rockitogden Posted February 24, 2007 Posted February 24, 2007 When I look at the on board enrgy screen, it shows AWD only when in electric mode. It appears that only the electric motor provides power to the rear wheels. When it kicks into engine mode, which is most of the time...it shows front wheel drive only. What is the deal with AWD?
Gryphon Posted February 24, 2007 Posted February 24, 2007 There is no drive shaft, so only the rear electric motor (AWD only) drives the rear wheels. Tom
Wing Posted February 24, 2007 Posted February 24, 2007 When I look at the on board enrgy screen, it shows AWD only when in electric mode. It appears that only the electric motor provides power to the rear wheels. When it kicks into engine mode, which is most of the time...it shows front wheel drive only. What is the deal with AWD? The enrgy screen only for reference. It cannot show the actual condition. AWD means All Wheel Drive. This is a typical automotive terms.
skyfish400h Posted February 24, 2007 Posted February 24, 2007 When I look at the on board enrgy screen, it shows AWD only when in electric mode. It appears that only the electric motor provides power to the rear wheels. When it kicks into engine mode, which is most of the time...it shows front wheel drive only. What is the deal with AWD? This is correct. Only electric power goes to the rear wheels, while the fronts can receive either electric or gas. This avoids the mass of a drive shaft going to the rear wheels. For all pracital purposes this is an AWD vehicle. AWD by defintion implies a part-time system as opposed to a 4WD vehicle which has full-time power to all 4 wheels. The power deliverd to the rear wheels is not trivial and makes for better acceleration. The system works flawlessly. I've had occasion to use it in slippery conditions and also under heavy acceleration and the AWD system keeps power going to the gournd under any circumstance without wheel spin.
wwest Posted February 25, 2007 Posted February 25, 2007 When I look at the on board enrgy screen, it shows AWD only when in electric mode. It appears that only the electric motor provides power to the rear wheels. When it kicks into engine mode, which is most of the time...it shows front wheel drive only. What is the deal with AWD? This is correct. Only electric power goes to the rear wheels, while the fronts can receive either electric or gas. This avoids the mass of a drive shaft going to the rear wheels. For all pracital purposes this is an AWD vehicle. AWD by defintion implies a part-time system as opposed to a 4WD vehicle which has full-time power to all 4 wheels. The power deliverd to the rear wheels is not trivial and makes for better acceleration. The system works flawlessly. I've had occasion to use it in slippery conditions and also under heavy acceleration and the AWD system keeps power going to the gournd under any circumstance without wheel spin. Your statements are correct, overall, but you're tending to confuse things a bit... 4WD/4X4 systems, systems that LOCK the rear driveline to the front (most of THESE are RWD derivatives), are considered PART-TIME since they can only be engaged on low traction surfaces and should NEVER be engaged on a high traction surface. And while these newer AWD systems are often referred to as FULL-TIME if one looks deep enough most are really not. What AWD seems to really mean, especially an AWD on a FWD "base", is that the manufacturer has adopted some method of automatically coupling the second axle into the drive train if/when the primarily driven wheels develop slippage.
jditom Posted February 25, 2007 Posted February 25, 2007 The car is a FWD for the most part but engages the rear thus (AWD) when you start from a stop, or there is slippery conditions. Most true AWD rigs have some kind of power to all 4 wheels all the time. MDX 90% front, 10% rear untill you need it then more to the rear. Audi, BMW 50% front, 50% rear etc. I would discribe our 400h AWD as a FWD and part time AWD SUV since when driving it is in FWD 95% of the time.
skyfish400h Posted February 26, 2007 Posted February 26, 2007 The car is a FWD for the most part but engages the rear thus (AWD) when you start from a stop, or there is slippery conditions. Most true AWD rigs have some kind of power to all 4 wheels all the time. MDX 90% front, 10% rear untill you need it then more to the rear. Audi, BMW 50% front, 50% rear etc. I would discribe our 400h AWD as a FWD and part time AWD SUV since when driving it is in FWD 95% of the time. I think this misses the point. Any AWD system is designed to provide traction at all 4 wheels is such a way as to accompish two things: 1) The user will not experience wheel spin when the available friction forces are overcome by torque and 2) The locomotive force is applied to the pavement in a way that maximizes acceleration (power distribution) The HSD system on these AWD Toyota products accomplishes BOTH of these things quite well. The details of how they are achived (wires vs shafts etc) are not material to the function they provide and neither is the % split between front and rear. From a requirements point of view they are exactly the same.
jditom Posted February 27, 2007 Posted February 27, 2007 The point is this is a different AWD system then every other one out there. They should call it a FWD with part time AWD, this would be more accurate. Calling it a AWD system makes it sound like its the same system that is on the RX 350. It is not and is way different.
SOMEONE ELSE'S GOT MY NAME Posted February 27, 2007 Posted February 27, 2007 The point is this is a different AWD system then every other one out there. They should call it a FWD with part time AWD, this would be more accurate. Calling it a AWD system makes it sound like its the same system that is on the RX 350. It is not and is way different. Not only correct, but discussed on numerous posts already . . . the search tool: a wonderful (and not often used enough) thing. :whistles:
jditom Posted February 27, 2007 Posted February 27, 2007 The point is this is a different AWD system then every other one out there. They should call it a FWD with part time AWD, this would be more accurate. Calling it a AWD system makes it sound like its the same system that is on the RX 350. It is not and is way different. Not only correct, but discussed on numerous posts already . . . the search tool: a wonderful (and not often used enough) thing. :whistles: Dude, Get a name! :)
wwest Posted February 27, 2007 Posted February 27, 2007 Didn't I read somewhere that the rear motors aren't used unless fairly aggressive acceleration is called for on startup? Other than with wheelspin/slip, of course.
skyfish400h Posted February 27, 2007 Posted February 27, 2007 Didn't I read somewhere that the rear motors aren't used unless fairly aggressive acceleration is called for on startup? That depends on your definition of "fairly aggressive acceleration"... While it is possible to drive this car such that the rear motors never provide an ounce of thrust, I don't think that justifies calling this car FWD or even "mostly FWD". The fact is if you put your foot down you have power to all 4 wheels, any time you want it. To me that's AWD.
jditom Posted February 27, 2007 Posted February 27, 2007 Didn't I read somewhere that the rear motors aren't used unless fairly aggressive acceleration is called for on startup? Other than with wheelspin/slip, of course. If you watch your monitor from a start (most of the time) it will use the front and rear electric motor until about 20 mph then go the FWD. Now for fun if you do a hard acceleration like a 0-60 test it will keep the rear motors on longer to aid in getting up to speed. I did this and the rear stayed on until about 35 mph. If you look at the Lexus web site they quote the AWD 400h as 0-60 of 6.9 sec and the FWD of 7.5sec. This is a AWD SUV but it is part time AWD which is now stated in the Lexus web site. Not trying to beat a dead horse but this is very different from most cars that are full time AWD. But it is still a great rig! From Lexus.com The RX 400h front-wheel drive (FWD) and part-time all-wheel drive (AWD) both interact with the Vehicle Dynamics Integrated Management (VDIM) [1] system for superior handling. With part-time AWD, the rear axle's electric motor activates the rear wheels for improved traction and better acceleration.
wwest Posted February 28, 2007 Posted February 28, 2007 Okay yawl, just what is AWD for, worth, if not to keep you up and going on adverse, packed snow, ice, roadbeds? And if that is its purpose in life then who in their right mind would be anything but "gingerly" with that gas pedal in those conditions. So, slippery roadbed, or even suspected slippery roadbed, would any of us be aggressive with that gas pedal? So where, what, is the advantage or bringing the rear motor online in high traction conditions? 0-60 times...??
Jim Nazium Posted February 28, 2007 Posted February 28, 2007 Okay yawl, just what is AWD for, worth, if not to keep you up and going on adverse, packed snow, ice, roadbeds? And if that is its purpose in life then who in their right mind would be anything but "gingerly" with that gas pedal in those conditions. So, slippery roadbed, or even suspected slippery roadbed, would any of us be aggressive with that gas pedal? So where, what, is the advantage or bringing the rear motor online in high traction conditions? 0-60 times...?? Stability, Traction and Sure footedness when things get slippery, Handling in inclement weather, Better performance, and as a means of "having" the added traction when you need it only while saving on wear and tear and better economy for all the "other" times when you do not need it. Cheers, MadloR
jditom Posted February 28, 2007 Posted February 28, 2007 We had 2 inches of snow in the hills this AM so I gave the 400h a try. I have owned some of the best AWD rigs made (Audi allroad, BMW X5, Landcruiser) for comparison. Up and out of the driveway in reverse (which is rear motor only). Cruised around the hills and watching the monitor to see when the rear wheels engaged. It worked very seemless when the car felt slipage in the front wheel they added traction to the rear. The 400h performed very well and mind you this was on the (c OEM tires). With some better tires or dedicated snows this SUV would do very well. I wonder if you drove most of your day on snow if you would put a strain on the rear motor? Anyway it was an impressive AM and gave the wife a green light to go have fun. When are those Bridgstones going to get here????? BTW the OEM Michelins also hydroplain in modest water so beware. :chairshot:
Gryphon Posted February 28, 2007 Posted February 28, 2007 BTW the OEM Michelins also hydroplain in modest water so beware.:chairshot: I've noticed this also in Arizona rains. (not much snow to experiment with however). Tom
wwest Posted March 1, 2007 Posted March 1, 2007 Okay yawl, just what is AWD for, worth, if not to keep you up and going on adverse, packed snow, ice, roadbeds? And if that is its purpose in life then who in their right mind would be anything but "gingerly" with that gas pedal in those conditions. So, slippery roadbed, or even suspected slippery roadbed, would any of us be aggressive with that gas pedal? So where, what, is the advantage or bringing the rear motor online in high traction conditions? 0-60 times...?? Stability, Traction and Sure footedness when things get slippery, Handling in inclement weather, Better performance, and as a means of "having" the added traction when you need it only while saving on wear and tear and better economy for all the "other" times when you do not need it. Cheers, MadloR The question is/was: What is the advantage if bringing the rear motor online in HIGH traction conditions?
skyfish400h Posted March 2, 2007 Posted March 2, 2007 What is the advantage if bringing the rear motor online in HIGH traction conditions? T H R U S T !
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