Why do you need lockers front and rear?
Member
Joined: Jul 2011
Posts: 133
Likes: 0
From: Elizabethtown, KY
Year: 92 XJ (RIP)
Model: Cherokee
Engine: I-6
The more I think about it, my guess is that you had a general hypothesis in your mind, and while you are developing your final hypothesis, you are looking for information to confirm or deny your hypothesis. That being said, what are you truly hoping to derive from your questions?
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
Just to be fair to the OP. he's not saying the engine doesn't produce the torque needed to propel a vehicle. He's talking about "applied torque" via traction. Meaning that torque produced by a motor that is not transmitted into traction is useless torque or zero applied torque. I will grant you that he's not doing the best job explaining himself and sometimes he seems contradictory, but if you can wade through what might first appear nonsense you'll see that he's asking people to explain the application of torque (or power), not the generation of torque, in quantifiable terms for his sake and whoever else wants to knows sake. What can I say? I've taken the bait. Lmfao
No4X4Yet statements post #17:
"I understand the workings of a differential. ARBs video are correct but dont touch on the issue of one locker."
Not in this thread, that I can find, but the previous thread, kinda on this same subject you touched on the one locked differential idea. And if I remember correctly you were asking if 1 locker would increase torque to the unlocked differential. The answer is, all other variables being equal, yes. Hang on, hear me out.
Let's go with the "one tire on ice, one on some surface with a coefficient of friction greater than 0" scenario that has been used. Open diff: tire with least amount of traction spins, minimal load on the engine, engine has no requirement to produce an equal and opposite force (increased torque). I didn't make this up, I'm not that smart. Locked diff: Same scenario, all other variables being equal One tire on ice, and one tire on other surface, not ice, are locked. Tire on other surface, not ice, increases load on engine due to friction, or as some would call, traction. Increased load equals increased demand for torque which will in turn increase torque output of the engine up to its mechanical limitations. At this point, with a 50/50 split transfer case, the transfer case is receiving some amount of torque, and transferring that torque equally to the front and rear drive shafts. So long as the demand for torque is inside the limitations of the engine, then the locked axle with one tire not on ice will, by default increase the torque supplied throughout the system. So yes a locked rear axle will in turn increase torque to your open front differential. I have not said that you will enjoy increased traction in the front with a locker in the rear. I am saying that torque in the system is increased due to the locker, all other variables remaining the same. And that can be a big step.
"So with no grip you no torque. Its not that the tire with no grip get all the power, but that it limits the power the engine produces and it doesnt produce enough to move the tire with grip" Kinda. This just means that your open diff is working like it was designed if I am understanding your statement.
Sorry for the long post, I just wanna stir the pot.
"I understand the workings of a differential. ARBs video are correct but dont touch on the issue of one locker."
Not in this thread, that I can find, but the previous thread, kinda on this same subject you touched on the one locked differential idea. And if I remember correctly you were asking if 1 locker would increase torque to the unlocked differential. The answer is, all other variables being equal, yes. Hang on, hear me out.
Let's go with the "one tire on ice, one on some surface with a coefficient of friction greater than 0" scenario that has been used. Open diff: tire with least amount of traction spins, minimal load on the engine, engine has no requirement to produce an equal and opposite force (increased torque). I didn't make this up, I'm not that smart. Locked diff: Same scenario, all other variables being equal One tire on ice, and one tire on other surface, not ice, are locked. Tire on other surface, not ice, increases load on engine due to friction, or as some would call, traction. Increased load equals increased demand for torque which will in turn increase torque output of the engine up to its mechanical limitations. At this point, with a 50/50 split transfer case, the transfer case is receiving some amount of torque, and transferring that torque equally to the front and rear drive shafts. So long as the demand for torque is inside the limitations of the engine, then the locked axle with one tire not on ice will, by default increase the torque supplied throughout the system. So yes a locked rear axle will in turn increase torque to your open front differential. I have not said that you will enjoy increased traction in the front with a locker in the rear. I am saying that torque in the system is increased due to the locker, all other variables remaining the same. And that can be a big step.
"So with no grip you no torque. Its not that the tire with no grip get all the power, but that it limits the power the engine produces and it doesnt produce enough to move the tire with grip" Kinda. This just means that your open diff is working like it was designed if I am understanding your statement.
Sorry for the long post, I just wanna stir the pot.
So I believe this is why reving the engine can help if your stuck. Increasing the torque to both wheels and possibly enough to make enough power to overcome the friction of the stuck wheels.
Similarly, applying the brakes will require more torque to maintain the same power, Torque times wheels speed. Again more torque to the stuck wheel.
The more I think about it, my guess is that you had a general hypothesis in your mind, and while you are developing your final hypothesis, you are looking for information to confirm or deny your hypothesis. That being said, what are you truly hoping to derive from your questions?
Last edited by No4x4Yet; Mar 19, 2013 at 08:57 AM.
Seasoned Member
Joined: Oct 2010
Posts: 486
Likes: 2
From: Colorado Rocky Mountains
Year: 1999
Model: Cherokee
Engine: 4.0 I6
This is all very interesting reading. My .02? If someone wants to understand what they could do from an engineering standpoint to improve the world of lockers, I would say this: find a way to make an electronically selectable locker for the 8.25 and D30 that is super durable and simple to install (like a lunchbox) and costs under $500.
Member
Joined: Jan 2012
Posts: 170
Likes: 0
Year: 2000
Model: Cherokee
Engine: I 4.0
This is all very interesting reading. My .02? If someone wants to understand what they could do from an engineering standpoint to improve the world of lockers, I would say this: find a way to make an electronically selectable locker for the 8.25 and D30 that is super durable and simple to install (like a lunchbox) and costs under $500.
CF Veteran
Joined: Jun 2012
Posts: 1,250
Likes: 3
From: California
Year: 1989
Model: Cherokee
Engine: 4.0L
I normally try to let these topics pass by me but I'll just add this part for you to think about. You're working with a dynamic system. You cannot simply say if an axle is locked then 50% of the "power" goes to each wheel. It's a dynamic system in constant change. You probably want to take college physics 101 (mechanics) before going any further. Or at least get somebody's old book from the course rather than trying to invent your own version of physics.
On a different point. If I was going to invent something new for the offroad axle that would be to figure out how to get rid of the pumpkin right in the center. It's basically in the worst possible place. But new ideas are hard to sell since the current setup has been around for such a long time.
On a different point. If I was going to invent something new for the offroad axle that would be to figure out how to get rid of the pumpkin right in the center. It's basically in the worst possible place. But new ideas are hard to sell since the current setup has been around for such a long time.
Last edited by McCaffrey; Mar 19, 2013 at 11:04 AM.
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
Well I have a mechanical engineering degree, although I'm workin for and electrical company right now. So my engineering physics aren't that fresh but this is why I like a nice technical discussion. It's tough to remember all the formulas and their relations when your not using them much.
I think it was atomic axles that make a solid axle with cv joints so it can raise the pumpkin. There is a point where your trying to reinvent the wheel. Engineering design is alot is compromising especially for the consumer market. The extra couple inches of clearance aren't really that beneficial and only s small group will really be interested in it.
I think it was atomic axles that make a solid axle with cv joints so it can raise the pumpkin. There is a point where your trying to reinvent the wheel. Engineering design is alot is compromising especially for the consumer market. The extra couple inches of clearance aren't really that beneficial and only s small group will really be interested in it.
Member
Joined: Jan 2012
Posts: 122
Likes: 0
Year: 99
Model: Cherokee
Engine: 4.0
You don't need lockers front and rear, but are beneficial while off-road. I believe that you are over thinking the issue. It is very simple, the axle is going to do the least amount of work possible. It will not turn an axle shaft under stress, it will transfer that energy to the shaft with the least amount of friction as to not harm itself.
All the locker will do is lock either side of the shafts into one unit, making both tires turn at the same RPM. Which is why when you have a locked axle and you make a turn the tires with chirp around the corner. The differential allows the inside tire to turn at a different rate. Unless you have a selectable locker (ie ARB).
Most people will probably tell you to get a rear locker as the rear end is usually the offender in getting you hung up.
All the locker will do is lock either side of the shafts into one unit, making both tires turn at the same RPM. Which is why when you have a locked axle and you make a turn the tires with chirp around the corner. The differential allows the inside tire to turn at a different rate. Unless you have a selectable locker (ie ARB).
Most people will probably tell you to get a rear locker as the rear end is usually the offender in getting you hung up.
::Regional Moderator::
Joined: Jul 2011
Posts: 2,912
Likes: 6
From: Over here...
Year: 1986
Model: Cherokee
Engine: 2.8
By wheeling your Jeep you can build it better and become a better driver. Theory is great, but if you don't already know how your rig operates offroad, how you want it to improve offroad, and the skills to use such improvements, what's the point? Go out and wheel your Jeep. That is the best classroom for what you're trying to learn.
CF Veteran
Joined: Jun 2012
Posts: 1,250
Likes: 3
From: California
Year: 1989
Model: Cherokee
Engine: 4.0L
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
Huh?
Ive been off roading and know hoe the open diffs can suck. The jeep isnt my main toy. That title goes to my mustang, so Id rather not spend more then I need to. And there isnt a lot of off roading around here in NY so I dont get to play nearly as much as some of your guys so I want to make the most of my trips.
By wheeling your Jeep you can build it better and become a better driver. Theory is great, but if you don't already know how your rig operates offroad, how you want it to improve offroad, and the skills to use such improvements, what's the point? Go out and wheel your Jeep. That is the best classroom for what you're trying to learn.
CF Veteran
Joined: Nov 2011
Posts: 7,387
Likes: 10
From: City of Trees, CA
Year: 93 2 door
Model: Cherokee
Engine: 4.0
benefits of a locker front and rear: less tire spin, more control because you can walk over obstacles at slower speeds
needed? no way. I dont recommend a locker to anyone who isn't having trouble getting through the trails they wheel
if you're struggling and holding people up, get a front locker. that alone will pull you over a surprising amount of new obstacles
start getting stuck again, get another locker. I love running locked/locked. but only because I like the slow control that my suspension can't make up for
DO NOT use a "poor mans locker." there was a guy on here awhile back who did that, talked all sorts of **** about it, then broke his spider gears, bought a locker and we haven't heard from him since
needed? no way. I dont recommend a locker to anyone who isn't having trouble getting through the trails they wheel
if you're struggling and holding people up, get a front locker. that alone will pull you over a surprising amount of new obstacles
start getting stuck again, get another locker. I love running locked/locked. but only because I like the slow control that my suspension can't make up for
DO NOT use a "poor mans locker." there was a guy on here awhile back who did that, talked all sorts of **** about it, then broke his spider gears, bought a locker and we haven't heard from him since