Lockers??

[hndrsonj]

Just wondering, what's your objection to welding-up the diff? A full spool from OEM costs $500 and welding-up the diff is free. If you're only doing this on one of the rear axles, say the middle, and that axle would not be driven on-road (free-wheeling), what's the problem?

My thoughts are, when you own a MV or 4x4 do it right use correct parts. If you can't don't do the mod. Just my 2 cents.

 

[oldMan99]

Just wondering, what's your objection to welding-up the diff? A full spool from OEM costs $500 and welding-up the diff is free. If you're only doing this on one of the rear axles, say the middle, and that axle would not be driven on-road (free-wheeling), what's the problem?

When the vehicle is turning the outside wheel must roll faster (More RPM) than the inside wheel. If the differential is a spool or otherwise welded both wheels will obviously be forced to make the same RPM no matter what. When off road or on very loose road conditions, (Snow, ice, mud, sand) this is not much of a problem since the ground surface allows for one or the other or both tires to slip as needed to allow for the turn. On hard surfaces with good traction, this can and will break parts.

Also, this can cause a serious plowing or understeer effect and many racers do not run a spool or welded diff just because of this.

This is the cool thing about a Detroit locker, (This applies ONLY to the DL, the other lockers all work differently) as the outside wheel travels faster it unlocks from the diff and is free to go faster than the inside wheel which remains powered (or not powered if it is a drag axle because it is currently not being powered).

To picture it in your head, think of this: You have a normal ratchet wrench with a socket on it and your tightening a self locking nut onto a bolt, (There is "Traction between the nut/bolt - You are the vehicle engine, the ratchet handle is the driveshaft, the ratchet head of the tool (The part with the gears inside) is the differential and the nut is the inside wheel) the guy holding the head of the bolt (The outside wheel) from moving is not using a wrench, he is using an air ratchet. All of a sudden he gets bored and hits the trigger on the air tool. (This is the outside wheel in a turn) The bolt head (Outside wheel) starts turning a lot faster than the inside wheel (your manual ratchet) what happens? Your ratchet (Differential) simply unlocks and the bolt (Outside wheel) "Freewheels" until your buddy gets off the trigger, (Vehicle is going straight again) and the bolt slows down to a speed equal to or less than the speed you are turning the nut.

In other words, (Assume for a moment a 1:1 ring/pinion so that 1 RPM of driveshaft = 1 RPM of axle) with a Detroit locker both wheels will ALWAYS be going AT LEAST the driveshaft RPM. Either wheel if free to go FASTER than that if it finds the need/ability but as long as the driveshaft is turning both wheels will spin at least as fast as that.

One "Problem" with the DL is that as soon as the slower powered (Inside) wheel speed catches up to the unlocked one, it locks back. If while making the turn the slower inside wheel looses traction and begins to spin, as soon as that wheel RPM matches the RPM of the outside wheel the outside wheel locks back in and begins to pull. While still in the turn if the inside wheel again gains traction and begins to pull the vehicle it will (Because it is again under load) it will slow down just enough so that it is slower than the outside wheel which is still having to travel further than the inside wheel and the outside will unlock and allow it to roll at a higher RPM again.

This is not really a true problem but this locking/unlocking action happening during a turn can occasionally cause the sensation of less than positive control on the vehicle. The lighter the vehicle the more you will get that sensation.

For instance, a guy in a Mustang that has stripped out all the extra weight for racing will really feel it a lot where a guy in a Deuce will probably never feel it unless he is really in tune with the vehicle and knows to "Look" for it.

A quirk with Detroit lockers is that some lock and unlock harder or softer than others. (This is unique to each unit (Like people, every one is different) and does not seem to depend on if it is shimmed loose or tight, it just is what it is..) This makes some people feel that the Detroit unit is harsh and ruins the ride and others to not even notice it is there. Add the individual sensitivity level (Remember the princess and the pea) and some people will really argue the fact that it is or is not good/tolerable blah, blah, blah. I can tell you that the "Worst" one I ever drove was completely tolerable to me and was actually kind of nice because if you were really paying attention to it (And you knew and understood how it worked and what was going on inside the diff case) you could tell for sure when it locked or unlocked and you knew it was working properly. On the other hand, the owners wife hated it.

Other than drag racing (Be it on asphalt or dirt/mud) or an application where the vehicle is ONLY operated off road and never on the road a spool or welded diff is usually more problem that benefit.

Running a spool or welded diff on the street will quickly tear up parts. If the axle is getting power or not really does not matter in this respect. Powered or not, the outside wheel still has to go faster than the inside wheel, the better the traction between road and tire, the more important this is.

The cool thing about the DL over an air locker is that it is always there, always working, no air compressor to wear out, no air line to break, no air valve to clog up, no wiring or plumbing to run. It is just there and works quietly in the background all the time.

Hope this helps, sorry it got so long.

 

[mudguppy]

... (This applies ONLY to the DL, the other lockers all work differently) ...

what other lockers?

 

[Unforgiven]

Old Man,

What if you need to reverse with full traction. Say you're stuck like DUG's friend was a few months ago, 3 axles deep in the mud. If you try reversing or maybe rocking back and forth to get out, will the Detroit Lockers still have full traction in reverse?

 

[mudguppy]

yes.

 

[DUG]

Thanks for all the great posts and info so far! I've been taking a lot of notes and learning a ton.

 

[oldMan99]

what other lockers?

Pretty much any/all other "Locker" or "Limited slip" units are going to work differently than the DL.

Old Man,

What if you need to reverse with full traction. Say you're stuck like DUG's friend was a few months ago, 3 axles deep in the mud. If you try reversing or maybe rocking back and forth to get out, will the Detroit Lockers still have full traction in reverse?

Yes. 100%.

In this case think of the ratchet in the example as being automatically reversed by the direction the driveshaft is turning.

Except in reality, the mechanism is simpler than that and there is nothing to switch into the other direction, it is the way the mechanism is built. Power in = power out 50% equally to both axles, no matter if it is left or right rotation of the input shaft.

Actually it is more like 50% to each applied equally with the ability to transfer 100% to the slower turning wheel. (This is directly opposite to the open diff (or most clutch types) where the power is transfered to the faster turning wheel (The one uselessly spinning in the air or mud) and none (Or very little) to the wheel that actually has traction.)

By the way, I believe Dug's friend needed more than just maximum traction. True 6x6 (3 axles with a locker (or in this case I suppose a spool) in each) is great but there comes a time that no matter how much power you can effectively apply to the ground, the ground has to cooperate at least somewhat. When your in a place that the ground is simply worthless, no matter how many wheels you have turning, you get to interact with Mr. Winch, Mr. Cable and most likely, Mr. Snatch block and quite possibly Mr. Shovel. Sometimes if your really lucky you also get to meet Mr. Jack, Mr. Lumber and a whole bunch of their associated friends.....

I think Doug's friend was (Emotionally) about the the point of shopping for a mail box and just calling it his new hunting camp....lol....

 

[mudguppy]

Pretty much any/all other "Locker" or "Limited slip" units are going to work differently than the DL. ...

ok, i didn't know if you meant specific to the 2.5T lockers.

my Ouverson lockers work exactly like the DL. and from what i've read about the Yukon, it operates the same way.

 

[DUG]

So any advice as to what to put in the front axle? I ASSuMEd that I could run a Detroit, OEM or Yukon as long as the hubs were unlocked on the street and I was careful off road. Others have told me that an air locker is best up front.

Thoughts?

What I was thinking so far would be locking hubs and a standard locker up front.

Locking hub and standard locker in the middle.

Air locker all the way back.

This way when I'm driving around tow on Scout trips I'm pretty much one wheel drive. When I get off road I start locking things in as needed.

Thoughts?

No checks have been written yet, but I hope to order front hubs soon.

 

[oldMan99]

ok, i didn't know if you meant specific to the 2.5T lockers.

my Ouverson lockers work exactly like the DL. and from what i've read about the Yukon, it operates the same way.

Cool.. just goes to show you, every day new products are developed and brought to market. I would guess/assume/think that the DL is old enough the patents have expired and now others are free to copy the design. .

Nothing wrong with copying a well proven design and it is entirely possible that either Ouverson or Yukon (or both) may have incorporated some changes to improve the design although after having used numerous DL's and seeing how well they work and how tough they are, improving the form/function would be pretty hard to do...

Since I have not played with either the Ouverson or Yukon and have no personal experience with them, obviously I will not/can not comment on their design/function/reliability.

It is good however to have options to choose from!

On a slightly different note.... I wish Ouverson would make an alternative gear set for the 5 ton trucks....

 

[oldMan99]

So any advice as to what to put in the front axle? I ASSuMEd that I could run a Detroit, OEM or Yukon as long as the hubs were unlocked on the street and I was careful off road. Others have told me that an air locker is best up front.

Thoughts?

What I was thinking so far would be locking hubs and a standard locker up front.

For the front this is exactly what I would do. When you head off the pavement, lock the hubs.

Locking hub and standard locker in the middle.

Air locker all the way back.

This way when I'm driving around tow on Scout trips I'm pretty much one wheel drive. When I get off road I start locking things in as needed.

Thoughts?

No checks have been written yet, but I hope to order front hubs soon.

OK, I need to make a disclaimer here; I have lots of experience with 2 axle vehicles but not with 3 axle vehicles but.....

The M916 and M920 both have Detroit lockers in both rear drive axles and full time hubs. However, the rear axle is not driven when on the street, it simply drags along behind the front tandem axle until you lock in the rear (The power divider) which also at the same time locks in the front (Steering) axle. (I "MAY" have that backwards... The mid axle may be the unpowered one and the aft the driving one on the street. I'll have to go back and read the TM again when I get a chance - The point is, they both have DL's and full time hubs but have a method of "Turning off" one of the axles on the street.)

As I understand it, the Deuce uses full time power to both of the tandems. I would think that in good traction (On road) having a locker in both rear axles could possibly (Likely?) cause unwanted binding between all the assorted moving parts in the tandems when turning. Likely this is one reason the 916/920 unlocks the power divider (and front axle) when on road. You could easily duplicate the function of the power divider by installing locking hubs in the aft axle, (The rear tandem).

Simply unlock the aft axle on the road and when you go off pavement or in snow/ice/mud when your out of the truck locking in the front hubs also lock in the aft axle hubs.

This gives you: On road true 2 wheel drive (Mid axle with locker) just like the 916/920. And off road true 6 wheel drive. Which is actually better than the 916/920 because they have an open front diff so you really only get 5 wheel drive from them.

I believe that you would find on road turning to be easier with the mid axle driving and the aft axle idle than you would with the aft axle driving and the mid axle idle. but, I could be wrong. However, (Assuming you have installed DL's in both rear axles) the good thing is that to change from mid power to aft all you have to do is swap the hubs. Doing so you can actually evaluate for yourself, in real world which one works best. Worst case is that after you swap the hubs you decide that you liked it better on the other axle and have to move them back. I would try the hubs on the aft axle first, drive it some then swap them to the mid axle and hopefully you like that location better and you get to leave them.

Now keep in mind this in not the voice of direct personal experience with a 3 axle vehicle. But I believe the theory is sound and makes mechanical sense. However, if someone with real world experience finds fault with "My plan" I'll certainly not argue. At least not until I get my own Deuce or 5 ton and try it myself. (Does anybody make locking hubs for the 5 ton?)

 

[jesusgatos]

When the vehicle is turning the outside wheel must roll faster (More RPM) than the inside wheel. If the differential is a spool or otherwise welded both wheels will obviously be forced to make the same RPM no matter what. When off road or on very loose road conditions, (Snow, ice, mud, sand) this is not much of a problem since the ground surface allows for one or the other or both tires to slip as needed to allow for the turn. On hard surfaces with good traction, this can and will break parts.

Thanks for the explanation, but I know how lockers and spools work. What I was asking is what you think the problem would be if a spool (or a welded diff) was used in an axle with locking hubs, and the hubs were unlocked when the vehicle was driven on-road. I think it would work just fine.

what other lockers?

Here's a link to an article I wrote for off-road.com a few years ago that gets into some of the trade-offs between different types of differentials.

 

[mudguppy]

... Here's a link to an article I wrote for off-road.com a few years ago that gets into some of the trade-offs between different types of differentials.

thanks, nice article.

but that wasn't what i was asking. i was asking about whether or not he was referring to the DL locker operating differently than the other [automatic] lockers offered for the 2.5T. they don't, so i wanted to clarify.

good link and addition to this thread, though!!!

 

[jesusgatos]

Oh I know, just quoted to lead into that link because I thought some of the people that read what oldman posted (was a good explanation) might wonder. Not deuce-specific, I know...

 

[Flat Black]

running a spool or Lincoln locker on the street is not going to tear up parts as some have suggested. It will wear your tires faster than normal if you drive a lot on the street, thats about it.

I have a pretty well built 80s Toyota 4runner with a spool in the rear and a Detroit in the front that I have driven on the road off and on for seven years without a single axle related issue. Would I run a spool in a daily driven truck, No. Is it ok for occasional street use, yes. Does it pay huge dividends off road with no locking/unlocking or limited slip action and no airlines or electric solenoids to install and run for a selectable locker, yes.
Will a spool ever break or wear out in a stock or mostly stock truck, not a chance.

 

[jesusgatos]

I was only suggesting using a welded diff in conjunction with locking hubs, which would completely eliminate any wear and tear on the drivetrain. With that said, I actually prefer to run a spool instead of a locker in most lighter off-road vehicles. Especially lifted, short-wheelbase vehicles like Jeeps. The handling/traction is just a lot more predictable. But would be a whole different ballgame with a 13,000lb truck. Would only run open, automatic or selectable lockers on-road.

 

[sewerzuk]

I was only suggesting using a welded diff in conjunction with locking hubs, which would completely eliminate any wear and tear on the drivetrain. With that said, I actually prefer to run a spool instead of a locker in most lighter off-road vehicles. Especially lifted, short-wheelbase vehicles like Jeeps. The handling/traction is just a lot more predictable. But would be a whole different ballgame with a 13,000lb truck. Would only run open, automatic or selectable lockers on-road.

Completely 100% agree with this statement; I have extensive experience with lockers in light, short wheelbase vehicles. Automatic lockers (in the rear axle) exhibit really unpredictable (and sometimes scary) tendencies; for those type of vehicles, I always prefer a spool. And, I truly believe that you actually do less damage to your drivetrain with the spool or welded spiders. The automatic lockers have a tendency to allow the tire to spin for a partial turn and develop some momentum before they lock, causing your axles to experience a large shock load. I broke axleshafts twice because of this; both times, one tire was up in the air, and the other was in a high traction situation. With a little gas, the tire in the air spun for a turn and then when the locker locked, the shock load (in conjunction with the traction, gearing, and other factors) broke my axle. The spool doesn't do this; it is always locked, making it predictable and preventing those shock loads (except, of course, if you are jumping your rig). I really disliked the detroit and lockrite lockers I ran in the rear of a few different vehicles; the occasional bang and jerk around the corner were characteristics that I couldn't get past. I currently run a spool in the back of my Samurai and a lockrite in the front, and it is about 80% driven on the street. This is an ideal setup for that vehicle...

I have never run a locker in the deuce, but my personal plan is to run the Grizzly locker in the front axle and an ARB in the rear tandem. I already have a set of MileMarker hubs on the front axle...

The grizzly locker is made by Yukon Gear; they are a respectable company with years of experience making good gearsets; I would be willing to bet that they are producing a quality locker, as well (though I don't have any firsthand experience, yet).

Here's a link to a good read on the Grizzly locker:
Yukon Grizzly Locker Rockwell 2.5 ton....AVAILABLE!! - Pirate4x4.Com Bulletin Board

 

[shovelheadmike]

Very good discussion. An automatic locker on a short wheelbase vehicle on the street can cause some unexpected excitement. However, that appears to not be as big an issue on a deuce where it is more of a problem making sharp turns and tire wear. I do know that automatic lockers are.notorious for causing understeer. I really ca.to.see an issue with a Lincoln locker if that axle has lockout hubs for street use. Yes, a spool is stronger, but many really built up 4x4s have been running them for years.

An ARB in the front would provide the best steering control on or.off.road.

I'd like to hear more about those M919 and M920s with the rear tandem disconnect. I think that would be great on my A3. Any ideas on how difficult that would.be to make work for.me?

 

[oldMan99]

I'd like to hear more about those M919 and M920s with the rear tandem disconnect. I think that would be great on my A3. Any ideas on how difficult that would.be to make work for.me?

As explained to me by someone very much more smarter than I are.... (A person very knowledgeable on the M920/916s and highly respected and much envied member of SS)

On the 920/916 it is not a "Disconnect".

It is called a, "Power divider" but this is actually kind of confusing. It works more like an air operated differential but between the 2 rear axles instead of in an axle between the 2 wheels.

To try to further explain, using the same explanation given to me; The power divider (PD) provides rotational power to both (Rear) axles all the time almost exactly the same way that an open differential gives power to both wheels all the time. When one wheel on an axle looses traction (in the 920/916 equipped with Detroit lockers) the locking diff in that axle takes over and keeps giving power to the wheel with traction, if that wheel also looses traction then the PD acting like an open differential quits powering the axle with traction and gives all the power to the axle w/o traction and forward movement quickly stops while the "Bad" axle spins both tires uselessly. "Engaging" the PD in this case is much like hitting the switch on an air locker as it locks the 2 axles together allowing the axle with traction to again get power even though the other axle has no traction at all and the truck once again moves.

To insure that I correctly understood this I then said/asked the following; So, if you take a 920/916 and remove the front axle driveshaft so that it will not get power ever (Until you replace the driveshaft) and jack up either the front or rear tandem axle (Both wheels of that axle off the ground) and apply power, the truck goes nowhere. Engage the PD (Like an air locking diff) and the remaining axle will then move the truck?

Swap the rear axle that is jacked up and run the same test will get the same result?

Further, if you use a "Normal" truck w/o some sort of locking differential (or replace the 920/916 locking diffs with open diffs) and all you have to do is jack up one wheel on either tandem and the truck does not move until you engage the PD?

The answer was, "Exactly".

This is why a truck with rear powered tandem axles without a PD or locking diffs will get stuck so easily, all it takes is one side of either rear axle to loose traction and game over.

I do know the M915 has a locker in only 1 of the rear axles but I do not remember which. I also believe it does not have a PD. I can ONLY guestimate that the reason they only put a locker in one of the axles is because w/o the PD ot allow differentiation between the rear axles when on hard ground with good traction a locker in both axles might cause some sort of binding and or excessive wear.

Since the 915 is primarily a road tractor and it's assignments should seldom have the truck used off of improved surfaces, I guestimate "They" decided that eliminating the PD and installing only 1 locker was a reasonable way to save some money but still provide a reasonable amount of traction in less than idea situations.

As for adapting the PD to an A3, I think it would be very expensive, time consuming and difficult at best and I can not see any benefit over that of doing one of the following:

A) Install a Detroit locker in 1 rear axle and an air locker in the other.
B) Install a DL in both axles and manual hubs on one axle.

Doing either you would have the same basic set up of the 915 (1 open diff, 1 locking diff) until you A: hit the air, or B: lock in the hubs, and then you have the same basic set up as the 920/916 with the PD engaged.

As I understand it the M919 is basically a M920 with a cement mixer apparatus mounted on it. Assuming that is correct, everything stated above for the 920/916 "SHOULD" also pertain to the M919.

I hope this helps.....

 

[Jakob]

I have been considering welding the front tandem and running the lockout kit. Then, when I can afford it, putting regular lockers front and rear tandem. I'm waiting to hear a good word on how a welded front tandem would act with the lockout kit unlocked.
I have a mud truck with a spooled rear axle as well, so I'm aware of the street manners and consequences on a four wheeled vehicle. I have little idea how a truck this large would act with a spool and then adding in a lockout kit on top of it even loses me further.