Differential Ignorance...

Looking for some input.

As I read through the posts on differentials I notice people calling parts like the Detroit Locker and Lockright "lockers" and making sure anything with a clutch pack is called a Limited Slip Differential, why?

I alway thought that whether it had dog teeth sliding across eachother (Lockright) or clutchpacks, in its purest mechanical form they were both limited slip differentials becasue they never truly locked. Now someting like a ARB Locker could be a locker becuase it literally locks the axle shaft together.

It seems to me detroit locker and lockright use these names as marketing ploys when in the end they are a truly nothing more than a limited slip differentials with a misleading name.

Dog gears lock. A detroit locks up just as tight as an ARB.

CRASH

you obviously don't understand where the term "limited slip differential" comes from.
locker doesn't allow any differentiation when the locker is in locked position, it's a spool. when detroit is locked it's a spool and there is no differentiation between wheel speeds. the difference between ARB and Detroit is in method of engagement. manual or automatic.
limited slip differential always allows some differentiation between wheels, therefore it cannot be called a locker.

dennisuello said:

you obviously don't understand where the term "limited slip differential" comes from.
locker doesn't allow any differentiation when the locker is in locked position, it's a spool. when detroit is locked it's a spool and there is no differentiation between wheel speeds. the difference between ARB and Detroit is in method of engagement. manual or automatic.
limited slip differential always allows some differentiation between wheels, therefore it cannot be called a locker.

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That's not quite correct, I don't think.

In an auto locker, when it's engaged, both wheels are going to turn at some minimum rate determined by the driveshaft. They may turn faster, and that's what leads to the ratcheting noise. Incidentally, that also allows them to work in turns.

Selectable lockers like ARBs, Ox, ElecTrac, etc. are spools when they're engaged. Most are open diffs when not engaged, the ElecTrac is the exception.

ChiXJeff said:

That's not quite correct, I don't think.

They may turn faster, and that's what leads to the ratcheting noise. Incidentally, that also allows them to work in turns.

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that's when the auto locker is disengaged, when no torque is applied to the locking mechanism. it allows it to differentiate, that's the clicking you hear when turning, the teeth of the locker ratcheting, but not quite engaging due to no forcr applied to them, but just try giving it some throttle while in turn.

What dennis said. When the "lockers" are engaged there is no differential movement between tires. Limited Slip differentials never engage. They are always capable of slipping. Limited slip diffs don't have to have clutch packs either, such as the TrueTrac.

"Lockers" are just mechanical devices that lock the axles together. Selectable lockers do it with some kind of powered (electric, air, or arm) actuator that can be manually engaged. Like Dennis said, automatic lockers lock when power is applied. Just like selectable lockers, when they disengage differential movement is possible.

Thanks you guys, from what I understand,

A limited slip differential never truly locks both axle shafts together it just allows torque proportioning so that the wheel with traction never recieves no power while the other one is free spinning.

A automatic locker acts as a spool until a torsional stress is sensed between the two axle shafts and at the point the teeth are allowed to slip past eachother.

Now heres my point,

1) An automatic locker allows for axle speed DIFFERENTIATION while the vehicle is turning.

2)An automatic locker is designed in such a way that there is LIMITED SLIPPING of the dog teeth across eachother when it disengages while the vehicle is turning.

Therefore,

1) I'm concluding an automatic locker could be called a limited slip differential and one would still be technically correct,

2)But a limited slip differential can not be called a locker because there is never a true locking of axle shafts.

Still not quite. Dog teeth don't slip, they are either engaged or disenganged. The main difference between selectable lockers and automati is that for instance the ARB is a normal open differential when it's not locked. Locked = spool.

Automatic lockers are best explained this way: Think of a bike's ratcheting mechanism on each side of the ring gear, each drives one wheel, making sure that none of the wheels can rotate slower than the ring gear, but allowing them to rotate faster. In a turn this leads to one-wheel drive, until you give enough throttle to spin the inner wheel to catch up with the outer, which then will also drive.

This is of course a simplification, real lockers work both ways, both forward and backwards, and they only allow one wheel to disengage at a time.

Ok, I think you are kinda missing one cruicial point though, you wrote......

1) An automatic locker allows for axle speed DIFFERENTIATION while the vehicle is turning.

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This is correct in the sense that when one wheel is ratcheting forward on the outside of a turn, however at this point the locker is DISENGAGED. If power (torque) was applied at the point when the ratcheting is occuring, the diff would lock and cause one of the tires to scrub some speed.

2)An automatic locker is designed in such a way that there is LIMITED SLIPPING of the dog teeth across eachother when it disengages while the vehicle is turning.

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Just because the vehicle is turning, does not mean that the locker has disengaged, if you read how you are supposed to drive a locker to make it seem transparent, it is reccomended that you coast through most turns as to keep the locker from engaging, kidna like if you turned your ARB locker off when you started a turn. Any time there is sufficient Torque applied to the pinion, the locker will engage an pretty much become a spool, even in a turn as long as you don't drop the throttle. Essentially you could mimic the actions of an auto locker with a selectable if you turn the switch on/off at the same time and under the same conditions as the auto would lock/unlock

Clear as mud right?:cheers:

Limited slip is biased by percentage, 60-40, 70-30, the tire that travels the farthest gets the most torque.
A Detroit type locker, locks, unlocks,ratchets, locks and slips one axle at a time (the one traveling the farthest in a corner), (hopefully). It biases in a right hand corner 100% to the left axle, if you gas it and the right axle matches speed with the left, the bias is 100% straight ahead, which works really well, if you want to make a quick 180 or 360 deg. turn.
Might be some holes in my reasoning, but I can tell you from experiance, the 360 deg. turn thing is gospel. There is a traffic circle near me, driven it a thousand times, dive in, accelerate, dive out (don´t accelerate) accelerate when the Jeep is straight again (a lot safer). Loading up one axle, then quickly loading up the other and accelerating, can turn you in a circle, on a wet street, about 90% sideways on a dry street. You know for a fact your locker is working well, lock, unlock,ratchet, lock.

I like a spool because it gives 100% torque bias to both of the tires all the time. It's a limited slip because it limits the slip to whichever tire gives up traction first. If both tires check out and I stay on the gas, it's an unlimited slip.

ChiXJeff said:

Selectable lockers like ARBs, Ox, ElecTrac, etc. are spools when they're engaged. Most are open diffs when not engaged, the ElecTrac is the exception.

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Now, to correct the correction, the ElecTrac is basically a TrueTrac with a solenoid. I don't think it's as tight as a spool even when engaged. However, you are correct that it defaults to acting as a limited slip when not engaged.

Hmm... I run a Powertrax No-Slip, and it's really smooth, it never clicks, bangs or give me any hints of it being there, except it works. I can give it full throttle in a turn, nothing scary happens, except the acceleration that is, and maybe I get a little wide, but no 360 turns. I also like to go sideways around roundabouts, works smooth as... smooth. It actually feels like the car is less willing to spin (i.e. do a 180) now than before, when I ran a traclok without the lsd additive (lasted a week..), which means I need more power to get the rear out in a turn, which makes it more predictable and needs more provoking.

Off road, it works like a charm... I dare to say it's the ultimate thing off road, because with a spool (or locked ARB or similar) the wheels will resist turnin.