels, vibration is there. WITHOUT the wheels and WITH the drums, vibration the same. NO DRUMS, no vibration, but then again, not much rotating mass with just the hubs.....

 

Well i put a dial indicator on the hub mating surface. I ran it in 1st gear since it was hard to turn the hub and not push in or out affecting the reading. I saw a max of .03 runout. Now when i check the bearing preload, I can push in and out and read about .05. Not sure if this is too much or not. I went with tightening the hub nut to 130 or so and then backing off about 120deg....

I can't find a max runout spec for the hub

 

not sure how you setting the wheel bearing, there may be a speck out there, but generically, load up the nut, rotate hub, back off nut till the hub has a little in/out play, then tighten nut until in/out play dissappears,secure lock tab this would be as close to zeo preload as you can get. that being said slighty less pre-load would be bettr than too tight,

If you are getting skewed reading s because you are pushing in on the hub, I'd say you dont have the bearings set tight enough, by hand you should not be able to move that hub in and out.

It is possible that your drum is way out of balance, there are places that can balance your wheel and drum while its on the truck (might be hard to find someone that can do it)
if you suspect the drums, try running one drum at a time to see if only one cause the vibration, just remember to shut the truck off in gear, rather than applying the brakes and causing the wheel cyl to blow, or shifting from D to P and hear that racket from the tranny as the spinning internals try to engauge the park pawl

 

You can move the hub .050", or .005"? Theres a big diff, and the former is way too loose. IIRC, even .005 is a bit loose, but not that far out. Tighten up the bearing and try it again.

 

.001 to .010 was long viewed as acceptable end play for a wheel bearing assembly. This is tight enough that the bearings can do their job properly, and loose enough that they don't over-heat in severe use.

That said, there have been several different methods come into play in the last few years. some say 50lbs then back it off 1/4, some say use end play as a spec, but in the real world, most use jam nuts, not these goofy little wedge pieces of junk.

Ford had a good idea with their ratcheting nut, where you tighten to 55lbs then back it off 8 "clicks" for a used bearing. Basically, that was as close to idiot proof as I have seen in an automotive application.

When I did my rear diff two years ago, I used a dial indicator, and set the end-play to 0, plus 1 tooth on a fine tooth ratchet. It seems to be working well.

Just food for thought.