Tracking down noise/vibration

[damarble]

I've got a head scratcher here, I've been dealing with a lot of high speed vibration and can't track it down. I've replaced track bar bushings, u-joints, had new driveshaft cut to size, shims to get my pinion angle spot on. Still I get this slight vibration with noise at 55+ mph. It varied a lot and was much harsher depending on speed before I put the driveshaft in today. Now it's a deep mmmmhhrrr.........mmmmhhrrr sound with vibe, at about 3 second on/off pulses. Like listening to a clock tick, perfect timing.

I don't know what else it could be now. Would rear end bearings do that? It's the only thing left and I think the guy that istalled my gears/rebuilt the axle screwed it up. it leaks from every seal and there's a 1/4 turn of slop in the pinion.

Thanks for any ideas.

 

[my pos mounty]

Hope you didnt pay him much. My rear diff was making a low hum on and off as you describe, eventually turning into a very loud whine. Loud enough that as i was passing other cars on the highway, THEY could hear it.
Im not sure what your noise/vibration is, just passing along my experiance.

How about front drive shaft u-joint? Wheel balance?? Front axles?

 

[99SportX]

If it is 55+ I would say get the wheels balanced.

It could be that the axle is pretty messed up as well, probably needs a complete rebuild anyway.

 

[corkey]

1/4 turn of slop in the pinion means trouble,, the gears might not be meshing very well, and the loading and unloading of the gears must be what is causing the hum,
i would take it back to the guy that did them and have them take it all apart and inspect evrything,, might be too damaged already,,

 

[damarble]

As far as I can tell, the front end is OK. There's no play in the wheel beerings, they turn freely, the ujoints doin't have any play. Again like the rear the pinion has a lot of slop. I've pulled the front driveshaft to elimate vibes from it and there's no difference either way.

I have not had the tires rebalanced since the first time when I bought them, I did get lifetime balance so I'll try that. They are 33" Truxus MT's with 20k on them.

The axle. Grr. I had a lunchbox locker in at so when I mentioned the play I was told it was normal. I ended up pulling the Aussie because the teeth wore down and weren't engaging. With the spiders back in it was just as bad. But too late, now it's out of warranty at least labor wise, I'm not sure on Yukon's warranty. They were installed about 1.5 years now. It would be great if I could get the gears replaced under warranty but I'm not sure I want him putting them back in again. :thumbdwn: To make matter's worse he's a very active member in our wheeling group so that will be fun.

So everyone agrees a bad rear end could cause this situation?

Edit- Just looked it up, the R&P only have a 1 yr warranty. I'm SOL.

 

[firemanpine]

Sounds like a bad rear to me. I am in the same situation looking for a new rear. I waited too long. I was going to have mine rebuilt but it is pretty bad. I am in the process of getting a low mileage rear axle assembly for around $350. I will have around another $100 in having it looked over, adjusted, cleaned and new fluid.

 

[damarble]

Well it's got to get me through the winter. I'm contemplating going full width this time, I have a FW HP44 squirreled away and there's got to be 20 F150 8.8s in the JY here going for $65.