Lockout hubs

[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

BTW, the lurching you describe is due to drivetrain wind-up due to the fact that the vehicle in question does not have a center differential. In a sharp turn and locked in 4WD, all four tires are turning at different speeds. Each axle can accomodate side-to-side differences but there is a huge front-to-rear difference on a tight turn. That's why the manufacturer's advise only using 4WD at lower speeds and/or on surfaces where the tires can slip (dirt, mud, snow, rain).

 

[plym49]

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.

Oh my goodness, is the water and ethanol injection guy going to let some spider gear precession ward him off? Please don't get old on us; we need your youthful enthusiasm.

 

[plym49]

On the new trucks with automatic lockouts, does the transfer case disconnect the front drive shaft from the rear drive shaft?

As far as I know, if it is a plain old 4WD vehicle then the transfer case disconnects the front driveshaft when in 2WD. Hence, the appeal of being able to independently control the dog clutch on the one axle to provide 2 WD low range (handy sometimes).

If it is an AWD vehicle, then there must be a center differential, and the front and rear driveshafts always turn. I am not aware of any AWD vehicles that provide a capability to disconnect the front axle ('cuz then they would not be AWD).

This might be different for the high-end, exotic vehicles from the like of Mercedes or Rover. They might have some very unusual setups. But then, anyone willing to spend six figures on a SUV deserves the complexity that comes as part of the package.

 

[stumps]

BTW, the lurching you describe is due to drivetrain wind-up due to the fact that the vehicle in question does not have a center differential. .

No! Not in this case, the truck has its hubs locked, but its transfer case is open (2WD). The lurching is caused by the universal joints on the front axles turning at a tight radius. Think about what would happen if a universal joint was set up so that the two shafts were at 90 degrees to each other. They would block. Well, as a universal joint gets farther and farther off of being straight the power transfer gets more and more lumpy, until you reach a point where the joint will lock and self destruct.

This is a major problem with having only one lockout hub on the front of a deuce. It too has universal joints, and when you are in a sharp turn, the tires are going to go lurch/scuff just like they do when both hubs are locked and you are in 2WD. As a result of your information on center shaft disconnects, and this discussion, I tried my F250 in 2WD with only one hub locked, and it is just as miserable in sharp turns as it is in 2WD with both hubs locked. In a sharp turn, the universal joints make the torque on the tire vary as it rotates. It changes from easy to hard as the universal joint pass through its torque humps. The tires go lurch/scuff, in a sharp turn, just like they do with both hubs locked and the transfer case in 2WD.

-Chuck

 

[patracy]

I can't tell you how many times I've left the passenger side locked by accident and how many miles I might have driven that way on multiple vehicles.

This is a major problem with having only one lockout hub on the front of a deuce. It too has universal joints, and when you are in a sharp turn, the tires are going to go lurch/scuff just like they do when both hubs are locked and you are in 2WD. As a result of your information on center shaft disconnects, and this discussion, I tried my F250 in 2WD with only one hub locked, and it is just as miserable in sharp turns as it is in 2WD with both hubs locked. In a sharp turn, the universal joints make the torque on the tire vary as it rotates. It changes from easy to hard as the universal joint pass through its torque humps. The tires go lurch/scuff, in a sharp turn, just like they do with both hubs locked and the transfer case in 2WD.

Uh huh Chuck, uh huh....

 

[plym49]

No! Not in this case, the truck has its hubs locked, but its transfer case is open (2WD). The lurching is caused by the universal joints on the front axles turning at a tight radius. Think about what would happen if a universal joint was set up so that the two shafts were at 90 degrees to each other. They would block. Well, as a universal joint gets farther and farther off of being straight the power transfer gets more and more lumpy, until you reach a point where the joint will lock and self destruct.

This is a major problem with having only one lockout hub on the front of a deuce. It too has universal joints, and when you are in a sharp turn, the tires are going to go lurch/scuff just like they do when both hubs are locked and you are in 2WD. As a result of your information on center shaft disconnects, and this discussion, I tried my F250 in 2WD with only one hub locked, and it is just as miserable in sharp turns as it is in 2WD with both hubs locked. In a sharp turn, the universal joints make the torque on the tire vary as it rotates. It changes from easy to hard as the universal joint pass through its torque humps. The tires go lurch/scuff, in a sharp turn, just like they do with both hubs locked and the transfer case in 2WD.

-Chuck

In response to your first paragraph above, perhaps that is what you get for driving a Ford.

In response to your second paragraph, if one wheel is physically disconnected from the center carrier, then the behavior on a sharp turn (even with the front driveshaft disconnected, as you state) is no different than if the axle was locked. You are describing an issue with the steering knuckle u-joints, and that has nothing to do with the spider gears. However, it would mean that your knuckle ujoint problem would only be on one wheel instead of two if you had only one hub unlocked.

If this is the problem with Fords, then perhaps one or both of your steering stops is not adjusted properly. Is the behavior the same for a left or right turn?

My Deuce has zero kickback at full steering lock left and right with the transfer case disengaged to the front. If I engage the transfer case to the front and make a sharp left or right turn on a dry road, then I experience some kickback exactly as the truck should (because you are not supposed to drive that way). I tried it for the sake of science and this thread.

 

[stumps]

In response to your first paragraph above, perhaps that is what you get for driving a Ford.

It's not a Ford thing, it's a universal joint thing. It happens on all 4WD vehicles that have universal joints in the front end.

In response to your second paragraph, if one wheel is physically disconnected from the center carrier, then the behavior on a sharp turn (even with the front driveshaft disconnected, as you state) is no different than if the axle was locked. You are describing an issue with the steering knuckle u-joints, and that has nothing to do with the spider gears. However, it would mean that your knuckle ujoint problem would only be on one wheel instead of two if you had only one hub unlocked.

Which is exactly why I said it is a universal joint issue. I said my peace about the spider gears a couple of posts back.

If you have lockout hubs on both wheels, the universal joints don't turn, and you get none of the lurch/scuff problem you get with universal joints and only a single lockout hub, or universal joints and a center drive shaft disconnect.

If this is the problem with Fords, then perhaps one or both of your steering stops is not adjusted properly. Is the behavior the same for a left or right turn?

The stops are adjusted to spec. The problem happens with both left and right turns as each puts the universal joints at approximately the same angle. The only way out of this issue is to either reduce the turning radius drastically, or to use CV joints.

My Deuce has zero kickback at full steering lock left and right with the transfer case disengaged to the front. If I engage the transfer case to the front and make a sharp left or right turn on a dry road, then I experience some kickback exactly as the truck should (because you are not supposed to drive that way). I tried it for the sake of science and this thread.

In 2WD with a deuce It isn't kickback. You can feel it in the steering wheel as a back and forth wobble of the wheel. I have felt it in sharp turns on every deuce I have driven. With the F250, the power steering masks the feeling, but you can hear it in the tires when on pavement. It is the cost of having a reasonably sharp turning radius on a 4WD vehicle that has universal joints in the front axle.

-Chuck

 

[Kohburn]

so now you are talking about feedback from sharp turns. nothing to do with longevity or fuel economy.

I can see how lockouts could be beneficial for UJ axles in that condition, but most driving is not at full lock and when it is you will be going slow. seems like a non-issue to me.

 

[stumps]

so now you are talking about feedback from sharp turns. nothing to do with longevity or fuel economy.

I can see how lockouts could be beneficial for UJ axles in that condition, but most driving is not at full lock and when it is you will be going slow. seems like a non-issue to me.

With the very few on road miles I drive my deuce, all of this talk of lockouts sounds like a non-issue to me... but that is not the point.

This very old thread (from 2009) is about issues affecting longevity of the front end parts, and fuel mileage. One lockout hub protects one U-joint from turning, improving its longevity, and to a very minor degree, fuel mileage, while making the spider gears spin very fast (as if you are in an infinitely sharp turn). Two lockout hubs protect both U-joints from turning, improving both U-joints' longevity, and leaves all of the differential gears quiet.

As far as I know, no one here has done any tests to determine whether long term spinning of the spider gears of one of these old differentials affects its wear and longevity. Stories about more modern differentials taking it fine are interesting, but not really applicable absent information about changes the manufacturer may or may not have made to allow that sort of operation.

As another example of such stuff. In the old days, it was considered a very bad thing to leave the clutch pedal depressed while idling at a stop sign/light. It put a lot of extra time and stress on the clutch throwout bearing. Modern hydraulic clutches, such as exist in Ford PU trucks from the mid 1980's are designed so the throwout bearing is loaded and spinning all the time, whether or not the clutch pedal is depressed... It has to in order to allow the clutch master cylinder to automatically adjust for clutch wear... The old rule about not leaving the clutch pedal depressed while idling at stop can now be broken without consequence.... But not on an old truck that doesn't have the beefy throwout bearing of the automatic adjusting hydraulic clutch systems.

Spinning the spider gears on a front differential is just like that. Apparently it can be a safe thing to do on a truck designed to take it, but could be a very bad thing to do on a truck that wasn't designed with that mode of operation in mind.

-Chuck

 

[Heath_h49008]

Some time to think about it...

What is the normal load on front spider gears? As 90% of the time the trucks are in 2 wheel drive, and even when turning they are turning rather slowly... not high.

What is the failure rate in that environment?

In the newly proposed environment where they are still under minimal load, but spinning at a vastly higher rate 90% of the time, we have a net increase in wear, and a multiplier to the failure rate of the spider bearing surfaces as well as the heat generated.

If you guys want, we can figure out the exact RPM we will be spinning those spiders at, and model the system.

When spiders fail, is it most often due to the gear surface failing? Or is it due to the bearing surface failing... in my experience, the gears tooth faces can live happily until the end of time in most differentials, the failures come from the bearing side of the spider. (Even in a pick-up when the "rod" wears and it sheers or becomes sloppy enough to allow binding.)

It would seem you are attempting to increase stress on the most failure prone part of a differential through high RPM operation. At the same time, you eliminate the spinning of the carrier and any lube movement that would be associated with it.

This is my wholly uninformed, completely idiotic opinion pulled directly out of thin air.

 

[Kohburn]

honestly i've never seen a set of spyder gears wear out, only fail from overloading. shock loading from spinning one tire on slick surfaces then having it grab, etc.

with zero load on the gears i would expect the only type of failure possible to be from overspeed on the bearing surfaces, that would depend on clearances and the oil. without a load the oil should have no problem isolating the metal and preventing any wear.

 

[VPed]

I have seen spiders and side gears on cars fail due to lack of lube while at high rpm. (One wheel burnouts on asphalt, dirt, mud, etc). Damage is to the outside bore where the side gear rides in the diff carrier, and to the bore shaft, and back side of the spiders. None of these areas have true bearings.

The main mechanism for distributing lube within the diff is the rotating ring gear. I envision a vitrtual rainstorm of oil at hiway speeds. Without rotation of the ring gear, how is lube supposed to get delivered to the two or three spider gears and both side gears remaining above the oil level?

If the ring gear does not rotate, the side gears will rotate at the same speed, in opposite directions. That means that the axle with the lockout hub is spinning in reverse at the same speed that the lockout hub is spinning forward. The side gears are spinning at the speed proportional to the ratio between the side and spider teeth. What is not spinning is the ring gear, pinion, primary reduction gearset, and drive shaft (all of the parts that do have true bearings). If the ring gear does not turn, only one or two side gears come close to the oil level, everything else is above the oil, and it is not raining oil.

BTW - One of the suggestions from this site for decreasing the incidence of gear oil leaking from the diffs is to run the oil level one knuckle down from the fill plug. This practice at least should not be combined with the one lockout deal, I would think.

That is my "food for thought opinion".

 

[plym49]

With the very few on road miles I drive my deuce, all of this talk of lockouts sounds like a non-issue to me... but that is not the point.

This very old thread (from 2009) is about issues affecting longevity of the front end parts, and fuel mileage. One lockout hub protects one U-joint from turning, improving its longevity, and to a very minor degree, fuel mileage, while making the spider gears spin very fast (as if you are in an infinitely sharp turn). Two lockout hubs protect both U-joints from turning, improving both U-joints' longevity, and leaves all of the differential gears quiet.

As far as I know, no one here has done any tests to determine whether long term spinning of the spider gears of one of these old differentials affects its wear and longevity. Stories about more modern differentials taking it fine are interesting, but not really applicable absent information about changes the manufacturer may or may not have made to allow that sort of operation.

As another example of such stuff. In the old days, it was considered a very bad thing to leave the clutch pedal depressed while idling at a stop sign/light. It put a lot of extra time and stress on the clutch throwout bearing. Modern hydraulic clutches, such as exist in Ford PU trucks from the mid 1980's are designed so the throwout bearing is loaded and spinning all the time, whether or not the clutch pedal is depressed... It has to in order to allow the clutch master cylinder to automatically adjust for clutch wear... The old rule about not leaving the clutch pedal depressed while idling at stop can now be broken without consequence.... But not on an old truck that doesn't have the beefy throwout bearing of the automatic adjusting hydraulic clutch systems.

Spinning the spider gears on a front differential is just like that. Apparently it can be a safe thing to do on a truck designed to take it, but could be a very bad thing to do on a truck that wasn't designed with that mode of operation in mind.

-Chuck

The venture capitalists have a term for those who steadfastly stick to their point in spite of information to the contrary. They call it 'breathing your own exhaust'.

Spider gears precess ALL THE TIME and under load, at that. Do you think for a minute that the tires on a driven axle are exactly the same OD all the time? Of course they aren't. Gear precession handles it. And they don't ear out.

They don't wear out on the millions of GM and Dodge and Jeep and etc. vehicles that disconnect only one axle.

Your statement that fuel mileage increases on a Deuce with one hub is small, while a Deuce with two lockouts would see a large increase, is illogical. Because you have not measured it. Tell you what, if one lockout did not improve mileage, the vehicle manufacturers would not feature them because they are always chasing fuel mileage and they would not leave anything obvious on the table.

We get it, you are emotionally invested in using two lockouts. It's your Deuce; set it up as you wish!

Some folks wear a belt and suspenders, too, but that does not mean there is an engineering reason to do so.

 

[Heath_h49008]

The amount of precession you're describing is a long way from the type of speeds the spiders would see with one lockout at 50mph.

You're talking about spinning the spiders at a constant 400-500 rpm with no real bearings and only splash lube.

As they spin, are they going to magically "suck" lube under them? Or will it be spun OUT from under them?

If the gears were immersed in lube, I would agree it would be viable, and it works with many other axles. The sticking point is the quality of old mineral lube, and how much is surrounding the spiders. If they are "dunked" each rotation and the backside has enough room for oil to get in and establish a good film, you're golden. If not, you're smoked. In either case you ARE increasing wear on the spiders... the only question is how much, and is it enough to matter.

Let's see how it works out for those who try it. The other option is to do some looking at the lube level vs carrier and how fast lube can enter the center on a stock 2.5 ton Rockwell.

 

[ODdave]

HAVING ONE LOCKOUT JUST LOOKS STUPID !

There....Done.

 

[Kohburn]

HAVING ONE LOCKOUT JUST LOOKS STUPID !

There....Done.

 

[stumps]

The venture capitalists have a term for those who steadfastly stick to their point in spite of information to the contrary. They call it 'breathing your own exhaust'.

Spider gears precess ALL THE TIME and under load, at that. Do you think for a minute that the tires on a driven axle are exactly the same OD all the time? Of course they aren't. Gear precession handles it. And they don't ear out.

For some folks, arguments always have to get to personal attacks...I'm not sure why. I think it it probably has to do with them assuming that everyone that has any disagreement with them is stupid.

Of course the spider gears turn in normal operation. If they didn't, there would be no point to their being. The thing is, they turn very slowly, a couple of RPM most of the time.. a little more in turns. If you disconnect one axle, they are going to turn around 1 to 3x axle speed depending on the ratio between the spiders and the side gears (the deuce appears to be 2:1). That puts them somewhere around 532 (1:1) to 1600 (3:1) RPM when driving highway speeds. Continuously.

They don't wear out on the millions of GM and Dodge and Jeep and etc. vehicles that disconnect only one axle.

And how many of those truck axles are used in deuces? You give me this information as fact, and I accept it. What you have not done is tell me what if any changes were made to the fit, finish, gear ratios, metallurgy, lubrication schemes, etc.. Deuces don't come with 1990's GM, Dodge, Ford, or Jeep axles designed for one axle disconnects. Truck owners manuals from the '50's and '60's when the deuces were designed warn against towing with only one axle removed. Why? Could it be that the engineers recognized that the spider gears would be spinning faster than they were designed to? Could it be that there is no reliable mechanism for lubricating the spiders when the ring gear isn't turning?

Your statement that fuel mileage increases on a Deuce with one hub is small, while a Deuce with two lockouts would see a large increase, is illogical. Because you have not measured it. Tell you what, if one lockout did not improve mileage, the vehicle manufacturers would not feature them because they are always chasing fuel mileage and they would not leave anything obvious on the table.

Read what I said again, I said the mileage cost of turning one universal joint is small.

We get it, you are emotionally invested in using two lockouts. It's your Deuce; set it up as you wish!

I have no investment in one lockout, two, or all 6. I have no lockouts on my deuce, and it will forever stay that way. I don't drive it enough on the highway to ever recover the cost of the modification.

Some folks wear a belt and suspenders, too, but that does not mean there is an engineering reason to do so.

As an engineer, I would say it has more than a little to do with how the cost of your pants falling down at a bad time compares with the cost of the extra suspenders.

The cost saved by putting only one lockout on your deuce may ultimately be eclipsed by the cost of replacing your axle. That risk is eliminated for the price of a second lockout hub.

-Chuck

 

[gringeltaube]

...... If you disconnect one axle, they are going to turn around 1 to 3x axle speed depending on the ratio between the spiders and the side gears (the deuce appears to be 2:1). That puts them somewhere around 532 (1:1) to 1600 (3:1) RPM when driving highway speeds. Continuously. ................

Yes, 850 rpm, with 9.00-20 @ 56 mph. (ratio is 1.78:1)

Could it be that there is no reliable mechanism for lubricating the spiders when the ring gear isn't turning?

They do in fact dip into the oil... (carrier lube access holes are positioned slightly below (normal)oil level... but only IF filled to factory-set oil level: inspection plug/hole starting to overflow! (NOT so if level was one knuckle, below...!)

The cost saved by putting only one lockout on your deuce may ultimately be eclipsed by the cost of replacing your axle. That risk is eliminated for the price of a second lockout hub.

Agreed.
Funny thing is nobody has mentioned yet the extra wear on that side, free-wheel hub bearing/bushing & axle shaft end - each one now turning in opposite directions, at 2x close to 500 ≈1000 rpm (!); plus the wear on spindle bushings; U- or CV-joints, internal oil seals... All that can be avoided with ONE PAIR of hubs!


G.

 

[stumps]

Funny thing is nobody has mentioned yet the extra wear on that side, free-wheel hub bearing/bushing & axle shaft end - each one now turning in opposite directions, at 2x close to 500 ≈1000 rpm (!); plus the wear on spindle bushings; U- or CV-joints, internal oil seals... All that can be avoided with ONE PAIR of hubs!


G.

I think it did get mentioned somewhere up in the previous posts. The rotation rate of the unlocked hub's axle, universals, etc... should be exactly the same as the locked axle, but in the opposite direction. The spiders are idler gears, so they don't contribute to the gear ratio when you have a: [Side gear] - [spider] - [Side gear] stack.

Otherwise, I agree with everything you said.

-Chuck

 

[gringeltaube]

The spiders are idler gears, so they don't contribute to the gear ratio when you have a: [Side gear] - [spider] - [Side gear] stack.

Very clear, Sir. I was just trying to help you out with the exact gear ratio....

.... so, 850rpm would be for the four 9T-spider gears rotating on the spider tips, reacting to the 16T-side gear, rotating at 477rpm... (1.78:1); to produce 477rpm to the other side gear, in the opposite direction, of course.................






(hah.... why did I have to come up with all those numbers when it was really my intention to stay out of this waaay too-long 1-hub-only-Deuce-front-axle pro&cons discussion....)



G.