Lockout hubs

[stumps]

I'm sure that someone can always conjure up an extreme situation. In your case, you probably should have been in 4WD, plus you were running on a cold soak.

If I can "conjure up" a situation on the first time I ever drove a 4WD truck with its hubs locked in snow, it is clearly a problem that should be watched. What I took away from that crash, I mean lesson, was if the truck's hubs are locked, and it is all slippery out, the truck must stay in 4WD! Even in situations where I would have been just fine in a 2WD vehicle... I had about 20 years of accident free 2WD driving experience in all weather when this happened to me.

Think for a second, if it is desirable for you to unlock your hubs to improve fuel efficiency, the very reason you are unlocking them is to reduce the friction caused by pumping the oil in the differential. In my F250, the difference between locked hubs 2WD driving and unlocked hubs 2WD driving is 10MPG vs 14MPG. That is about 28%. If my fuel consumption increases by 28% just from spinning the gears and pumping the oil in the differential, that means that there is 28% more power consumed by pushing the extra set of differential gears when in 2WD.

[ OBTW, that mileage test was done during the summer months when I had been using the truck in 4WD to get unstuck on my farm, and forgot to unlock the hubs. I drove the truck on the highway for the rest of the week with locked hubs in 2WD, and was shocked at how quickly I went through a tank of gas. ]

Most of the time an extra 28% drag on one wheel won't matter, but when it is slippery out, that wheel is going to skid to a stop first.

Many manual transmissions won't shift under similar conditions. Does that mean we should not have manuals?

Ever hear of a straw man fallacy?

The person commenting was stating that there would be pull all the time, under all driving conditions. This is simply not the case.

And clearly he is right. You might not feel the pull for all of the gear reduction in your manual steering, or the power assist in your power steering, but there is more friction going on on the wheel that it is pushing all of the gears in the differential vs the wheel that has the unlocked hub... about 28% more friction.

This idea that Jeep and Dodge build trucks with only one locking hub is certainly news to me. I was just walking the lot at the Ford dealer, and all of his 4WD trucks had two locking hubs on the front. More reason to stay with Ford, I guess.

-Chuck

 

[patracy]

The fact is is....

GM fullsize trucks had a central axle disconnect in the 90's.
Gm also had this in the S10 line of trucks.
Dodge had this as well in their trucks in the 90's all the way up to 2000.
Jeep had this as well in the 90's.
Even Ford had this in a few trucks.

Almost all of them were a vacuum actuated central axle disconnect.

There's even a company that makes "kits" to remove the troublesome actuators and install a cable lockout.

4x4 Posi-Lok - 4WD Engagement Systems

Ya'll can keep on dancing around the facts if you want.

 

[stumps]

The fact is is....

GM fullsize trucks had a central axle disconnect in the 90's.
Gm also had this in the S10 line of trucks.
Dodge had this as well in their trucks in the 90's all the way up to 2000.
Jeep had this as well in the 90's.
Even Ford had this in a few trucks.

Are we still talking about using only one hub lockout on a front axle, or has this morphed into something else?

Almost all of them were a vacuum actuated central axle disconnect.

Which simply disconnects the front drive shaft from the front differential, right?

There's even a company that makes "kits" to remove the troublesome actuators and install a cable lockout.

4x4 Posi-Lok - 4WD Engagement Systems

Ya'll can keep on dancing around the facts if you want.

I can't help thinking you are talking about something other than using a lockout on only one hub on the front axle of a deuce, and whether or not it will cause one one wheel to have more drag than the other.

Am I misunderstanding something?

-Chuck

 

[patracy]

The "long" axle has a disconnect in it. Effectively causing the same "single lockout hub" effect everyone is talking about. The short side axle is still coupled and causing the differential's spider gears to spin.

 

[stumps]

The "long" axle has a disconnect in it. Effectively causing the same "single lockout hub" effect everyone is talking about. The short side axle is still coupled and causing the differential's spider gears to spin.

And you don't think that will increase fuel consumption over a two hub lockout?

-Chuck

 

[ODdave]

The fact is is....

GM fullsize trucks had a central axle disconnect in the 90's.
Gm also had this in the S10 line of trucks.
Dodge had this as well in their trucks in the 90's all the way up to 2000.
Jeep had this as well in the 90's.
Even Ford had this in a few trucks.

Almost all of them were a vacuum actuated central axle disconnect.

There's even a company that makes "kits" to remove the troublesome actuators and install a cable lockout.

4x4 Posi-Lok - 4WD Engagement Systems

Ya'll can keep on dancing around the facts if you want.

I forgot, which one of those was the good design ? Lol

 

[Kohburn]

spinning the spider gears under no load has much less friction than the ring gear spinning the pinion and the drive shaft up to the transfer case.

the scenario portrayed was the latter and will have noticable drag

spinning the spider gears which leaves the ring gear, pinion, drive shaft all imobile has rather insignificant drag.

 

[stumps]

On further reflection, the friction loss due to only unlocking one hub wouldn't be as much as the 28% my F250 suffers when both hubs are locked in 2WD, because the ring and pinion gears are not moving in that condition, only the spider gears.

...BUT,...

What about those spider gears? In normal straight down the road operation, they are not spinning at all. In normal operation, they only spin when the right wheel is turning at a different speed than the left wheel... such as what happens when you are in a turn, or you use dis-similar sized tires. If you lock only one hub, the spider gears are going to be turning as if one wheel is at a dead stop, and the other wheel is rotating at the normal rate for the speed you are going.

...Is that a good thing?...

Looking at the manual for my F700's big Rockwell differential, the spiders in that truck are plain bearings, meaning that the gears are rotating directly on the steel shafts without the benefit of rollers, or ball bearings. Clearly a bearing that isn't meant to turn very fast or very often.

Thinking back to the owners manuals for some of the big trucks I have owned, under the section on towing, they specifically warn that if you have to tow rear wheels down for more than a couple of miles, pull both rear axles, not just one. The spider gears are the reason for that warning.

So, if you use just one lockout hub on your front axle, you are spinning the heck out of your spider gears, and contributing to the shortening of their life... Regardless of wheel drag reasons, it is probably not a good idea for just that reason.

Note that this argument doesn't apply to using a single lockout hub on one of the rear axles of the deuce's tandem axles. This is because the drive shaft will be connected to both axles, and all of the guts of both differentials will be spinning as they normally do... the spider gears will be stationary on the unlocked axle.

-Chuck

 

[stumps]

spinning the spider gears under no load has much less friction than the ring gear spinning the pinion and the drive shaft up to the transfer case.

the scenario portrayed was the latter and will have noticable drag

spinning the spider gears which leaves the ring gear, pinion, drive shaft all imobile has rather insignificant drag.

Your post came out while I was typing my last post. You are right, but what you aren't considering is the spider gears on our big Rockwell differentials are not designed to spin much, or very often. They only spin when the right and left wheels are turning at different speeds, and usually that isn't happening to any great degree.

If the car/truck companies are making their automatic hubs only disable one half axle, they must have put frictionless bearings on the spider gears. If they didn't, the differentials would burn up pretty quickly.

-Chuck

 

[patracy]

If the car/truck companies are making their automatic hubs only disable one half axle, they must have put frictionless bearings on the spider gears. If they didn't, the differentials would burn up pretty quickly.

-Chuck

Nope, wrong again. Here's a pic of the internals from a D60 dodge front end. (I didn't take pics of mine when I rebuilt the front end of my truck. Just the standard conical washer shims.

https://venturestruckparts.com/index.php?main_page=product_info&cPath=3_7&products_id=220

 

[plym49]

And you don't think that will increase fuel consumption over a two hub lockout?

-Chuck

It might, but good luck measuring it. Remember, the front driveshaft is not rotating, so the ring and pinion are not turning. The spider gears precess is all.

 

[plym49]

On further reflection, the friction loss due to only unlocking one hub wouldn't be as much as the 28% my F250 suffers when both hubs are locked in 2WD, because the ring and pinion gears are not moving in that condition, only the spider gears.

...BUT,...

What about those spider gears? In normal straight down the road operation, they are not spinning at all. In normal operation, they only spin when the right wheel is turning at a different speed than the left wheel... such as what happens when you are in a turn, or you use dis-similar sized tires. If you lock only one hub, the spider gears are going to be turning as if one wheel is at a dead stop, and the other wheel is rotating at the normal rate for the speed you are going.

...Is that a good thing?...

Looking at the manual for my F700's big Rockwell differential, the spiders in that truck are plain bearings, meaning that the gears are rotating directly on the steel shafts without the benefit of rollers, or ball bearings. Clearly a bearing that isn't meant to turn very fast or very often.

Thinking back to the owners manuals for some of the big trucks I have owned, under the section on towing, they specifically warn that if you have to tow rear wheels down for more than a couple of miles, pull both rear axles, not just one. The spider gears are the reason for that warning.

So, if you use just one lockout hub on your front axle, you are spinning the heck out of your spider gears, and contributing to the shortening of their life... Regardless of wheel drag reasons, it is probably not a good idea for just that reason.

Note that this argument doesn't apply to using a single lockout hub on one of the rear axles of the deuce's tandem axles. This is because the drive shaft will be connected to both axles, and all of the guts of both differentials will be spinning as they normally do... the spider gears will be stationary on the unlocked axle.

-Chuck

In practice, the spider gears spinning under no load is not a problem at all.

The base problem is that most folks are so invested in the seemingly logical symmetry of having two lockout hubs, it is difficult to grasp this alternate concept.

Back in the bad old days, 4WD vehicles had two manual locking hubs on the front axle. Symmetry.

Then, the industry advanced and began to develop automatic hubs. And, lo and behold, there was a realization that only one axle needed to be disconnected.

All those millions of Chevy and Jeep and Dodge and Ford and so on vehicles with automatic hubs: it it really just one axle that is being disconnected. Truth.

Some, like GM, use thermal actuators. An element gets hot, expands, and engages a dog clutch on the passenger side axle shaft to engage the front axle. This happens simultaneously when you engage 4WD with the transfer case shift lever. On my Chevy 4x4, I added my own switch and eliminated the factory switch on the transfer case so that I can easily engage low range in 2WD - a useful modification.

On Jeeps, they instead use a vacuum actuator to engage the dog clutch on the axle.

Aftermarket or home brew 'posi-lock' products replace the stock thermal or vacuum actuator with a cable. Not because the stock setups are unreliable, but because some owners might want to add 2WD low range or other reasons.

So here is an experiment that you can perform if you still doubt this approach. Buy a pair of lockout hubs for your Deuce, but only install the one on the passenger side. See if the truck starts pulling to the left (differently than your truck drove beforehand). If you are unhappy, install the second hub on the front. If you are pleasantly surprised, install the second hub in the rear so that you can cruise without powering both bogies.

 

[stumps]

So here is an experiment that you can perform if you still doubt this approach. Buy a pair of lockout hubs for your Deuce, but only install the one on the passenger side. See if the truck starts pulling to the left (differently than your truck drove beforehand). If you are unhappy, install the second hub on the front. If you are pleasantly surprised, install the second hub in the rear so that you can cruise without powering both bogies.

I'm perfectly willing to accept that the friction from the spider gears will be small enough to not really matter as far as pulling on the steering goes. I don't believe that over the long term this isn't a reliability problem, though. It will also cause drive-ability problems. I know that with my F250, sharp turns are miserable when the hubs are locked regardless of whether you are in 2WD, or 4WD... That nice lurch/skuff... lurch/skuff... lurch/skuff... feeling in a sharp turn that all drivers of 4WD trucks with U-joints are familiar with. A 4WD truck with U-joints is going to do that with 1 hub locked, or two. Just tried it with my F250, and it sure does...

I am glad that you all informed me of how automatic hubs work. I certainly won't be buying any truck that has them. Nor will I be installing only one lockout hub on the front axle of any truck.

-Chuck

 

[ducer]

It seems we all have valid points and opinions. We could debate this forever. I would just like to add it does not seem fair to try compare 60 year old technology and metalurgy to current technology and metalurgy. As for my truck I will err on the side of safety and reliability and waste the money on 2 locking hubs when I can afford to do so.

Denny

 

[plym49]

I'm perfectly willing to accept that the friction from the spider gears will be small enough to not really matter as far as pulling on the steering goes. I don't believe that over the long term this isn't a reliability problem, though. It will also cause drive-ability problems. I know that with my F250, sharp turns are miserable when the hubs are locked regardless of whether you are in 2WD, or 4WD... That nice lurch/skuff... lurch/skuff... lurch/skuff... feeling in a sharp turn that all drivers of 4WD trucks with U-joints are familiar with. A 4WD truck with U-joints is going to do that with 1 hub locked, or two. Just tried it with my F250, and it sure does...

I am glad that you all informed me of how automatic hubs work. I certainly won't be buying any truck that has them. Nor will I be installing only one lockout hub on the front axle of any truck.

-Chuck

I can understand your reticence. BT,DT. When I bought my Chevy 4x4 brand new over 25 years ago, I was initially appalled when I learned what 'automatic hubs' really meant. After that, I was seriously concerned about exactly the type of wear you describe. And then, finally, I realized that there were no problems and after thinking it through I realized that there was never anything to worry about. That same truck now has over 300,000 hard miles on it, perhaps half of that at 75 mph, and the front axle/spiders gears/automatic axle disconnect mechanism are all perfect.

This is one of those things where the facts are the facts and one's feelings and emotions and prejudices quite another. I do not mean that in a bad way.

 

[stumps]

I can understand your reticence. BT,DT. When I bought my Chevy 4x4 brand new over 25 years ago, I was initially appalled when I learned what 'automatic hubs' really meant. After that, I was seriously concerned about exactly the type of wear you describe. And then, finally, I realized that there were no problems and after thinking it through I realized that there was never anything to worry about. That same truck now has over 300,000 hard miles on it, perhaps half of that at 75 mph, and the front axle/spiders gears/automatic axle disconnect mechanism are all perfect.

This is one of those things where the facts are the facts and one's feelings and emotions and prejudices quite another. I do not mean that in a bad way.

Are we sure that the design, fit, finish, and metallurgy in our 45 year old deuce spider sets are the same as is in a 25 year old Chevy that was made for automatic hubs?

I remember a time when car engines lasted about 100K miles before they were burning oil, had sloppy rod and main bearings, and needed a rebuild. Chrysler invented a new way of finishing the cranks that all but eliminated rod and main bearing wear, new cylinder finishes, rings, filters, and oils happened which made it pretty likely that an engine would get to 200K without problems.

OTR trucks from the 50's and 60's had ample warnings about towing with only one axle removed. And yet now there are trucks that drive that way 99% of the time. The old guys weren't stupid, and they designed and built our deuces.

Also, in searching about for information on automatic locking systems, I couldn't help but noticing that all I saw were CV joints on the axles, not U-joints. Which is on your Chevy? Our deuces seem to have mostly U-joints.

Interesting discussion.

-Chuck

 

[clinto]

I remember a time when car engines lasted about 100K miles before they were burning oil, had sloppy rod and main bearings, and needed a rebuild. Chrysler invented a new way of finishing the cranks that all but eliminated rod and main bearing wear, new cylinder finishes, rings, filters, and oils happened which made it pretty likely that an engine would get to 200K without problems.

Don't forget the biggest reason modern engines last so much longer-electronic fuel injection systems capable of accurately metering the fuel going into the cylinder and only injecting what's necessary. Older engines with carbs, no matter how well tuned, inevitably "washed" the oil off the bores and rings, leading to much increased wear.

All of your other points are valid (modern moly rings vs. older cast irons, cleaner lighter oils, etc.). Just wanted to add this.

 

[Heath_h49008]

Clinto hit the nail on the head as far as engine longevity.

289/302 Ford (as one example) 1965 100k was good, in 1993 200k+ was common. The difference was the injection system. After a particularly cold winter, the old guys used to talk about the "good old days" when they could be assured of having engines to rebuild from "black death" of fuel washed and destroyed cylinders.

As for the wear on the spiders... are the spiders in the Rockwell immersed in lube, or even splashed with lube when the carrier isn't turning? I'm trying to picture the lube level and how it would get into the stationary carrier.

For my money, $250 isn't worth the experiment if it goes south. It might work, but I won't be the guinea pig.

 

[trukhead]

On the new trucks with automatic lockouts, does the transfer case disconnect the front drive shaft from the rear drive shaft? Does the front drive shaft turn from the torque after it has gone through a differential?

I can see a single lockout being effective if the drive-line is turning all the time regardless of being in 2wd or 4wd.

My cousins new Silverado is a light duty truck that has 2wd, all wheel drive and I think an all wheel drive with a lock in the transfer case. The heavier duty-work trucks have a more conventional 4wd set up I am told. I am curious to know if indeed they only lock out one wheel on his front-end.

My A3 I think would benefit from 2 front lockouts due to the fact that I can disconnect the whole internal gear-sets from revolving if and only if the transfer case also disconnects the front drive shaft as well.

I think the CUCV benefits from 2 lockouts as well because one does not have to turn all those gears as well through lube and friction resistance. If one wheel is turning an axle shaft and the other wheel is disconnected from the its respective shaft, then the carrier section will react and and influence the disconnected axle shaft to turn in the opposite direction in proportion to the amount the carrier is stationary or turning as a reaction to friction. I just see that extra friction means extra effort to turn the front wheels.

I think the advantage to 2 lockouts for systems designed for them is appropriate and single lockout systems are specifically designed for use with single lockouts.

 

[plym49]

Are we sure that the design, fit, finish, and metallurgy in our 45 year old deuce spider sets are the same as is in a 25 year old Chevy that was made for automatic hubs?

I remember a time when car engines lasted about 100K miles before they were burning oil, had sloppy rod and main bearings, and needed a rebuild. Chrysler invented a new way of finishing the cranks that all but eliminated rod and main bearing wear, new cylinder finishes, rings, filters, and oils happened which made it pretty likely that an engine would get to 200K without problems.

OTR trucks from the 50's and 60's had ample warnings about towing with only one axle removed. And yet now there are trucks that drive that way 99% of the time. The old guys weren't stupid, and they designed and built our deuces.

Also, in searching about for information on automatic locking systems, I couldn't help but noticing that all I saw were CV joints on the axles, not U-joints. Which is on your Chevy? Our deuces seem to have mostly U-joints.

Interesting discussion.

-Chuck

Good questions. Do newer (25 years old! not that new) use 'better' steel? Or maybe cheaper steel, because the newer lubricants can be trusted to provide more protection? Does Chevy use 300K miles as a design point?

I would not worry about it.

In answer to your other question, Chevy uses CV joints and Jeep uses universal joints. Chevies have IFS, so there is more articulation at the spindle is why.