Let me end the controversy.
The REAL TIME 4WD Dual Pump System has a hydraulic clutch and a
differential mechanism in the rear differential assembly.
Under normal conditions the vehicle is driven by front wheels .
However depending on the driving force to the front wheels and the road
conditions , the system instantly transmits appropiate driving force to
the rear wheels without requiring driver input.The switching mechanism
between 2WD & 4WD is intergrated into the rear differential assembly to
make the system light & compact.
In addition , the dual pump system switches off the rear
wheeldrive force when braking in a forward gear. Thi allow the ABS
system to work properly.
When there is a difference in rotation speed between the front
wheels (clutch guide) and rear wheels(hypoid driven gear) , hydraulic
pressure from the front and rear oil pumps( NOTE 2 PUMPS) engage the
differential clutch and drive force from the transfer assembly is
applied to the rear WHEELS( PLURAL LEFT & RIGHT AT THE SAME TIME)
The hydraulic pressure control mechanism in the oil pump body selects
4 WD mode when the vehicle is started abruptly , or when accelerating in
a forward or a reverse gear ( causing rotation difference between the
front and rear wheels) or when braking in reverse gear . lt switches to
2WD mode when the vehicle is driven at a constant speed in forward or
reverse gear(when there is no rotational difference between the front
and rear wheels) or when braking in a forward gear.



For more details and/or pictures contact me and will arrange a snail
mail transfer of data. No l don't have a scanner and l type via hunt
and peck so this epistle was long and tedious.
Thank MSN for "Spell-Check"


Regni
Only Wiith Age Comes Wisdom

> When there is a difference in rotation speed between the front
> wheels (clutch guide) and rear wheels(hypoid driven gear) , hydraulic
> pressure from the front and rear oil pumps( NOTE 2 PUMPS) engage the
> differential clutch and drive force from the transfer assembly is
> applied to the rear WHEELS( PLURAL LEFT & RIGHT AT THE SAME TIME)

I don't know why you are screaming. (all caps above) but I do hope you are
not trying to say that if 4WD is activated on a CR-V then both rear wheels
will have the same power applied to them. I can go out tonight and shoot a
video of my CR-V and post it on a website somewhere if you like. This video
will show you that it is possible to have one rear tire spinning and the
other one stuck in place.

In fact I may just go ahead and do that anyways.

Rene

This is exactly the definition I was looking for.  Very Mechanical.
 
So my next question is this.
 
You mentioned both rear tires will turn if the system detects slippage or differing speeds of Tire rotation.
 
Will Both Front Tires turn as well then?
 
Basically If I understand your description if you are stuck in mud all four tires or at least 3 will turn and thus aid in getting you unstuck.
 
 
These seems to me to be as good as any true 4WD truck?
 
 
 
 

OK now I'm confused again.
 
 

What about the Drive force transfer assembly  applied to the front Tires?
 
2 tires or 1
 
 

Both rear tires can spin. Both will not necessairy spin. Same goes for the front.
 
If you are stuck in the mud, chances are that only one front and one rear tire will spin... the ones with the least traction.
 
This is not as good as any true 4WD truck as a TRUE 4WD truck will behave exactly as my quad does, all 4 wheels will spin at the same speed. This is only good at low speeds and on surfaces where the tires can slip on the ground. By this I am referring to when you turn a TRUE 4WD vehicle the wheels on the outside of the turn travel farther the the wheels on the inside. Something has to give. If not slippage on the surface then something in the drivetrain will go pop!
 
Differential slip can be your friend. Locking you differentials is something that most people (especially those that buy a CR-V) who stay primarily on highways and only seldom venture off of the beaten path (even then is's usually not a very unbeaten path) will never need or want to have to worry about using.
 
The CR-V is a good 4WD vehicle and can handle itself... but it is not an off-road vehicle! Some of us use it like one (me me me) but we also have to understand that it is no where as capable as a true off-road vehicle is.
 
Any questions?
 
Rene
 
 

So has anyone developed a way to temporarily lock or trick the 4wd system
into staying in 4wd for a short period of time (like crossing a patch of
soft sand or mud...)

Anybody????

other then keeping the front tires spinning, nope. It's a mechanical system,
no wiring trickery is going to work here unfortunately.

The only way I can see would be to air down the front tires big time so they
are turning faster then the rear tires (or replacing the front tires with
shorter rubber). But even then it would have to be more then a 2% (iirc)
difference in speed.

Rene

I spoke to a Honda Service Technician last
night regarding the CRV Real-Time 4WD and other manufacturer’ all wheel
drive systems.? They all basically work the same.? They are limited Slip front
and rear which means most likely it is mainly a front wheel drive vehicle and
both front tires will spin but if it is detected that one tire has less
traction or less friction the torque or power will be transferred to that tire
(same as on any front wheel drive car). ?Now with the CRV as the front tires
spin faster, the rear tires will engage, but again if you where to get stuck
like in your picture with two tires (Lets say your right rear and front) in
snow, mud or on glare Ice and the left front and rear tires on pavement the
left tires will do nothing and the right tires will spin.? Thus the real time
4WD will do nothing to help you get out.

 

But a vehicle that allows you to place it
in 4WD Low or High the rear tires will actually have locked differential but
the front will have limited slip so you could have a front tire spinning while
the other front tire does nothing and both rear tires will spin to aid in
getting you unstuck.? Even vehicles similarly priced like the Jeep Liberty have
a better 4WD system for getting you Unstuck.

 

As the Service Technician indicated Honda
is not after this more rugged market within Canada and is trying to appeal to
the upper class that want a good quality SUV with more traction for highway, or
city driving but not for off road type of driving.

 

 

Rgds

 

Hi Shawn,

Your description of how the CRV's drive train works is a good one, but
I thought I'd clarify the 4WD Low or High description a bit...

A transfer case with a Low and High range doesn't improve a vehicle's
traction. My Land Rover has a high and low range, but will still get
stuck if one front wheel and one rear wheel don't have any traction.
Why? Because its front and rear differentials are of the "open" design
and not limited-slip. So the Jeep Liberty would have a better chance of
getting unstuck, not because of a low-range transfer case, but rather
because of a limited-slip differential.

A limited-slip differential, like the one on the Honda Pilot, would be
a nice addition to the CRV. Maybe it will be in the next generation
version.

Take care.

Karl

I was just about to say the same. I got stuck in my 4WD truck yesterday
while facing downhill. (Plow on front makes her kinda front end heavy
sometimes. (IMG:style_emoticons/default/smile.gif) ) Only one front and one rear tire would spin. As far as I
know limited slip and locking rear differential are still two completely
different beasts as well. (If you are wondering about my truck and my cr-v
experiences check out my website at www.geocities.com/renejeddore)

The way I take it is that a limited slip can still have one tire turning
faster then the other (the limited part) while a locking rear differential
locks both rear tires at the same speed. Limited slip is still good for use
on dry pavement. Locked rear differential is only good in a perfectly
straight line or on a slippery (loose) surface.

Rene

Limited Slip Differential, from a site found throud bings post...

If you have a limited slip differential, You have a 3 wheel drive; the LSD
(no drug jokes please) reacts to excessive "Slip" (speed differences)
between the two wheels. When enough is "Detected", it slowly engages, untill
both wheels are getting the same amount of power (almost, but close enough
for most driving). This is obviously better for traction.

The CR-V does not have a LSD front or rear. LSDs are available for Civics
and other cars for drag racing purposes.

This is fun isn't it! I think we are all learning a bit here today (and the
past few days.)

Rene

Rene wrote
"I don't know why you are screaming. (all caps above)
Some things need to be emphasised.

but I do hope you are not trying to say that if 4WD is activated on a
CR-V then both rear wheels will have the same power applied to them.
Yes. The same power . But they may not have the same traction.

I can go out tonight and shoot a video"

Bring it on.


Regni
Only Wiith Age Comes Wisdom

Perhaps the confusion is with the definition of Limited Slip.

The service Technician indicated all Front Wheel Drive cars are Limited
Slip as opposed to locked differential or Pausy traction (Spelling?)


??

Shawn Graham
Cost Accountant, Operations Finance
Alcatel Canada Inc.
349 Terry Fox Drive
Kanata, Ontario
K2K 2V6

Tel: 613-784-3958
Fax: 613-591-1960
Email: shawn.graham@...

Sgraham wrote
" turn if the system detects slippage or differing speeds of
Tire rotation.?
Will Both Front Tires turn as well then ?"
etc.


Power will be applied to all wheels
And here again , traction will dictate .


Regni
Only Wiith Age Comes Wisdom

Ok, I will have the video tomorrow hopefully... when I can see more then a
few feet in front of me and the wind is a bit calmer.

Hard to see in the picture but it is nasty out!

Rene

P.S. That's my truck (with open differentials) with the plow gear on the
front! (IMG:style_emoticons/default/smile.gif)


> Bring it on.


Attachment: (image/jpeg) 168-6813_img.jpg [not stored]

Limited slip is a special kind of differential. As far as I know our CR-Vs
have what's referred to as an open differential.

Pausy = Posi = positive traction = GM Limited Slip (just got off of the
phone with my mechanic, GM put it on some trucks and called it posi-trac).

Limited Slip found on some vehicles, but not many (afaik).

Locked differential is a very special item. It is not found on 99% (my
figure here) of 4WD/AWD vehicles. You should only go slow and you need a
loose surface to make a turn without breaking anything.

Some front wheel drive cars may be limited slip. Most I know of are not
however. Go out in a friends front wheel drive car. put one tire on ice and
the other on pavement and try to pull away with any amount of speed. See how
fast you move forward.

I can guarantee you that the front wheel drive vehicles that I have been in
are not Limited Slip... unless limited slip works a lot like an open
differential. Only one tire will spin. I can go home this evening and try
out a 2003 Toyota Celica GT (nope, not the better GT-S which probably has a
LSD), a 1993 Mazda Precedia V6 (maybe this one has a LSD, it definately gets
around better with all-seasons then the Celica with pure studded winter
tires), a 1995 Honda Civic DX, a 1988 GMC Sierra 4x4, a 2000 Honda CR-V and
a Polaris SportsMan 400 Quad with True 4WD and I can video the differences.
I only have a dial up so I will not be able to email these videos to people
but I would be willing to upload them once for storage on a web site
somewhere.

This could prove to be interesting for me as I never considered a LSD in the
Precedia being the reason why it gets around so nicely.

Rene