Wrecked my TTB

Yes, thanks! I like your one tire jacked test.

Nothing Special wrote

Rusty_S85 wrote

Yep, I have always wondered why they even offer lockers for 4wd applications.  I can see a posi but not a out right locker.  But the TTB unit I was looking at they dont offer a truetrack gear posi like I will be running in my 9", only a stock open type differential or a locker type.

Because that's where the biggest market is?  The vast majority of people who would buy a locker already bought a 4WD.  And while the front axle is usually considerably weaker than the rear, most people seem to agree that a locker in the front is more helpful than a locker in the rear in most situations.

And the Eaton TrueTrac is made for the Dana 44 TTB.  I would assume the Eaton posi is as well, but the posi is a clutch-type limited slip, not the gear type like the TrueTrac.

And having had lockers in three different rear axles and two fronts and a TrueTrac in one rear axle, I'll say that a TrueTrac doesn't come CLOSE to the performance of a locker.  Sometimes that's good because it doesn't have the bad manners of a locker.  But if you have one tire getting no traction (common in rock crawling or when ice is a factor) a TrueTrac does very little.  The TrueTrac works best when both tires get at least semi-decent traction.

I dont do rock crawling. mine is a daily driver and there may be ice but the whole design of the truetrac in every document from Eaton themselves state that it transfer power to the wheel with better traction just like a clutch style posi, but if both wheels have the same amount of traction then there will be no transfering of power.  So if I was going down the road and hit a patch of ice both tires will have the same amount of traction and wouldnt have a shift in power.  But if I move off the road slightly and my right tire hits the dirt on the side of the highway that less traction there will force a shift to the left tire on the pavement.

As far as ice itself goes, with AT tires just about all name brand ones ive seen stated they provide traction on ice/snow/mud so like my KO2`s even hitting a patch of ice there should still be some kind of traction on both wheels even if there is one wheel slipping more than the other.

I haven't driven on ice or snow with Big Blue's Truetrac, yet, but I have turned corners on asphalt when it had just started raining.  As you know, that brings the oil to the surface and makes things slick.  Apparently one of the tires started to spin so the Truetrac sent power to the other tire and both spun and I went sideways.  I got off and eased into it again, and now I was going straight, and it came loose again.  I tried it several times and before I felt the first tire slip the diff had sent power to the other one and I was walking sideways again.

I'm not at all saying that a Truetrac is bad.  I'm just saying that it will transfer power if one wheel slips, and if neither has much traction you'll be spinning.

Rusty_S85 wrote

I dont do rock crawling. mine is a daily driver and there may be ice but the whole design of the truetrac in every document from Eaton themselves state that it transfer power to the wheel with better traction just like a clutch style posi,...

The TrueTrac does transfer torque (which means it also transfers power) to the tire with more traction.  Clutch-type limited slips like the Eaton posi also transfer torque/power to the tire with more traction.  But the two types do this through very different means.

Rusty_S85 wrote

... but if both wheels have the same amount of traction then there will be no transfering of power.  So if I was going down the road and hit a patch of ice both tires will have the same amount of traction and wouldnt have a shift in power.  But if I move off the road slightly and my right tire hits the dirt on the side of the highway that less traction there will force a shift to the left tire on the pavement....

I agree with all of that

Rusty_S85 wrote

... As far as ice itself goes, with AT tires just about all name brand ones ive seen stated they provide traction on ice/snow/mud so like my KO2`s even hitting a patch of ice there should still be some kind of traction on both wheels even if there is one wheel slipping more than the other.

I had BFG A/Ts on my truck for the first few winter that I've had the TrueTrac.  Late this summer I put on a new set of Michelin M&S rated tires, so I have personal experience with both of those setups.  Yes, they get some traction on ice, not exactly the same as having one tire in the air.  But at the top of the slight hill 3 blocks from my house, where every morning in the winter I have to stop at the stop sign with my right tires on ice that's been polished by everyone trying to start there, I can spin the right tire as much as I want as the truck s-l-o-w-l-y pulls ahead with the left tire on bare pavement.

I used to have an F-150 with a Detroit locker.  That truck would accelerate at that stop sign as hard as I ever chose to accelerate without any noticeable wheel spin.  But on the other end of the spectrum, the trucks I've had with open diffs, or the worn out clutch-type limited slip that used to be in my current truck would accelerate even slower than the TrueTrac, and sometimes I'd need to back up and move over to the middle of the road to get off the ice.

So yes, a decent tire will get some traction on ice.  But it's often not enough to make a TrueTrac work anywhere close to as good as a locker.  It's better than an open diff.  A LOT better in some situations.  But it's not much better than an open diff at the top of that hill 3 blocks from my house.


After living with both a TrueTrac and a few different automatic lockers I'm not sure which I prefer in my daily driver truck.  The TrueTrac definitely has better road manners, but a locker definitely works better in my real-world usage.  Generally I'm willing to put up with the worse manners, so generally I'd say I'd rather have an automatic locker in my daily driver than a TrueTrac.

But there are two things that tip me toward a TrueTrac.  One is that I feel better about loaning my truck out with a TrueTrac than I do with an automatic locker.  Others (including my kids and wife) aren't used to an automatic locker, and it can bite you a lot more easily than a TrueTrac if you don't know what to expect.  Also an automatic locker isn't so great for towing, and I want this truck to be able to tow heavy trailers.

(There's also  third reason, I already have the TrueTrac and I don't want to pay to change it out)


And none of this is to say that you shouldn't get a TrueTrac for your truck.  A lot of people use them and love them.  My first post was to say that if the original poster wants the performance of a locker in snow, he likely will be disappointed with the performance of a TrueTrac.  On the other hand, if someone doesn't want the bad manners of a locker, and wants to reduce the risk of grenading an axle, a TrueTrac is definitely a great option.

Gary Lewis wrote

I haven't driven on ice or snow with Big Blue's Truetrac, yet, but I have turned corners on asphalt when it had just started raining.  As you know, that brings the oil to the surface and makes things slick.  Apparently one of the tires started to spin so the Truetrac sent power to the other tire and both spun and I went sideways.  I got off and eased into it again, and now I was going straight, and it came loose again.  I tried it several times and before I felt the first tire slip the diff had sent power to the other one and I was walking sideways again.

I'm not at all saying that a Truetrac is bad.  I'm just saying that it will transfer power if one wheel slips, and if neither has much traction you'll be spinning.

An open diff always sends the same amount of torque to both sides.  So it almost always will only spin one tire because almost always one tire will spin with less torque than it takes to spin the other one.  A rolling tire doesn't like to slide sideways.  A spinning tire is already sliding, so it doesn't care which way it slides.  So an open diff is definitely best for stability.

The good thing about any traction aiding diff is that it will send more torque to the tire with more traction.  That lets you put more power to the ground, but it also means that it's likely that you will be able to spin both tires.  And if the road is pretty slippery it will be likely that you WILL spin both tires.  So not traction-aiding dioff will ever be as stable as an open diff (except a selectable locker that IS an open diff when not engaged).

Yep.  I think the ideal diff is a selectable locker.  As you know, I have one on the front of Big Blue, but you may have forgotten/not known that I have one on the back of Blue.  Just pull the 4wd switch out and it locks the rear up to something like 10 MPH, at which point it turns off.  Would be ideal for the top of your hill.

Nothing Special wrote

Rusty_S85 wrote

I dont do rock crawling. mine is a daily driver and there may be ice but the whole design of the truetrac in every document from Eaton themselves state that it transfer power to the wheel with better traction just like a clutch style posi,...

The TrueTrac does transfer torque (which means it also transfers power) to the tire with more traction.  Clutch-type limited slips like the Eaton posi also transfer torque/power to the tire with more traction.  But the two types do this through very different means.

Rusty_S85 wrote

... but if both wheels have the same amount of traction then there will be no transfering of power.  So if I was going down the road and hit a patch of ice both tires will have the same amount of traction and wouldnt have a shift in power.  But if I move off the road slightly and my right tire hits the dirt on the side of the highway that less traction there will force a shift to the left tire on the pavement....

I agree with all of that

Rusty_S85 wrote

... As far as ice itself goes, with AT tires just about all name brand ones ive seen stated they provide traction on ice/snow/mud so like my KO2`s even hitting a patch of ice there should still be some kind of traction on both wheels even if there is one wheel slipping more than the other.

I had BFG A/Ts on my truck for the first few winter that I've had the TrueTrac.  Late this summer I put on a new set of Michelin M&S rated tires, so I have personal experience with both of those setups.  Yes, they get some traction on ice, not exactly the same as having one tire in the air.  But at the top of the slight hill 3 blocks from my house, where every morning in the winter I have to stop at the stop sign with my right tires on ice that's been polished by everyone trying to start there, I can spin the right tire as much as I want as the truck s-l-o-w-l-y pulls ahead with the left tire on bare pavement.

I used to have an F-150 with a Detroit locker.  That truck would accelerate at that stop sign as hard as I ever chose to accelerate without any noticeable wheel spin.  But on the other end of the spectrum, the trucks I've had with open diffs, or the worn out clutch-type limited slip that used to be in my current truck would accelerate even slower than the TrueTrac, and sometimes I'd need to back up and move over to the middle of the road to get off the ice.

So yes, a decent tire will get some traction on ice.  But it's often not enough to make a TrueTrac work anywhere close to as good as a locker.  It's better than an open diff.  A LOT better in some situations.  But it's not much better than an open diff at the top of that hill 3 blocks from my house.


After living with both a TrueTrac and a few different automatic lockers I'm not sure which I prefer in my daily driver truck.  The TrueTrac definitely has better road manners, but a locker definitely works better in my real-world usage.  Generally I'm willing to put up with the worse manners, so generally I'd say I'd rather have an automatic locker in my daily driver than a TrueTrac.

But there are two things that tip me toward a TrueTrac.  One is that I feel better about loaning my truck out with a TrueTrac than I do with an automatic locker.  Others (including my kids and wife) aren't used to an automatic locker, and it can bite you a lot more easily than a TrueTrac if you don't know what to expect.  Also an automatic locker isn't so great for towing, and I want this truck to be able to tow heavy trailers.

(There's also  third reason, I already have the TrueTrac and I don't want to pay to change it out)


And none of this is to say that you shouldn't get a TrueTrac for your truck.  A lot of people use them and love them.  My first post was to say that if the original poster wants the performance of a locker in snow, he likely will be disappointed with the performance of a TrueTrac.  On the other hand, if someone doesn't want the bad manners of a locker, and wants to reduce the risk of grenading an axle, a TrueTrac is definitely a great option.

Of course for me I am going the TrueTrac cause I want a posi in my truck for improved traction.  Not looking for a locker, my choices was to go with a traditional locker and run the posi additive or go with a gear locker and just run the same old gear oil as in an open.  I like that idea better plus I have seen some posi`s at work that were quite tight on the clutches and trying to make a turn results in a ratcheting effect as the tire hops as its not wanting to slip.  I didnt want that either on a daily driver especially with 31x10.50-15 tires.

Currently I have the open so I can get a currie third member with a traditional posi or a truetrac and swap it in with the gears I am looking at.  So I can go either way if need be still.

ArdWrknTrk wrote

....  You are always going to have problems with a true locker if you have traction.
Any time you are turning, each front wheel is traveling a different arc, with much different distances.

This is why we have differentials to begin with!
https://youtu.be/yYAw79386WI

So, you found the weak link in your setup.
Probably a lot better than splitting your carrier.  

What part do you want to fail?
Because geometry and physics say you can't have both axles turning together.

I was thinking more about this thread and realized that I hadn't commented on this.  Stevenscoffee didn't say what type of locker he has.  But if it's an automatic locker it will not cause binding.  In fact, an automatic locker in a front axle will actually reduce the amount of binding you have when turning in 4WD.

Most differentials are really misnamed.  "Limited slip" differentials offer a limited amount of grip, while doing nothing to limit slip once the slip starts.  And "automatic locking" differentials actually are better considered "automatic unlocking" differentials.

Automatic (un)lockers will always freely allow one tire to go faster than the ring gear.  So when you are going around a corner it will automatically unlock and let the axles turn separately.  And this will happen freely whether you are coasting or accelerating.  The only way you can keep it from disengaging is to spin the inside tire.  Then the ring gear catches up to the outside tire.  With the outside tire not going faster it won't unlock.  But it's not like people often say who think you need to get off the power to allow an automatic locker to unlock.  It knows nothing about power, all it knows is relative speed.  So any time one tire wants to go faster than the ring gear it can.  Period.


When you go around a curve the front tires track wider than the rear, so the front tires need to turn faster than the rear.  But when yo are in 4WD the transfer case (that has no differential) won't allow that so you get some bind.  But an open front diff will allow the inside tire to slow down a little while the outside tire goes a little faster.  An automatic locker on the other hand won't let the inside tire slow down, although it will allow the outside tire to speed up.  So the average speed of the front tires is faster in a curve with an automatic locker.  That's why you'll actually get less bind turning with an automatic locker in the front than with an open diff.


That said, open diffs protect axles because they will only send as much torque through either axle as the tire with the least traction will support.  That can be considerably less torque than the tire with the most traction can support, and a locker will send that higher amount to that tire.  That's why it's a lot easier to break axles with a locker.


And I've been talking here like I'm a big fan of automatic lockers in a front axle.  I'm not, at least in all situations.  I think an automatic locker in the front could well be the most effective choice for most serious fourwheeling (better than other types of diffs in the front and better than any type of diff in the rear).  But the road manners are a lot worse than with an automatic locker in the rear.  At low speeds it's just very significant torque steer as the diff makes the tires try pretty hard to straighten themselves out when you are turning or will make it pull toward the tire with the least traction if there's a significant traction difference.  But at higher speeds that torque steer can be deadly.  The first time I changed lanes on a snowy freeway in 4WD with an automatic locker in the front, when the left front tire hit the snow between the lanes the truck pulled so abruptly to the left that it had moved 10 feet before I was able to catch and correct it.  Fortunately I was trying to change into that lane and knew it was empty.  The second (and last) time I changed lanes with the front locker I thought I was ready.  I back off the gas quite a bit (just enough to keep speed, not accelerating at all) and the truck only jumped over about 5 feet.  I shifted into 2WD at that point.

Rusty_S85 wrote

Of course for me I am going the TrueTrac cause I want a posi in my truck for improved traction.  Not looking for a locker, my choices was to go with a traditional locker and run the posi additive or go with a gear locker and just run the same old gear oil as in an open.  I like that idea better plus I have seen some posi`s at work that were quite tight on the clutches and trying to make a turn results in a ratcheting effect as the tire hops as its not wanting to slip.  I didnt want that either on a daily driver especially with 31x10.50-15 tires.

Currently I have the open so I can get a currie third member with a traditional posi or a truetrac and swap it in with the gears I am looking at.  So I can go either way if need be still.

Sounds like the TrueTrac will be a good choice for you.

Nothing Special wrote

Rusty_S85 wrote

Of course for me I am going the TrueTrac cause I want a posi in my truck for improved traction.  Not looking for a locker, my choices was to go with a traditional locker and run the posi additive or go with a gear locker and just run the same old gear oil as in an open.  I like that idea better plus I have seen some posi`s at work that were quite tight on the clutches and trying to make a turn results in a ratcheting effect as the tire hops as its not wanting to slip.  I didnt want that either on a daily driver especially with 31x10.50-15 tires.

Currently I have the open so I can get a currie third member with a traditional posi or a truetrac and swap it in with the gears I am looking at.  So I can go either way if need be still.

Sounds like the TrueTrac will be a good choice for you.

Thats what I figured, my truck is more of a pavement truck only time my truck goes off road is when I go out of town and I drive out onto the ground we have or I take a back dirt road.  I did hear the TrueTrac is better in a mud/dirt/sand situation than a straight open diff though.

Rusty_S85 wrote

....  I did hear the TrueTrac is better in a mud/dirt/sand situation than a straight open diff though.

Definitely!  Any time both tires get some traction a TrueTrac won't let the tire with the least traction be such a limiting factor.  It's just when there's a LARGE difference in traction between the two sides where the TrueTrac tends to fall short.

The driveway at my folks cabin is a little steep and is usually covered in leaves.  When the leaves are wet I usually needed 4WD to get up with the old worn out clutch type limited slip (almost an open diff).  I can almost always get up in 2WD with the TrueTrac.

This is deep!  I've read it a couple of times and I keep coming back to figure it out.  Thanks, Bob!  

You're welcome!  I've spent a lot of time thinking about lockers and discussing them with others.  I'm a mechanical engineer who's designed and supported a manufacturing line for clutches, as well as being a life-long fourwheeler, so they're really in my wheelhouse.  I really enjoy getting in conversations like this!

I particularly like the "(un)locker" description.  Makes sense to me.

And after you explained your experiences with one in the front I'll stay with my e-locker, thank you very much!

I appreciate the commentary, Bob.

I honestly don't think of anything (Torsen, trutrac, automatic, whatever) as a 'locker'
If you've got a spool.....

So, maybe I'm all wet here.
I never asked, and we never heard.
I have seen welded spiders and lunchboxes do some damage though.

Maybe it wasn't a TTB trying to be a live axle that ripped Stephen's yoke open.

ArdWrknTrk wrote

I appreciate the commentary, Bob.

I honestly don't think of anything (Torsen, trutrac, automatic, whatever) as a 'locker'
If you've got a spool.....

"It's just semantics", but since "semantics" is defined as "the branch of linguistics and logic concerned with meaning", and since the entire point of communication is to communicate meaning, "it's just semantics" is equivalent to saying "it's just the entire point."

Jim, I'm not saying that to put you down in any way, but just to explain why I am a little picky about word choice.

As I said above, "automatic lockers" are better thought of as "automatic unlockers."  Along the same line, "selectable lockers" might be thought of as "selectable unlockers."  What both of them do is "lock" the two sides together with no possibility of the tires turning different speeds (much like a spool), but unlike a spool they will also unlock to allow the differential to not bind things up.  An automatic locker will ALWAYS unlock (automatically) to prevent that bind, while with a selectable you need to tell it.  So a selectable locker will bind things up if you don't disengage it.

So things like a Detroit (Locker), OX, ARB, and all of the "lunchbox lockers" are best thought of as lockers.  They don't allow for any slip, but they will disengage (in one of two very different ways, automatic or selectable).

On the other hand, limited slip differentials never really lock.  They will always allow slip if a big enough load is applied.  So people talk about a (Detroit) TrueTrac, a Torsen, a PowrLok, a Traction Lock or a Posi as a "locker," but that's wrong and misleading (and yes, the names "PowrLok" and "Traction Lock" don't help dispel the confusion).

And while I'm there, "Detroit" is sort of a brand name owned by Eaton.  Under that brand are (at least) the Detroit Locker (often called just "a Detroit") and the Detroit TrueTrac (usually called just "TrueTrac").  But I think some people see "Detroit TrueTrac" and since they know that a "Detroit" is a locker, they think the Detroit TrueTrac is a locker.  But it's not.

And "Posi" is often used an the generic word for a clutch-type limited slip, or for any limited slip, or worse yet, for any limited slip or locker.  "Posi" is Eaton's brand name for their clutch-type limited slip, much like "Kleenex" is Kimberly-Clark's brand name for facial tissue.  Just like Puffs facial tissue, any brand of toilet tissue, or worse yet, any thing made of paper aren't Kleenex, Traction Locks, TrueTracs and lockers aren't "Posi's".

ArdWrknTrk wrote

So, maybe I'm all wet here.
I never asked, and we never heard.
I have seen welded spiders and lunchboxes do some damage though.

Maybe it wasn't a TTB trying to be a live axle that ripped Stephen's yoke open.

You're definitely not all wet (maybe just a little damp? ).  If he has a selectable locker then it might have been a "live axle" that broke his U-joint.  But if it was an automatic locker, then bind during turning couldn't have been the cause.

And even if he does have a selectable locker, or even a spool for that matter, it's likely not the torque from the bind in a turn that broke it.  Like with an open diff under power, the bind torque from a spool is limited to the torque required to slip the tire with the least traction.  What breaks most spool or locker equipped axles is engine torque (multiplied by the trans, transfer case and axle gearing).  When you are on the power too much and one tire gets heavily loaded, that's the recipe for axle breakage.  Open diffs ad limited slips will limit that torque load based on what the other tire will support, but spools and lockers can give it all to the one side.

Nothing Special wrote

ArdWrknTrk wrote

I appreciate the commentary, Bob.

I honestly don't think of anything (Torsen, trutrac, automatic, whatever) as a 'locker'
If you've got a spool.....

"It's just semantics", but since "semantics" is defined as "the branch of linguistics and logic concerned with meaning", and since the entire point of communication is to communicate meaning, "it's just semantics" is equivalent to saying "it's just the entire point."

Jim, I'm not saying that to put you down in any way, but just to explain why I am a little picky about word choice.

As I said above, "automatic lockers" are better thought of as "automatic unlockers."  Along the same line, "selectable lockers" might be thought of as "selectable unlockers."  What both of them do is "lock" the two sides together with no possibility of the tires turning different speeds (much like a spool), but unlike a spool they will also unlock to allow the differential to not bind things up.  An automatic locker will ALWAYS unlock (automatically) to prevent that bind, while with a selectable you need to tell it.  So a selectable locker will bind things up if you don't disengage it.

So things like a Detroit (Locker), OX, ARB, and all of the "lunchbox lockers" are best thought of as lockers.  They don't allow for any slip, but they will disengage (in one of two very different ways, automatic or selectable).

On the other hand, limited slip differentials never really lock.  They will always allow slip if a big enough load is applied.  So people talk about a (Detroit) TrueTrac, a Torsen, a PowrLok, a Traction Lock or a Posi as a "locker," but that's wrong and misleading (and yes, the names "PowrLok" and "Traction Lock" don't help dispel the confusion).

And while I'm there, "Detroit" is sort of a brand name owned by Eaton.  Under that brand are (at least) the Detroit Locker (often called just "a Detroit") and the Detroit TrueTrac (usually called just "TrueTrac").  But I think some people see "Detroit TrueTrac" and since they know that a "Detroit" is a locker, they think the Detroit TrueTrac is a locker.  But it's not.

And "Posi" is often used an the generic word for a clutch-type limited slip, or for any limited slip, or worse yet, for any limited slip or locker.  "Posi" is Eaton's brand name for their clutch-type limited slip, much like "Kleenex" is Kimberly-Clark's brand name for facial tissue.  Just like Puffs facial tissue, any brand of toilet tissue, or worse yet, any thing made of paper aren't Kleenex, Traction Locks, TrueTracs and lockers aren't "Posi's".

ArdWrknTrk wrote

So, maybe I'm all wet here.
I never asked, and we never heard.
I have seen welded spiders and lunchboxes do some damage though.

Maybe it wasn't a TTB trying to be a live axle that ripped Stephen's yoke open.

You're definitely not all wet (maybe just a little damp? ).  If he has a selectable locker then it might have been a "live axle" that broke his U-joint.  But if it was an automatic locker, then bind during turning couldn't have been the cause.

And even if he does have a selectable locker, or even a spool for that matter, it's likely not the torque from the bind in a turn that broke it.  Like with an open diff under power, the bind torque from a spool is limited to the torque required to slip the tire with the least traction.  What breaks most spool or locker equipped axles is engine torque (multiplied by the trans, transfer case and axle gearing).  When you are on the power too much and one tire gets heavily loaded, that's the recipe for axle breakage.  Open diffs ad limited slips will limit that torque load based on what the other tire will support, but spools and lockers can give it all to the one side.

and when you say automatic unlocker are you talking about the ratcheting lockers that as you go around a corner the teeth are supposed to slide out slightly and slip or ratchet?  or are you refering to something like a limited slip?  I assume you are refering to the ratcheting style of lockers but just want to make sure I am understanding right.

I personally dont think a locker of any kind ratcheting or spool belongs on a vehicle that is driven on the street.  It can be unnerving with a tight limited slip with the traditional clutches, we have a camaro at work with a LS transplant and 4L60E and that thing has such a tight limited slip just trying to drive it around a corner it makes so much noise you dont know if the car is falling apart or not.

For me personally, I would just stick with a open differential for my truck but I am running 31x10.50-15 tires all around but my 306 I am building should make some where around 380hp - 395hp and around 400 - 415trq.  I know with an open differential I wouldnt really break anything but I also dont want to smoke one expensive KO2 tire either.  A locker would probably be bad news for my U joints, I dont think my C6 or 9" axle would be a problem in failing with 400 - 415 trq even with torque multiplication of the hughes tow converter or the E4OD planetary gear set upgrade.  But I question the U-joints how ever and I wouldnt want to be going down the highway doing 75 mph and have something like what happened to the original poster and have a U joint shatter.  Ive seen what happens when a failure like that happens at highway speeds, it will smash the gas tank, it will destroy the underside of the cab and bed and be a wrecking ball for anything in its way till the axle either stops spinning or is spit out the rear of the truck.

Rusty_S85 wrote

and when you say automatic unlocker are you talking about the ratcheting lockers that as you go around a corner the teeth are supposed to slide out slightly and slip or ratchet?  or are you refering to something like a limited slip?  I assume you are refering to the ratcheting style of lockers but just want to make sure I am understanding right....

Yes, I'm talking about the ratcheting kind of lockers.  Detroit Locker, Yukon Grizzly, LockRight, Aussie Locker, Spartan Locker, that type.  Limited slips aren't lockers and I don't use the term "locker" referring to them.

Rusty_S85 wrote

I personally dont think a locker of any kind ratcheting or spool belongs on a vehicle that is driven on the street.  It can be unnerving with a tight limited slip with the traditional clutches, we have a camaro at work with a LS transplant and 4L60E and that thing has such a tight limited slip just trying to drive it around a corner it makes so much noise you dont know if the car is falling apart or not....

You are certainly entitled to your opinion, and as long as you're talking about your own vehicle, my opinion (or anyone else's) doesn't carry any weight.

But an automatic locker is nothing like a tight clutch-type limited slip.  A clutch-type limited slip ties the two sides together, just like a spool, until the torque exceeds the slip torque of the clutches.  If it's set up tight enough it is effectively a spool.  That's almost always a problem on ice (even the limited slip in my truck that was too worn out to start on the top of that hill was too tight for coasting around a corner on ice).  But if it's set up really tight it can even act like a spool on the street.

But like I've been saying, an automatic locker will always freely allow one tire to turn faster, so you never get that kind of bind going around a corner with one.  You might hear a clicking from the clutches, but there won't be any bind.

That's not to say automatic lockers have good street manners.  Lot's of people don't like them on the street, and as I said earlier, I don't really want one in a truck that I'm letting my kids drive.  But their bad manners have nothing to do with the bad manners of a tight limited slip.

When you go around a corner the locker unlocks and lets the outside tire go faster.  But that means that it's only driving the inside tire.  That gives noticeable torque steer which some people find too annoying.

Having one wheel drive also means that it's really easy to spin that tire if you get on the power too much (and "too much" might be really just a little, depending on conditions).  When you do spin the inside tire it goes faster (duh!) and it will soon be going the same speed as the outside tire.  Once the outside tire isn't trying to go faster than the inside tire the locker will reengage, and there's no slip, so it will reengage abruptly.  That sudden load can easily break the outside tire loose as well, making the back end kick out pretty abruptly.  That's the bad manners that make me less willing to have my kids or wife driving it, especially in the snow.

But automatic lockers are completely predictable if you understand them.  And if you are able and willing to adjust your driving to manage the lockers quirks they aren't bad on the street (personally I think they are much easy to live with than a clutch-type limited slip).  But not everyone is able to drive to a locker, and even fewer are willing to.  So they definitely aren't for everyone.

Rusty_S85 wrote

For me personally, I would just stick with a open differential for my truck but I am running 31x10.50-15 tires all around but my 306 I am building should make some where around 380hp - 395hp and around 400 - 415trq.  I know with an open differential I wouldnt really break anything but I also dont want to smoke one expensive KO2 tire either...

An open diff really isn't much worse than any traction-aiding diff in most circumstances.  An open diff will give you twice as much force pushing you forward as the tire with the least traction is capable of providing.  The best that any traction-aiding diff can add is the additional force that the tire with the most traction can provide.  And in most situations that difference isn't huge.

Where the difference is significant is in things like rock crawling where one tire might be in the air, or on ice when one tire is on pavement, or in drag racing (and from what you said above I'd group your needs with that) where the driveshaft torque tries to lift the right rear tire.  It's places like that where limited slips, lockers and spools can provide enough benefit to outweigh their downsides.  

Rusty_S85 wrote

... A locker would probably be bad news for my U joints, I dont think my C6 or 9" axle would be a problem in failing with 400 - 415 trq even with torque multiplication of the hughes tow converter or the E4OD planetary gear set upgrade.  But I question the U-joints how ever and I wouldnt want to be going down the highway doing 75 mph and have something like what happened to the original poster and have a U joint shatter.  Ive seen what happens when a failure like that happens at highway speeds, it will smash the gas tank, it will destroy the underside of the cab and bed and be a wrecking ball for anything in its way till the axle either stops spinning or is spit out the rear of the truck.

A rear locker wouldn't be particularly bad for your U-joints.  You are much more likely to break an axle shaft with a locker than you are anything in the driveshaft.  It's just that the U-joints in front axles are the weak link there.  So breaking an axle U-joint with a front locker is a pretty common thing.

And locker-induced failures aren't likely to happen on the freeway.  They are generally due to torque overloads, and that can't really happen at 75 mph.  Instead they'll happen when you dump the clutch, or start bouncing the truck trying to climb up a rock.

So I don't think you should be too worried about a rear locker for those safety concerns.  But I'm still not saying that you'll like a locker.  I think a TrueTrac sounds like a really good fit for that application.

I have had LS in both my 86 K5 Blazer and my 02 Durango in the snow and even pulling a trailer (Blazer) and never did I feel un  easy on how the trucks were going to react even around corners.

I have a Lock Right locker in my 75 factory v8 AMC Gremlin, 92" wheel base car.
I have only tried moving it in snow because I had to and even with both back wheel "locked" it was not moving but I think that was mostly because no weight over the rear drive wheels.

Driving when dry out any "little" power around a corner would lock and the tires would make noise.
That's not cool with the police around.
I have driven the car in the rain and that was a lot of fun "not" if you were not ready for it around a corner. Ken Brock had nothing on me in the rain

I also run a Detroit Locker in my 70 AMC Javelin drag car and has worked great in the car.
I figured if I ever went to a spool in the drag car I would use the DL in my 70 Javelin street car.

A lot of weather to run a locker or a LS for me had to do with what I was going to do with the car or truck and ease to install.
The 86 & 02 trucks were factory installs, the Lock Right I installed as was the Detroit Locker, both for drag racing at the time.
Dave ----

Nothing Special wrote

Yes, I'm talking about the ratcheting kind of lockers.  Detroit Locker, Yukon Grizzly, LockRight, Aussie Locker, Spartan Locker, that type.  Limited slips aren't lockers and I don't use the term "locker" referring to them.

Thats what I thought but I wanted to make sure.

Nothing Special wrote

You are certainly entitled to your opinion, and as long as you're talking about your own vehicle, my opinion (or anyone else's) doesn't carry any weight.

But an automatic locker is nothing like a tight clutch-type limited slip.  A clutch-type limited slip ties the two sides together, just like a spool, until the torque exceeds the slip torque of the clutches.  If it's set up tight enough it is effectively a spool.  That's almost always a problem on ice (even the limited slip in my truck that was too worn out to start on the top of that hill was too tight for coasting around a corner on ice).  But if it's set up really tight it can even act like a spool on the street.

But like I've been saying, an automatic locker will always freely allow one tire to turn faster, so you never get that kind of bind going around a corner with one.  You might hear a clicking from the clutches, but there won't be any bind.

That's not to say automatic lockers have good street manners.  Lot's of people don't like them on the street, and as I said earlier, I don't really want one in a truck that I'm letting my kids drive.  But their bad manners have nothing to do with the bad manners of a tight limited slip.

When you go around a corner the locker unlocks and lets the outside tire go faster.  But that means that it's only driving the inside tire.  That gives noticeable torque steer which some people find too annoying.

Having one wheel drive also means that it's really easy to spin that tire if you get on the power too much (and "too much" might be really just a little, depending on conditions).  When you do spin the inside tire it goes faster (duh!) and it will soon be going the same speed as the outside tire.  Once the outside tire isn't trying to go faster than the inside tire the locker will reengage, and there's no slip, so it will reengage abruptly.  That sudden load can easily break the outside tire loose as well, making the back end kick out pretty abruptly.  That's the bad manners that make me less willing to have my kids or wife driving it, especially in the snow.

But automatic lockers are completely predictable if you understand them.  And if you are able and willing to adjust your driving to manage the lockers quirks they aren't bad on the street (personally I think they are much easy to live with than a clutch-type limited slip).  But not everyone is able to drive to a locker, and even fewer are willing to.  So they definitely aren't for everyone.

It is mainly the mannerism that I am talking about why I feel that they dont belong on the street.  Doesnt mean people cant run it if thats what they want.  Sort of like people that run real hot cams in their cars that results in very little vacuum for power brakes as well as bad mannerism on the street but people still use them.

I think the majority of people out there wouldnt like a locker period even an automatic style locker.  Most people today are spoiled with modern technology.

Nothing Special wrote

An open diff really isn't much worse than any traction-aiding diff in most circumstances.  An open diff will give you twice as much force pushing you forward as the tire with the least traction is capable of providing.  The best that any traction-aiding diff can add is the additional force that the tire with the most traction can provide.  And in most situations that difference isn't huge.

Where the difference is significant is in things like rock crawling where one tire might be in the air, or on ice when one tire is on pavement, or in drag racing (and from what you said above I'd group your needs with that) where the driveshaft torque tries to lift the right rear tire.  It's places like that where limited slips, lockers and spools can provide enough benefit to outweigh their downsides.  

Of course, the open diff is more of a safe bet when you are unsure of a diff style.  I actually settled on the TrueTrac some 6 years ago and considering I am buying a Currie third member to change my gear ratio so all I have to do is pull my axles out a bit pull the OE third member and throw in the new one and be back on the road vs having my OE third member rebuilt, I have an option of a OE limited slip or the truetrac.  Price wise when I last looked they were both about $1,200 if I remember right.  I figure it would be better for me with my limited off road use but should provide better street mannerism for me especially with me driving on winding back country roads at 60 - 75 mph.

Nothing Special wrote

A rear locker wouldn't be particularly bad for your U-joints.  You are much more likely to break an axle shaft with a locker than you are anything in the driveshaft.  It's just that the U-joints in front axles are the weak link there.  So breaking an axle U-joint with a front locker is a pretty common thing.

And locker-induced failures aren't likely to happen on the freeway.  They are generally due to torque overloads, and that can't really happen at 75 mph.  Instead they'll happen when you dump the clutch, or start bouncing the truck trying to climb up a rock.

So I don't think you should be too worried about a rear locker for those safety concerns.  But I'm still not saying that you'll like a locker.  I think a TrueTrac sounds like a really good fit for that application.

I was going off how the U-joints are typically the weakest link when it comes to power with traction.  Maybe its different when dealing with a truck and a hotrod build that has slicks loading up going down the strip.

But now I am kind of curious on the automatic lockers how they would feel driving a short wheelbase flareside with one.  Ive driven cars with them but never something like a truck like mine with very low weight on the rear axle.