Real time 4WD: how does it work?

Dear Honda,

I'm trying to research on how Honda's real time 4WD work? I guess this is an assymetric 4WD system where it starts off in FWD mode first. But how often will power shift to the rear wheels, even if it's slipping? I ask because the CR-V comes with traction control on the front wheels. If traction control prevents the front wheels from slipping in the first place, how does power ever get re-directed to the rear wheels?

Is there an engineering site on Honda's web site that describes how this works?

Thanks

 

It works well. Not as good as a full-time system like a Subie though.
That $1200 is well spent money though. Years later, a V with Real-time AWD is still worth the extra dough you spent to get it in the first place.
Look on youtube at all of the CRV in deep snow, mud videos. It is more capable than most people realize.

 

Thanks for the reply. There's another thread on this site that I read about 4WD on the highway and I think some of the replies there relate to how the 4WD system works. So that helped. But there was also a post about how this one person lost a little control in the snow when the traction control kicked in on the front wheels and since there was no change of speed on the wheel slippage, the rear wheels didn't kick in. I guess that's the only downside on this real time 4WD system.

 

There is a post somewhere on our EOC forum about this. You can search there. I'll try to look it up as well.

 

http://automobiles.honda.com/models/engineering_featuredemos.asp?NUM=7&ModelName=CR%2DV

here you go

 

Thanks for the link. It's a very simple explanation to a complex system.

 

I opted out of the 4 wheel drive as I do not plan on ever taking it out in conditions where it would need to be in 4 wheel drive. Call me old fashion, but I thought it was weird not to be able to control when it was or wasn't in 4 wheel drive. I am used to the old lockin' the wheels things. Over the last week we have had ice...then snow. In both cases the CRV handled great....my VSA came on once (trying to go uphill on ice from a dead stop.) While it would help the resale down the road, I just couldn't justify spending the extra dough....especially since we don't get real bad weather here...and if we did, I would stay inside. Let us know what you decide....

 

I was thinking of the same thing. My experience with RWD and FWD cars in snow when we lived in Boston is that if you have winter tires or at least all season tires, you should be fine. The annoying thing is that people with SUVs think they are king of the roads and that they are ok with AWD/4WD when it snows. And yet, during snow storms, you see a bunch of them either stranded or involved in an accident.

Those of you still thinking about 4WD vs 2WD should read this article from May 1999 of C&D magazine.

http://www.caranddriver.com/article.asp?section_id=4&article_id=3888&page_number=1

Thanks.

 

The annoying thing is that people with SUVs think they are king of the roads and that they are ok with AWD/4WD when it snows. And yet, during snow storms, you see a bunch of them either stranded or involved in an accident.

Amen to that! You can't imagine the # of 4WD and AWD vehicles that have accidents here in Las Vegas when the road is wet from just Rain... Yes you read right, RAIN. I would hate to think what the roads would look like after a snow.

Being from the Midwest myself, (Ohio) I was taught how to properly navigate in inclement weather. To me it does not matter if the vehicle is AWD or not. The same cautions should be applied. First and foremost being (& this escapes most Vegas drivers) SLOW DOWN!!!

I myself like the Realtime 4WD on my 99. It comes in real handy on sandy beaches @ Lake Mead and for navigating mountain trials on Mt Charleston.

 

2007 Video in SNOW

ironsteel:

The link you posted was from 1999. Not only has car technology (like the V itself) drastically changed, but tire tech has as well. Check out this video of a UK dude in deep snow with his new 2007 6-speed diesel V. (Wish we had a diesel here)

http://www.youtube.com/watch?v=k4ItdQgHA0o

 

How about this guy in his 1st gen who is obviously half-crazy to do this on a street with parked cars and trees. However, note the rear tires throwing snow.

http://www.youtube.com/watch?v=II5cVw8Lugg&NR

 

Is that any ease way or indication that the Real Time 4WD works or running on CRV?

 

Get on dirt or gravel or mud. Floor it. Wipe grin off face.

 

I didn't finish reading the article but instead felt the need to state the obvious: In Winter, get Winter tires. Then you have the best of both worlds, AWD and good traction.

I've got Winter tires and rims for my Silverado Z71 and will also get them for my CR-V when the time comes. Yes, I'm one of those people that "own the road" when it snows, and I'm also one of the people that stops to pull out the Ford with the stock tires that thought he could keep up with me. Where I live we're always last to be plowed, and if it's snowing bad enough sometimes we never get plowed. There are days in Winter where only having FWD just isn't a good idea and staying home isn't an option. My wife's job title changed and we no longer can count on being able to carpool. So we sold the Impala (with a nice set of snow tires I might add) and bought the CR-Vw/AWD.

Octo13er

 

Power Train Description

http://www.hondanews.com/categories/844/releases/3653

 

Here, on the Honda CR-V, engineering overview site you can get some good descriptions of the various goodies that the CR-V has:

http://automobiles.honda.com/models/engineering_overview.asp?ModelName=CR%2DV

.

 

Real Time 4WD functionality

So... I read the real time 4WD explanation on the link provided in one of the mails in this thread. It mentions dual hydraulic pumps transferring power to the rear wheels when the front wheels lose traction. Does that mean that both rear wheels become drive wheels, or does it basically function like a normal 2WD without traction control where you really have only one drive wheel? I had a 1999 Subaru Outback that could get stuck with both drivers side wheels on ice even though both passenger side wheels were on dry ground. That really surprised me for a vehicle marketed as AWD. I believe the new Subarus won't do that.
At least the CRV has traction control in the front which would presumably prevent that from happening.

 

The 2010 Forester does´nt seem to have any kind of helpsystem to prevent the situation you described. Ne and a friend tested that with a 2010 Forester on a 15% upphill. One side wheels on gravel, and the other side on ice. The Forester slipped backwards. Did the same with my 2008 CR-V. The wheels on ice made a very short slip and then the brakes were applied on the slip side moving torque to the other side and the car moved up like if the 4 wheels where on tarmac. I am very impressed with Hondas Realtime 4wd-system. And not so impressed by Subarus symmetrical awd;-)

So... I read the real time 4WD explanation on the link provided in one of the mails in this thread. It mentions dual hydraulic pumps transferring power to the rear wheels when the front wheels lose traction. Does that mean that both rear wheels become drive wheels, or does it basically function like a normal 2WD without traction control where you really have only one drive wheel? I had a 1999 Subaru Outback that could get stuck with both drivers side wheels on ice even though both passenger side wheels were on dry ground. That really surprised me for a vehicle marketed as AWD. I believe the new Subarus won't do that.
At least the CRV has traction control in the front which would presumably prevent that from happening.

 

I would love to have a 4WD lock on the CR-V I know it goes against the vehicles soul of being easy to use but someties you want 4wd locked in. I havent gotten a chance to use it in the snow but am looking forward to it performing well.

 

How does 4wd real time works

Dear fellows.

Does anyone knows how 4wd real time system works on 2007 CR-V?

Greetings everyone, from Portugal.

 

Dear fellows.

Does anyone knows how 4wd real time system works on 2007 CR-V?

Greetings everyone, from Portugal.

A simple explanation is there are two pumps one for the front and one for the back. There is a clutch pack connecting the front to back which is normally disengaged. As the wheels turn they turn the pumps. When the wheels turn at the same speed so do the pumps and they create equal pressure so the clutch pack stays disengaged. Once the front or back wheels begin to turn at different speeds the pumps also turn at different speeds creating different pressures which causes the clutch pack to engage connecting the front to back so they can all turn at the same speed which is now four wheel drive. Since the wheels are now turning at the same speed the pump pressure equalizes allowing the clutch pack to disengage and it is back to two wheel drive and the process repeats as needed.

 

There's a video that explains this on the Honda USA web site.

 

how it works?

Hi, That is a great explanation, thanks, and it makes sense, my only question is as it cuts in/out as required, it seems to me that if you are on surface that is totally slip/grip, the system will be cutting in/out continuously, making the driving feel very juddery (does that make sense), if i could have a button that did one thing, it would be to select permanent 4wd for speeds upto 25-30mph, then the slip grip situation wouldnt occur. however, i'm very happy to have a crv (given the current weather forecasting)

 

Hi, That is a great explanation, thanks, and it makes sense, my only question is as it cuts in/out as required, it seems to me that if you are on surface that is totally slip/grip, the system will be cutting in/out continuously, making the driving feel very juddery (does that make sense), if i could have a button that did one thing, it would be to select permanent 4wd for speeds upto 25-30mph, then the slip grip situation wouldnt occur. however, i'm very happy to have a crv (given the current weather forecasting)

The operation of it cutting in and out is pretty smooth, it's on a multi-plate clutch.

 

Multiple Threads Merged.

 

I think a 4x4 lock button would be an advantage All the other compact suvs like the toyota rav ,kia santa fe and mitstubishi outlander have this . the lock system automatically disengages at speeds above 25 mph
I have had subarus with permanent awd up to now so in the coming winter will have a chance to see how my new honda crv compares.

 

Here is a very good demonstration of some of the various systems trying to climb a slight incline with rear grip, front grip, one front grip and one rear grip. The CR-V is first to go. The CR-V is Asymetrical real time AWD. http://www.youtube.com/watch?v=2OzK-oRPCbs

 

The Subaru video has been discussed before in this forum. Many forum members felt that the video was very pro-Subaru, and there was discussion about whether the comparison was fair.

In the tough winter in the Northeast US a few months ago, my 4WD CRV drove just fine. Driving sensibly, it drove right through several inches of snow without any problem. I felt the 4WD, ABS and/or VSA kick in as appropriate, clearly working to keep the car straight and in control.

Whatever the technology is on the CRV, I am happy with it.

 

IME the CRV has been a good snow/ice performer even with a/s Michelin x....I have intentionally spun the CRV front wheels on snow covered roads and driveways with a decent incline and got nothing but forward motion. Turning the VSA off on the same snow covered incline road produced some excitement (front wheel spin/side shifting) but confident forward motion again. The CRV was momentarily stuck passing through an unplowed road that exceeded the ground clearance that would be challenging for any suv.