OK, maybe a dumb question, but.....
2010 F250 with the dreaded ESOF. Outside of a few leaky vacuum lines over the years, it's been pretty much trouble free for me. But, I have got into the habit of manually locking the hubs when I snowplow so I'm sure I'm in 4 wheel drive. I unlock them again when I'm done and will be doing non-4x4 required driving on cleared roads.
A couple of people told me to just leave the hubs manually locked and just shift the transfer case back to 2wd.
So, dumb question: is this advisable? Wouldn't having the hubs locked be mechanically tough on some part of the system? Otherwise, why would you even need the provision to lock and unlock them?
Thanks!

 

Leaving the hubs locked just allows the axle shafts to stay engaged and rotate with the wheels keeping all components in motion (not powered while transfercase is in 2wd) all the way back to the transfercase. As long as the transfercase is indeed back in 2wd the front end is not powered and just rotating at speed. Ive had no ill effects leaving my 05 and 06 F250's hubs locked all winter long (3-4 months) for the past 14 years ive owned both trucks.

 

On my last F-250, a 2007 with a manual 4x4 system, I would pretty much leave the front hubs locked all winter. In 12 years of ownership this never caused an issue.

 

And it's not a dumb question.

 

Agreed not a dumb question. And leaving them locked causes zero issues mechanically.

The whole impetus behind lockouts was gas mileage. You have a bit more drag in the front end at highway speed. It's negligible but can add up.
edit: this was more relevant in the 70's on full-time 4x4 rigs w the NP203

Others argue you're "saving" the front diff and u-joints by allowing them to sit idle. But if using quality parts this argument makes little sense. EVERY SINGLE TIME you're driving in 2wd you're using the rear diff and rear u-joints, and how often do those fail? Furthermore allowing parts to sit idle for years at a time only encourages rust and corrosion-- really not much different than sitting in a vehicle for 10 hours and then trying to first stand.

 

I'm not sure about newer trucks but my 03 will wear the front tires funny if I leave the front hubs locked in.

 

They wear funny due to the slight drag of pushing the entire driveline in the front rather than it being powered and trying to go at the same speed as the rear in 4wd. Some people don't care or will accept that phenomenon. Is it bad for anything? Well its not the best for the xfer case, Your forcing the chain and sprockets in one direction pushing when hubs are locked and xfer is disengaged , then you engage the 4wd and pull the chain in the other direction, wears the chain 2x as fast and wallows the cuts in the sprockets, it also spins the front drive shuttle on the main shaft while its not fully supported.

 

All my trucks, minus my 66 F100 which is 2wd, I leave the hubs locked year round, never had any ill effects, I'll unlock them if heading down the hill and I remember, but it's a 50/50 chance of that, not a dumb question.
Never had any tire wear issues on any of them, even my work truck stays locked in 90%+ of the time.

 

Leave mine locked 4 moths out of the year with no issues.

 

As a powertrain engineer, this is false. The chain doesn't really care which sprocket moves it, it's the same wear regardless if it's moving. The chain is in an oil bath, so long as the oil is in good shape the chain won't really wear much at all. It doesn't really hurt the teeth in the sprockets either - they are typically hardened steel. The front drive shaft and output shaft on the transfer case are ALWAYS fully supported via the bearings in the front differential and internal to the transfer case. Your entire argument comes across as not understanding how a transfer case is built and works.

Leaving front hubs locked in doesn't hurt anything, really. If anything it helps keep bearings/bushings/seals in better shape over time, as it coats them in a film of oil and keeps them from dry rotting or seizing up. When I had trucks with locking hubs, I would lock them in when the first snow fell, and not unlock them until at least April, so a good 4 months. I would also engage them from time to time during the rest of the year when off-roading, and would usually forget until I got back home. Never had any major issues, just typical maintenance.

As for why front tires wear different when the front hubs are locked in, it likely has more to do with the increased drag amplifying some kind of suspension/steering issue. You probably have a ball joint or tie rod end going bad, and the increased drag of the rest of your 4WD system is making it show up. The tires shouldn't wear different with the hubs locked vs. unlocked.

 

Figured put my vacuum hub failed in the lock position when I saw the puddle of gear lube on the ground. Coincidence?

 

Yes. Hubs don't have gear lube in them. Your gear lube came from a bad axle seal. Discovering the hub had failed was just a happenstance from tearing things down.

 

You should see the 3 or 4 threads in the 2017+ superduty forum. It appears for 2024 Ford made the passenger axle shaft 100% live and only has the driver side as a vacuum actuated hub now. Talk about guys freaking out yet not really understanding how the original system worked in the first place and that other manufacturers have had and have a single live axle or a completely live front end without issue for a long time.

 

I was unaware of this change - you're saying there's basically no lockout hub on the passenger side front axle? That's an interesting concept that I would think is either going to have the driver's side axle shaft spinning the opposite direction, OR forcing the front driveshaft to turn. Unless there's an electronic disconnect inside the front differential to eliminate that issue. Still, it doesn't explain why one front axle shaft would be live while the other isn't.

It's an interesting concept that I'd really like more information on - I've never seen it done that way, but I don't see any advantages to it. I have only ever seen both front axle shafts live, or both have some kind of lockout (even Ford's system for the F150), whether there is a disconnect in the front differential or not.

 

Virtually anything with a CAD is this way.

The bubble body F150s are one.

Pretty much all GM IFS is another.

2nd Gen Rams and all the YJ stuff that used a vacuum CAD are another. I honestly don't know how 3rd Gen+ Rams do it with IFS (never had a reason to work on one)

My JL is the same way, but electric rather than vacuum.

The idea is that with an open diff any "break in the chain" stops power to the front wheels. THEN if you "unlock" one hub and stop powering the d/s by shifting the t-case to 2hi, nothing spins (much) due to the peg leg diff. Obviously a true locker wouldn't stand for this. And I imagine it burns up limited grips?