Outer Limits 4x4 Board

Just wondering what you thought of it?

For those who don't know what it is:

http://www.eatonperformance.com/differe ... etrac.html

In the LSD area .. it's the best IMOP .. but again IMOP don't waste money in LSD ..

Locker or nothing ..

Unlike a normal speed sensing LSD it's a torque sensing LSD. It works before slip occurs. The only issue is the 3 or 5:1 max split ratio. But brake assist or better yet traction control solves that.

I don't understand the Locker is better attitude. Why would you want to lock a diff and have one wheel dragging you back or slipping all the time. If you think about it putting the power to the wheel with the most torque is the best possible thing to do.

But I don't own one. I couldn't get one in a hurry when I smahsed my corwn wheel, so ARB's it was, fitted my an ARB agent. Predictably, they failed first decent trip out. Oh didn't I wish for my old Lokka then.

Paul

There not very strong. And major failures are common.

In the PDF at the bottom of the page it says 32 inch tyres is the max tyre size you can use.

Don't get me wrong .. If i have the chance to fit a LSD and locker device in my axles .. nice .. pretty nice.

But thinking in off road .. when you need traction ( real traction ) in a hurry the LSD don't work or at least IMOP it don't help as you want ..

In that case you must need a locker that " locks " and pull you out the hole ..

alot of rover guys use them with traction control very sucessfully but i think on a "normal" 4by with none of that fancy stuff they wouldnt be very useful. they are no better than a shimmed gq diff from what i hear

I have seen 2 break in a rover that spends 90% of its life on road with Traction Control.

me3@neuralfibre.com wrote: Why would you want to lock a diff and have one wheel dragging you back or slipping all the time. If you think about it putting the power to the wheel with the most torque is the best possible thing to do.

Why would you want to generate 150hp with your engine only to have to brake it down to 50 hp at the wheels to make the diff work? In any case, they do still drag and slip wheels when being braked to make them work. They're not telepathic or perfect. They MIGHT work with traction control for mild use but for actual offroad work they arent a patch on lockers.

me3@neuralfibre.com wrote: But I don't own one.
Paul

Once again, you have answered your own question.

They don't work they way you image they will, which is true for a lot of your theory.

My experience comes from a hummer (H1) which is the perfect environment for them- auto, so left foot braking is easy, and the portal box ratio means they are dealing with less torque and more speed, which they should respond to well.

They still break and driving a 3 tonne car up a greasy hill with your foot hard on the brake is just dumb.

That car got airlockers and never had another issue.

Steve.

Gwagensteve wrote:

me3@neuralfibre.com wrote: Why would you want to lock a diff and have one wheel dragging you back or slipping all the time. If you think about it putting the power to the wheel with the most torque is the best possible thing to do.

Why would you want to generate 150hp with your engine only to have to brake it down to 50 hp at the wheels to make the diff work? In any case, they do still drag and slip wheels when being braked to make them work. They're not telepathic or perfect. They MIGHT work with traction control for mild use but for actual offroad work they arent a patch on lockers.

me3@neuralfibre.com wrote: But I don't own one.
Paul

Once again, you have answered your own question.

They don't work they way you image they will, which is true for a lot of your theory. :roll:

My experience comes from a hummer (H1) which is the perfect environment for them- auto, so left foot braking is easy, and the portal box ratio means they are dealing with less torque and more speed, which they should respond to well.

They still break and driving a 3 tonne car up a greasy hill with your foot hard on the brake is just dumb.

That car got airlockers and never had another issue.

Steve.

I'm not saying they are better. I don't own one (but would like to).
What I am saying is that a solid locker like a spool or ARB is just dumb. It guarantees you'll be dragging one wheel or the other, taking traction away from the good wheel to drag the one on the outside of the turn. Evne a minor corretion needs some slip, thats' why they invented the differential.
The approach of "lock it solid is best" is just crude engineering. It may be simple and practical, but it's far from an optimal or ideal solution.

Paul

Yep, lockers are crude - but they work, and are predictable.

This is not true of a trutrak/torsen I only speak from experience with a car that was designed to run them as part of the design brief.

Somtimes, you just need to resist overcomplicating something.

in any case, you only drag a wheel if that wheel has lower traction.

Currently, I run a welded rear , and will be properly spooling that diff and adding an airlocker to the front. I feel that is the most dependable, most cost effective and most flexible arrangement. ofr my application.

My car is not a commuter and its a tray so I don't have to worry about the rear slipping into trees etc due to the spool, so I see no advantage in the added complexity of any sort of rear diff.

Adding TC to control an already complex diff (as you have discussed before) is just stupid - adding a complex system to control a complex diff, and if either fails you have poor performance.

In a daily driven car, I can't see a better solution than two airlockers.

Steve.

I can handle that.

I prefer mechanical over air lockers for the same reason.

Paul

me3@neuralfibre.com wrote:I'm not saying they are better. I don't own one (but would like to).

What I am saying is that a solid locker like a spool or ARB is just dumb. It guarantees you'll be dragging one wheel or the other, taking traction away from the good wheel to drag the one on the outside of the turn. Evne a minor corretion needs some slip, thats' why they invented the differential.
The approach of "lock it solid is best" is just crude engineering. It may be simple and practical, but it's far from an optimal or ideal solution.

Is it really wrong to take the surface into account in engineering though? Lockers are only useable on soft surfaces. Soft surfaces allow slip.

chimpboy wrote:

me3@neuralfibre.com wrote:I'm not saying they are better. I don't own one (but would like to).

What I am saying is that a solid locker like a spool or ARB is just dumb. It guarantees you'll be dragging one wheel or the other, taking traction away from the good wheel to drag the one on the outside of the turn. Evne a minor corretion needs some slip, thats' why they invented the differential.
The approach of "lock it solid is best" is just crude engineering. It may be simple and practical, but it's far from an optimal or ideal solution.

Is it really wrong to take the surface into account in engineering though? Lockers are only useable on soft surfaces. Soft surfaces allow slip.

Lockers do 3/10 of f-all in low traction surfaces. The ideal sitation for a locker is when there is a large differential in traction between wheels. The best example is rocks where one wheel is in the air. In sand they *can* be a detriment, as the forced wheel slip can induce a bogging action. Sam way powering out in second can be better in sand due to not overpowering the limited traction.

It's not wrong to take the surface into account, but if the surface is the same across the wheels, then as you turn, one wheel must slip.

There are plenty of comments re. using brakes as wasting power being silly. Well if it takes (arbitrary units) 10 units to make the low traction wheel slip, and the wheel with grip has 20 units available, 10 are wasted on the other wheel leaving 10 to propel the car. If that 10 is not enough to propel the car it will slip too. What happens then is the wheel with traction then slips until both are driving again with 30 units of drive, and the situation repeats. Hence the "shuffling" type motion of a locked diff. A mechanical locker simply lets the outside wheel freewheel doing no work, giving 20 units of drive. A normal diff drive both with nearly equal torque (althugh not equal power) giving 20 units of drive until the outside wheel slips. A spring based clutch pack LSD fights itself all the time, silly idea. A wedge based LSD (patrol) fights itself based on how much power is applied. A torsen based LSD gives 20 units to the high traction wheel and 10 to the low traction wheel - 30 in total.

That's why I say lockers are crude.

However gwagonsteve is right in saying they are simple and predictable.

The one thing everyone has missed in the mechanical locker discussion is their two true downsides.
1. They can be caught in transition as a weak state
2. They induce "interesting" handling as they transition from "Drive" to Driven" due to the one wheel drive behaviour. Normally chassis / axle / tyre flex hides it, but it shows up if you know what to look for. Downhill front diff is a good example as you transition from engine to wheel braking.

Paul

Actually, your missing the biggest problem with power braking to make the diffs work.

if you need any sort of momentum to get the car up the hill.

if I need 50kw at the wheels to get the car up the hill at the speed I need to carry if I am going to make the top, but I have to brake the wheels to make the diffs work and that leaves me with 30kw..... Im sitting at the bottom.

Under momentum the "dragging wheel" effect of the locker is irrelevant, and that's the thing- the dragging wheel problem isn't a problem in anything other than theory - A) if the wheel that would have dragged if it was locked isn't powered anyway, who cares - there's no net loss in traction

B) The dragging wheel helps to slow the car - a little like a cutting brake

C) with the trutrack, there is a still a dragged wheel - it's just being done by you on the brake- to make the other wheel work.

you can write thousands of words of theory Paul.... but it's just theory. I have driven the best application for those diffs ever in the H1 and they are inferior to airlockers even in that application.

Spend you money however you like, I am sure you will let us know you have made the right choice... oh, that's right.... you have an airlocker

Maybe you shoudl dig this thread when you have your trutrack and traction control setup and talk to us then.

Steve.

yeh but cant a torsen based mechanical locker drive through the first layer of gravity?

(starting to sound alot like another thread)

I had Truetracs fitted to the front and rear of my V8 4Runner years ago. I did consider the Detroit Soflocker etc but I was not keen on their possible road manners for everyday driving and in the wet etc

IMHO the Truetracs are the absolute ducks nuts LSD and having the V8 a minimum of an lsd in the rear was essential. They give great normal traction.

But they are not on par with a full locker.

Even riding the brakes etc it was still possible for one wheel to free spin. This was around the time ARB were also hinting they may do a front locker for the IFS 4Runner etc and I kept hounding them. Eventually it was released so the first swap was an ARB in the front.

Again I had given a lot of consideration to fitting a rear ARB but the big problem was in normal mode it was still an open centre and this was useless with the V8 even taking off in a normal situation let alone in the wet or gravel and I also find an lsd a lot safer etc. So I stayed with the Truetrac.

I then heard that Detroit were developing a Truetrac that could also be locked to be called the Electrac After many months and further emails it was released but its design meant it was only available for the Dana diffs and they were not going to develop one for the Toyota. Bugger, as that was what I definately needed and wanted as there is noway to beat a full locker. But it still bugged me for months and then the solution hit me .

I put a Dana44 in my 4Runner and then imported an Electrac. After a bit of work and dollars I had the ultimate setup with the trusty Truetrac LSD for normal road use and soft 4wd use etc but now it could also be fully locked.

I've had it in for sometime now and it has to be the absolute ultimate setup for my purposes .

Here's some simple old pics

http://members.iinet.net.au/~ozrunner/Dana44.html

http://members.iinet.net.au/~ozrunner/Electrac.html

Why would you ever want a locker if you had an trutrack? 400000 words of theory PROVE how much better the truetrack is

Steve.

Whoa back there fellas.......

It's just the internet!

I'm used to it. I think free exchange of information can be inflamatory, reminds me of Australian Parliment.

Paul

me3@neuralfibre.com wrote:I'm used to it. I think free exchange of information can be inflamatory, reminds me of Australian Parliment.

Paul

This is my pet Go-at. Heer name is Twenty. She has a Lokka in the rear to help her climb mountains. She's not a mountain Go-at but she could be cos she's got a lokka.

Ruffy wrote:

me3@neuralfibre.com wrote:I'm used to it. I think free exchange of information can be inflamatory, reminds me of Australian Parliment.

Paul

This is my pet Go-at. Heer name is Twenty. She has a Lokka in the rear to help her climb mountains. She's not a mountain Go-at but she could be cos she's got a lokka.

Hello, ruffy's back. She's standing funny Ruffy, you didn't make her walk funny fiddling with her differential did you mate. You can't use diff oil as lube, the RSPCA will have you. Maybe hydraulic oil would work better.

Paul

me3@neuralfibre.com wrote: Hello, ruffy's back. She's standing funny Ruffy, you didn't make her walk funny fiddling with her differential did you mate. You can't use diff oil as lube, the RSPCA will have you. Maybe hydraulic oil would work better.

Paul

I'm not back, i've always been here it's just that last time you whinged your poor little heart out to the mods they asked me politely to steer clear of you for a while to shut you up... Well 'ive done that..

As for Twenty... She's mine and i'll do what i want with her..


And i don't know much about Lokka's except to say i think that automatic lockers are for people who can't or don't want to think about when they should be using there locker.
Crude or not, air lockers work.

I'm still struggling with why I need to worry about a dragging tyre.

It's like the 1st layer of gravity thing - trying to fix a problem that doesn't exist.

I want a locker but one that doesn't actually lock both wheels together.

Steve.

I dont think you can do any better than locked diffs and strong axles.

When you have weak axles then things arnt as clear cut.

Back in the day when we all used to run toyota diffs there was a hill climb that I could do with toyota limited slips and traction control and no air locker rig could make - because they would always break CVs.

I could drive the hill 5 times in a row - and an air locker rig would break 5 times in a row. (could be exaggerating here but hopefully you get the idea).

Solid lockers are really good with strong axles.

If your axles arnt that strong (especially in the front) then maybe a limited slip will make it more capable because you can drive harder with less breakage.

Sam