I have a problem, and I'm sure glad for my FTE friends, a plethora of quality mechanics I can turn to, especially considering that I am a novice to 4x4 trucking. I took my 99 F250 SD, 4x4, v10 our this afternoon to test the 4 wheel drive. Snow is coming and I have plowing to do. When changing my front brakes and calipers earlier this week, I noticed the vacuum line to the ESOF was dry-rotted on both the nipple (at the knuckle) end and the end that attached to the hose adapter assembly on the frame. That explained why I did not have 4x4 when I tested it a week earlier in the rocks. I didn't know about locking the hubs then, but thanks to FTE, I do now. Anyway I clipped the dry rotted hose at both ends and reattached the ESOF. Tonight, I shifted in the 4x4 high, felt it kick in, and felt a bit of resistance, thinking it was simply those extra tires that were being driven, but was glad my little nip and tuck trick worked. Overall it drove OK. About a mile late, I drove into a parking lot, began to turn left, and I thought my wheels were coming off! I felt an awful grinding-line vibration coming from the left wheel and it almost felt like I was skidding, though I assume that was just an effect. After taking it out of 4x4, no problem turning. So I did some testing. I disconnect the vacuum hoses, plugged them with small bolts, and went out to try it again. When the hubs are in AUTO, I kick into 4x4 and no problem. But when the hubs are in LOCK, I get that same grinding feeling while turning, both left and right. Only while turning - it feels OK when i am going straight.

What say ye?

 

Are you turning on hard ground in FWD? If you are your binding the front end agaist the rearend, and you can break somethink doing this.

 

I am a big time novice in 4-wheeling. I guess we are not supposed to run 4WD on hard terra firma, and can only use 4WD on loose ground (mud, dirt, snow, etc).

I only rolled a few feet each time so I doubt I broke anything. I was too scared to move very far. Does it hurt to go straight down the road in 4WD drive?

 

Ok...the 4x4 system must have some slippage. So going straight...no problem (HINT: should not be done on a hard dry surface). However, when you try and turn while engaged in 4x4 on a hard dry surface...there is NO slippage in the drive train (the front tires are turning at the same rate). You get the hopping and grinding feel. That is normal.

HINT: DO NOT do that anymore...unless on dirt or some loose surface. You might break something. Keep that in mind.

Glad to hear that you got the ESOF functioning again. Good find!

Hope this helps...

biz

 

Fortunately I had FTE to turn to before making the mistake a problem. Thanks for the posts and the advice!

 

On another note, when you disconnected the vacuum lines and put it into 4WD with the hubs in auto, you only engaged the front drive shaft and axle. You hubs were NOT locked because there was no vaccum. The axle was turning, but it wasn't driving the front wheels. Once you put the hubs in the LOCK position you locked the hubs, then you were driving the wheels.

Just a suggestion, if you know you are gonna be using 4WD alot, leave the vacuum line plugged, along with the hub, and just use the lock position. You're hubs will last a lot longer. You can drive in 2WD with the hubs locked and you won't cause any damage. All you are doing is turning the axle and driveshaft, they're not being powered, as the t-case is is not engaged. No harm, no foul. If you are not gonna use 4WD that often, just unlock them.

 

I disagree with above,you are putting wear on the front drive line components
front drive shaft u-joints,front axle u-joints,bearings,spyder gears in the front diff,needle bearings in the hubs.
Plus think of the few mpgs you are losing turning all that doesn't need to be turned.
Unlock the hubs and run in 2wheel drive.
Key thing is to excersize the 4wheel drive system once a month/week and it will be there when you need it.
Rich

 

Even though I am a novice, I have a tendency to agree with 40Fords, especially about the once a month exercise. What do others say?

 

I agree with FortyFords. Ford, and most other manfacturers, recommend engaging the 4X4 periodically to excercise the the system. It also gives you a heads up if there is a problem.

 

There is almost no resistance with those parts turning in there and the difference in MPG is almost unnoticeable. It's an open diff all you are doing is turning parts taht are meant to turn. As far as wear and tear, you are actually keeping them lubed. You don't have to keep the hubs locked, but it doesn't harm a thing doing it, especially if you are using it a lot.

The vacuum system is one of the things that causes the hubs (bearings actually) to fail. The vaccum from engaging the hubs actually pulls on the seals in the hub and ACCELERATES the hub failure. Reason for this is once the seal is worn, it begins to pull the grease from the bearings and thus the failure. Guys that don't use 4WD much see longer life in their hubs and bearings for this reason.

 

BFR250 - do you recommend that I keep my ESOF vacuum line disconnected? I will only use 4x4 if the snow demands it. This is the first year that I will plow and I imagine it might come in handy. But, I will always know when I need to get out and lock the hubs. Right now I have the ESOF vacuum line plugged though I could easily connect it back to the nipple on the knuckle.

 

If the line already rotted on you, I would cap it and the nipple on the hub. If you don't mind getting out and setting them, they work just like normal hubs. If you really don't use 4WD that much, it's cheap insurance to keep the rather expensive (approx $400 per side) unitized bearings from grenading on you.

Another alternative is to buy some of the Warn Premium manual hubs. MUCH stronger than the stock units and sealed much better. Very easy install and they run about $160.

 

Rich, here's something for you:

The needle bearing that the axle rides in that is inside the wheel bearing (inner spindle bearing), that needle bearing is spinning whenever the tire spins. With the axles UNLOCKED, that little needle bearing is turning. With the hubs LOCKED, that needle bearing is not being used.

Then, to add to that, with the hubs locked, the differential bearings, ring/and/pinion and u-joints are not seeing any load with the hubs locked. So the wear there is infinitesimal, and can be good because it's slinging the oil around.

What I mean is, there is no real "wear" difference between hubs locked and unlocked. Matter of fact, there is "wear" on a bearing with the hubs UNLOCKED, and that bearing is usually the first thing that needs servicing on the front-end.

MPG wise, I never saw a difference between hubs locked and unlocked.

 

Art
when your hubs are locked your axles are turning, which when you turn the front wheels left or right the front axle u joints are binding or trying to get into position to alow the wheels to turn.This is wearing on the u-joint plus the needle bearing in the hub along with the inner axle seals.Because that needle bearing is the only thing supporting the axle stub on the outboard side.

The wear on the spyder gears is in the turns,yes its a open diff but they are turning when its not needed.Its wear even though its being lubed .it's still being worn.Even though your engine is lubing your crank bearings they are still wearing.

When you drive away on a cold day in the winter after your truck sat all night.Its stiff and the gear lube is cold an thick you are using fuel to get that front drive line to turn. Of course untill it warms.
But I see the difference in my fuel mileage .The mpgs loss may be small.

Rich

 

I'll stick by my statement that because there's no load on the front drivetrain, there's a VERY SMALL amount of wear, not enough to worry about.

Granted in tight turns, the axle stubs flop around like a fish out of water... but because there's no load, there's not enough wear to care about.

Based on previous experience with my '74 highboy, and now my '01 for the last 4 years, like the last 2 winters driving all the time with the hubs locked, and the fact that I just replaced those needle bearings and check the u-joints, I can definitively say, there's no wear. One needle bearing got water in it from the snow, and roasted itself. The other side was 100% perfect. U-joints were perfect both sides, seals, etc.

And the spiders and pinion/diff-carrier bearings are certainly not worn because of running in 4x2 with the hubs locked. There is NO LOAD on these components, so the "wear" is about 1/10000th of what it would be in 4x4.

I just think WAY too many people say "don't run with your hubs locked, it wears out the front-end" - that is an absolute exageration...