The wheel that is spinning has zero torque, while the wheel on the ground has 100% of the torque.
I think about it like this with a locker. If you have one wheel in the air and the other on the ground, which one is twisting its axle more? The one on the ground will twist its axle more because its tire has resistance. The tire in the air won't twist its axle because it doesn’t have any resistance to turning.
I don't think torque is split 50/50 all of the time with a locker like it is with an open diff. Perhaps it is split 50/50 when both are on pavement (I know that you know this is bad, so I'll avoid that conversation).
You have a solid tube bar. Let's say its 3 feet long (for visualizations sake). You hold one end of the bar in a vice. It does not rotate. You hold the middle of the bar with your hands. You apply a torque at the middle of the bar. The end which is not in the vice will rotate, but the amount it rotates is the same amount as the amount you rotated the tube at the center. The end that is in the vice has not rotated, but the tube between the vice and your hand has twisted. This twist takes torque. So 100% of the torque went to one end and 0% went to the other end. Your hand is like a locked differential. The free end is like a wheel is in the air. The end in the vice is like a wheel on the ground.
So what you are saying if I understand it correctly is that torque can only be applied if there is resistance. If you run a car with all 4 wheels in the air, where does the torque from the engine go? That is the only thing puzzling me now.
'So what you are saying if I understand it correctly is that torque can only be applied if there is resistance.' Yes
'where does the torque from the engine go' This is the puzzling question most of the time.
If all the wheels are in the air the torque generated by the engine will go into drive train losses (as it always does heat/noise). It will also go into rotational inertia when it spins the tires/drive train up to speed. This can take fractions of a second before the engine will reach it's redline (since there is not much resistance to turning it). Once the engine is redlining, WOT or otherwise, fuel will be cutoff to the system with today’s electronics so that damage is not done to the engine. So the engine actually creates a small amount of torque to spin the drive train up, and after that it just stops making torque. An engine can be rated at 100 hp, but that doesn't mean it is always making that amount. The engine can make anywhere between 100 hp, and probably a couple of negative horses (engine brake), so there is a wide variation possible whether the driver wants it or not.
Ok that makes sense somewhat. Like a few weeks ago when I was in 4wd Lo with the trooper in mud upto and over the wheels and I was spinning all 4 of em bouncing off the rev-limiter barely moving along but finally was able to power my way out of the mud-pit.
If a wheel is "locked," the engine is STILL applying torque. The brake does not ABSORB the torque - it simply COUNTERS the torque!
Since I don't know the inner workings of these particular devices, I'll just ask how does this sound to you? Since the wheel is not spinning, the viscosity of the transmission fluid changes and alters the amount of torque delivered.
There is no need for an LSD on the GS300, nor ANY lexus with TRAC. For a RWD vehicle as long as both rear wheels have a reasonably close or equal, level of traction, the open diff'l will deliver equal torque to both rear wheels.
TRAC only comes into play if one rear wheel begins to slip and then TRAC will instantly apply, release, apply, release, etc, the brake to that wheel, using the on/off cycling of the brake to modulate the frictional coefficient of that wheel such that it's rotational rate roughly equals that of the opposite wheel.
If this condition persists for more than a few hundred milliseconds and the operator does not react quickly and lift the throttle then the TRAC ecu will itself dethrottle the engine.
The Sequoia, ML, and I think the new LC, AWD systems work the same way except TRAC will use the brakes on any wheel or wheel to alleviate wheelspin.
Three open diff'ls with TRAC to insure true AWD operation on most surfaces, dry, slippery, snow, ice, etc.
The Sequoia only locks the center diff'l in L4 and with the transmission shifter in "low", otherwise it uses TRAC to apportion torque in AWD mode if slippery conditions are encountered.
I was thinking of locked brakes in which case there is no dissipation of the torque by heating since no work is being done. It's just a balance of torques.
I have been pretty puzzled by this. The earlier FWD RX300 version of TRAC simply dethrottled the engine.
Almost no (acknowledging that there are exceptions) AWD or 4WD vehicle has an LSD or anything equivalent for the front wheels.
For FWD TRAC my suspicion has been that alternate on/off application of brakes on only one front wheel would feed back to the steering wheel in much the same way ABS does to the brake pedal and that might provoke an improper reaction on the part of the driver.
So I suspect that dethrottling is the only action that can reasonably be chosen for FWD TRAC implementation.
From reading their marketing literature, I know that the Accord applies the brakes and the Maxima dethrottles plus shifts to higher gear if necessary. I'm just not sure if that's the ONLY thing they do.
An open differential will not ensure that the POWER to the wheels attached to it will remain equal. The power of the engine will be directed to the wheel that is easier to rotate.
Paisan, I think your descriptions of the difference between a "posi" rear and an open rear diff are not correct. Also I do not believe the tire that rotates must be on the inside of a vehicle with an open diff.
If you did a burn out with a vehicle having an open diff (either rear or front) only one tire would leave a mark. It could be either side depending on the tread of the tire and the traction provided by the road surface under each tire. The tire facing the least resistance will begin rotating and as it out acclerates the opposite wheel on the open diff, more power will be directed to the wheel already spinning causing it to spin even faster causing even more of a "burn-out" until traction on that tire is achieved.
A posi-rear will have an entirely different effect during a burnout. (I know as I recall the burnouts in a 69 GTO back in highschool with a posi rear). The tracks on the road will be from both wheels however one will typically be greater than the other. A posi rear will, by its design, assure that some of the engine's power will go to both wheels under all conditions regardless of traction (ie the two burnout marks from both tires spinning).
having a posi rear for this reason alone was part of the "cool" factor.
An LSD wouks in a similar fashion but less agressively ensuring that some power is directed to both wheels attached to it while still ensuring smooth operations around turns.
That downside of a posi rear was its tendency to hop if accelerated to hard in turns.
If you could limit the level of engine torque to just below "burn-out" (the point at which either rear wheel starts "slipping", {BURNING OUT!}) would you agree that in this case equal torque is being delivered to both rear wheels?
You are right though tide with the brakes locked. The energy dissipation won't go into heating the brakes. Well actually no 'work' is being done, so you could say there is no energy being transferred in the system. The torque will try to twist the axles, and the brakes, and the frame though if your wheels are locked and you're revving the engine.
wwest: on your question "If you could limit the level of engine torque to just below "burn-out" (the point at which either rear wheel starts "slipping", {BURNING OUT!}) would you agree that in this case equal torque is being delivered to both rear wheels?"
Yes, up to the point of slippage an open differential will equally distribute power to both wheels receiving their power from that diff. All of the designs from Toyota, GM and every manufacturer are trying to meet the demands of multiple requirements.
Keep the power coming, prevent power from overtaking traction, transfer power when traction is lacking, keep the vehicle moving in the direction the operator intends, design the drivetrain to accomodate all speeds, angles and radius of turns and I'm sure there are more. A pretty healthy list of requirements.
Some designs are good at achieving some objectives, some make sacrifices to be better at others, some are compromises across the board. Its my opinion that an awd system, deliverying some power to all wheels under all circumstances at all speeds, utilizing mechanical differentials to distribute and transfer power across the drivetrain combined with the electronics and computerization to minimize or prevent slippage when the power exceeds the traction is the best of all worlds. Offer it with the ability to turn the traction control off for very rare occaisions and the ability to lock any differential for those really rare events and off-roading and you got all the bases covered.
Throw in 4wd lo and you'd even make paisan a happy 4 wheelin guy:)
Dark day for my beloved Isuzu. It's a shame the Assender will replace the Trooper. It's just another GM clone aka mini-van-suv. Not a bad vehicle, but the true SUVs have all but been extinct now.... Sorry for the babbling...
Been away, and see this topic has been explored quite a bit. I think this angle was alluded to in some of the posts...
The position that an open diff is always in a 50/50 mode is correct (even with a spinning tire)but what is reaching the ground is not the potential torque output of the engine (at the running rpm).
In the situation of a open diff vehicle sitting on ice, spinning one wheel and not moving, you can go from idle to redline and all you do is spin the one tire faster. You could then replace the engine with a hand crank and you would be able to spin the tire also (although slower).
The question of where did the torque go? The little bit required to spin the tire is all that was generated. You could spin the tire with a hand crank. (but but... I had a supercharged 454 at 5000 rpm...)lol
As you can conclude (it was touched on in previous posts), measuring torque output from rotating machinery (including jet engines, etc) requires a resisting torque up to the capacity of the engine.
In the context of the open diff and spinning tires the torque is limited by the available friction between the spinning tire and road surface. The engine torque didn't go anywhere, it just wasn't generated.
can be a bit of a handful because of their tendency to"walk" as they grab traction on different sides as one moves along.4wd Hi helps because power is then split to the open front diff.and control is a bit better.
With a 129" wheelbase, that breakover angle will keep it from doing any serious off roading.
I'm disappointed. It's a Trailblazer XL clone, with the GMC look. Isuzu has a longer warranty and a V8 option, so I'd pick that over the GMC or Chevy, but I can't imagine it'll bring many new buyers.
Help! I have a Suzuki Grand Vitara '99 and I am having some strange loud popping noises which sound like they are coming from the front differential. When my vehicle was under warranty it did this all the time; uphill, downhill, turning, etc. I had the front diff replaced and everything was just hunky dory until last summer when I was ascending a steep, holey, bumpy and mostly dry road that the vehicle could not handle in 2wd or 4hi. Now the thing pops about every 30 seconds when going up steep terrain although there are no sounds on snow/ice, on level terrain, moderately rolling or the steepest downhills. I am afraid the front diff is damaged again, as I understand that I have a totally mechanical system with no such things as viscous couplings or center differentials. The vehicle is now out of warranty and the dealer understands that I am willing to pay for another repair, but they are telling me that the popping noise is just pressure release on the front axle and while it is kind of loud and disconcerting, it is normal operation and not to worry. I feel like I am being handed a line of bull. Any other Suzuki owners have similar experiences? I hear Toyotas (the older ones) make some noise too, and I was told by a 4wd specialty shop, who did test my vehicle, that the dealer may be right. Be assured that I have never driven my 4wd L or H on dry pavement and I usually don't even use the 4wd off-road unless I have to. However, some of the steep, dry dirt hills I have climbed have been hard-packed (lots of friction for dirt). Any opinions?
My understanding is that it has the same (mostly useless) AWD system as the HL and the RX. I'd gladly trade up from my 01 AWD RX to the 03 Rav4 if it comes out with the Sequoia system.
Living here in a Northern climate I swore to myself that I would NEVER own a FWD car and the AWD RX (70/30 F/R torque bias) seemed a good compromise. It's a compromise alright, but their's, not mine.
Rav, HL & RX: 50/50 torque split F/R only applies if both ends have equal traction coefficient, all the way down to zero. "Instant" torque split on suddenly encountering disparate traction coefficient is about 90/10 F/R, best case once the VC stiffens up is 70/30.
Yeah, RAV4, Highlander, and RX300 use center viscous couplings, with no low range. Basically the same as Subaru's for manual trannys. They are full-time and good for rain or snow, or when the surface changes from slick to sticky, since you don't have to engage or disengage them.
The Highlander has optional traction control, and the RX300 makes it standard along with stability control. Highlander and RAV4 also offer an optional LSD.
If this has already been covered, I apologize. Regardless of what BMW calls its drive system, I would like to understand how it all works.
I have a 325xi sedan and I know it feels stable. I haven't had the opportunity to drive it in snow or any adverse weather. Could somebody describe to me with some detail as to what will happen when it gets in the snow and wheels start losing grip? I know it has a 68/32 split rear/front, but will it shift that ratio around if wheels slip?
68/32 split remains all the time regardless if the wheels are sliping or not. The front does not receive that much power compared to the rear but this is where the FUN factor is.
The VC will vary the power to the front. If it didn't the center diffy would blow up on turns! The #s that they give you for torque split on VC units is the "standard" or the % split which it strives to achive. Unless you have a center locking diffy, (One of the only regular cars I've found this in is the XT6 manual tranny model) it will vary the power. Even with a center locking diffy you can't engage it on dry pavement.
A VC is a hermetically sealed "box" with a fluid inside that has a specially formulated base, normal, viscosity and expansion rate due to heating of the fluid specific to an application.
The base viscosity determines the "normal" (non-heated) coupling co-efficient. The rate at which the fluid expands determines the "attack" rate, the rate at which the coupling co-efficient increases due to heating from the disparate rotational rates of the two sets of clutch plates.
Some manufacturers also add a gas "bubble" of a controlled size to initially delay the onset of high coupling and still have a high rate of "attack" once the size of the bubble is minmized by increasing fluid pressure.
My 911 only applies 10% of the drive power to the front wheels because the base viscosity of the fluid determines that factor.
I suppose that if I were to run it in tight circles continuously then what you say would be true, but in normal use the VC will not "tighten" above 10% until the expanding fluid "volume" overcomes the volume of the gas bubble.
So in "normal" use, "standard" turns, the VC's coupling co-efficient remains at 10%
Oh, by the way, most manufacturers will tell you that the "attack" rate of their VC is on the order of hundreds of milliseconds.
When slip is detected it will shift around the power due to the viscous fluid in the center diffy, always trying to keep it at the X%/X% ratio setup by the manufacturer. They can put in different fluids that will try "harder" to maintain this or ones that will try "less hard" to do this. For instance on the 911 if you put the rear wheels on Ice it would shift more power to the front than 10%
"always trying to keep it at the ratio setup by the factory"
No, a properly set up VC will vary the ratio, dynamically, shortly after the onset and duration of disparate rotational rates of the two sets of clutch plates.
For instance the factory quotes the RX300 as 70/30 F/R while in reality 30% is the absolute most torque, at best, it will ever transfer to the rear. The RX, and likely the HL, are predominantly FWD vehicles with virtually no torque (maybe 5%) transferred to the rear on initial front axle slippage.
I'm sure you have documentation to support your 70/30 claim on the Toyota vehicles. To my knowledge those torque splits given by manufacturers is the initial split in non-slip conditions. For instance the ones I know of for sure are:
Subarus: 4EAT AWD: 80/20 up to 60/40 during slippage MT AWD: 50/50 up to 20/80 and 80/20 during slippage 4EAT AWD w/VTD: 45/55 up to 60/40 and 40/60 during slippage
Isuzu TOD: 2wd mode: 0/100 locked TOD mode: 15/85 >5mph with slippage: up to 50/50 4wd low mode: 50/50 low range gearset
On a four wheel drive dyno the RX never delivered more than 25% of the available torque to the rear wheels.
They, Lexus, (acurately) quote torque split as 50/50 and that is likely the truth on high traction surfaces, low traction surfaces are yet another story.
I plan to purchase a Jeep Liberty sometime this month and would appreciate any information on the Selec-trac system.
I reside in a hilly, rural area of Michigan with a moderate amount of snowfall. Can someone explain how the Selec-trac (Full-time 4 wheel drive) option works on the Liberty and how good is this system? Also, how would the optional Trac-Lok rear differential fit into the workings? Does it make sense to have a limited slip rear end bolted on with this option?
Can anybody out there explain how the AWD system on the Pilot and MDX works? What I want to know is when it works. When does it send power to all four wheels? Does it offer full time power split to all four wheels above 18mph?
I've gotten what appear to be conflicting answers on this subject. I'm not sure if that's because the people who have bought these vehicles don't know how and when it works, or if they even care.
Comments
-mike
The wheel that is spinning has zero torque, while the wheel on the ground has 100% of the torque.
I think about it like this with a locker. If you have one wheel in the air and the other on the ground, which one is twisting its axle more? The one on the ground will twist its axle more because its tire has resistance. The tire in the air won't twist its axle because it doesn’t have any resistance to turning.
I don't think torque is split 50/50 all of the time with a locker like it is with an open diff. Perhaps it is split 50/50 when both are on pavement (I know that you know this is bad, so I'll avoid that conversation).
I hope one of my examples can make sense :-)
-mike
Yes
'where does the torque from the engine go'
This is the puzzling question most of the time.
If all the wheels are in the air the torque generated by the engine will go into drive train losses (as it always does heat/noise). It will also go into rotational inertia when it spins the tires/drive train up to speed. This can take fractions of a second before the engine will reach it's redline (since there is not much resistance to turning it). Once the engine is redlining, WOT or otherwise, fuel will be cutoff to the system with today’s electronics so that damage is not done to the engine. So the engine actually creates a small amount of torque to spin the drive train up, and after that it just stops making torque. An engine can be rated at 100 hp, but that doesn't mean it is always making that amount. The engine can make anywhere between 100 hp, and probably a couple of negative horses (engine brake), so there is a wide variation possible whether the driver wants it or not.
-mike
Since I don't know the inner workings of these particular devices, I'll just ask how does this sound to you? Since the wheel is not spinning, the viscosity of the transmission fluid changes and alters the amount of torque delivered.
tidester
Host
SUVs
-mike
TRAC only comes into play if one rear wheel begins to slip and then TRAC will instantly apply, release, apply, release, etc, the brake to that wheel, using the on/off cycling of the brake to modulate the frictional coefficient of that wheel such that it's rotational rate roughly equals that of the opposite wheel.
If this condition persists for more than a few hundred milliseconds and the operator does not react quickly and lift the throttle then the TRAC ecu will itself dethrottle the engine.
The Sequoia, ML, and I think the new LC, AWD systems work the same way except TRAC will use the brakes on any wheel or wheel to alleviate wheelspin.
Three open diff'ls with TRAC to insure true AWD operation on most surfaces, dry, slippery, snow, ice, etc.
The Sequoia only locks the center diff'l in L4 and with the transmission shifter in "low", otherwise it uses TRAC to apportion torque in AWD mode if slippery conditions are encountered.
tidester
Host
SUVs
Almost no (acknowledging that there are exceptions) AWD or 4WD vehicle has an LSD or anything equivalent for the front wheels.
For FWD TRAC my suspicion has been that alternate on/off application of brakes on only one front wheel would feed back to the steering wheel in much the same way ABS does to the brake pedal and that might provoke an improper reaction on the part of the driver.
So I suspect that dethrottling is the only action that can reasonably be chosen for FWD TRAC implementation.
-mike
Paisan, I think your descriptions of the difference between a "posi" rear and an open rear diff are not correct. Also I do not believe the tire that rotates must be on the inside of a vehicle with an open diff.
If you did a burn out with a vehicle having an open diff (either rear or front) only one tire would leave a mark. It could be either side depending on the tread of the tire and the traction provided by the road surface under each tire. The tire facing the least resistance will begin rotating and as it out acclerates the opposite wheel on the open diff, more power will be directed to the wheel already spinning causing it to spin even faster causing even more of a "burn-out" until traction on that tire is achieved.
A posi-rear will have an entirely different effect during a burnout. (I know as I recall the burnouts in a 69 GTO back in highschool with a posi rear). The tracks on the road will be from both wheels however one will typically be greater than the other. A posi rear will, by its design, assure that some of the engine's power will go to both wheels under all conditions regardless of traction (ie the two burnout marks from both tires spinning).
having a posi rear for this reason alone was part of the "cool" factor.
An LSD wouks in a similar fashion but less agressively ensuring that some power is directed to both wheels attached to it while still ensuring smooth operations around turns.
That downside of a posi rear was its tendency to hop if accelerated to hard in turns.
Are you saying that a open diff DOES split torque 50/50?
I'm only asking because I read different opinions just about everyday.
Open diff'l, RWD:
If you could limit the level of engine torque to just below "burn-out" (the point at which either rear wheel starts "slipping", {BURNING OUT!}) would you agree that in this case equal torque is being delivered to both rear wheels?
a locker can split torque from 0/100 to 50/50 to 100/0 and anywhere in-between. It all depends upon the traction conditions of the wheels though.
:-)
Yes, up to the point of slippage an open differential will equally distribute power to both wheels receiving their power from that diff. All of the designs from Toyota, GM and every manufacturer are trying to meet the demands of multiple requirements.
Keep the power coming, prevent power from overtaking traction, transfer power when traction is lacking, keep the vehicle moving in the direction the operator intends, design the drivetrain to accomodate all speeds, angles and radius of turns and I'm sure there are more. A pretty healthy list of requirements.
Some designs are good at achieving some objectives, some make sacrifices to be better at others, some are compromises across the board. Its my opinion that an awd system, deliverying some power to all wheels under all circumstances at all speeds, utilizing mechanical differentials to distribute and transfer power across the drivetrain combined with the electronics and computerization to minimize or prevent slippage when the power exceeds the traction is the best of all worlds. Offer it with the ability to turn the traction control off for very rare occaisions and the ability to lock any differential for those really rare events and off-roading and you got all the bases covered.
Throw in 4wd lo and you'd even make paisan a happy 4 wheelin guy:)
-mike
The position that an open diff is always in a 50/50 mode is correct (even with a spinning tire)but what is reaching the ground is not the potential torque output of the engine (at the running rpm).
In the situation of a open diff vehicle sitting on ice, spinning one wheel and not moving, you can go from idle to redline and all you do is spin the one tire faster. You could then replace the engine with a hand crank and you would be able to spin the tire also (although slower).
The question of where did the torque go? The little bit required to spin the tire is all that was generated. You could spin the tire with a hand crank. (but but... I had a supercharged 454 at 5000 rpm...)lol
As you can conclude (it was touched on in previous posts), measuring torque output from rotating machinery (including jet engines, etc) requires a resisting torque up to the capacity of the engine.
In the context of the open diff and spinning tires the torque is limited by the available friction between the spinning tire and road surface. The engine torque didn't go anywhere, it just wasn't generated.
-mike
I'm disappointed. It's a Trailblazer XL clone, with the GMC look. Isuzu has a longer warranty and a V8 option, so I'd pick that over the GMC or Chevy, but I can't imagine it'll bring many new buyers.
-juice
The vehicle is now out of warranty and the dealer understands that I am willing to pay for another repair, but they are telling me that the popping noise is just pressure release on the front axle and while it is kind of loud and disconcerting, it is normal operation and not to worry. I feel like I am being handed a line of bull. Any other Suzuki owners have similar experiences? I hear Toyotas (the older ones) make some noise too, and I was told by a 4wd specialty shop, who did test my vehicle, that the dealer may be right.
Be assured that I have never driven my 4wd L or H on dry pavement and I usually don't even use the 4wd off-road unless I have to. However, some of the steep, dry dirt hills I have climbed have been hard-packed (lots of friction for dirt).
Any opinions?
Living here in a Northern climate I swore to myself that I would NEVER own a FWD car and the AWD RX (70/30 F/R torque bias) seemed a good compromise. It's a compromise alright, but their's, not mine.
Isn't there a Lexus version of the 4Runner? Maybe that would fit your needs.
Good luck
The Rav, HL and RX get a center viscous with a 50/50 torque split IIRC.
-mike
The Highlander has optional traction control, and the RX300 makes it standard along with stability control. Highlander and RAV4 also offer an optional LSD.
-juice
I have a 325xi sedan and I know it feels stable. I haven't had the opportunity to drive it in snow or any adverse weather. Could somebody describe to me with some detail as to what will happen when it gets in the snow and wheels start losing grip? I know it has a 68/32 split rear/front, but will it shift that ratio around if wheels slip?
Thanks,
Paul
-mike
-mike
The #s that they give you for torque split on VC units is the "standard" or the % split which it strives to achive. Unless you have a center locking diffy, (One of the only regular cars I've found this in is the XT6 manual tranny model) it will vary the power. Even with a center locking diffy you can't engage it on dry pavement.
-mike
The base viscosity determines the "normal" (non-heated) coupling co-efficient. The rate at which the fluid expands determines the "attack" rate, the rate at which the coupling co-efficient increases due to heating from the disparate rotational rates of the two sets of clutch plates.
Some manufacturers also add a gas "bubble" of a controlled size to initially delay the onset of high coupling and still have a high rate of "attack" once the size of the bubble is minmized by increasing fluid pressure.
My 911 only applies 10% of the drive power to the front wheels because the base viscosity of the fluid determines that factor.
I suppose that if I were to run it in tight circles continuously then what you say would be true, but in normal use the VC will not "tighten" above 10% until the expanding fluid "volume" overcomes the volume of the gas bubble.
So in "normal" use, "standard" turns, the VC's coupling co-efficient remains at 10%
Oh, by the way, most manufacturers will tell you that the "attack" rate of their VC is on the order of hundreds of milliseconds.
-mike
No, a properly set up VC will vary the ratio, dynamically, shortly after the onset and duration of disparate rotational rates of the two sets of clutch plates.
For instance the factory quotes the RX300 as 70/30 F/R while in reality 30% is the absolute most torque, at best, it will ever transfer to the rear. The RX, and likely the HL, are predominantly FWD vehicles with virtually no torque (maybe 5%) transferred to the rear on initial front axle slippage.
Subarus:
4EAT AWD: 80/20 up to 60/40 during slippage
MT AWD: 50/50 up to 20/80 and 80/20 during slippage
4EAT AWD w/VTD: 45/55 up to 60/40 and 40/60 during slippage
Isuzu TOD:
2wd mode: 0/100 locked
TOD mode: 15/85 >5mph with slippage: up to 50/50
4wd low mode: 50/50 low range gearset
-mike
They, Lexus, (acurately) quote torque split as 50/50 and that is likely the truth on high traction surfaces, low traction surfaces are yet another story.
I reside in a hilly, rural area of Michigan with a moderate amount of snowfall. Can someone explain how the Selec-trac (Full-time 4 wheel drive) option works on the Liberty and how good is this system? Also, how would the optional Trac-Lok rear differential fit into the workings? Does it make sense to have a limited slip rear end bolted on with this option?
Scott
--------------------------------------------------------------------------------
-mike
I've gotten what appear to be conflicting answers on this subject. I'm not sure if that's because the people who have bought these vehicles don't know how and when it works, or if they even care.