bad rear end shake at 50mph

[bigjohnny1974]

I recently got a free brake inspection done on my 02 sport trac. I noticed the technician using a sledge hammer to knock loose my rear hubs. Afterwards I noticed a shake coming from the rear around 50mph. I took it back and they could not find a problem. Anyone has suggestions what might have happened? Bent axle shaft or hub? My tires and rims checked out fine, and have new drums. Oh and on another note. I jacked up the rear of the truck and hit the gas some to get the wheels moving. Passengers side tire has a wobble to it.

 

[sr139fox]

Rotate the tires front fo rear. If problem follows, you have a bad tire. Problem solved.
Dave p.

 

[ncranchero]

Bent axle, probably due to the idiot with the sledgehammer. I've changed three on Rangers and Sport Tracs. Axles aren't as tough as you'd think.

 

[bigjohnny1974]

Sorry for the late response, but thanks for the input. I rotated the tires, checked the play in the tires for the wheel bearing. The only play I had was due to the c clips on the axle. Everything checked out fine. I changed out both axles and the problem is still there. do you think I missed something while checking the wheel bearings or could it be bad u-joints? Oh and the truck has almost 150,000 miles on it. Thanks again for the previous input.

 

[ncranchero]

Did you not check the wheels/axles for running true before you replaced the axle shafts? Bent axles with the wheel still mounted is easy to see.
Yes, it could be the u-joints. Hammering the axle wouldn't cause the joints to go bad though. Raising the vehicle leaving the rear end hanging may affect a worn out joint.

 

[mrbrett]

I am wagering on bent wheel, from the sledge.

Alternate possibility is the bent axle flange as suggested above. To diagnose that on my Jeep (similar axle design) I put the rear axle on jack stands and idled in 1st gear. Stop taking parts off when you can see the wobble. Mine came from bent drums.

e.g. Idle with the wheels and tires on. Observe wobble. Remove wheels and tires, observing rotor. If there's no wobble, your issue is with the wheel. If the rotor is wobbling too, it's likely the axle flange.

Edit: I didn't see that you changed both axle shafts. Gotta be the wheel/tire, but I'd let it run on jack stands to see which one is bent.

 

[ncranchero]

I would assume the wheel was off before the beating began. Mine had the 50-55 MPH wobble and it was a bent axle flange.OP didn't say if the replacement axles he installed were new or used.

 

[mrbrett]

OP didn't say if the replacement axles he installed were new or used.

Valid point, I was assuming new as there are a lot of aftermarket options due to the popularity of the 8.8 in the off-road world.

 

[bigjohnny1974]

They are new axles. The shaking isn't as bad as before though but a shake is still there. Today at work I was checking my differential cover to make sure there was no leaks. Cover was good but I did find that my pinion seal is leaking a little now.

 

[mrbrett]

Pinion nut loose?