Ect & 4 wd
02-08-18, 03:23 PM
#2
Lead Lap
In the RX, the vehicle is always in AWD (All-Wheel Drive), which isn't the same as 4WD (Four-Wheel Drive), switching power to whatever wheel(s) needs it. You can't switch the AWD off or on, but you can "lock" the AWD on so that all 4 wheels are always driven evenly.
Anyway, the snow button starts the car in second gear--rather than first gear--from a dead stop to prevent wheel spin when accelerating.
So, YES, use the snow button whenever weather conditions require it.
Anyway, the snow button starts the car in second gear--rather than first gear--from a dead stop to prevent wheel spin when accelerating.
So, YES, use the snow button whenever weather conditions require it.
Last edited by RickC5; 02-09-18 at 04:35 AM.
02-11-18, 10:08 AM
#3
Thought so.
The RX 350 AWD model features an electronically controlled Active Torque Control AWD system. Active Torque Control AWD uses an electronically controlled coupling ahead of the rear differential to vary torque distribution anywhere from 100:0 to 50:50 front to rear, depending on driving dynamics and road conditions. When accelerating, or starting off on a low-grip surface, torque is quickly provided to all four wheels. At steady speeds, torque is sent only to the front wheels, enhancing fuel efficiency.
To help provide handling agility and control, the AWD system increases rear-wheel torque when the vehicle’s front tires start to lose traction and decreases rear-wheel torque when the vehicle’s rear tires start to lose traction. On rough or sandy terrain, an AWD LOCK switch provides enhanced traction performance for low-speed maneuvering (if in LOCK mode, the system reverts to AUTO mode when speed exceeds 25 mph). To help prevent a tight corner-braking condition (shuddering) during low-speed cornering, the system reduces rear wheel torque.
http://pressroom.toyota.com/releases...e+models.print
SNOW mode simply changes torque applied to the wheels and how transmission shifts gears and vehicle accelerates. It's like going in molasses. So that tires do not slip. Sure, you can use it in LOCK (if that's what you mean by 4WD) mode but you'll get out of it as soon as you get to 25mph. Out of LOCK, or permanent 4WD mode.
The RX 350 AWD model features an electronically controlled Active Torque Control AWD system. Active Torque Control AWD uses an electronically controlled coupling ahead of the rear differential to vary torque distribution anywhere from 100:0 to 50:50 front to rear, depending on driving dynamics and road conditions. When accelerating, or starting off on a low-grip surface, torque is quickly provided to all four wheels. At steady speeds, torque is sent only to the front wheels, enhancing fuel efficiency.
To help provide handling agility and control, the AWD system increases rear-wheel torque when the vehicle’s front tires start to lose traction and decreases rear-wheel torque when the vehicle’s rear tires start to lose traction. On rough or sandy terrain, an AWD LOCK switch provides enhanced traction performance for low-speed maneuvering (if in LOCK mode, the system reverts to AUTO mode when speed exceeds 25 mph). To help prevent a tight corner-braking condition (shuddering) during low-speed cornering, the system reduces rear wheel torque.
http://pressroom.toyota.com/releases...e+models.print
SNOW mode simply changes torque applied to the wheels and how transmission shifts gears and vehicle accelerates. It's like going in molasses. So that tires do not slip. Sure, you can use it in LOCK (if that's what you mean by 4WD) mode but you'll get out of it as soon as you get to 25mph. Out of LOCK, or permanent 4WD mode.
02-12-18, 01:01 PM
#5
Lead Lap
02-12-18, 02:58 PM
#7
the false sense of security is with the tires. the tires are probably an up to 6x multiplier whereas the awd is only up to 3x. This is my arbitrary ranking.
I would agree that Lexus implementation is not top tier so maybe it only a 2x versus say a 2.5 or 2.7 that other systems have. But way too much focus on that. Throw good tires on and it'll make up for it.
I would agree that Lexus implementation is not top tier so maybe it only a 2x versus say a 2.5 or 2.7 that other systems have. But way too much focus on that. Throw good tires on and it'll make up for it.
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02-13-18, 05:05 AM
#8
Lead Lap
Yeah, I can surely do that. When the weather gets really bad, the LC is what we use. For really tight turns (off-road) the LC actually has a button that will lock up the inside rear tire so it acts as a pivot point for the truck to turn on. Really interesting stuff.
I wonder if those roller folks were "allowed" to push the "AWD Lock" button on the RX, and what the results would have been? I also think that roller test--while interesting--wasn't a very good representation of reality. Acura must have financed it.
I wonder if those roller folks were "allowed" to push the "AWD Lock" button on the RX, and what the results would have been? I also think that roller test--while interesting--wasn't a very good representation of reality. Acura must have financed it.
Last edited by RickC5; 02-13-18 at 05:10 AM.
02-16-18, 08:23 AM
#10
Lexus Champion
Just a couple things to note here, there is no center differential in the RX.
Rear wheels can be locked-up for short duration through the electromechanical coupling mentioned a few posts above. That would be the 50:50 torque distribution.
Anything between 100:0 (FWD) and 50:50 (4WD) is achieved via friction inside the coupling, similar to a slipping clutch, and will cause premature wear/overheating if it were to stay in that mode for prolonged periods of time (AWD).
4WD lockup kicks in during starting from standstill and in some straight-line high speed acceleration cases. It is disengaged at low speeds during turning operation to accommodate for different rotational speed of the front and rear axles.
4WD lock button raises the thresholds at which point the vehicle reverts to FWD operation.
Most modern crossovers are engineered to operate this way in the name of FWD architecture they're based on and fuel economy.
Those in need of hard-core AWD/4WD systems should look elsewhere (4Runner Limited/Lexus GX).
I came to a conclusion that Audi's Dynamic mode is most suitable for snow.
Rear wheels can be locked-up for short duration through the electromechanical coupling mentioned a few posts above. That would be the 50:50 torque distribution.
Anything between 100:0 (FWD) and 50:50 (4WD) is achieved via friction inside the coupling, similar to a slipping clutch, and will cause premature wear/overheating if it were to stay in that mode for prolonged periods of time (AWD).
4WD lockup kicks in during starting from standstill and in some straight-line high speed acceleration cases. It is disengaged at low speeds during turning operation to accommodate for different rotational speed of the front and rear axles.
4WD lock button raises the thresholds at which point the vehicle reverts to FWD operation.
Most modern crossovers are engineered to operate this way in the name of FWD architecture they're based on and fuel economy.
Those in need of hard-core AWD/4WD systems should look elsewhere (4Runner Limited/Lexus GX).
I came to a conclusion that Audi's Dynamic mode is most suitable for snow.
02-16-18, 09:59 AM
#11
Instructor
Just a couple things to note here, there is no center differential in the RX.
Rear wheels can be locked-up for short duration through the electromechanical coupling mentioned a few posts above. That would be the 50:50 torque distribution.
Anything between 100:0 (FWD) and 50:50 (4WD) is achieved via friction inside the coupling, similar to a slipping clutch, and will cause premature wear/overheating if it were to stay in that mode for prolonged periods of time (AWD).
4WD lockup kicks in during starting from standstill and in some straight-line high speed acceleration cases. It is disengaged at low speeds during turning operation to accommodate for different rotational speed of the front and rear axles.
4WD lock button raises the thresholds at which point the vehicle reverts to FWD operation.
Most modern crossovers are engineered to operate this way in the name of FWD architecture they're based on and fuel economy.
Those in need of hard-core AWD/4WD systems should look elsewhere (4Runner Limited/Lexus GX).
I came to a conclusion that Audi's Dynamic mode is most suitable for snow.
Rear wheels can be locked-up for short duration through the electromechanical coupling mentioned a few posts above. That would be the 50:50 torque distribution.
Anything between 100:0 (FWD) and 50:50 (4WD) is achieved via friction inside the coupling, similar to a slipping clutch, and will cause premature wear/overheating if it were to stay in that mode for prolonged periods of time (AWD).
4WD lockup kicks in during starting from standstill and in some straight-line high speed acceleration cases. It is disengaged at low speeds during turning operation to accommodate for different rotational speed of the front and rear axles.
4WD lock button raises the thresholds at which point the vehicle reverts to FWD operation.
Most modern crossovers are engineered to operate this way in the name of FWD architecture they're based on and fuel economy.
Those in need of hard-core AWD/4WD systems should look elsewhere (4Runner Limited/Lexus GX).
I came to a conclusion that Audi's Dynamic mode is most suitable for snow.
the sad part of all this is that the new electronic systems removed the mechanical complexity and weight (supposedly). Yet, the newer cars weight at least 300 lbs more than before...........
04-05-19, 08:46 PM
#12
Driver School Candidate
Driving uphill on rollers is the same as driving uphill on snow/ice, i.e., you better be concerned.
I recently learned the hard way that the RX350 notion of 4WD lock is seriously misleading. The lock button only changes the power distribution between front and back axles, and does nothing for side to side slippage. I was slightly bottomed out in the snow, and was in a position where one front wheel and one rear wheel were spinning. Under those conditions, the two wheels with traction received zero power. Even though I was pointed slightly downhill and had some gravity assistance, I was stuck even though I potentially had 2 unused wheels that could have helped to propel me.
In other words, if you lose traction on one front and one rear wheel, you are stuck. I erroneously thought "4WD lock" would always send at least some amount of power to all 4 wheels, but in reality, you are only guaranteed to have power delivered to 2 wheels -- one front, and one rear.
I recently learned the hard way that the RX350 notion of 4WD lock is seriously misleading. The lock button only changes the power distribution between front and back axles, and does nothing for side to side slippage. I was slightly bottomed out in the snow, and was in a position where one front wheel and one rear wheel were spinning. Under those conditions, the two wheels with traction received zero power. Even though I was pointed slightly downhill and had some gravity assistance, I was stuck even though I potentially had 2 unused wheels that could have helped to propel me.
In other words, if you lose traction on one front and one rear wheel, you are stuck. I erroneously thought "4WD lock" would always send at least some amount of power to all 4 wheels, but in reality, you are only guaranteed to have power delivered to 2 wheels -- one front, and one rear.
04-05-19, 08:52 PM
#13
Driver School Candidate
That roller test is a very good representation of reality... it exactly replicates how my 2015 RX350 handles in the snow with "AWD Lock" (and Snow ECT) turned on. As I mention in my previous post, as soon as one front and one rear tire simultaneously lose traction, you are dead in the water/snow. Not only did I eventually get stuck, I also experienced the side to side sliding that you see in the roller test.
04-08-19, 01:08 PM
#14
Intermediate
For me my RX is exactly what I wanted and I'm very happy with it's winter performance.
I never got stuck in the snow last winter. Every time I needed to start moving uphill on a snow covered road it went without hesitation.
I wanted a raised Camry with AWD and that's what I bought. If you all wanted off-road vehicles, why didn't you buy them instead?
I never got stuck in the snow last winter. Every time I needed to start moving uphill on a snow covered road it went without hesitation.
I wanted a raised Camry with AWD and that's what I bought. If you all wanted off-road vehicles, why didn't you buy them instead?
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