Outer Limits 4x4 Board

steven101 wrote:

midi73 wrote:

blkmav wrote:

me3@neuralfibre.com wrote:Q. When one front wheel is in the air spinning freely, and the other is getting no power, how much weight is on the opposite rear that is supposed to push you forward and have traction?
A. Next to none. If one front is in the air, the opposite rear has next to no weight on it.

This is why you need it in the front

No, this is why you need it in the back. All the weight of the car is transfered over the back wheels, therefore giving far better traction, than being in the front trying to drag the back up with one wheel still spining. If it is in the back, it doesnt matter if the front wheel still spins.

If theres so much weight and traction on the rear wheels you dont need the locker, you need it on the front where you have just lost 50% of the power

Agreed

midi73 wrote:

blkmav wrote:

me3@neuralfibre.com wrote:Q. When one front wheel is in the air spinning freely, and the other is getting no power, how much weight is on the opposite rear that is supposed to push you forward and have traction?
A. Next to none. If one front is in the air, the opposite rear has next to no weight on it.

This is why you need it in the front

No, this is why you need it in the back. All the weight of the car is transfered over the back wheels, therefore giving far better traction, than being in the front trying to drag the back up with one wheel still spining. If it is in the back, it doesnt matter if the front wheel still spins.

Not true. With open diffs, then across an axle, the maximum torque delivered to the wheel with the most traction is the same as can be delivered to the wheel with the least traction.
eg. If the car weighs 3000kg and is climbing a steep rutted hill the rear has one wheel with weight (1900KG) and one wheel just touching (100KG) then there is a maximum equivalent of 200KG (2x100KG) traction avaialble at the rear wheels. With a locker this increases to 2000KG (1900 + 100). (count the zero's)

As there is only 1000KG weight on the front wheels due to the hill, with one in the air, this is split to 1000KG one side and 0KG the other giving a maximum equivalent of 0KG traction (0+0=0) with open diffs. With a front locker this increases to 1000KG.

2000KG beats 1000KG in terms of putting power down.

Remember, across an open diff, the BEST you get is 2x the WORST wheel's traction.

Please note, the weight numbers used here are for comparitive purposes. I haven't tried to convert them to real forces with coefficient of friction, interference bahaviours, torque splits etc. It is simply comparitive between wheels, but the effect is equivalent.

There is traction on ONE rear wheel. The trick is getting enough torque there to do something useful. This is what a locker does. They don't aid traction, they allow a diff to deliver more torque to one wheel.

Paul

me3@neuralfibre.com wrote:

midi73 wrote:

blkmav wrote:

me3@neuralfibre.com wrote:Q. When one front wheel is in the air spinning freely, and the other is getting no power, how much weight is on the opposite rear that is supposed to push you forward and have traction?
A. Next to none. If one front is in the air, the opposite rear has next to no weight on it.

This is why you need it in the front

No, this is why you need it in the back. All the weight of the car is transfered over the back wheels, therefore giving far better traction, than being in the front trying to drag the back up with one wheel still spining. If it is in the back, it doesnt matter if the front wheel still spins.

Not true. With open diffs, then across an axle, the maximum torque delivered to the wheel with the most traction is the same as can be delivered to the wheel with the least traction.
eg. If the car weighs 3000kg and is climbing a steep rutted hill the rear has one wheel with weight (1900KG) and one wheel just touching (100KG) then there is a maximum equivalent of 200KG (2x100KG) traction avaialble at the rear wheels. With a locker this increases to 2000KG (1900 + 100). (count the zero's)

As there is only 1000KG weight on the front wheels due to the hill, with one in the air, this is split to 1000KG one side and 0KG the other giving a maximum equivalent of 0KG traction (0+0=0) with open diffs. With a front locker this increases to 1000KG.

2000KG beats 1000KG in terms of putting power down.

Remember, across an open diff, the BEST you get is 2x the WORST wheel's traction.

Please note, the weight numbers used here are for comparitive purposes. I haven't tried to convert them to real forces with coefficient of friction, interference bahaviours, torque splits etc. It is simply comparitive between wheels, but the effect is equivalent.

There is traction on ONE rear wheel. The trick is getting enough torque there to do something useful. This is what a locker does. They don't aid traction, they allow a diff to deliver more torque to one wheel.

Paul

Sometimes all the theory in the world doesn't mean squat, the fron make a huge difference on hill climbs, as others have stated, the rears tend to be on the ground...............all works in reality

cloughy wrote:

me3@neuralfibre.com wrote:

midi73 wrote:

blkmav wrote:

me3@neuralfibre.com wrote:Q. When one front wheel is in the air spinning freely, and the other is getting no power, how much weight is on the opposite rear that is supposed to push you forward and have traction?
A. Next to none. If one front is in the air, the opposite rear has next to no weight on it.

This is why you need it in the front

No, this is why you need it in the back. All the weight of the car is transfered over the back wheels, therefore giving far better traction, than being in the front trying to drag the back up with one wheel still spining. If it is in the back, it doesnt matter if the front wheel still spins.

Not true. With open diffs, then across an axle, the maximum torque delivered to the wheel with the most traction is the same as can be delivered to the wheel with the least traction.
eg. If the car weighs 3000kg and is climbing a steep rutted hill the rear has one wheel with weight (1900KG) and one wheel just touching (100KG) then there is a maximum equivalent of 200KG (2x100KG) traction avaialble at the rear wheels. With a locker this increases to 2000KG (1900 + 100). (count the zero's)

As there is only 1000KG weight on the front wheels due to the hill, with one in the air, this is split to 1000KG one side and 0KG the other giving a maximum equivalent of 0KG traction (0+0=0) with open diffs. With a front locker this increases to 1000KG.

2000KG beats 1000KG in terms of putting power down.

Remember, across an open diff, the BEST you get is 2x the WORST wheel's traction.

Please note, the weight numbers used here are for comparitive purposes. I haven't tried to convert them to real forces with coefficient of friction, interference bahaviours, torque splits etc. It is simply comparitive between wheels, but the effect is equivalent.

There is traction on ONE rear wheel. The trick is getting enough torque there to do something useful. This is what a locker does. They don't aid traction, they allow a diff to deliver more torque to one wheel.

Paul

Sometimes all the theory in the world doesn't mean squat, the fron make a huge difference on hill climbs, as others have stated, the rears tend to be on the ground...............all works in reality

Agreed 100% theory is one thing imo practice is completely different. As always best answer is to do both

steven101 wrote:

midi73 wrote:

blkmav wrote:

me3@neuralfibre.com wrote:Q. When one front wheel is in the air spinning freely, and the other is getting no power, how much weight is on the opposite rear that is supposed to push you forward and have traction?
A. Next to none. If one front is in the air, the opposite rear has next to no weight on it.

This is why you need it in the front

No, this is why you need it in the back. All the weight of the car is transfered over the back wheels, therefore giving far better traction, than being in the front trying to drag the back up with one wheel still spining. If it is in the back, it doesnt matter if the front wheel still spins.

If theres so much weight and traction on the rear wheels you dont need the locker, you need it on the front where you have just lost 50% of the power

No, you usually need lockers for rutted hills. I find generally that both front wheels are very light on, one not touching at all because all the weight is transfered to the back. But in the back one wheel is compressed up in the guard the other is hanging, dropped into the rut. most of your weight and traction is in that one compressed back wheel, so a rear locker gives drive to that back wheel.
The reason that a rear locker causes the front to kick up more is because you are now able to drive into that rut that before the locker, you would have just had wheelspin and stopped. You just have to be aware of this and drive accordingly.

Look, sorry if this is ranty but here goes.
I hear this "theory means jack" thing a lot.

THEORY cannot be completely different to practise. Theory is there to explain operation in practice. They can never be contradictory or the theory is wrong.

Heat rises, and theory proves it. If the theory indicated that heat sunk but in practice it rose, then the theory is flawed.

Sorry that's the semantics of it.

Wht you mean is that "whilst the theory indicates XXX I have found that in practise the effect of YYY is greater than the theory would indicate.

Paul's explanation is 100% correct, it is EXACTLY what happens in practice regardless of what car you drive or what locker you have or what terrain you are on.

It also explains why a car on a slick muddy hill gets very little advantage from lockers- NO wheels have sufficient traction.

I agree there is no substitute for twin lockers, but in steep country where the front is lightly loaded, a front locker can deliver less ultimate traction because there is less weight on the front end. End of story.

If that is enough traction to do the job you need, then great, but the facts are a front locker delivers less traction.

I do agree that a front locker only will help to keep the front down, but whilst it might do this, it still might not permit enough traction to drive the obstacle.

Steve.

Same hill same spot all V8s the runners are rear locked the Lux front.







The fact remains that the front wheels not losing traction and maintaining a constant speed, stop the front wheel kicking into the air. The rear locked with all the traction to the rear bog down and spit skyward.

Gwagensteve wrote: It also explains why a car on a slick muddy hill gets very little advantage from lockers- NO wheels have sufficient traction.



Steve.

Or the fact, that sometimes, 2 wheels spinning at twice the speed for the same given gear ratio and engine RPM than 4 spinning at half the speed may get you to the top Alot more variables in it, you over simplifying now

Man, its like dealing with engineers here, all theory

The really complicated theory is the effect on the wheel loading of the car when the added drive force of a front locker only pulles the front end down.

As an exmple on a radius arm equipped car, that drive force will compress the bushes (and actually compress the front suspension and help to make the front suspension work.

I don't doubt this is real and makes the car feel better, I just don't think it adds as much capability as some of the proponents of front lockers only believe.

Ive had a front only locked car, the only advantage I could see was that you could steer the front wheels to grab traction, sometimes keeping you pointing you straight, or not

The wheel lifting comparison I dont agree with, for a start the 4 runners are IFS front and coil rear, a lot less roll stiffness in the rear, so of corse they are going to pick up, also both seem to have their front right wheels jammed into the rut more than the lux forcing them to pick up more.

Also the lux is leaf rear This would add more roll stiffness to the rear, aiding in keeping the front down.

More to do with suspension than people think.

Mock

weld the front

lock the rear.

but only after you have installed something like what i just thought of.

Would be quite easy for someone good with electronics.

a little gadget that attaches to freewheeling hub. It would have a small battery,servo and radio for auto actuation from in vehicle.
take it off when you get back on road and flick them on charge just like a mobile phone.

This would allow welded or spooled front diffs.

you only need one side, but both sides and it would be pretty useful.
probably very cheap to make, cost 50-100 a side.

Jes

ljxtreem wrote: More to do with suspension than people think.

Mock

the most important part in any car

personally id go locker front weld rear they arent that bad on the road just need to learn to drive with one, and with a car set up like yours i doubt it see's the road much.

Here we go again!!!!!



In my experience with only having a rear for some years i'd say Rear only will be used alot more often but not help as much. Front only get used a lot less but when needed usually aids you more than the rear. Rock crawling i'd say front.

Cheers Dan

Ruffy wrote: Here we go again!!!!!



In my experience with only having a rear for some years i'd say Rear only will be used alot more often but not help as much. Front only get used a lot less but when needed usually aids you more than the rear. Rock crawling i'd say front.

Cheers Dan

Agreed. Rock crawling - front. General use - rear.

I'm locked front and rear and most of the time I run most everything with just the rear locked. When I get into some tough rock crawling I lock both.

Ruffy wrote: Here we go again!!!!!



In my experience with only having a rear for some years i'd say Rear only will be used alot more often but not help as much. Front only get used a lot less but when needed usually aids you more than the rear. Rock crawling i'd say front.

Cheers Dan

cloughy wrote:

Ruffy wrote: Here we go again!!!!!



In my experience with only having a rear for some years i'd say Rear only will be used alot more often but not help as much. Front only get used a lot less but when needed usually aids you more than the rear. Rock crawling i'd say front.

Cheers Dan

Have either of you guys been rock crawling? Both ends on rocks.

I feel this is an appropriate time for an old favourite ...

sierrajim wrote:

cloughy wrote:

Ruffy wrote: Here we go again!!!!!



In my experience with only having a rear for some years i'd say Rear only will be used alot more often but not help as much. Front only get used a lot less but when needed usually aids you more than the rear. Rock crawling i'd say front.

Cheers Dan

Have either of you guys been rock crawling? Both ends on rocks.

your a shit stirrer

Mock

Theres no way i'm welding the front. My mate did that and his is a bugger to steer.

Is there anyone in the sydney area with a welded diff sierra that could give me a demo on how it would feel?

jessie928 wrote:weld the front

lock the rear.

but only after you have installed something like what i just thought of.

Would be quite easy for someone good with electronics.

a little gadget that attaches to freewheeling hub. It would have a small battery,servo and radio for auto actuation from in vehicle.
take it off when you get back on road and flick them on charge just like a mobile phone.

This would allow welded or spooled front diffs.

you only need one side, but both sides and it would be pretty useful.
probably very cheap to make, cost 50-100 a side.

Jes

Hey you stole my idea...

i think this would be the goods, as you could lock and unlock front wheels seperatly, prob be hard on the cv's though..

the only thing that stopped me was that the hubs need to rotate by nearly 180deg to lock, i dont see how this could be achieved with a ram..

some kind of worm drive servo would be the go.. anybody have any ideas?

i can,
but im about to leave for the snow and wont be back till next week.

90Mav wrote:

jessie928 wrote:weld the front

lock the rear.

but only after you have installed something like what i just thought of.

Would be quite easy for someone good with electronics.

a little gadget that attaches to freewheeling hub. It would have a small battery,servo and radio for auto actuation from in vehicle.
take it off when you get back on road and flick them on charge just like a mobile phone.

This would allow welded or spooled front diffs.

you only need one side, but both sides and it would be pretty useful.
probably very cheap to make, cost 50-100 a side.

Jes

Hey you stole my idea...

i think this would be the goods, as you could lock and unlock front wheels seperatly, prob be hard on the cv's though..

the only thing that stopped me was that the hubs need to rotate by nearly 180deg to lock, i dont see how this could be achieved with a ram..

some kind of worm drive servo would be the go.. anybody have any ideas?

Jumny's have elecontroic locking hubs, they'd be probably fit.

j-top paj wrote:i can,
but im about to leave for the snow and wont be back till next week.

Let us know when your back mate. Where bouts you based? I'm at the bottom ish of the blue mountains

StarkRavingSimmo wrote:

j-top paj wrote:i can,
but im about to leave for the snow and wont be back till next week.

Let us know when your back mate. Where bouts you based? I'm at the bottom ish of the blue mountains

fairfield/smithfield area. should be back on wednesday

StarkRavingSimmo wrote:Theres no way i'm welding the front. My mate did that and his is a bugger to steer.

Is there anyone in the sydney area with a welded diff sierra that could give me a demo on how it would feel?

No diffent than having a proper locked font in the rough stuff,
unlock a hub between rough stuff.

Mock

booflux wrote:Same hill same spot all V8s the runners are rear locked the Lux front.







The fact remains that the front wheels not losing traction and maintaining a constant speed, stop the front wheel kicking into the air. The rear locked with all the traction to the rear bog down and spit skyward.

I know this track at Cruiser park. I remember Chuck in Chipfat did it without lifting a tyre off the ground. Some of the front high angles here are due to the rear pushing and the torque from that further unweighting the front, like a drag car under acceleration. That just proves the power is getting to the ground.

Paul

I theory its totaly impossible for a bumble bee to fly.

RUFF wrote:I theory its totaly impossible for a bumble bee to fly.

How so??

I notice it's all the TOYota drivers saying rear first

I drive a Nissan with a rear LSD that works

Not so applicatable in the serria arena, but front locker can help reduce the shock loading from lifing that front wheel and spinning it while the other is stationary, then slamming it down causing nasty effects.



I drive a paj so I am sure I would go for the front first.