Dumb question about 4 wheel drive on my 72 C20

[Brettd85]

OK dumb question...

I have a 1972 C20 4x4, picture below. It has factory front locking hubs. If I put it in 4 wheel drive with the hubs NOT locked, will I still get 4 wheel drive? Well technically 1 wheel rear and 1 front since they are open diffs. Or do I have to lock the front hubs for the fronts to get any power? Reason I ask is its snowing here and I figure with front hubs locked it could be annoying on the street taking turns and things if I encounter some road without snow. Thanks for helping a dummy.

[too much stuff]

You will have to lock in the hubs to have 4x4. You can lock them in and run in 2wd until you need 4x4 if you want.

[Brettd85]

So did they never sell a 4x4 without front locking hubs? It appears as an option.

[dmack91]

GM had full time four wheel drive on the 73 and up trucks, but I didn't think they had it on the earlier versions.

[Brettd85]

Any reason not to drive year round with the hubs locked? but just in 2wd.

[Jerry Jones]

Originally Posted by Brettd85

Any reason not to drive year round with the hubs locked? but just in 2wd.

It is rough on the front end running gear to run with the hubs locked and on a solid no slip surface.

[Brettd85]

Isnt there still an open differential in the front end?

And why wouldnt you just drive around in 4wd all the time, but if you really needed 4wd, then lock the hubs?

[1972K20]

In those conditions, the best bet is to lock both front hubs, but leave the transfer case in 2wd or 2H until you needed 4wd.

[71blksuper4x4]

I am pretty sure it won't shift into 4wd without the hubs locked. Lock out hubs were an option. They came with driving flanges if not. Trevor

[CG]

There is a thread on running with the hubs locked all the time and just shifting it into 4x4 when you need it and the consensus was it was fine to do. Thats how Ive been running mine (course I dont drive it much) lately and it seems fine. Let me find the thread and link it here for you...

Ok here is the link, its pretty interesting... http://67-72chevytrucks.com/vboard/s...d.php?t=431023

[68 C-10 Panel]

Ok I might be able to help here... First i know you guys love pics so here is my 4x4...we call her "swampwater" anyway about the hubs locked or not the key thing for you would be the open diff in the front. If the hubs are locked and the transfer case is in 2w the front driveshaft is disconnected from the driveline. In this case as you go around a corner and the wheels travel different distances around said corner the driveshaft will rotate as the spider gears move. There should be no bind or load such as when there is a limited slip diff or worse yet a locker. if you put it in 4hi then the driveshaft will be forced to rotate and the pinion will follow but there will still be minimal bind ( only under acceleration ). So that may be alot of info but only use what you need. short story the hubs locked in 2wd should show no adverse wear. but be sure you have an open diff. oh by the way if you want to see this in action just throw the truck in 2wd lock the hubs and lift one wheel and rotate it you will see the front driveshaft rotate to allow for the difference in cornering .

[vectorit]

You could have one hub sticking, since they over time get gunked up. Might be a good time to have them serviced?

Locked hubs on dry pavement in 2wd will put excessive wear on the hubs, and it will make the truck handle poorly causing irregular wear on the tires as well.

[Jerry Jones]

Originally Posted by 71blksuper4x4

I am pretty sure it won't shift into 4wd without the hubs locked. Lock out hubs were an option. They came with driving flanges if not. Trevor

The transfer case will shift into 4wd, but wont do anything with the hubs not locked, it will just free spin the front drive shaft and axles but the wheels wont drive without locking.

[Brettd85]

Originally Posted by Jerry Jones

The transfer case will shift into 4wd, but wont do anything with the hubs not locked, it will just free spin the front drive shaft and axles but the wheels wont drive without locking.

So again, why wouldnt we just run in 4wd all the time and if you want real 4 wheel drive, you lock the hubs?

[Brettd85]

Maybe answer to my question is mileage. You are spinning more than you have to. Thanks for the comments so far gents.

[vectorit]

Once you try to parallel park on dry pavement in 4wd you will know why. Your tires will chirp, and the truck will jerk about.

Yes, lock the hubs to engage the front wheels.

Gas MPG will take a big dip.

[Brettd85]

Originally Posted by vectorit

Once you try to parallel park on dry pavement in 4wd you will know why. Your tires will chirp, and the truck will jerk about.
.

Why? With an open diff its no different than in the rear. Right?

[vectorit]

The turning radius is tighter than a rear wheel, thus causing binding on the tire tread and stress on the knuckles.

There needs to be some "give" on the road surface the tread is on.

All my reference is towards the "Old school" straight axle, and four wheel drive components.
The new stuff on cars and trucks with all wheel drive, have much more smarts and technology to keep wheels spinning either under power or not to avoid these old 4wd issues from happening.

[Brettd85]

Originally Posted by vectorit

The turning radius is tighter than a rear wheel, thus causing binding on the tire tread and stress on the knuckles.

There needs to be some "give" on the road surface the tread is on.

All my reference is towards the "Old school" straight axle, and four wheel drive components.
The new stuff on cars and trucks with all wheel drive, have much more smarts and technology to keep wheels spinning either under power or not to avoid these old 4wd issues from happening.

Again, doesnt an open diff allow the wheels to spin at different speeds?

[vectorit]

Yes, an open differential allows different speeds through a turn.

Again:

When a driver shifts from two- to four-wheel drive in a vehicle with part-time four-wheel drive, he or she locks together the front and rear axles, so the front and rear wheels rotate at the same speed. This improves straight-line traction.

Since the part-time system has no center differential, there is no way for the two axles to rotate at different speeds in a corner. So, part-time systems shouldn't be engaged unless the vehicle is on very slippery road conditions such as deep snow and mud where wheels can slip as necessary for turning.

If you try driving one of these vehicles on dry pavement with four-wheel drive activated, you will likely feel an awkward, binding sense as you turn a corner. It's also possible to damage drive system components on these vehicles and cause premature tire wear if you travel in four-wheel drive on dry pavement.

[1malo68]

Seems as though it wasn't a dumb question after all. It got a lot of responses. If I don't get a chance to go 4 wheeling, at least once a month I either lock in my hubs and leave the transfer case in 2H or leave my hubs unlocked and the transfer case in 4H for a couple of miles just to keep all of the seals from drying out. I've never had a problem doing that. I think ( and correct me if I'm wrong ) what your saying is you want to drive around with your hubs locked in and in 2WD but shift the transfer case to 4WD when you need it so you don't have to get out of the truck? Yes, if you leave them locked in all of the time, it will cause a lot of unecessary wear and kill your gas mileage, but if you have an open diff and it makes you happy and it's not too obnoxious to drive, I say go for it. Just my opinion FWIW

[special-K]

Originally Posted by Brettd85

OK dumb question...

I have a 1972 C20 4x4, picture below. It has factory front locking hubs. If I put it in 4 wheel drive with the hubs NOT locked, will I still get 4 wheel drive? Well technically 1 wheel rear and 1 front since they are open diffs. Or do I have to lock the front hubs for the fronts to get any power? Reason I ask is its snowing here and I figure with front hubs locked it could be annoying on the street taking turns and things if I encounter some road without snow. Thanks for helping a dummy.

First of all,your truck is a K/20. C/20 is a 2wd. To answer your question...The hubs and transfer case need to be engaged to complete the link between the wheels and drivetrain. The original design these trucks use had the wheels (hubs) always engaged and it was just a matter of engaging the front drive at the transfer case.

Originally Posted by Brettd85

So did they never sell a 4x4 without front locking hubs? It appears as an option.

Lock out hubs were an aftermarket improvement that became a factory option,then a standard feature. Once they came out it was rare to see a truck without them. They allow the front wheels/hubs to 'free wheel" just like a 2wd. The drive axle and driveshaft lay dormant in 2Hi/Free hubs.

Originally Posted by Brettd85

Any reason not to drive year round with the hubs locked? but just in 2wd.

In good traction/dry pavement there is no "slip" between the front and rear and side to side. True,most axles are open,but open doesn't mean only one wheel always spins. It's one "or" the other spins and turning on dry pavement puts all four wheels through the stress of going from one to another,which binds the system which is when parts are most likely to break. The stress can be side to side from the front wheels turning on different radius' and/or front to back from the same reason.

Originally Posted by Brettd85

Isnt there still an open differential in the front end?
Yes,but you are still binding between all the wheels. Just try it,you'll see.

And why wouldnt you just drive around in 4wd all the time, but if you really needed 4wd, then lock the hubs?

Why would you? Isn't it easier to just reach down and pull the lever than to stop and get out to turn the hubs?...possibly in the mud,snow,or water? Besides,you are turning more drivetrain which is what the hubs are designed to avoid.

Originally Posted by Brettd85

So again, why wouldnt we just run in 4wd all the time and if you want real 4 wheel drive, you lock the hubs?

Again...nevermind,just look above ^

Originally Posted by Brettd85

Maybe answer to my question is mileage. You are spinning more than you have to. Thanks for the comments so far gents.

Originally Posted by Brettd85

Why? With an open diff its no different than in the rear. Right?

By locking the hubs both wheels are tied together and they turn at different rates. The whole point of lock out hubs is to save wear and tear on all parts,including tires,that are only needed for 4wd.They are actually "Lock-out" hubs,not "Locking" hubs. The point is to lock out the drivetrain.

Originally Posted by Brettd85

Again, doesnt an open diff allow the wheels to spin at different speeds?

Yes,but look at this. You have a 3/4t truck with a beefy rear axle,yet the front axle is the same as used in a 1/2t. It is only meant for use as an "additional" axle. if it was meant for full-time use it would be as beefy as the rear. Why not put 100,000 miles on your rear while putting 5,000 on your lighter front? It costs up to 3x as much to rebuild a front axle as it does a rear. 4wd front axles need work 10x as much as rears...at least in 3/4 tons. Why not use the system as it was designed? People put a lot of thought into this system and it really works well and has for a long long time.
I hate the thought of parts spinning right next to each other at high rates of speed that are designed to engage. That's what I picture when I leave a truck in 4wd and have the hubs locked out. I don't worry about the opposite because that's how it was meant to be and the risk point is inside the transfer case which is a gear box designed to select different gears and keep them engaged or disengaged while spinning at high rates of speed.

[68panelman]

Originally Posted by Brettd85

So did they never sell a 4x4 without front locking hubs? It appears as an option.

I have seen 67-72 3/4 tons with just a drive flange on the hub.Many 4x4 spids have the option locking frt hubs.

[csb#356]

When it snows i drive around all the time with the hubs locked. If i feel like i will need 4wd I shift into 4wd then shift back out when i get out of the nasty area. I usually do this without stopping the truck. I might do this 5 or so times on the way to work and that is why i leave them locked, I can't realistically get out and lock them in every couple blocks and then get back out when I drive 50 yards and theres not any more snow. Therefore when theres snow on the ground leave your hubs locked in, When it melts and you dont need extra traction or your goin on the highway unlock em. Now is it going to wear out the front end faster. Obviously having the front axle turning is going to put more wear on it than having it not turning. You just have to decide wether or not that bothers you. Thats the best I know how to explain it. Good luck in the winter!

P.S. I never really have experianced the truck trying to jerk around when taking corners on dry pavement with hubs locked(in 2wd of course) unless turning about as sharp as you can or theres gravel or something. And that happens even when the hubs aren't locked sometimes.

[steelhorse]

You will get better gas milage and better wear on your tires if the hubs are unlocked.The truck will also accelerate quicker dur to less drag on the driveline.