posi axle question
Lead Driver
Joined: Feb 2013
Posts: 5,006
Likes: 72
From: Roseville, MN
If you want to try to prove me wrong (assuming you have a vehicle with a Detroit), safely support one back tire in the air and, with the trans in neutral, safely apply torque to the driveshaft. Twist it in the forward direction (CW as looking from the front). You won't be able to turn it of course because it will be trying to turn the tire that's on the ground. But while you are doing that, have someone try to spin the tire that's in the air in the forward direction. If you're right they won't be able to turn it because applying torque to it should lock it up like a spool. But I bet what you'll find is that it turns pretty easily while you still can't turn the driveshaft.
Lead Driver
Joined: Feb 2013
Posts: 5,006
Likes: 72
From: Roseville, MN
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."
"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."
And to be fair to Sales people, the Detroit literature that Briansshop quoted isn't WRONG, it's just not right. Detroit lockers do function essentially like a spool in that they positively drive both tires, and they do permit a differentiation variance in wheel speed in corners. It's just the technical "how" isn't correct.
Fleet Owner
Joined: Jul 2006
Posts: 20,347
Likes: 803
From: Mi'kma'ki
"When torque is not being applied, the Detroit Locker is allowed to unlock, permitting a differentiation variance in wheel speed while negotiating turns."
well it doesn't make any sense right? if it did this,then you would need to coast around your turns.no accelerating up around hilly roads for you.
because if the above could be said,then this also could be said;
When torque is being applied, the Detroit Locker is not allowed to unlock, thus not permitting a differentiation variance in wheel speed while negotiating turns.
well it doesn't make any sense right? if it did this,then you would need to coast around your turns.no accelerating up around hilly roads for you.
because if the above could be said,then this also could be said;
When torque is being applied, the Detroit Locker is not allowed to unlock, thus not permitting a differentiation variance in wheel speed while negotiating turns.
Lead Driver
Joined: Feb 2013
Posts: 5,006
Likes: 72
From: Roseville, MN
They do function the same in forward and reverse. Also whether driving or compression braking (which is really important when crawling down a steep, rocky hill in 4-low).
And although the hardware is different, the Lock-Rite does the exact same thing. I don't know 100%, but I'm thinking that pretty much all of the automatic lockers (including all of the "lunchbox" lockers) do too.
Cargo Master
Joined: Nov 2013
Posts: 2,168
Likes: 3
From: South Central,MO
If you want to try to prove me wrong (assuming you have a vehicle with a Detroit), safely support one back tire in the air and, with the trans in neutral, safely apply torque to the driveshaft. Twist it in the forward direction (CW as looking from the front). You won't be able to turn it of course because it will be trying to turn the tire that's on the ground. But while you are doing that, have someone try to spin the tire that's in the air in the forward direction. If you're right they won't be able to turn it because applying torque to it should lock it up like a spool. But I bet what you'll find is that it turns pretty easily while you still can't turn the driveshaft.
Posting Guru
Joined: Aug 2007
Posts: 1,852
Likes: 1
From: Sonoita Hills, AZ
"When torque is not being applied, the Detroit Locker is allowed to unlock, permitting a differentiation variance in wheel speed while negotiating turns."
well it doesn't make any sense right? if it did this,then you would need to coast around your turns.no accelerating up around hilly roads for you.
because if the above could be said,then this also could be said;
When torque is being applied, the Detroit Locker is not allowed to unlock, thus not permitting a differentiation variance in wheel speed while negotiating turns.
well it doesn't make any sense right? if it did this,then you would need to coast around your turns.no accelerating up around hilly roads for you.
because if the above could be said,then this also could be said;
When torque is being applied, the Detroit Locker is not allowed to unlock, thus not permitting a differentiation variance in wheel speed while negotiating turns.
Lead Driver
Joined: Feb 2013
Posts: 5,006
Likes: 72
From: Roseville, MN
That's not how it worked in your Jeep because that's not how Detroits work. They can certainly be harder on tires because they are usually putting the torque to one tire (open diffs always put equal torque to both tires). That makes it harder to start without spinning the inside tire. But when you do spin it, it's because you put too much torque to it, not because it's locked to the outside tire.
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Lead Driver
Joined: Feb 2013
Posts: 5,006
Likes: 72
From: Roseville, MN
OK, I finally bothered to look up what the manufacturer says about Detroit lockers. I don't know where Briansshop got his quote, but what I found is completely different, but says exactly what Phy and I have been saying. If you want to look it up yourself, here's the link: Detroit Locker
but if you want to just read it, it says:
edit: By the way, the "or slower" applies to compression braking. When compression braking around a curve a Detroit will not allow either tire to go faster than the ring gear, but will unlock to allow the inside tire to go slower.
but if you want to just read it, it says:
Detroit Locker
The Detroit Locker is a 100%-automatic locking differential that provides ultimate traction for mild to extreme vehicle applications. Its unique, bullet-proof design is engineered to keep both wheels in drive mode - even is one wheel is lifted off the ground.
Operation
During straight-line driving, the Detroit Locker captures 100% of available torque and sends it equally to both wheels. In turns and maneuvers, the internal components unlock to allow one wheel to spin faster or slower as necessary (free wheel). When the vehicle returns to a straight-line driving path, the components re-engage and provide power to both wheel ends.
Detroit lockers do not lock under power. They always "allow one wheel to spin faster or slower as necessary (free wheel)".The Detroit Locker is a 100%-automatic locking differential that provides ultimate traction for mild to extreme vehicle applications. Its unique, bullet-proof design is engineered to keep both wheels in drive mode - even is one wheel is lifted off the ground.
Operation
During straight-line driving, the Detroit Locker captures 100% of available torque and sends it equally to both wheels. In turns and maneuvers, the internal components unlock to allow one wheel to spin faster or slower as necessary (free wheel). When the vehicle returns to a straight-line driving path, the components re-engage and provide power to both wheel ends.
edit: By the way, the "or slower" applies to compression braking. When compression braking around a curve a Detroit will not allow either tire to go faster than the ring gear, but will unlock to allow the inside tire to go slower.
Posting Guru
Joined: Aug 2007
Posts: 1,852
Likes: 1
From: Sonoita Hills, AZ
Mine was apparently defective. Because both my tires would lock(when turning and under load) and the inside would spin, chirp and slip causing premature tire wear. It didn't just do it once, it did it for 30,00 miles.
Fleet Mechanic
Joined: Aug 2005
Posts: 1,277
Likes: 89
From: MD
OK, I finally bothered to look up what the manufacturer says about Detroit lockers. I don't know where Briansshop got his quote, but what I found is completely different, but says exactly what Phy and I have been saying. If you want to look it up yourself, here's the link: Detroit Locker
but if you want to just read it, it says:
edit: By the way, the "or slower" applies to compression braking. When compression braking around a curve a Detroit will not allow either tire to go faster than the ring gear, but will unlock to allow the inside tire to go slower.
but if you want to just read it, it says:
Detroit Locker
The Detroit Locker is a 100%-automatic locking differential that provides ultimate traction for mild to extreme vehicle applications. Its unique, bullet-proof design is engineered to keep both wheels in drive mode - even is one wheel is lifted off the ground.
Operation
During straight-line driving, the Detroit Locker captures 100% of available torque and sends it equally to both wheels. In turns and maneuvers, the internal components unlock to allow one wheel to spin faster or slower as necessary (free wheel). When the vehicle returns to a straight-line driving path, the components re-engage and provide power to both wheel ends.
Detroit lockers do not lock under power. They always "allow one wheel to spin faster or slower as necessary (free wheel)".The Detroit Locker is a 100%-automatic locking differential that provides ultimate traction for mild to extreme vehicle applications. Its unique, bullet-proof design is engineered to keep both wheels in drive mode - even is one wheel is lifted off the ground.
Operation
During straight-line driving, the Detroit Locker captures 100% of available torque and sends it equally to both wheels. In turns and maneuvers, the internal components unlock to allow one wheel to spin faster or slower as necessary (free wheel). When the vehicle returns to a straight-line driving path, the components re-engage and provide power to both wheel ends.
edit: By the way, the "or slower" applies to compression braking. When compression braking around a curve a Detroit will not allow either tire to go faster than the ring gear, but will unlock to allow the inside tire to go slower.
I'll add that my F350 has a Detroit in it and it drives like rugermack says his does. Bucks,barks the inside tire anytime I'm on the throttle in a turn.
Posting Guru
Joined: Aug 2007
Posts: 1,852
Likes: 1
From: Sonoita Hills, AZ
Detroit has a trouble shooting guide, explains why it would do it. I guess I should have looked into it. After looking at the trouble shooting guide, I might go after the bent housing, I trussed it, but it may have been bent before I did it. No way to tell now, my son got rear ended in it by a texter, and it was totaled.
Brian, I would read the trouble shooting guide before it eats up your tires. Tires are expensive.
Brian, I would read the trouble shooting guide before it eats up your tires. Tires are expensive.
Lead Driver
Joined: Feb 2013
Posts: 5,006
Likes: 72
From: Roseville, MN
My Jeep, F-150 and Bronco all did / do the same thing. But it's NOT because the Detroit locks under power, it's because you are putting all of the torque to the inside tire. Especially in a pickup where the rear axle doesn't have a lot of weight on it, and even more so in a heavy pickup like an F-350, the inside tire (that is carrying less weight than the outside tire due to weight transfer in a corner) can't drive the truck forward. That's why I always say that I do not recommend an automatic locker in a truck that will be used for towing. And, as much as I like(d) the lockers in all of my vehicles, I'll never put one in a 3/4 or 1 ton truck (unless I'm building it to be an off-road vehicle).