4WD and the FEH
#1
09-30-2009, 05:01 PM
Join Date: Mar 2006
Location: Ventura, CA
Posts: 942
4WD and the FEH
This is a bit of a Subaru commercial, but I like the ramp system that was used to test the AWD systems of the various vehicles:
http://www.youtube.com/watch?v=ooQRxlChvMw
Any thoughts on how the FEH AWD would perform on the ramp tests? Would it be as good as the Subaru seems to be?
NOTE:
[This is a spin-off from the end of another thread, "FEH and extreme cold climates-any issues?": https://www.greenhybrid.com/discuss/...23/index6.html ]
http://www.youtube.com/watch?v=ooQRxlChvMw
Any thoughts on how the FEH AWD would perform on the ramp tests? Would it be as good as the Subaru seems to be?
NOTE:
[This is a spin-off from the end of another thread, "FEH and extreme cold climates-any issues?": https://www.greenhybrid.com/discuss/...23/index6.html ]
#3
09-30-2009, 08:29 PM
Re: 4WD and the FEH
C/P from the other thread:
Hmm, good video! The FE/FEH is a asymmetric 4WD but until '09 the FEH didn't have traction control but still neither would perform as good as the Subaru which has symmetric AWD.
Being a asymmetric 4WD, you'd have the steering torque they mentioned in the video. If you have AdvanceTrac(>'09 FEH) and traction at one wheel, you could climb the ramp. Without AdvanceTrac(<'09 FEH), you can't call it AWD either, it's just 4WD!
P.S. Another meaningless post from BillyK.
Hmm, good video! The FE/FEH is a asymmetric 4WD but until '09 the FEH didn't have traction control but still neither would perform as good as the Subaru which has symmetric AWD.
Being a asymmetric 4WD, you'd have the steering torque they mentioned in the video. If you have AdvanceTrac(>'09 FEH) and traction at one wheel, you could climb the ramp. Without AdvanceTrac(<'09 FEH), you can't call it AWD either, it's just 4WD!
P.S. Another meaningless post from BillyK.
#4
10-01-2009, 07:00 AM
Re: 4WD and the FEH
In the real world winter ice & snow driving I've experienced in my 46 driving years, I NEVER have had only the front wheels on ice, and the rear wheels on concrete! Or any one wheel on a bare surface while the other three are on ice. I mean, get real here. (That's the reason for BillyK's BS meter, which I thought was funny).
Usually the whole street is glaze ice, and all 4 wheels are spinning. That's the real world. All cars with AWD would probably do well in that situation, don't you think?
#5
10-01-2009, 08:07 AM
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Re: 4WD and the FEH
Yes, not real-world but it's about time someone starting explaining the differences in the myriad of F/awd systems out there in the marketplace. So the "ramp" is a good start.
In my "real-world" I would settle for simple RWD and a set of tire chains when the going gets (d)icy. In the meantime I want NOTHING to do with Symmetrical AWD, F/awd or R/awd. I simply do not want engine "drive" of any kind, leading or lagging, on my front wheels when it is most important, becomes most important for their BASE use, directional control.
In my "real-world" I would settle for simple RWD and a set of tire chains when the going gets (d)icy. In the meantime I want NOTHING to do with Symmetrical AWD, F/awd or R/awd. I simply do not want engine "drive" of any kind, leading or lagging, on my front wheels when it is most important, becomes most important for their BASE use, directional control.
#6
10-01-2009, 08:29 AM
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Re: 4WD and the FEH
C/P from the other thread:
Hmm, good video! The FE/FEH is a asymmetric 4WD but until '09 the FEH didn't have traction control but still neither would perform as good as the Subaru which has symmetric AWD.
Being a asymmetric 4WD, you'd have the steering torque they mentioned in the video.
Only if it uses halfshafts that are of unequal lenth.
If you have AdvanceTrac(>'09 FEH) and traction at one wheel, you could climb the ramp.
Possibly not, if the TC function of AdvanceTrac meets the current "standard" then it will be much too agressive to allow forward motion on that ramp. TC is often highly aggressive on FWD and F/awd vehicles so as to mostly alleviate the danger of loss of directional control.
Without AdvanceTrac(<'09 FEH), you can't call it AWD either, it's just 4WD!
Toyota has now learned, learned the hard way via public outcry, that TC is NOT the answer. Look at the HL's performance on the ramp test...
More recent Toyota and Lexus F/awd have a PB to allow the driver to switch off TC when stuck and need to use a bit of wheelspin. Obviously THAT was deemed not a good "fix" in the long term so Toyota (Venza) and Lexus (2010 RX350) are now adopting the FE/FEH F/awd technique.
P.S. Another meaningless post from BillyK.
Hmm, good video! The FE/FEH is a asymmetric 4WD but until '09 the FEH didn't have traction control but still neither would perform as good as the Subaru which has symmetric AWD.
Being a asymmetric 4WD, you'd have the steering torque they mentioned in the video.
Only if it uses halfshafts that are of unequal lenth.
If you have AdvanceTrac(>'09 FEH) and traction at one wheel, you could climb the ramp.
Possibly not, if the TC function of AdvanceTrac meets the current "standard" then it will be much too agressive to allow forward motion on that ramp. TC is often highly aggressive on FWD and F/awd vehicles so as to mostly alleviate the danger of loss of directional control.
Without AdvanceTrac(<'09 FEH), you can't call it AWD either, it's just 4WD!
Toyota has now learned, learned the hard way via public outcry, that TC is NOT the answer. Look at the HL's performance on the ramp test...
More recent Toyota and Lexus F/awd have a PB to allow the driver to switch off TC when stuck and need to use a bit of wheelspin. Obviously THAT was deemed not a good "fix" in the long term so Toyota (Venza) and Lexus (2010 RX350) are now adopting the FE/FEH F/awd technique.
P.S. Another meaningless post from BillyK.
#7
10-01-2009, 08:38 AM
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Re: 4WD and the FEH
Interesting video. However, not real-world.
In the real world winter ice & snow driving I've experienced in my 46 driving years, I NEVER have had only the front wheels on ice, and the rear wheels on concrete! Or any one wheel on a bare surface while the other three are on ice. I mean, get real here. (That's the reason for BillyK's BS meter, which I thought was funny).
Usually the whole street is glaze ice, and all 4 wheels are spinning. That's the real world. All cars with AWD would probably do well in that situation, don't you think?
In the real world winter ice & snow driving I've experienced in my 46 driving years, I NEVER have had only the front wheels on ice, and the rear wheels on concrete! Or any one wheel on a bare surface while the other three are on ice. I mean, get real here. (That's the reason for BillyK's BS meter, which I thought was funny).
Usually the whole street is glaze ice, and all 4 wheels are spinning. That's the real world. All cars with AWD would probably do well in that situation, don't you think?
Well, in at least one respect it really is "real-world".
Getting up and going from a dead stop with all four wheels on ice, or trying to start up an incline in that situation. Oftentimes having the ability to drive, firmly drive, more than 1 wheel, say 2, 3, or even 4, will make the difference.
I have had instances wherein it took all 4 tirechains to get up and going initially. But once underway, with momentum now operating in my favor, wish I could remove the chains. At least I was able to switch to RWD only "on the fly", '92 Jeep.
Last edited by wwest; 10-01-2009 at 08:59 AM.
#8
10-01-2009, 08:51 AM
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Re: 4WD and the FEH
AdvanceTrac...
My first experience with TC, Traction Control, was on a newly purchased 1992 LS400. I quickly discovered it to be a royal PITA. Even the slightest level of wheelspin, a wet plastic strip marking a crosswalk, and the rear brakes would be applied and the engine INSTANTLY dethrottled. Once TC activated then recovery, regaining control of the throttle, often took several seconds.
I did note that by ~2000 some of the RWD Lexus models had revised TC firmware. Upon wheelspin detection the brakes would still begin to be applied but engine dethrottling was delayed by a few seconds, presumably to allow the driver to "switch" to throttle "feathering" mode. Abating loss of traction on a RWD or R/awd vehicle is not nearly as critical as is a FWD or F/awd vehicle.
TC, of necessity, uses a rather simple "bang-bang" on/off servo loop process, much like ABS, and therefore does not have the "finesse" with feathering the throttle "just so" that a learned and experienced driver can have, can use, in truly slippery roadbed conditions. Other than the (sometimes) constructive use of wheelspin, that's the other advantage of being able to switch TC off.
I soon developed the habit of switching it off simultaneously with starting the engine. I don't think I would do that with TC on a FWD or F/awd vehicle, far too dangerous.
My first experience with TC, Traction Control, was on a newly purchased 1992 LS400. I quickly discovered it to be a royal PITA. Even the slightest level of wheelspin, a wet plastic strip marking a crosswalk, and the rear brakes would be applied and the engine INSTANTLY dethrottled. Once TC activated then recovery, regaining control of the throttle, often took several seconds.
I did note that by ~2000 some of the RWD Lexus models had revised TC firmware. Upon wheelspin detection the brakes would still begin to be applied but engine dethrottling was delayed by a few seconds, presumably to allow the driver to "switch" to throttle "feathering" mode. Abating loss of traction on a RWD or R/awd vehicle is not nearly as critical as is a FWD or F/awd vehicle.
TC, of necessity, uses a rather simple "bang-bang" on/off servo loop process, much like ABS, and therefore does not have the "finesse" with feathering the throttle "just so" that a learned and experienced driver can have, can use, in truly slippery roadbed conditions. Other than the (sometimes) constructive use of wheelspin, that's the other advantage of being able to switch TC off.
I soon developed the habit of switching it off simultaneously with starting the engine. I don't think I would do that with TC on a FWD or F/awd vehicle, far too dangerous.
Last edited by wwest; 10-01-2009 at 08:57 AM.
#9
10-01-2009, 08:56 AM
Re: 4WD and the FEH
Interesting video. However, not real-world.
In the real world winter ice & snow driving I've experienced in my 46 driving years, I NEVER have had only the front wheels on ice, and the rear wheels on concrete! Or any one wheel on a bare surface while the other three are on ice. I mean, get real here. (That's the reason for BillyK's BS meter, which I thought was funny).
Usually the whole street is glaze ice, and all 4 wheels are spinning. That's the real world. All cars with AWD would probably do well in that situation, don't you think?
In the real world winter ice & snow driving I've experienced in my 46 driving years, I NEVER have had only the front wheels on ice, and the rear wheels on concrete! Or any one wheel on a bare surface while the other three are on ice. I mean, get real here. (That's the reason for BillyK's BS meter, which I thought was funny).
Usually the whole street is glaze ice, and all 4 wheels are spinning. That's the real world. All cars with AWD would probably do well in that situation, don't you think?
You actually understand BillyK's pictures only posts? Not sure if that's aimed at the thread or a certain person? Can't tell because BillyK. never expalins his some of his picture stories!
Last edited by wptski; 10-01-2009 at 09:39 AM.
#10
10-01-2009, 09:37 AM
Re: 4WD and the FEH
I expect that within a year or two we will see the FE/FEH F/awd models with a bit of "overdrive" to the rear so that like the SH-AWD system more than 50% of the engine torque can go to the rear upon front wheelslip/spin. That way maybe the TC firmware can be made less aggressive and not leave F/awd owners "dead in the water".
