Rear Locking Diff Question?
#1
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#4
the reason is because it is true locked diff, no slippage, so if you could lock it up people would either be breaking $h1t, or crashing because they couldn't control the truck under heavy power. it is also the reason even in 4x4 it shuts itself off about 40kph. its meant to be there when you are off road moving slow and need max traction or in sever weather conditions.
what is wrong with open diff in 2wd by the way?
what is wrong with open diff in 2wd by the way?
#5
the reason is because it is true locked diff, no slippage, so if you could lock it up people would either be breaking $h1t, or crashing because they couldn't control the truck under heavy power. it is also the reason even in 4x4 it shuts itself off about 40kph. its meant to be there when you are off road moving slow and need max traction or in sever weather conditions.
what is wrong with open diff in 2wd by the way?
what is wrong with open diff in 2wd by the way?
It should be the owner's responsibility whether or not to screw something up IMO. I mean my old Tacoma had the rear locker by a push of the button. I love my Ford much more than the Taco by all means but Toyota didn't seem to think it would be a factor for their buyers.
#6
i don't know about the taco but i would guess it was a locking diff with clutches which would allow slippage, so if you did drive on dry roads you would break anything.
if Ford gave the person the option dollars to donuts they would get sued or huge warranty claims. what i would like to see is a hybrid of limited slip with the ELD feature. giving the best of both worlds.
if Ford gave the person the option dollars to donuts they would get sued or huge warranty claims. what i would like to see is a hybrid of limited slip with the ELD feature. giving the best of both worlds.
#7
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#10
I know it it isnt the same but a similar idea. Lots of ranger guys did the "brown wire mod" to allow 2wd low range, it put the transfer case in 4wd low, but did not lock in the hubs IIRC. Might be a similar mod to do the new ELD in the FX4s.
#11
no its not power goes to both wheels equally until traction is lost.
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From Wiki
One undesirable side effect of a conventional differential is that it can reduce overall torque - the rotational force which propels the vehicle. The amount of torque required to propel the vehicle at any given moment depends on the load at that instant - how heavy the vehicle is, how much drag and friction there is, the gradient of the road, the vehicle's momentum, and so on. For the purpose of this article, we will refer to this amount of torque as the "threshold torque".
The torque applied to each driving roadwheel is a result of the engine and transmission applying a twisting force against the resistance of the traction at that roadwheel. Unless the load is exceptionally high, the engine and transmission can usually supply as much torque as necessary, so the limiting factor is usually the traction under each wheel. It is therefore convenient to define traction as the amount of torque that can be generated between the tire and the road surface, before the wheel starts to slip. If the total traction under all the driven wheels exceeds the threshold torque, the vehicle will be driven forward; if not, then one or more wheels will simply spin.
To illustrate how a differential can limit overall torque, imagine a simple rear-wheel drive vehicle, with one rear roadwheel on asphalt with good grip, and the other on a patch of slippery ice. With the load, gradient, etc., the vehicle requires, say, 2,000 newton metres (1,480 ft·lbf) of torque to move forward (i.e. the threshold torque). Let us further assume that the non-spinning traction on the ice equates to 400 N·m (300 ft·lbf), and the asphalt to 3,000 N·m (2,210 ft·lbf).
If the two roadwheels were driven without a differential, each roadwheel would be supplied with an equal amount of torque, and would push against the road surface as hard as possible. The roadwheel on ice would quickly reach the limit of traction (400 N·m), but would be unable to spin because the other roadwheel has good traction. The traction of the asphalt plus the small extra traction from the ice exceeds the threshold requirement, so the vehicle will be propelled forward.
With a differential, however, as soon as the "ice wheel" reaches 400 N·m, it will start to spin, and then develop less traction ~300 N·m. The planetary gears inside the differential carrier will start to rotate because the "asphalt wheel" encounters greater resistance. Instead of driving the asphalt wheel with more force, the differential will asymmetrically split the total amount of available torque, and will apply a vast majority of torque to the ice wheel to spin faster, and the asphalt wheel will remain stationary, compensating for the stopped wheel by extra speed of the spinning ice wheel. The actual torque on both roadwheels will be the same - limited to the lesser traction of 300 N·m each. Since 600 N·m is less than the required threshold torque of 2000 N·m, the vehicle will not be able to utilise the output from the engine, and will not move.
An observer will simply see one stationary roadwheel on one side of the vehicle, and one spinning roadwheel on the opposite side. It will not be obvious that both wheels are generating the same torque (i.e. both wheels are in fact pushing equally, despite the difference in rotational speed). This has led to a widely held misconception that a vehicle with a differential is really only "one-wheel-drive". In fact, a normal differential always allows the transmission of equal torque to both driven roadwheels; unless it is a specific type of differential, such as locking, torque-biasing, or limited slip type.
driving down straight road equal torque both wheels, when traction is lost the when with least amount of traction spins.
One undesirable side effect of a conventional differential is that it can reduce overall torque - the rotational force which propels the vehicle. The amount of torque required to propel the vehicle at any given moment depends on the load at that instant - how heavy the vehicle is, how much drag and friction there is, the gradient of the road, the vehicle's momentum, and so on. For the purpose of this article, we will refer to this amount of torque as the "threshold torque".
The torque applied to each driving roadwheel is a result of the engine and transmission applying a twisting force against the resistance of the traction at that roadwheel. Unless the load is exceptionally high, the engine and transmission can usually supply as much torque as necessary, so the limiting factor is usually the traction under each wheel. It is therefore convenient to define traction as the amount of torque that can be generated between the tire and the road surface, before the wheel starts to slip. If the total traction under all the driven wheels exceeds the threshold torque, the vehicle will be driven forward; if not, then one or more wheels will simply spin.
To illustrate how a differential can limit overall torque, imagine a simple rear-wheel drive vehicle, with one rear roadwheel on asphalt with good grip, and the other on a patch of slippery ice. With the load, gradient, etc., the vehicle requires, say, 2,000 newton metres (1,480 ft·lbf) of torque to move forward (i.e. the threshold torque). Let us further assume that the non-spinning traction on the ice equates to 400 N·m (300 ft·lbf), and the asphalt to 3,000 N·m (2,210 ft·lbf).
If the two roadwheels were driven without a differential, each roadwheel would be supplied with an equal amount of torque, and would push against the road surface as hard as possible. The roadwheel on ice would quickly reach the limit of traction (400 N·m), but would be unable to spin because the other roadwheel has good traction. The traction of the asphalt plus the small extra traction from the ice exceeds the threshold requirement, so the vehicle will be propelled forward.
With a differential, however, as soon as the "ice wheel" reaches 400 N·m, it will start to spin, and then develop less traction ~300 N·m. The planetary gears inside the differential carrier will start to rotate because the "asphalt wheel" encounters greater resistance. Instead of driving the asphalt wheel with more force, the differential will asymmetrically split the total amount of available torque, and will apply a vast majority of torque to the ice wheel to spin faster, and the asphalt wheel will remain stationary, compensating for the stopped wheel by extra speed of the spinning ice wheel. The actual torque on both roadwheels will be the same - limited to the lesser traction of 300 N·m each. Since 600 N·m is less than the required threshold torque of 2000 N·m, the vehicle will not be able to utilise the output from the engine, and will not move.
An observer will simply see one stationary roadwheel on one side of the vehicle, and one spinning roadwheel on the opposite side. It will not be obvious that both wheels are generating the same torque (i.e. both wheels are in fact pushing equally, despite the difference in rotational speed). This has led to a widely held misconception that a vehicle with a differential is really only "one-wheel-drive". In fact, a normal differential always allows the transmission of equal torque to both driven roadwheels; unless it is a specific type of differential, such as locking, torque-biasing, or limited slip type.
driving down straight road equal torque both wheels, when traction is lost the when with least amount of traction spins.
Last edited by Deano-FX4; 07-31-2009 at 10:23 PM.
#15
...the Traction Control system will also help the open diff.
From the Owners Guide:
From the Owners Guide:
Excessive wheel spin is controlled in two ways, which may work
separately or in tandem: Engine Traction Control and Brake Traction
Control. Engine Traction Control works to limit drive-wheel spin by
momentarily reducing engine power. Brake Traction Control works to
limit wheel spin by momentarily applying the brakes to the wheel that is
slipping. Traction Control is most active at low speeds.
separately or in tandem: Engine Traction Control and Brake Traction
Control. Engine Traction Control works to limit drive-wheel spin by
momentarily reducing engine power. Brake Traction Control works to
limit wheel spin by momentarily applying the brakes to the wheel that is
slipping. Traction Control is most active at low speeds.