If I'm understanding you correctly I think I'd describe it a little differently. It sounds like what you are saying is that when you turn on gravel you spin the inside tire. If I've got that right it's not that the locker doesn't unlock in that situation, it's just that you are spinning the inside tire. Automatic lockers only drive the inside tire in a turn, so it's pretty easy to break it loose. When that happens the inside tore will catch up in speed to the outside tire, and then the outside tire will start to get torque. The thing that can make this a little twitchy is that when the locker reengages it kind of hammers the outside tire, so it's not that hard to break it free too. Yes it can be fun, but you do need to be careful with it too.

Even on pavement it's pretty easy to break one tire loose when starting around a corner. This is the reason I would not recommend an automatic locker in a truck that is expected to do a lot of towing. With a heavy load but not a lot of weight on the back tires it can be difficult to start without spinning a tire. And it's hard on the driveline to hammer it like that too much. That's why I'm thinking more of putting a TrueTrac in the rear of my pickup, I'll leave the lockers for my Bronco.

 

Sorry,but this is wrong.

An automatic locker drives BOTH axles the same speed when power is being put through it,regardless if the vehicle is going straight or in a turn.

The inside tire spins because it's being driven the same speed as the faster moving outside tire.

Coasting or no input power, is the ONLY time you get a difference in wheel speed with a locking diff.

 

Automatic lockers, like Detroit Lockers, won't let either wheel turn slower than the ring gear. When going around a corner, the inside wheel is driven at the same speed as the ring gear, and the outside wheel will unlock and overrun. If enough power is applied to break the inside wheel loose, it will speed up until the ring gear catches up to the outside wheel speed, at which point the locker will lock the outside wheel back in.

 

Ok,one more time. This is from Detroit:

"The Detroit Locker is an automatic locking differential designed to lock both wheels of the axle together automatically with power input, when forward or reverse torque is applied, so that both wheels are providing 100% power to the ground. This action creates essentially a "spool" that solidly connects the axle shafts together. When torque is not being applied, the Detroit Locker is allowed to unlock, permitting a differentiation variance in wheel speed while negotiating turns."

 

That might be what Detroit says, but it's not what a Detroit does. As I said before, and as Phy said just above, automatic lockers, including Detroits, never let either tire turn slower than the ring gear, but they will always let one tire turn faster. So when you go around a corner the outside tire is allowed to overrun the ring gear and only the inside tire is driven. Only if the inside tire catches up to the outside tire (when you straighten out, or if the inside tire spins) will the locker drive the outside tire.

If you were right and automatic lockers always drove both tires the same speed, then you'd always scrub tires when driving through a corner. And that doesn't happen. I've put over 100k miles on a Lock Right in an F-150, over 20k on a Detroit in a CJ5 and over 20k on another Detroit in my Bronco. They will definitely power around a corner without spinning or skidding a tire, but if you get on the power too much they will break the inside tire free.

 

Once the power is applied an automatic locker will act like a spool, if you don't notice the skipping, sliding or otherwise increase in speed that the inside tire will have to maintain to keep pace with the farther distance the outside tire is traveling depends on the road surfaces/tires traction and transmission type (manual or automatic)/vehicle weight etc.
Just because you do not notice something does't mean something it isn't happening. Automatic lockers always maintain the same speed WHEN power is applied, any amount of torque will cause this and this is why automatic lockers do scrub tires WHEN the power/torque is applied.
What makes you think it isn't happening? because you don't always feel it?
Many different aspects affect vehicles differently: wheelbase, manual versus automatic transmissions, vehicle weight, a tires traction (dependent on rubber compound and tread pattern as well as road surfaces etc.) and type (bias or radial) all conspire to either add or reduce the scrubbing effect when traveling through a corner under load/power.

You're wrong an automatic locker won't ACCELERATE through a corner w/o the inside tire matching the outside tires speed, it's just not noticeable in all vehicles on all highways etc. due to many variables. That's why you never notice a rear tire skidding, slipping or otherwise traveling faster then the ground it's covering at highway speeds, but it has to in order to travel the same distances the outside tire does which is obviously covering more ground due to the larger arc of it's turn.

Cheers D

 

As I stated earlier it's not enough power it's any power. Otherwise what is the magical amount of load or torque input that it takes to make an automatic locker work like a spool?
I have a spool in the rear axle of a Jeep I own and it goes through SOME corners (under load or coasting it doesn't matter, but the noises associated with a spool or an automatic locker when locked up are decreased when operating with no load or very little throttle versus heavy load/torque input) w/o making a sound of rubber chirping/barking (usually only ones that are at higher speeds and that are less sharp then the turns it makes at very low speeds), that vehicle travels through corners under load/with throttle at highway speeds and you can't here or tell that the inside tire is traveling faster then the outside tire , but it is or do you deny that?

The inside tire is not always noticeable when it BREAKS LOOSE, this is why lockers are very transparent on long sweeping turns at highway speeds when operated with power applied, but the inside tire does have to cover more ground then the outside tire when under load/throttle and this can be done w/o any noticeable noises or sensations at times (because of the many variables like I've stated in my other post before this one).

Cheers D

 

This correctly explains the CORRECT operation of an automatic locker.

Cheers D

 

For starters clutch type limited slips set-up tight are far from a spool and in fact are not even close to an automatic locker in the smoothness of there operation while still being able to give excellent power to both tires in most any scenario (these were a hot set-up before selectable differentials became all the rage due the fact daily driven 4x4's could operate w/o all the banging and loading/unloading of an automatic locker on the street with excellent traction results on severe trails, the downside was they needed to be rebuilt often to maintain their performance because of the clutches wearing out (Power-Lok diff.'s were used for their stronger design over a Trac-Lok).
Also the True-Trac is actually a worm gear limited slip differential as it has no clutches to ever wear out, making it an excellent all purpose traction aiding device and one that offers excellent performance in the front axle of a 4x4 that will be operated on icy/slippery roads while in four wheel drive.

You state that an automatic locker can be quirky on the street and this can be true for sure, but what can make a real difference to the noticeable affects of an automatic locker like the Detroit No-Spin (the correct name for the original automatic Detroit Locker) are things like vehicle weight and wheelbase an automatic or manual transmission even torque output can play a role in the quirkiness of an automatic locker for street and trail use and tires along with road surfaces play important factors as well (this is based off the many 4x4 vehicles I've owned with Detroit Lockers some in the rear and others in the front and rear together).
What I mean by this is a 4x4 F-250 weighing 6,000Lbs. with a big block and an automatic tranny will barely notice the affects of a Detroit locker in the rear axle versus a 3,500Lb. 4 cyl. Jeep with a 94" wheelbase and a manual tranny will really notice the affects that an automatic locker equipped rear axle can play on the driver. Even comparing two Ford 4x4's one a F-150 with a long wheelbase and auto. trans. versus a short wheelbase F-150 and manual tranny the attitude that a locker can play n the rear axle can be very different with each vehicle (again the tires, road surfaces and driving styles etc. will also contribute to offer a different affect on the noticeable operation of the vehicle).


While Nothing Special is right about an automatic locker causing harsh and even dangerous effects on the steering of a vehicle used in slippery streets while in four wheel drive (most caused by the loading or engaging of the locker and the dis-engaging of the locker causing an unwanted affect on the steering much like when a rear locker shifts the vehicle around as it loads and unloads as power removed and applied respectively) the same is not true for a limited slip particularly the Detroit True-Trac as this particular Gear Driven Limited Slip differential does not affect the steering when in four wheel drive even when slippery/icy roads are traversed (making it an excellent choice for front axle applications). I say this based on firsthand experiences with this differential while being used in a number of different 4x4's that I've owned and used on all street conditions (and off-road terrains) in all the seasons here in Canada. Using a limited slip like the factory available to Fords Trac-Lok clutch type limited slip diff. is also an option as they can be used w/o ill effect due to their weaker limited slip status, since they are not a tight LSD they do not create those handling issues however in turn they do not offer very good traction either and are a LSD I never recommend using (I actually refer to a Trac-Lok as an Unlimited Slip diff.).

Cheers D

 

I apologize if my first post was a little harsh, my intent was not offend anybody. It's just that I've read so many threads over the past that are trying to offer assistance to someone in need of correct advice only to have many posting up their limited and often times incorrect advice.

I've been running vehicles with lockers front and back for over twenty years and in that time have built more then a dozen 4x4's, six of them with Detroit differentials front and rear and many others using lunchbox lockers like Aussie, Spartan, Lock-Rite and the Detroit Gear-Less (plus a few spools and welded diff.'s too).
I'm not claiming to be an industry expert or even a mechanic (most of my diff.'s were set-up by a professional), but regarding four wheeling I do have a lot good information to share when talking 4x4 experiences with daily driver vehicle set-up's (that are designed to work well on road and off road) particular with locking differentials.

Cheers D

 

There are many factors that can be discussed regarding traction aiding differentials like an automatic, selectable or limited slip differential especially if being used in a front axle.
However it can be difficult for someone who has never spent any time behind the wheel of a locker equipped 4x4 to understand some of the more discreet nuances that can make the purchase of a newly installed locker in their 4x4 less then an enjoyable one.

Some things to note about a locker equipped 4x4 that can be different then driving an open diff. 4x4 (in no particular order) are:

An automatic locker in a rear axle application will push the vehicle to the outside of the turn. The rear axle drives the vehicle in the direction the rear axle is facing, this can be especially noticeable on tight switchbacks making three or more point turns a regular ordeal. If you can recognize how an automatic locker works it makes it all more easy to understand.

An automatic locker like the name implies functions automatically meaning any amount of power (torque) application will cause the rear axles to lock together like a spool. The affects of this are many:

Like the rear axle wanting to drive the vehicle in whatever direction the rear axle is facing.

Another less talked about issue is when the application of power causes the locking of both axles to shift the vehicle towards the drivers side of the vehicle.

Likewise the 4x4 shifts towards the passengers side when the power is reduced enough to allow for the load to be withdrawn causing the dis-engaging the axles. This shifting or movement of the vehicle is due to the rear axles tires driving the vehicle as the torque is applied in the direction of that torque (as the driveshaft loads the rear axle and the tires grip the road the vehicle is thrust towards the left front corner of the vehicle).

This aspect is significantly more noticeable in a manual equipped 4x4 and a shorter and lighter 4x4 is also more effected by this as well. An operator of a 4x4 equipped with an automatic locker will learn learns to be smooth with the application of power in order to reduce this unwanted action of the vehicle loading and unloading or settling and un-settling as the vehicles rear axles engage and dis-engage.

I'll update this post with more info. regarding the effects a locker puts on a 4x4, but it may take a few days to add anymore due to the time of year etc.

Cheers D & Merry Christmas

 

There's a lot here, but how do you eat an elephant? One bite at a time. I still contend that I’m right about how automatic lockers work, and to the extent that you say I’m incorrect you are the one that’s wrong. But to start taking bites...


Your post wasn’t harsh, and it didn’t offend me. It came across as arrogant. That was your 10th post on this forum. We don’t know you from Adam, but it read like you were telling us that your time was too valuable to actually respond at that time, and, if we were lucky, you’d find some time to set us children straight.

I’ve also been driving locker-equipped vehicles for over 20 years. I’m a mechanical engineer, I worked for General Motors for 2 years. The company I’ve worked for in the past 27 years makes non-automotive clutches. We don’t make friction disk clutches (the kind of clutch in a clutch-type limited slip) or dog clutches (the kind of clutch in lockers), but we compete against both technologies so we do work to understand out competition. I haven’t set up my own gears, but I did install the Lock-Rite in my F-150 and figured out how it works in the process, and I played around with a demonstrator model of a Detroit in a store once until I figured out how it worked. I don’t say this to try to one-up you, but if we’re establishing credentials, mine are pretty good.


The question in your second sentence above illustrates why you don’t correctly understand how lockers work. Torque doesn’t affect how they work at all. They work based on direction of movement and speed. If the ring gear is trying to go faster than a tire, the dog clutch on that side will pull that tire along with it at the same speed. But if one tire is trying to go faster than the ring gear, then the dog clutch on that side will disengage, allowing that tire to overrun the ring gear. So it’s not a question of power (enough or any) at all. It’s simply about relative speed.

I suppose you could say that effectively the locker reengaged when the torque is high enough to spin the inside tire up to the same speed as the outside tire. But that confuses the issue, because, as I said, it’s not about the torque at all. It’s about when the outside tire isn’t trying to go faster than the inside tire.

I will agree that a spool will go through some corners without NOTICEABLE scuffing. But that doesn’t mean that all diffs that go through a corner without noticeable scuffing are working like a spool. And to your question at the end of your third sentence above, yes, I deny that the inside tire is traveling faster than the outside tire when traveling through corners under load/with throttle at highway speeds with a locker. It’s going slower.

I will also agree that it’s not always obvious when an inside tire breaks loose. As you say in other places, the load that tire is carrying, the wheelbase and track width of the vehicle, whether the transmission is manual or automatic, and the road surface all are factors in how harsh or mild the event will be. But I can drive my Detroit-equipped Bronco in a full-lock turn on clean, dry asphalt, under power, and there is none of the tire scrub that would be there if it had a spool. Because the locker allows the outside tire to go faster than the inside tire.


Clutch-type limited slips have a friction clutch between the two axle shafts. Like the clutch in front of a manual transmission, they will keep both sides of the clutch going the same speed until it takes more torque than the clutch can transmit. At that point the clutch will slip, allowing the two sides to go different speeds, generating heat and wearing themselves out in the process, but still transmitting the level of torque at which it slips. Setting up a clutch-type limited slip “loose” means the maximum torque it will transmit is low (similar to pushing the clutch pedal down part way). Setting it up “tight” means it will transmit a lot of torque before it slips. Taken to the theoretical limit, if it was set up “infinitely tight” it would transmit an infinite amount of torque without slipping. That’s what a spool does, so yes, a tight limited slip starts to approach the function of a spool. Obviously you can’t set up a limited slip “infinitely tight”, but you can easily set it up tight enough that it won’t slip when turning an empty pickup on slightly slippery surfaces.

You are correct that a True-Trac (as well as a Gleason Torsen) does not have clutches, but rather works with carefully designed contact angles between gears. That’s why I usually call standard limited slips “clutch-type limited slips” and either say “gear-type limited slip” or “True-Trac” when talking about them.

As I said above, I agree that there are a lot of factors that minimize or emphasize the quirks of an automatic locker in a rear axle.

And I will again admit (as I did above) that I have very limited experience with traction-aiding diffs in front axles. So perhaps a True-Trac might not be a problem on a snowy freeway, I’m extrapolating there. But my description of why an automatic locker is dangerous in a front axle is more complete and more correct than yours. You say it’s due to the engaging and disengaging of the locker shifting the vehicle like it does with a locker in the rear. Rear lockers give torque steer because when one tire doesn’t get traction (or when the outside tire isn’t being driven because it’s overrunning in a corner) they are pushing only one side of the vehicle. It’s like how if you push forward on only one side of the handle of a grocery cart it will turn. A locker in the front axle will have this same effect, but it also has a much more significant one. Because not only is it pushing the vehicle from one side, but it’s also trying to turn the steering wheel. Think about what would happen if you jacked up both front tires, unlocked the steering wheel, and pushed forward on the back of one of the front tires. It would pivot around the balljoints, turning the other front tire and the steering wheel in the process. This is what happens when only one front tire is being driven, or even if both are being driven but not with the same torque. Going back to the jacked up front wheel experiment, if someone else was pushing forward on the other front tire the same time and with the same force you were, the forces would balance and you would not move the steering. That’s what open diffs do, deliver the same torque to both sides so it stays balanced. Lockers will deliver all of the torque to one side which gives the largest effect. But both clutch-type and gear-type limited slips can deliver more torque to one side than the other, and this will have the same effect as a locker. Again, because it’s not ALL of the torque (like a locker), it won’t be to the same extent. And again, having never tried it myself I can’t say whether the extent that it does cause that effect would be a problem or not. If you say it doesn’t cause any problems, then great for you, and it’s good that you are sharing your experience so others can make their decisions. But for me it’s not worth the risk of trying it, I can just put a selectable locker in the front and not worry about it.


I’ve already responded to everything from this post so I won’t repeat it. But to summarize here, I agree with you on much of the “what”, but little of the “why” or “how”.


Again, I generally agree with what you say in this post about how a vehicle responds with a locker. I still don’t agree with some of the “why” or “how”.


To paraphrase someone (I’ve heard this attributed to Mark Twain, but I can’t find the source), “it ain’t that he don’t know nothin’, it’s that he knows so much that ain’t so.” I think that statement applies to you, and I’m sure you believe equally strongly that it applies to me. Short of getting together in a parking lot and driving vehicles around I ’m not likely to change your mind, and you’re not likely to change mine. That OK. I’m willing to keep this exchange gong as long as it’s bringing new experiences and new arguments into the discussion. But I don’t expect that it will reach a conclusion.

 

Dialed-In, I'll be content to agree to disagree with you.

Cheers, and have a great Christmas!

Phy

 

well its kinda obvious that it can't be correct that the lockup is controlled by torque because if this was the case,then you couldn't dream of towing on the street with a LSD.the thing would eat the tires up and you'd bark around corners all the time.it would be a complete mess.it needs to let one wheel spin quicker than the other even under torque or else you could forget about turning.
it seems logical to me that if Nothing Special and Phy are incorrect about LSD operation,then why would even bother messing with LSD's.there wouldn't be any point.we would all just run lockers lol.

 

Wow,that's pretty funny. I guess you know better than the "engineers" that designed and built the Detroit Locker.

Really?

But hey,whatever., everyone's entitled to an opinion...even a wrong one.

Merry Christmas!