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How does limited slip work? Clutch packs inside the differential create additional resistance. This resistance is always present. It is called preload. So, whenever one side wants to start rotating faster than the other, this resistance (preload), in addition to the traction present at the wheel has to be overcome before a tire can spin. Traction and preload have to be high enough to keep tires from spinning but low enough to still allow tires to rotate at different speeds in a turn. Since the preload has to be kept low enough to allow safe cornering the slowing effect on wheels that want to spin is marginal. It works in easy off-road conditions and on mildly slippery roads. For serious off-road use and very slippery roads (snow, ice) limited slip is not powerful enough. It limits slip but it does not prevent it completely So I believe that a typical factory installed limited slip is in fact different to a Detroit Locker/ Lockright The Detroit Locker and the Lockright are perhaps better thought of as automatic locking diff's in that they lock and unlock without driver imput. If that is correct, I suspect that in icy road condition, they may behave differently to true limited slip diffs as you've described?
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An open diff rear is not one wheel drive. Its either two wheel drive or zero wheel drive. If you have traction both tires put equal power to the ground. If you break one free neither tire puts power to the ground so its zero wheel drive
Sorry, but you're incorrect. Get stuck with an open dif and see how may tires turn. I guarantee you it won't be two or zero. Or ... Do a burn out with an open dif and see many tracks it leaves. No, you are incorrect again. I am well aware that in an open differential when one tire loses traction it spins, and you dont go anywhere. You are confusing yourself by seeing that one tire spin. One tire spinning with no traction does not equal power to the ground and does not equal one wheel drive. An open differential applies essentially equal power to the ground through both tires. Either both tires apply power to the ground or neither do. If one tire spins due to loss of traction, neither tire is putting power to the ground and that equals zero drive.
Sean
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Well ... We'll just have to agree to disagree. Although, I'm still trying to wrap my head around zero wheel drive during a one wheel burn out that somehow makes the car go forward. Is that half wheel drive? I'm confused.
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Lockers definitely behave differently but nothing one can't get use to. You control the locking and unlocking of the automatic lockers with the throttle. For instance if you let off the throttle when going into and thru a turn the rear unlocks and stays unlocked until you rethrottle. Or making a turn say from a side street you'd not use alot of throttle thereby limiting the amount torque to the axles. Sounds more complicated than it is. Honestly I'd be completely satisfied with an aftermarket limited slip but cost is a factor. If it wasn't I might as well go with one of the better automatic lockers or better yet an on-command locker. All three types require the disassembly of the carrier requiring the ring and pinion gears to be set up again. More than likely I'll try one of the so called "lunchbox lockers" that in most cases don't require carrier removal so I can install myself. http://www.cherokeeforum.com/f51/how-install-lunchbox-locker-lots-pics-67601/
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With an open differential, both tires put the same (or essentially the same) power to the ground in all scenarios. The tire with the least traction is the limiting factor.
So if one tire is spinning and one is not and the rig is inching forward, both are acutally putting a small amount of power (essentially equal) to the ground.
If you think about it, its pretty easy to understand. If one wheel is completly off the ground, neither tire moves the rig forward. If one wheel has only a tiny bit of traction like during a burnout, both tires aplly power the ground to move the rig foward, the amount of power put to the ground is limited by the traction of the tire thats spinning since it has the least traction (and on an open diff its usually on the side with less vertical force due to the rotation of the driveline and weight distribution). Increase the traction and increase the power to the ground.
Sean
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Yep. All the rotational energy goes to the side with the least resistance. Hence your one wheel burn out.
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Guns don't kill people, drivers with cell phones kill people.
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+1 So simple even a caveman can understand it.
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Lockers definitely behave differently but nothing one can't get use to. You control the locking and unlocking of the automatic lockers with the throttle. For instance if you let off the throttle when going into and thru a turn the rear unlocks and stays unlocked until you rethrottle. Or making a turn say from a side street you'd not use alot of throttle thereby limiting the amount torque to the axles. Sounds more complicated than it is. Honestly I'd be completely satisfied with an aftermarket limited slip but cost is a factor. If it wasn't I might as well go with one of the better automatic lockers or better yet an on-command locker. All three types require the disassembly of the carrier requiring the ring and pinion gears to be set up again. More than likely I'll try one of the so called "lunchbox lockers" that in most cases don't require carrier removal so I can install myself. http://www.cherokeeforum.com/f51/how-install-lunchbox-locker-lots-pics-67601/ I appreciate what your saying and all I was try to get to is that on this thread three different types of diff are being referred to: 1) Limited Slip 2) Automatic locker 3) Driver selectable locker.. I think some folks were equating a limited slip diff to an automatic locker..they are not the same hence may behave differently on an icy road.... I've not come across the lunch box style before; certainly seems to be an easier installation.. regards, Peter
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Yep. All the rotational energy goes to the side with the least resistance. Hence your one wheel burn out. Thats my understanding also.. You guys ever come across fiddle brakes? I've never had a 4x4 that used them, but they seemed to be popular on "competition" 4x4 rigs at one point functioning almost like a "poor mans locker".. As I understand it, they were essential a hand brake on each half shaft so any wheel that was loosing traction could be manually braked (locked) to send the power to the other... Regards, Peter
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"I think some folks were equating a limited slip diff to an automatic locker.." Yea,I believe your right.
As far as the "lunch box" lockers go their less expensive but not as strong. One nice thing is if you don't like it you just replace your spider gears.
I've never heard of fiddle brakes but I can appreciate the concept. I know that if your in a situation where you've completely lost traction with your open rear you can gently apply the brakes to HOPEFULLY get more torque applied to the wheel that's not spinning. Kind of a last resort before getting down and dirty.
Last edited by EZEARL; 01/15/13.
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most farm tractors have a brake for each rear wheel. but they also have a diff lock pedal, so no need to use brakes for traction.
Guns don't kill people, drivers with cell phones kill people.
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Basically the same as your tracked equipment.
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Purely from a performance perspective, I wonder how people rate electronic traction control compared to a limited slip diff?
Its sad to say that factory fitted diff locks of any description are *almost* a thing of the past on modern 4x4's and it is seemingly being replaced by electronic traction control.
I have ridden in a friends Discovery so equipped over what I would term moderate off road conditions, and I was actually very impressed with it, although I have yet to see how it performs in serious mud or sand...
Last edited by Pete E; 01/15/13.
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An open diff rear is not one wheel drive. Its either two wheel drive or zero wheel drive. If you have traction both tires put equal power to the ground. If you break one free neither tire puts power to the ground so its zero wheel drive
Sorry, but you're incorrect. Get stuck with an open dif and see how may tires turn. I guarantee you it won't be two or zero. Or ... Do a burn out with an open dif and see many tracks it leaves. No, you are incorrect again. I am well aware that in an open differential when one tire loses traction it spins, and you dont go anywhere. You are confusing yourself by seeing that one tire spin. One tire spinning with no traction does not equal power to the ground and does not equal one wheel drive. An open differential applies essentially equal power to the ground through both tires. Either both tires apply power to the ground or neither do. If one tire spins due to loss of traction, neither tire is putting power to the ground and that equals zero drive. I agree with this. In a burnout with an open dif, 1 wheel is spinning - no traction, and the other is doing nothing - no traction because it isn't turning. The same thing happens on ice, just a lot easier. If one wheel spins, the other doesn't take over. It doesn't do anything. If one wheel with a LS dif spins, the other DOES take over.
“In a time of deceit telling the truth is a revolutionary act.” ― George Orwell
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Its sad to say that factory fitted diff locks of any description are *almost* a thing of the past on modern 4x4's and it is seemingly being replaced by electronic traction control.. Most Chevy 4x4's come factory equipped with the Eaton locking rear diff. Look for G80 on the options list in the glove box or window sticker. It IS a locker, according to Eaton.
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Purely from a performance perspective, I wonder how people rate electronic traction control compared to a limited slip diff? Depends on whose traction control you are talking about. Mercedes traction control is pretty impressive for on highway use. It cuts power and even will apply the breaks if you pitch the car sideways. I find it a bit annoying as I like the occasional drift. Or as my 16 y/o son says, it's no fun.
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Used to be pretty common with dune buggy type vehicles based on the VW platform to have two hand brake levers. The OEM was a single handbrake lever between the seats pulling wires on both left and right rear wheels so add a second lever and have each lever pullings wires on one side only. Mostly after the success of the VW platform I think the same setup was used a lot in other vehicles but a step on the parking brake setup is harder to modify.
To repeat myself - folks are indeed talking past each other a little bit -- my own experience has been that I never wished I had open differentials, I've been happy with some more sophisticated devices and even with a clutch type posi in front as well as rear I've found clutch type posi to be better on the highway. For a truck full of wet garbage a Detroit Locker has many advantages.
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The factor chevy "government" limited slip is not as good as a trutrac.
Leave the lunchbox lockers alone for road use. I had one break and thats the last time that will happen to me and they really suck on a short wheelbase vehicle.
I guess my question is how fast you plan on driving?
Last edited by JohnnyLoco; 01/15/13.
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I was wondering how you were liking that outfit Wyo.
Overall you dig? I love it when I kill it I will buy another, I drive around 100 miles a day in it and never had a problem, I pushed down an un-plowed road with about 18 in of snow today and never spun a tire. I'm getting about 40 MPG this winter, I did pull a 51 MPG tank this summer.
�The constitution of the United States asserts that all power is inherent in the people, that they may exercise it by themselves, that it is their right and duty to be at all times armed!� � Thomas Jefferson
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