I really need some understanding of how this could happen. I feel so bad for my brother. He has a 2001 F350 7.3L with auto trans, auto locking front hubs. Not sure what axle he has.

We left the lake Monday morning and were headed home about 150 mile drive. I had a blow out on my trailer and had to drive in to the nearest town to find a new tire. Long story there, I actually had two tires fail. Anyway my brother pulled over and waited for me. His truck sat for about two hours before I got everything put back together and we were back on the road. We had only traveled about 60 miles by then. We hadn't been back on the road more then 5 minutes when I see him pulling over to the shoulder. He called me and said he heard a clunk in the front end and as he slowed down to get over he was down to about 25- 30 mph and the front end completely locked up and caused a 6' skid mark. He was able to get the truck off the road but said he heard all kinds of metal grinding as he did. By the time I pulled back around and got to him there was gear oil on the ground. We called for a tow and the truck is in the shop.

The mechanic says he believed the passenger side 4wd hub was not completely disengaged and that caused the axle to spin twice the speed as the other side and that is what caused the failure. He said we should always back up a few feet after disengaging the hub. I still don't understand what he is saying. The hub only locks the wheel to the axle. The differential is open and it is meant to spin both wheels independently. I just am not understanding how having only one hub locked in would create such a problem.

My brother is looking at a complete front axle rebuild. Bearings, seals, ring and pinion, I don't know what else. We are headed over to the shop now to take a look.

Help me understand how this happened.

 

I'm not sure about how the hub being locked caused the problem. It is something I would like to understand.


For the axle, another option is one out of a junkyard. It should be way less expensive than a rebuild.

Was the 6' skid mark just on the passenger side?

 

Driving with one hub in will not by itself cause catastrophic failure. Whatever failed would have eventually let go anyway.

 

I was wrong, it was the drivers side. We went a looked at the truck. The pinion bearing was melted to the shaft. He spent over an hour just getting the pinion out of the diff. I really think you are right, something was going to fail. It sure looks to me like the pinion seal failed and with no gear oil the bearing got so hot it seized up. He is looking at new ring, pinion, bearings, seals. The spider gears look okay, the axle shafts look okay. The locking hubs need to be disassembled and serviced. Estimate is at 1800.00 including some over night shipping charges, the tow and tax.

Guess we should just be thankful none of this happened while we were across the border in Mexico a few weeks ago. Or that it didn't lock up when he was doing 60 mph.

 

Look at Craigslist- over here there are 3 D60 front ends for sale for $600-800.
Also Pick n Pull should have some...

Good luck!

 

A good salvage yard find would be cheaper than rebuilding.

 

I agree, but that is my brother's decision. He would rather know it is done right then risk another failure using an axle with unknown mileage.

 

Here are a couple. You didn't specify what gears he has. These are all 3.73.

 

Thanks thomabb, how did you get that info?

 

www.car-part.com


Searchable database. Good resource if you have salvage yards in your area that are members.

 

Even if the rear is toasted couldn't you just remove the locking hubs (if they failed), cover them with plastic baggies and rubber bands and drive the truck to home and/or destination and get it taken care of at home?

 

So was the transfer case dry?

 

the transfer case is fine. One locking hub was toast, just so locked up it could not be salvaged. Everything is fixed and back on the road. I just think the pinion bearing failed somehow. I guess it happens.

 

The locking hubs need to be disassembled and serviced.

Or replaced with manual locking hubs!

 

I remember reading somewhere that driving on the highway at high speed with the hubs locked would tear apart the front diff and blow the front end. I think it was only a problem on some trucks, probably with age