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To lock or not to lock.

hwcurtice

hwcurtice

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Not really the question.

The question really is. What do you mean by locked or unlocked? Is this similar to a limited slip differential? Or closer to 'Posi-traction'?

And what is an 'open Differential'? I read that, and I envision a differential that has no cover, gears exposed, but I know that isn't right.
 
An open differential has a spider gear assembly. This allows the wheels to differentiate in a corner. (ie. one wheel can spin faster than the other) this is great for on road driving, but when off road, it delivers power to the wheel with the LEAST amount of traction. And that wheel ONLY recieves all the power.

A locked differential, allows both wheels to recieve 50% of the power each. So both wheels will spin at the same rate. Some locking units (like the detroit or "AUTO" locker) will allow the wheels to differentiate in corners by using clutches. But when you apply power, it locks together and makes both wheels spin.

Other "SELECTABLE" lockers like the ARB or OX locker, have a spider gear assembly so on road, the wheels will differentiate. But when you engage the locker, it freezes the spider gears in place and acts as a spool, (ie. both wheels locked together all the time)

A limited slip or posi has clutches. When one wheel begins to spin, it delivers power to the other wheel to gain traction to move the vehicle.
 
Open differential = whereby one tire is NOT mechanically linked to the one on the other side. Each side is individually powered by the driveshaft. The tire with the LEAST traction will do a burnout and the OTHER tire will just sit there, looking pathetic

Locked differential = whereby both tires ARE mechanically linked together. The driveshaft turns the ring & pinion and in so doing, causes both tires to turn at the exact same time

Spool = a LOCKED DIFFERENTIAL, whereby the housing itself is nothing more than the two splined shafts for the axles and a mounting for the ring gear. A simple, solid unit, primarily for drag racing. Lightweight and durable. But does not allow for turning without scrubbing (dragging) the tires during cornering

Mini Spool = replaces the guts in a Open diff, with the guts of a Spool. Less durable than a full spool because of size, but with similar characteristics.

Limited slip = typically a set of clutches PARTIALLY cause both tires to turn. When one tire slips, the clutches develop friction, thereby causing the opposit side to begin to turn. The tighter the clutches are shimmed together, the more the traction to the opposit side

Detroit locker = a mechanically locking differential, that will allow it to dis-engage for cornering - but still ALWAYS sends power to the tire that is going the SLOWEST (typically the inside tire) - and when ENGAGED - send power to BOTH tires, just like a LOCKED DIFFERENTIAL.

ARB locker = an OPEN diffenential (just like most every stock application) that uses an AIR actuated solinoid to ENGAGE and send power to BOTH tires, just like a LOCKED DIFFERENTIAL

Welded (aka LINCOLN LOCKER - named after the Lincoln welders) is when you've welded the internals of an OPEN diffenential, creating a mechanically linked axles (tires) of full LOCKER

OX locker = similar to the ARB only uses a cable to operate instead of an air line (I think, I think, I think)

Detroit Truetrac = a pretty cool design of a Limited Slip, that uses hellically cut gears instead of clutches to give good limited slip traction. The advantage is no clutches to wear out.

Eaton E-locker = similar to the ARB only uses a electic solinoid to operate instead of an air line or a cable.

Detroit Electrac = harder to find unit, that uses a Truetac set of internals, but when you engage (E-locker) the electric solinoid, then it becomes a true LOCKER. This unit is both a LIMITED SLIP and a LOCKER.

and there's probably a few other I can't think of right now.
 
Last edited:
KarlVP said:
A locked differential, allows both wheels to recieve 50% of the power each. So both wheels will spin at the same rate. Some locking units (like the detroit locker) will allow the wheels to differentiate in corners by using clutches. But when you apply power, it locks together and makes both wheels spin.
Click to expand...

There are NO clutches in a Detroit. Hence it's one of the most popular. NO Clutches means NO WEAROUT, equally greater full traction and reliability.

ANY mechanically locking differential can and occasionally will break. But the Detroit is a good as can be purchased. The ARB is a very popular option, however early designs were more prone to failure due to a 3 piece case design. Current ones are now a two piece case, and have increased reliablity of the case itself. However ARB still are a more complicated design, requiring a air supply to actuate the unit. This requires internal differential seals (of the internal air solinoid) and they have some failures there. Plus you have to have a regulated air supply to actuate the unit, and they have some additional failures there.

The ARB -v- Detroit is a little mini-feud between wheelers, with about a 50/50 result (IMHO).
 
To answer your question, for the purpose of offroading, locked means locked. Solidly locked. A limited slip does just that, slips. You don't want that.

Tony's list above is good. Remember, no slippy slip.

But the question is more complicated if you plan to drive on the road. An automatic locker, such as a Detroit or Lock Right, can be downright annoying in street driving. They clunk and clack and try to steer for you, and the shorter your wheel base, the more annoying they get. You may want to opt for a selectable, such as an ARB or E-Locker, so that it behaves just like your stock differential when disengaged.

Another consideration is that a locker, especially in your front axle, can wreck your tight turning radius on the trail, and a front locker tends to do a little steering of its own as well. Yet another reason to opt for a selectable.
 
KarlVP said:
A locked differential, allows both wheels to recieve 50% of the power each. So both wheels will spin at the same rate. Some locking units (like the detroit or "AUTO" locker) will allow the wheels to differentiate in corners by using clutches. But when you apply power, it locks together and makes both wheels spin.
Click to expand...

Not exactly true... A locker,when locked, will allow 50% of the power to each wheel if they have equal traction.
As traction is lost on one tire the power is transmitted to the other axle up to available traction. So if one tire is in the air and the other is bound up solid, it will supply all the power to the bound axle to the point it breaks it.
 
GaryTJ said:
Not exactly true... A locker,when locked, will allow 50% of the power to each wheel if they have equal traction.
As traction is lost on one tire the power is transmitted to the other axle up to available traction. So if one tire is in the air and the other is bound up solid, it will supply all the power to the bound axle to the point it breaks it.
Click to expand...

I never believed that 50% to each wheel rule, the torque is not split amongst the axles, nor wheel, torque is evenly applied as an output of the driveline. Torque is not split either from one wheel to the other, nor is it split from one axle to the other. Torque is evenly applied from the output of the engine thru the remaining drivetrain. It doesn't get split or halved. I'm not calling you out on that, I just never really understood or believed that often poor description of the distribution of power.
 
Long&Low said:
I never believed that 50% to each wheel rule, the torque is not split amongst the axles, nor wheel, torque is evenly applied as an output of the driveline. Torque is not split either from one wheel to the other, nor is it split from one axle to the other. Torque is evenly applied from the output of the engine thru the remaining drivetrain. It doesn't get split or halved. I'm not calling you out on that, I just never really understood or believed that often poor description of the distribution of power.
Click to expand...

Torque is mulitplied and divided freely throughout the drivetrain.
Torque is multiplied by any gear reduction (transmission, t-case, ring & pinion), and divided by all (non-slipping) outputs.

Without getting too technical, think about it this way - in 2wd, in a straight line, on dry pavement, with a spooled rear end, are you more likely to twist an axle shaft with both tires on the ground, or with one tire in the air? Of course the answer is with just one tractive tire. Whether you believe it or not, when both tires have equal force against them, the torque is halved between them.

And if you shift into 4wd, you've cut the realized torque at each wheel in half again.



Differentials add another variable once something starts slipping, but that's a lot more typing.
 
TreeClimber said:
There are NO clutches in a Detroit. Hence it's one of the most popular. NO Clutches means NO WEAROUT, equally greater full traction and reliability.

ANY mechanically locking differential can and occasionally will break. But the Detroit is a good as can be purchased. The ARB is a very popular option, however early designs were more prone to failure due to a 3 piece case design. Current ones are now a two piece case, and have increased reliablity of the case itself. However ARB still are a more complicated design, requiring a air supply to actuate the unit. This requires internal differential seals (of the internal air solinoid) and they have some failures there. Plus you have to have a regulated air supply to actuate the unit, and they have some additional failures there.

The ARB -v- Detroit is a little mini-feud between wheelers, with about a 50/50 result (IMHO).
Click to expand...

Early 3 piece cases are more prone to instalation error, but are not necessarily weaker cases. The 3 piece did not like being set up without the correct amount of preload. The ARB's are simple it's the guy installing it that's complicated.:hi:
 
PITYOTA said:
Early 3 piece cases are more prone to instalation error, but are not necessarily weaker cases. The 3 piece did not like being set up without the correct amount of preload. The ARB's are simple it's the guy installing it that's complicated.:hi:
Click to expand...

Oh-----How would you know :fawkdancesmiley: :fawkdancesmiley: :D
 
PITYOTA said:
Early 3 piece cases are more prone to instalation error, but are not necessarily weaker cases. The 3 piece did not like being set up without the correct amount of preload. The ARB's are simple it's the guy installing it that's complicated.:hi:
Click to expand...

Yeah, what he said. But as TechTim once told me, all diffs need proper preload. I happen to be a Detroit guy, and you veerrrryyy seldom see the case bolts fail. Yet I've seen lots of (early) ARBs fail that way. Does that mean only ARB installers are poor? Undoubtably, the same guys are installing the Detroits too. My own opinion? Tires are too big for the size axles people are using nowadays, and due to better axle metalurgy, they hold up. But that added stress now goes into the ring & pinions and the carriers themselfs. Badabing Badabooooom.


crash said:
Oh-----How would you know :fawkdancesmiley: :fawkdancesmiley: :D
Click to expand...

Our fearless leader goin' off topic in the tech area! Watch out or I'll have a mod edit you :haha: :haha: :haha:
 
To spool or not to spool

Does anyone have any experience running both a Detroit and an ARB (i.e. ran each in the front axle at some point). Could you tell the difference between the two? Is there a scenario where they would perform noticeably different?
 
dezertdog said:
Does anyone have any experience running both a Detroit and an ARB (i.e. ran each in the front axle at some point). Could you tell the difference between the two? Is there a scenario where they would perform noticeably different?
Click to expand...


Yes. The ARB could be turned off :fawkdancesmiley:
 

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