Is the new Honda Element 4wd or just AWD
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JHZR2
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Crvs say 4wd, but I believe they are just an automotive awd system. definitely no selectable transfer case.
I think they just put 4wd on there to invoke an image, not because it is a true 4wd type system.
I think they just put 4wd on there to invoke an image, not because it is a true 4wd type system.
AFAIK neither have a transfer case, or at least, no ability to manually change.
They're referred to as "real time 4 wheel drive" aka RT4WD. Which basically means a variant of AWD.
It's primarily a FWD system, with the rear wheels assisting as needed. The CR-V and Element use a "Dual Pump" system. There is a PTO on the transmission, with a conventional propeller shaft going back to the rear unit. When the transmission turns, the propeller shaft turns as well. I don't know if the ratio is 1:1 or not. At the same time, as the vehicle rolls, the rear wheels roll, spin the half-shafts, and spin the differential in the rear unit.
This is where the Dual Pump system comes in. There is a pump at the front of the rear unit and a pump at the back of the rear unit (this rear unit is probably 18" long, front to back). The front pump is driven by the propeller shaft and the rear pump is driven by the differential from the spinning wheels. When there is a speed difference between the front and rear pumps, fluid is used to mechanically activate a clutch in the rear unit which connects the propeller shaft to the differential, providing power to the rear wheels.
This is different from the VTM-4 used in the MDX/Pilot/Ridgeline models. That is a fully electronic system that uses wheel speed inputs and throttle inputs to not only react to wheel speed differences but to also anticipate them. For example, the VTM-4 system can modulate the rear clutches (PWM) to engage during acceleration (even if no wheel speed difference is detected per se). It also has the ability to act as a limited-slip unit, modulating power to the wheel with the most traction. In the VTM-4 system, there is no rear differential, and the rear wheels are not physically connected to each other as they are in the Dual Pump design. The VTM-4 relies completely on clutches. You can also lock the rear wheels together in the VTM-4 system with a button on the dash. Up to 6 mph, the rear clutches receive full current (6 amps) and lock. From 6 to 18 mph, the current is modulated until after 18 mph, where it drops to 0 and there is no manual lock action. The system still operates above 18 mph, but the manual lock function is disabled above that speed.
You cannot manually lock the Dual Pump system on the CR-V/Element.
This is where the Dual Pump system comes in. There is a pump at the front of the rear unit and a pump at the back of the rear unit (this rear unit is probably 18" long, front to back). The front pump is driven by the propeller shaft and the rear pump is driven by the differential from the spinning wheels. When there is a speed difference between the front and rear pumps, fluid is used to mechanically activate a clutch in the rear unit which connects the propeller shaft to the differential, providing power to the rear wheels.
This is different from the VTM-4 used in the MDX/Pilot/Ridgeline models. That is a fully electronic system that uses wheel speed inputs and throttle inputs to not only react to wheel speed differences but to also anticipate them. For example, the VTM-4 system can modulate the rear clutches (PWM) to engage during acceleration (even if no wheel speed difference is detected per se). It also has the ability to act as a limited-slip unit, modulating power to the wheel with the most traction. In the VTM-4 system, there is no rear differential, and the rear wheels are not physically connected to each other as they are in the Dual Pump design. The VTM-4 relies completely on clutches. You can also lock the rear wheels together in the VTM-4 system with a button on the dash. Up to 6 mph, the rear clutches receive full current (6 amps) and lock. From 6 to 18 mph, the current is modulated until after 18 mph, where it drops to 0 and there is no manual lock action. The system still operates above 18 mph, but the manual lock function is disabled above that speed.
You cannot manually lock the Dual Pump system on the CR-V/Element.
They are AWD and reactive not proactive. They attempt to engage after vehicle senses its stuck.
IMHO Honda AWD(recent CRV) is poor based on experiences in my family's vacation home. It gets 8"-16" wind drifted snow in driveway crossing an open field from wind and neighbor plows when he gets to it. They get stuck. It seems like FWD with occasional kick of the rear wheels.
My wife's 2005 Legacy motors right through as front/rear always turn. Also rear both both mostly spin(LSD) too. The amazing thing is Subaru with manual transmission uses pure fluid shear for AWD and absolutely no electronics. Old design that sketched in the late 1980's and it really works.
Its too bad Honda does not include a software based center diff locker like I have seen in Toyota (RAV4) and Kia Sorrento. My sisters 2008 RAV4 which gets stuck in these conditions claws its way out when the center locker is turned on. I think it shuts off above 20+MPH.
IMHO Honda AWD(recent CRV) is poor based on experiences in my family's vacation home. It gets 8"-16" wind drifted snow in driveway crossing an open field from wind and neighbor plows when he gets to it. They get stuck. It seems like FWD with occasional kick of the rear wheels.
My wife's 2005 Legacy motors right through as front/rear always turn. Also rear both both mostly spin(LSD) too. The amazing thing is Subaru with manual transmission uses pure fluid shear for AWD and absolutely no electronics. Old design that sketched in the late 1980's and it really works.
Its too bad Honda does not include a software based center diff locker like I have seen in Toyota (RAV4) and Kia Sorrento. My sisters 2008 RAV4 which gets stuck in these conditions claws its way out when the center locker is turned on. I think it shuts off above 20+MPH.
agree on crv AWD behavior. IIRC it's also similar to volvo's system. Hokie above nailed it.
The thing is-- once the pumps have a fluid differential, which engages the driveshaft, the very nature of the clutches being locked means that both pumps are spinning the same and the fluid pressure differential then zeroes out, they unlock, then if more slippage occurs then the cycle repeats. so, either a front wheel needs to constantly spin, or the system pulses in and out.
In 7-8" of snow, the system was nicely adequate in the gen-1 crv we had. It was effective and gave a boost over just fwd. I too had an AWD legacy, however, and the subaru ran circles around it in the slick stuff.
M
The thing is-- once the pumps have a fluid differential, which engages the driveshaft, the very nature of the clutches being locked means that both pumps are spinning the same and the fluid pressure differential then zeroes out, they unlock, then if more slippage occurs then the cycle repeats. so, either a front wheel needs to constantly spin, or the system pulses in and out.
In 7-8" of snow, the system was nicely adequate in the gen-1 crv we had. It was effective and gave a boost over just fwd. I too had an AWD legacy, however, and the subaru ran circles around it in the slick stuff.
M
Originally Posted By: rjundi
Its too bad Honda does not include a software based center diff locker like I have seen in Toyota (RAV4) and Kia Sorrento. My sisters 2008 RAV4 which gets stuck in these conditions claws its way out when the center locker is turned on. I think it shuts off above 20+MPH.
I think it's too bad Honda couldn't just scale-down the VTM-4 system for the smaller AWD vehicles it has. The MDX is in a word remarkable in snow. Even on sheer ice, which we get a lot of here, it simply works.
I look forward to trying the CR-V in the snow this winter. CR-V owners seem to be happy with the performance.
Its too bad Honda does not include a software based center diff locker like I have seen in Toyota (RAV4) and Kia Sorrento. My sisters 2008 RAV4 which gets stuck in these conditions claws its way out when the center locker is turned on. I think it shuts off above 20+MPH.
I think it's too bad Honda couldn't just scale-down the VTM-4 system for the smaller AWD vehicles it has. The MDX is in a word remarkable in snow. Even on sheer ice, which we get a lot of here, it simply works.
I look forward to trying the CR-V in the snow this winter. CR-V owners seem to be happy with the performance.
Originally Posted By: rjundi
The amazing thing is Subaru with manual transmission uses pure fluid shear for AWD and absolutely no electronics. Old design that sketched in the late 1980's and it really works.
Based on how I understand the CR-V system to work, I would probably classify it as operating on "fluid shear" also, or at least a pressure differential. What is the difference, and how does the Subaru system operate?
The amazing thing is Subaru with manual transmission uses pure fluid shear for AWD and absolutely no electronics. Old design that sketched in the late 1980's and it really works.
Based on how I understand the CR-V system to work, I would probably classify it as operating on "fluid shear" also, or at least a pressure differential. What is the difference, and how does the Subaru system operate?
not entirely accurate... manual subies use (used? it's been a while since I've owned one) fluid shear as a limited slip application INSIDE a center differential. so there is a solid driveline to all 4 wheels with a limited slip center diff. in practical terms, if I dropped the clutch on wet pavement, I had something spinning both in front and behind me....
the automatics use a viscous clutch with electronic-modulated lockup between the front and rear.
the automatics use a viscous clutch with electronic-modulated lockup between the front and rear.
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Originally Posted By: Hokiefyd
Originally Posted By: rjundi
The amazing thing is Subaru with manual transmission uses pure fluid shear for AWD and absolutely no electronics. Old design that sketched in the late 1980's and it really works.
Based on how I understand the CR-V system to work, I would probably classify it as operating on "fluid shear" also, or at least a pressure differential. What is the difference, and how does the Subaru system operate?
Subaru constantly has a 50/50 split of power with manual transmissions at all times. The fluid shear is simply is shifting the power front to back as needed.
In automatics Subaru uses a full time 90/10 split normally and shifts it as sensed electronically via a clutch pack.
I think the major advantage of the older Subaru design that still holds its own is power is always going to the front and rear wheels.
This video depicts the Subaru vs CRV. Basically what I observed in our family's driveway. CRV's are really nice vehicles but if you need AWD, not so much as I think its more FWD+ a little boost.
In the following case Subaru is automatic since a turbo motor(scoop in hood):
http://www.youtube.com/watch?v=Ki9ad5UCmwo
Subaru and Audi come off the drawing boards with AWD in the design and hence their superiority in cars and car based SUV's. Every other maker retrofits a FWD platform with mixed results and many compromises.
Originally Posted By: rjundi
The amazing thing is Subaru with manual transmission uses pure fluid shear for AWD and absolutely no electronics. Old design that sketched in the late 1980's and it really works.
Based on how I understand the CR-V system to work, I would probably classify it as operating on "fluid shear" also, or at least a pressure differential. What is the difference, and how does the Subaru system operate?
Subaru constantly has a 50/50 split of power with manual transmissions at all times. The fluid shear is simply is shifting the power front to back as needed.
In automatics Subaru uses a full time 90/10 split normally and shifts it as sensed electronically via a clutch pack.
I think the major advantage of the older Subaru design that still holds its own is power is always going to the front and rear wheels.
This video depicts the Subaru vs CRV. Basically what I observed in our family's driveway. CRV's are really nice vehicles but if you need AWD, not so much as I think its more FWD+ a little boost.
In the following case Subaru is automatic since a turbo motor(scoop in hood):
http://www.youtube.com/watch?v=Ki9ad5UCmwo
Subaru and Audi come off the drawing boards with AWD in the design and hence their superiority in cars and car based SUV's. Every other maker retrofits a FWD platform with mixed results and many compromises.
If the CRV had spun up one of the front wheels from time to time it would've made the climb easily. Probably they left all the electronic nannies on in the CRV so it couldn't...
Before we got our Tracker we used my parents first gen CRV in deep snow and it worked pretty good, you just have to keep on the gas to keep the rear axle locked in. Its not good for technical terrain but for getting up a snowy street its not a bad system.
Technically, once the clutch pack is locked(and if the clutch is strong enough), it could transfer 100% of power to either front or rear axle, just like a real 4WD truck, which would be superior to a manual trans subaru system, with a semi open centre diff. If you stay on the gas in the CRV, once the pressure starts to bleed off, one of the front tires will spin up and lock the clutch again. I assume its pretty easy to overheat the clutch for a long long climb but it never happened in our experience.
Descending is the real issue with the CRV system as now your 4WD climbing truck, turns back into a Civic with alot of front brake bias and no help from the rear axle.
The odd time our driveway turns into an ice rink we can go down our hill in the Tracker using 1st in 4low and dragging the brakes slightly with 2 tires in the snow bank. I think almost any of the part time AWD/4WD systems can't pull this trick off.
Before we got our Tracker we used my parents first gen CRV in deep snow and it worked pretty good, you just have to keep on the gas to keep the rear axle locked in. Its not good for technical terrain but for getting up a snowy street its not a bad system.
Technically, once the clutch pack is locked(and if the clutch is strong enough), it could transfer 100% of power to either front or rear axle, just like a real 4WD truck, which would be superior to a manual trans subaru system, with a semi open centre diff. If you stay on the gas in the CRV, once the pressure starts to bleed off, one of the front tires will spin up and lock the clutch again. I assume its pretty easy to overheat the clutch for a long long climb but it never happened in our experience.
Descending is the real issue with the CRV system as now your 4WD climbing truck, turns back into a Civic with alot of front brake bias and no help from the rear axle.
The odd time our driveway turns into an ice rink we can go down our hill in the Tracker using 1st in 4low and dragging the brakes slightly with 2 tires in the snow bank. I think almost any of the part time AWD/4WD systems can't pull this trick off.
Thanks for that video. It looks like that Subaru probably has a limited-slip differential also. That helps a ton, even on dedicated 4WD/AWD vehicles. You could see one of the rear tires on the CR-V spinning, but since one of each of the front/rear tires was off the ground, there was no forward motive power available.
This happens on open-diff Jeeps also. We had a '96 Grand Cherokee with UpCountry suspension and rear LSD and it'd run circles around '96 Limiteds (with open diffs) on Jeep Jamborees.
This happens on open-diff Jeeps also. We had a '96 Grand Cherokee with UpCountry suspension and rear LSD and it'd run circles around '96 Limiteds (with open diffs) on Jeep Jamborees.
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