I have a wheel speed hum and I know its not from the tires as I just put new ones on a couple days ago. Also I put new wheel bearing/hub units in just over a year ago. My front driveshaft has play in it when I'm parked in 2wd. Could this cause my wheel speed hum?

 

If the play is up and down or side to side, yes it could be, there should be none. If the play is in a twisting motion of the shaft there should not be very much then that should be OK. You can remove the shaft and drive it then you will know if the shaft is the problem or not.

 

The play is in the twisting motion not up/down or sideways and there's just a little motion when twisting. This wheel speed hum is driving me insane. I hope it isn't the hub assymblys again??

 

It does sound like a bearing. At what speeds are you hearing the hum? Did you install one of the cheaper hubs or a SKF or Timkin?

 

I hear it at all speeds, low to high! It's really loud coasting at 55mph and a really high pitch at 70mph+. I can't remember what brand I put in, got them at advanced auto parts and I believe they were SKF!

 

So I took my front shaft off and the noise has almost gone away completely, not sure if the sound with the shaft off is just my tires(see sig). The cardone joint looks to have a plastic boot between the u-joints and that has a small crack in it. I really think the horrible hum is from the front shaft. Any ideas? I'm taking it to the shop tomorrow afternoon to see what they say. Oh the u-joints by the cardone joint are spicer but the u-joints by the front diff are original I think and my truck is pushing 180k miles.

 

There is a bearing inside the cardon joint. The crack in the seal on the cardon joint could allow water and crude to enter the joint. The joint is in constant flexing when the shaft is turning and as it wears it can cause the shaft to get a little out of balance and if it gets worse and breaks it can destroy the transfer case.

Hopefully you have found the cause of your noise.

 

Well found that my driver hub assembly was shot and got that replaced as I don't have the time to do it myself but also found the source of my wheel speed hum, the front diff pinion bearing. They recommended doing a full overhaul on all the diff bearings...close to $1k. Ouch!