Front axel engagement

[KyFarm]

I have an '04 F250 4wd. It has an electric engagement switch to go into 4hi or lo. If I turn it on I get power to one side of the front axel. If I get out and lock the hubs then I have power to both wheels. That system seems to be what all modern 4wd trucks have whether it is electrically actuated or using a manual shifter.

On these old truck you get no power to either front wheel until you lock the hubs (and switch to 4lo or 4hi) and then you are in a lock situation and it is my understanding that is best for only going in a straight line.

What is the different system that enables modern trucks to send power to at least one front wheel without getting out of the truck and why are they not being commonly adapted to these sweet old trucks that we all love to have?

Thanks for any help on this question......

[Chevy1TonFun]

The electronic system only shifts the t-case into gear. The hubs are either manual locking or auto locking. With manual hubs you need to lock them by hand. With auto locking hubs, they will engage when torque is applied to the wheels.

[KyFarm]

I know that there are auto-locking hubs but I thought that those didn't have an exterior selector for "free" or "lock".

I have been in the following 4x4 trucks and all worked the same way, Front hubs say "free" or "lock" and if you leave them in "free" and engage the t-case you get power to one side of the front axel. We do this all the time on my farm to go through mud to get to my grain bin to grind grains. Neither my cousin or I have ever had to get out and lock the fronts once engaging the t-case ( to get pull from one wheel). Here are the trucks that I have been in that work that way: '94 F-350 diesel, 97 1/2ton dodge gasser, '04F250 gasser, '06 3/4ton dodge.

Since I have had to get out and lock the hubs if one front is spinning with no traction and the other isn't I thought it was a differential issue. I just need more knowledge,

thanks for any help

[Chevy1TonFun]

When you have locking hubs in the free position they are not engaged to the drive axle. This means the wheels spin free from the axle assembly. If you have the hubs in the lock position then your wheel are engaged to the drive axle. You need your hubs to be in the lock position in order to use your 4wd. I believe when you are telling us that when you have your hubs in the free position and the tcase in 4wd that one of the wheels spin. This could possibly be from the force of the axle spinning fast enough that the wheel is catching some of that force causing it to spin.
I hope this helps.

[odog]

I kinda understand what you are saying, a friend of mine had an 01 f350 wth locking hubs. He swore up and down that by turning the knob in the cab, it would engage the front axle, without having to get out and lock in the hubs. I just always thought he was confused about the difference between auto locking hubs and manual ones. Maybe I was the one confused. Who knows

[wyomech]

we have a f250 2000 if you turn the knob on the dash to 4x4 it runs vacuum to o both front hubs and engages them even if they are in the free position,or you can manually lock them in.

[andrewmp6]

I believe the hubs are vacuum powered check the lines to each make sure they ain't messed up or clogged.

[KyFarm]

Originally Posted by wyomech

we have a f250 2000 if you turn the knob on the dash to 4x4 it runs vacuum to o both front hubs and engages them even if they are in the free position,or you can manually lock them in.

Now where are getting somewhere. If a newer truck can have vacuum engagement on the front hubs why couldn't an older truck?

[coops714x4]

I have a 71 K20 and a 2003 S10 ZR5. yes it is nice when you need the 4wd to just turn a know or push a button inside the cab and have it engaged, but in my opinion its more electronics,wiring, or whatever makes it work. that makes for more things that can go wrong with it so it won't work when needed. I'll gladly get out and lock my hubs in any day to keep from having all the "extra" wiring. besides its part of the beauty and simplicity of these old trucks. I say if you want modern features get a modern truck.

[rcbildr]

Originally Posted by KyFarm

Now where are getting somewhere. If a newer truck can have vacuum engagement on the front hubs why couldn't an older truck?

From what I've heard and read, the vacuum system isn't very good at all and is expensive to repair. Most of the time when they break, they get replaced with manual hubs.

[KyFarm]

Originally Posted by coops714x4

I say if you want modern features get a modern truck.

Basically I was just curious of the different systems. If it was something that was mechanically easy but possibly expensive then I could have put it on the list and maybe gotten there someday. Now I clearly see that buying and installing a vacuum hub system would be at least problematic and certainly overly expensive. I am still learning about these old vehicles however and knowledge is power.

I know that some like to keep their vehicles as completely original as possible and there is nothing wrong with that if that is what you want. Everybody has a different idea about their vehicle.

But there are a great many "modern features" ( I suppose that it would depend on what you define as a modern feature) that find their way on a huge number of these trucks without sacrificing what folks love about 67-72 chevys. For example - LS engines, Fuel injection systems, working AC , radial tires, suspension upgrades, brake upgrades, FM (and better) radios, modern seats and the list could go on and on.

Like I said though, I am still learning and I really appreciate the information given to me by those posting above

[odog]

I like the idea of pushing a button, but I love knowing that when I get out and physically turn the knob on the hubs, they are locked. I trust what I can ohysically see or do, and I have a hard time when I am stuck in the mud, trusting that the vacuum or electrical system is locking the hubs in for me.

Just me.

[6772owner]

From what I know the Ford system operates as follows... the "free" position means that the hubs are disengaged when the truck is in 2wd and the "lock" means that the hubs are locked regardless of the position of the switch.

The hubs are engaged with vacuum and teh common problem with them is a foam seal at the hub that leaks. We had to replace these seals all the time when we did ball joints and such at my previous job. I may not be 100% correct, but I believe this to be true...

[BLAZERMAN]

Originally Posted by KyFarm

On these old truck you get no power to either front wheel until you lock the hubs (and switch to 4lo or 4hi) and then you are in a lock situation and it is my understanding that is best for only going in a straight line.

If its just a matter of not getting out to lock your hubs in then just leave them locked most of the time around the farm..your not going to hurt anything whether your in 4 wheel drive or not. I've owned lots of these old trucks that never even came with a lockout from the factory..in fact I've probably seen more harm done by an axle that never gets engaged than by one thats mostly locked in. And as far as only driving in a straight line when locked in these old trucks is not true unless you have a locker in your front axle..otherwise you can drive it like any other truck in 4 wheel drive. Allthough if your working your truck in 4 low you might be carefull and not turn your wheels at full lock in either direction.

[lowrollin70gmc]

Many newer trucks front hubs have "Auto" and "locked" as positions as a way to manually over ride a broken front selector.

I don't like auto hubs because more stuff breaks and I like positive engagement. If the weather outside is nasty snow and slick I'll engage the hubs before I start driving. Then just shift the t-case if necessary. Easier to engage them before being stuck and won't hurt if you're driving on slick surfaces. I've had electric and vacuum hubs fail leaving me with a 2WD truck somewhere I shouldn't have been.