Unit hub bearings, axle shaft seals....?

[paulkeith]

Fellas,

I've got two shot unit hub bearings at 140k. I'm looking to snag a set of timken replacements.

i have some questions:

I noticed while noticing that the axleshaft had up and down play inbetween the knuckle and inner C, I found that I have an oil leak out of the axle tube on the driver's side. Is there an axleshaft seal? I'm assuming the failing bearing caused this seal to fail by allowing some movement?

Is there another bearing besides the unit hub that supports the axleshaft in the knuckle? Will replacing the unit hub eliminate the play I currently have?

thanks,
Paul

edit: oh, how do I know which wheel studs I have? (coarse or fine thread?)

here's a pic i took during my brake job:

 

[DaveBen]

We all are screwed by the UNIT BEARINGS. They are NOT serviceable or separately changeable. You MUST buy the unit from an parts store or Ford.

Dave

 

[bendog]

Or you could buy the Dynatrac kit which replaces everything with the non-unit bearing style.

 

[paulkeith]

We all are screwed by the UNIT BEARINGS. They are NOT serviceable or separately changeable. You MUST buy the unit from an parts store or Ford.

Dave

yeah, i know that. i was looking at the timkens.


anyway, i just did a little more investigating, and now have a new set of questions:

if i remove my lockout hub thing, i can move the stub end of the axle shaft around maybe 1/8" inside the unit beaing. this in turn moves the steering ujoint, and also the short side axle shaft.

what holds the stub shaft in place? is it the unit bearing? what holds the outer end of the inner shaft in place? is there a bearing in the end of the axle tube?

thanks,
Paul

 

[DaveBen]

The hub shaft holds in the axle shaft. It floats within the axle housing and can not go anywhere. It is NOT held tight, but loose. It will move in all directions a little bit. Get a book on your truck!!

Dave

 

[paulkeith]

i've got an electronic maintenance manual in addition to the weaksauce chilton's manual, and actually spent about 3 hours trying to figure out the exact assembly before i even posted. thanks for the bold red text though.

My question was if the axle shaft bearing within the unit hub should allow any movement of the stub shaft

 

[DaveBen]

Yes it should allow some limited laterail movement, about 1/32" or so. (.062)

Dave

 

[paulkeith]

well durn, cuz i've got about 1/4" if not more. If i grab the end of the stub shaft inside the hub and reach around and grab the u joint i can wiggle the thing all over the place. i hope i haven't trashed the bearing race on the stub shafts...

is it likely that i've also damaged the hub seal? I've heard/read its a really tight press fit onto the stub shaft and into the knuckle.


ediT: when you say lateral, do you mean in and out of the axle housing? my play is in this direction:

 

[bushpilot]

only way to know is to pull it off...mine seems to have a fair amount of
movement (when i pulled replaced the ball joints)...the bearings
and shafts were all in tact and perfectly fine !

 

[paulkeith]

yeah, i really dont know what the heck is going on now. It all started with a sound I'd hear while coasting. Best desciption I could think of would be a branch with dry leaves stuck under the truck dragging on the ground. After hearing the sound I started investigating to see if I had any movement anywhere, as i suspected unit bearings... I noticed some play in the axleshaft ujoint and stub shaft. I jacked up a tire to do the 12/6 3/9 check, and found a barely perceptible movement at 12/6, which I now think is the lower balljoint. I can't see or generate any movement by hand...I can generate an EXTREMELY small movement if I put the truck on jackstands and a jack under the knuckle...but I pretty much have to have my finger wedged inbetween the knuckle and inner C to feel it. I'd need a dial indicator to really prove it to myself.

I took the tire and rotor off and ran some lugs back on over my 2' breaker bar and CANNOT generate any play in the unit bearing. I did find the said large amount of play in the stub shaft, but I don't know if its normal or not. It seems like it would be really hard for one bearing to locate the shaft 100%, but the .250"+ amt of play I've got concerns me.

So what's confusing me is the noise is now gone (???!), and there's no play in the wheel mounting surface. I think I may have accidentally had the hubs in manual locked position. I dont know if a trashed spindle axleshaft bearing plus the hubs locked would generate my scraping noise. Seems like having the shaft spinning would prevent that bearing from doing any work in the first place. I've gone from thinking there was nothing wrong to almost overnighting a set of unit bearings to now thinking nothing is wrong again. I do intermittently get a dull clunk/pop while turning sharply...almost feels like a rubbing tire...but I couldn't reproduce it driving around last night. argh!

Paul