hub noise? diff?

[vipersinu2]

I think my vibration is coming from my transfer case.


http://youtu.be/GPGT0JyaMlw

http://youtu.be/jXnOO0qdhy0

 

[Tech By Trade]

For ***** and giggles I would suggest changing your front U joint. 10 bucks vs thousands for a transfer case thats probably is fine.

http://www.explorerforum.com/forums/showthread.php?t=404003&highlight=joint
Most expensive U joint change in history. I bet ya there was a problem with the transfer case:thumbdwn: a little metal is fine. If it is grey but not full of Christmas trees its fine. Buddy almost made the same mistake on his f150.

 

[thebrakeman]

update:
A couple of weeks ago, the noise did indeed get worse. Before, I could only get the noise at 35+mph when warmed up; now I can get it cold, as low as 15mph, and the noise/vibration is really bad by 40mph. Swerving in either direction, the noise gets slightly worse (not much), but it's equally increased left or right. Mechanic was backed up, but confirmed things this weekend. He wanted to let things cool down, then check the fluid condition again today, but is nearly convinced it's the rear diff bearings.
...

Well, after I wrote this last update, I got a call from the mechanic. With the fluid cold again, he was still not convinced, and didn't want to waste my money (I appreciate that). So he got the truck out on the freeway and drove it fast to really heat things up. Got it back on the hoist, and finally got some clear noise/vibration up in the air....in the front, not rear!!

Seems to be the bearing for something he called the "stub shaft", which I think is what comes out of the front diff, but not sure if it goes to the right or left. He feels very confident he now has a positive diagnosis, but his parts guy is having trouble finding the parts. Fortunately, he said it's an easier fix. If the parts are reasonable, should be a cheaper fix, too.

 

[thebrakeman]

Mechanic checked the stub-shaft bearing/bushing that he suspected (which is in the housing between front diff and front-right axle shaft), but everything looked great there. So he cracked open the front diff, and found some grimy residue that is clinging to everything like paste, and some signs of metal flakes, though not a lot. This was late yesterday afternoon when he was closing up.

I met him at the shop this morning so he could show me. He said all the gearing looks great, although neither of us were aware that this front diff has been overhauled at some point before I bought it. He will be pulling off the bearing caps in the front diff to inspect the bearings, and find the cause of the grime and flakes.

Question:
The root cause has been very hard to find on this. I saw on another thread where the front driveshaft has a u-bolt at the front diff that is a common failure. But, that was on a V6 (mine is V8). That other vehicle also felt the vibration get stronger when he forced the center diff to locked. Mine does not change at all when I lock the axle together.

Mechanic said he already ruled out all driveshafts. Should I ask specifically about that u-bolt, or do my symptoms not fit that failure?

 

[Tech By Trade]

Its the same on the V8. CV joint coming out of the transfer case, U joint on the front axle. The reason they they can get away the speed variation of the shaft caused by the U joint is the low drive angle, because the diffy's don't move, the Independent suspension and the cv shafts move, the Axel is stationary. Just swap the U joint for $#1T's and giggles and I bet it goes away. It's a $15 part. Problem is you cant pull the shaft and do it in a vice due to the CV joint on the back, so you need to swap it under the truck. Easily done if you have a U-joint tool.

Its not a very robust system, that is why it is used on cars, and not usually trucks, although it is becoming more common. A solid drive axle is more resilient but you loose that cushy ride and control of independent suspension.

 

[thebrakeman]

The vehicle is literally at a shop, on a hoist, with the front plate off of the front diff. So I'm going to let him inspect those bearings while he's that far in. But I'm going to inform him about the common issue with the U-bolt before I give him the go-ahead for a rebuild.

I understand that it's a cheap part, and you recommend just changing it. But is there a way to know that it's failed/failing? Unusual play? If that were the problem, would my issue get worse when I lock the axles, as the other thread indicated?

 

[thebrakeman]

Just got message from mechanic. Evidence of a spun outer race.
ugg...

 

[Tech By Trade]

Only way to tell would be to pull it and check the pins and the shafts for wear. Might as well replace the U joint if you are doing that.
Sorry to hear about the race.
Chalk another one up to fords fine engineering.
Good Luck.

 

[thebrakeman]

Well, as said, there is evidence that the front diff has been overhauled previously, based on non-stock markings on 1 of the internal parts (pinion, I think he said?). The moving bits all looked good, but 1 of the side-gear outer races spun.

Last week, he pulled the front diff to a bench, replaced both side-gear bearings, and is ready to reinstall. He should be putting back into vehicle today, and hopefully good news (no noise).

 

[thebrakeman]

Final update:
Replacement of both front sidegear bearings eliminated all noise and nearly all vibration. Minor vibration felt in the steering was traced to the front driveshaft. Swapped with rebuilt driveshaft cured all ills.

As mentioned, the mechanic noticed that the front diff had been overhauled before. He suspects that the driveshaft vibration was the root cause (maybe both times).

 

[Explorer_PL]

AT least the truck drives nicely now, I am sure.
How many miles ?
I wonder from the cost perspective how the parts and labor to do that goes against a remanufactured unit ?