My 98 CRV Build, RT4WD Inside...
#27
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
that a sick build bud. never really seen anyone do that with a crv. keep posting. would love to know a bit more about it.
#29
Honda-Tech Member
Thread Starter
Re: My 98 CRV Build, RT4WD Inside...
I have an entire turbo kit (minus IC piping, and injectors) sitting on my shelf at home for this thing (Turbonetics 60-1, BB, "Big shaft", .70 a/r compressor, .63 a/r turbine.)
There is a couple things that is preventing me from installing it all.
1) fabrication. My main excuse is that my welder is broke lol. I need to make custom IC piping and get creative with the downpipe as well. This will still retain p/s and a/c so there is going to be some extensive fabrication involved. (putting off fixing my welder, is keeping me from fabricating that stuff, and ultimately making me stick to my plans instead of saying "screw it" and fabbing/installing the turbo stuff before I iron the rest of the stuff out....basically the broken welder is my "fail safe" haha)
2) breaking stuff. From the little racing i've done this year, its already needing things replaced. I've got a bad wheel bearing in the left front, ALL of the suspension bushings need replaced, Lower ball joints that i replaced last year (after a stuck upper control arm incident) are junk again (low quality parts) etc etc....basically, this thing has 199,xxx thousand miles on it...and a LOT of repair/replace needs to happen to a LOT of parts on this thing before i get too serious with HP. already weak components tend to take a **** super fast when you start laying down serious HP lol. (I would rather be slow, than broken )
Video of the "Time Attack" event courtesy of Shenrie!!! (cam is mounted on the roof of his Civic hatch) Dont mind my "off" in the vid, I had a crash course in fuel managment that day....coming down off the bank, into the infield...apparently its the perfect directional force to make 3/8's of a tank of gas move completely away from the fuel pump pick up and apparently when that happens you loose all power from the engine
I knew there was a slew of cars behind me (My first time racing in a crowd as well) So when the engine fell on its face, I lost all concentration and just locked up the brakes because I thought the car had actually died (as in turned off) and pretty much panic'd lol...In turn, running off into the dirt.
Might have an update at the end of the weekend...Since i've been following 88ED8's build, ive convinced myself to do his "big axle conversion" with my spare diff....but in the mean time, i figured why the hell not weld up the stock diff since the spider gears will be replaced by b-series fwd gears anyways! At least give me an idea how part time 3 wheel drive will handle during the winter months...
#30
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
i like the course... its technical!??! loooks like more fun to me... i remember the first time
i ran my V on the track a lot of peeps were punning me but when they saw that it can keep
up w/ some of the novice drivers/cars that shut them down! one thing that made me push
my V much further is that im using a bucket seat, im well strapped down while attcaking
those corners and turns, before the bucket seat.. my knees and legs were swelling after
each track days.. i have to lean and use then against the sidings and shifter console for
me not to be thrown nside..LOL!
anyway nice vid!!!
i ran my V on the track a lot of peeps were punning me but when they saw that it can keep
up w/ some of the novice drivers/cars that shut them down! one thing that made me push
my V much further is that im using a bucket seat, im well strapped down while attcaking
those corners and turns, before the bucket seat.. my knees and legs were swelling after
each track days.. i have to lean and use then against the sidings and shifter console for
me not to be thrown nside..LOL!
anyway nice vid!!!
#32
DO IT ON ALL FOURS
Re: My 98 CRV Build, RT4WD Inside...
What exactly is giving you problems with install ideas? Where are you wanting to place the turbo in the engine bay? Also what were you thinking for an intercooler?
Also, just my perspective but your driving is all over the place. Stick to it and keep practicing, eventually you should get better.
Also, just my perspective but your driving is all over the place. Stick to it and keep practicing, eventually you should get better.
#33
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Re: My 98 CRV Build, RT4WD Inside...
^^^ it was his first day on a track ever (other than a dragstrip). He was just feeling out the different lines and getting a feel for how the V would do on certin lines, basically finding its limits. none of us are pros by any means, just out having a good time taking life off our cars. IMHO, he has jumped leaps and bounds this season (from what Ive seen in the past) with the very little seattime hes had. Plus, he puts family first, like a real man should do, and its kept him from a LOT of events this season. This time next year, if hes able to make a few events, I guarantee he will have much better lines
Lol, but it would be a little easier for him if he stayed with one vehicle or even vehicle type...integra to gs300 to crv (then to a civic coupe when that project is done).
Lol, but it would be a little easier for him if he stayed with one vehicle or even vehicle type...integra to gs300 to crv (then to a civic coupe when that project is done).
#34
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
I'd be a happy man if mine behaved like this..
http://www.youtube.com/watch?v=YiQ6F...feature=relmfu
http://www.youtube.com/watch?v=YiQ6F...feature=relmfu
#35
Honda-Tech Member
Thread Starter
Re: My 98 CRV Build, RT4WD Inside...
i like the course... its technical!??! loooks like more fun to me... i remember the first time i ran my V on the track a lot of peeps were punning me but when they saw that it can keep up w/ some of the novice drivers/cars that shut them down! one thing that made me push my V much further is that im using a bucket seat, im well strapped down while attcaking those corners and turns, before the bucket seat.. my knees and legs were swelling after each track days.. i have to lean and use then against the sidings and shifter console for me not to be thrown nside..LOL!
anyway nice vid!!!
anyway nice vid!!!
What exactly is giving you problems with install ideas? Where are you wanting to place the turbo in the engine bay? Also what were you thinking for an intercooler?
Also, just my perspective but your driving is all over the place. Stick to it and keep practicing, eventually you should get better.
Also, just my perspective but your driving is all over the place. Stick to it and keep practicing, eventually you should get better.
As far as my driving...Shenrie hit it on the head. I am all over the place on purpose. That vid was taken during my second session ever on that track. 1st session i just felt things out and got used to having other cars on the track with me. 2nd session I was hunting for a proper line to take...3rd session I was flat out trying for the best time possible. Ended up with a 35.02 which was .8 seconds off a modified Subaru wagon, and about 3.5 seconds off the fastest (record lap setting) Evo's and Miata's. So yea I suck when it comes to turning left and right...but then again, this is my hobby that I do when I can...Not trying to be a pro here lol (the goal for next year is to finish in the top half of the results, not the bottom half lolololol)
You and me both man, hot damn that thing is a beast! Just googled it and checked out the build thread on it...Impressive!!
#36
Honda-Tech Member
Thread Starter
Re: My 98 CRV Build, RT4WD Inside...
^^^ it was his first day on a track ever (other than a dragstrip). He was just feeling out the different lines and getting a feel for how the V would do on certin lines, basically finding its limits. none of us are pros by any means, just out having a good time taking life off our cars. IMHO, he has jumped leaps and bounds this season (from what Ive seen in the past) with the very little seattime hes had. Plus, he puts family first, like a real man should do, and its kept him from a LOT of events this season. This time next year, if hes able to make a few events, I guarantee he will have much better lines
Lol, but it would be a little easier for him if he stayed with one vehicle or even vehicle type...integra to gs300 to crv (then to a civic coupe when that project is done).
Lol, but it would be a little easier for him if he stayed with one vehicle or even vehicle type...integra to gs300 to crv (then to a civic coupe when that project is done).
#37
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
i remember my Vs maiden voyage on the track...LOL! i was all over the place too! i was
trying different lanes and approach also assessing what kind of driving should i be thinking
once im in my V, coz i tell you its different from driving a regular car.. its like making the
crv and you as one, itll develop through time and lots of track days.. i have my V on track
for almost 2 full race seasons but still im discovering new things/tricks everytime we head
out.. every start of the track season i would ask the course officials if i could run w/ the
newbies coz itll give me enough time to adjust before i ran w/ the pro's and novices...
too bad we havent had that much track sessions this year compared to the past 2-3years!
trying different lanes and approach also assessing what kind of driving should i be thinking
once im in my V, coz i tell you its different from driving a regular car.. its like making the
crv and you as one, itll develop through time and lots of track days.. i have my V on track
for almost 2 full race seasons but still im discovering new things/tricks everytime we head
out.. every start of the track season i would ask the course officials if i could run w/ the
newbies coz itll give me enough time to adjust before i ran w/ the pro's and novices...
too bad we havent had that much track sessions this year compared to the past 2-3years!
#38
Re: My 98 CRV Build, RT4WD Inside...
just got a couple things:
First off the car I recently bought a 2000 Cr-V tr4wd ex 5 speed with 160k miles on it, car is 100% unmolested stock base which is what i was looking for on a project like this, since i have never owned a crv or know anyone that has i wanted a solid base upon which to beast
Next this thread is f'n awesome it answered a ton of questions i had on my Cr-V from the shims to finding out parts will be available and most likely recently priced once I break something
Last but not least when i bought this car i also sold my 03 type s for cash plus a partial trade and what that trade included was a: 1.8L ls/vtec, block is studded with cp 9:1 pistons, cp rings, eagle rods, seriously pnp'd itr head casting with itr springs and retainers with b16 stg2 cams, any bolts that can be arp are, with a turbonetics 20g turbo w/ a stg 2 turbine, b16 mani, evo 460cc injectors, greddy bov, no name waste gate im gonna be going with a air2water IC setup(need to keep system as sealed as possible) and some other misc sh*t. The motor will be going in in about 3 weeks prolly then after break in will be putting the turbo on. The end factor of this build is to have actually have an off road Cr-V that has some power behind it but until the lift kit comes in(takes about 3 months) i will be running around on the normal tires around 12 lbs of boost. I am having it done at a local performance shop im all about doin stuff myself but this car will also be my daily so i need it to be turn key everyday and be done quick and not have problems so for this im turning to a professional lol but we will be posting a build thread and lost of pics for y'all and ill be sure to put updates on how it does under boost @ around 300hp maybe a little more how it feels will determine the amount of boost we throw at it.
First off the car I recently bought a 2000 Cr-V tr4wd ex 5 speed with 160k miles on it, car is 100% unmolested stock base which is what i was looking for on a project like this, since i have never owned a crv or know anyone that has i wanted a solid base upon which to beast
Next this thread is f'n awesome it answered a ton of questions i had on my Cr-V from the shims to finding out parts will be available and most likely recently priced once I break something
Last but not least when i bought this car i also sold my 03 type s for cash plus a partial trade and what that trade included was a: 1.8L ls/vtec, block is studded with cp 9:1 pistons, cp rings, eagle rods, seriously pnp'd itr head casting with itr springs and retainers with b16 stg2 cams, any bolts that can be arp are, with a turbonetics 20g turbo w/ a stg 2 turbine, b16 mani, evo 460cc injectors, greddy bov, no name waste gate im gonna be going with a air2water IC setup(need to keep system as sealed as possible) and some other misc sh*t. The motor will be going in in about 3 weeks prolly then after break in will be putting the turbo on. The end factor of this build is to have actually have an off road Cr-V that has some power behind it but until the lift kit comes in(takes about 3 months) i will be running around on the normal tires around 12 lbs of boost. I am having it done at a local performance shop im all about doin stuff myself but this car will also be my daily so i need it to be turn key everyday and be done quick and not have problems so for this im turning to a professional lol but we will be posting a build thread and lost of pics for y'all and ill be sure to put updates on how it does under boost @ around 300hp maybe a little more how it feels will determine the amount of boost we throw at it.
#39
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
I am trying to get a LSD made for the Honda CRV '98-'01 AWD trans, it is not gunna happen anytime soon I'd imagine but I'm looking for people who are interested in this idea as well, lmk?!
#40
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
of our Vs is similar to a LSD... one issue that'll occur is to how itll affect the engagement
of the 4wd, i think if we could hack some parts from 4wd dsm's or evo we could make this
happen...
for one thing i was looking for a 5spd rtawd tranny then, i was looking to buy the obx lsd
from ebay, i bought the lsd but couldnt find a tranny 2-3yrs back, i was so eager on what
would be the effect... in my thought " this is one expensive experiment " LOL!
now, since you guys are more knowledgeable than me, of course! we should make this into
a good upgrade/mod for our Vs...
#41
Re: My 98 CRV Build, RT4WD Inside...
I was trying to figure out if LSD could be swapped into a 5 speed tranny last summer too. Once numbers started comin in and I saw how broke I was about to be, I bailed on it. I hope you guys can figure it out cause I would LOVE a little more hook up and my CRV.
Keep up the good work on the build! You got some interesting stuff on here.
Keep up the good work on the build! You got some interesting stuff on here.
#42
Honda-Tech Member
Re: My 98 CRV Build, RT4WD Inside...
Anyone who may know, what is the rear diff ratio on the Kseries rt-4wd? I know the Bseries rt-4wd rear diff ratio is 2.5333333, I'm wondering what the K stuff is.
#44
Honda-Tech Member
Thread Starter
Re: My 98 CRV Build, RT4WD Inside...
Thanks for the compliments guys! Havent worked on this pig lately...been busy with family/holiday stuff and super busy at work lately. I've been tossing around lots of ideas on the rt4wd system, and havent settled on a plan of action yet. I want to implement something that will be relatively easy to duplicate for everyone else, while still maintaining the "automatic" nature of the system, but allowing for a manual or electronic change in the TCD activation. But something that doesnt require extensive modification of the system.
now im tossing around the idea of using an ABS pump to control the fluid pressure of the rear pump (since its the only one that really matters) which is controlled via the ECU based on ABS wheel speed sensors....would take a chipped ecu running one of the popular tuning softwares to accomplish this...but could be invaluable for the "tuner" looking to improve upon the stock system. still in the brainstorming stage here.
also toying with the idea of lifting the crv for the winter...coming up with $$ to buy wheels/tires is the hardest part during this time of year lololol.
Right now i've taken the 18's and Azenis off for the winter....currently sitting on 5 lug prelude "blades" with 225/55/16 Hankook snow tires...Cant wait for the local snow hill to open!! Will get pics of her in "winter mode" this weekend...
now im tossing around the idea of using an ABS pump to control the fluid pressure of the rear pump (since its the only one that really matters) which is controlled via the ECU based on ABS wheel speed sensors....would take a chipped ecu running one of the popular tuning softwares to accomplish this...but could be invaluable for the "tuner" looking to improve upon the stock system. still in the brainstorming stage here.
also toying with the idea of lifting the crv for the winter...coming up with $$ to buy wheels/tires is the hardest part during this time of year lololol.
Right now i've taken the 18's and Azenis off for the winter....currently sitting on 5 lug prelude "blades" with 225/55/16 Hankook snow tires...Cant wait for the local snow hill to open!! Will get pics of her in "winter mode" this weekend...
#46
Honda-Tech Member
Thread Starter
Re: My 98 CRV Build, RT4WD Inside...
Ok just to keep some information stored in one place...I had a friend (Shenrie on here) pick up a wagon rt4wd manual, and here is the ratio's posted in the Honda Service Manual for the wagon.
manual 4wd:
SL - 4.512
1st - 3.384
2nd - 1.950
3rd - 1.275
4th - .941
5th - .783
reverse - 3.000
reduction - 4.428
rear diff:
reduction - 2.529
ring gear - 43t
dr pinion - 17t
side gear - 16t
pinion - 10t
this may or may not help someone...but I just wanted to make sure I posted it on here for people to find.
manual 4wd:
SL - 4.512
1st - 3.384
2nd - 1.950
3rd - 1.275
4th - .941
5th - .783
reverse - 3.000
reduction - 4.428
rear diff:
reduction - 2.529
ring gear - 43t
dr pinion - 17t
side gear - 16t
pinion - 10t
this may or may not help someone...but I just wanted to make sure I posted it on here for people to find.
#48
Re: My 98 CRV Build, RT4WD Inside...
your research has been very insightful and i like your theory w/ the shims, but to me it seems like adding shims would only change the speed of engagement, thus making it come it sooner... remember the "pressure plate" is still only exerting a certain amount of force... however if you played w/ the relief valve, as shown in your diagram, that would increase pressure to the clutch pack, increasing the holding strength of the clutches... i think a combination of the two will make for a great combination... i will experiment w/ this on my awd ek... heres the link for my build, as i dont want to clog up yours w/ pics of my stuff... awd starts on page 3...
https://honda-tech.com/forums/forced-induction-16/ek-sleeper-top-mount-back-door-ic-c-2976240/
pay attention to the description of the relief valve...
https://honda-tech.com/forums/forced-induction-16/ek-sleeper-top-mount-back-door-ic-c-2976240/
pay attention to the description of the relief valve...
#49
DO IT ON ALL FOURS
Re: My 98 CRV Build, RT4WD Inside...
"draggbody" - This system is a very basic hydraulic system. Thanks for the schematics; do you have more?
"fast2camciv" are there any updates on this or has it been abandoned?
"fast2camciv" are there any updates on this or has it been abandoned?
Last edited by It Wasn't Me; 01-23-2012 at 12:13 AM. Reason: quote removed. just report it next time.
#50
Re: My 98 CRV Build, RT4WD Inside...
from my all data program...
Description and Operation
DESCRIPTION
REAR DIFFERENTIAL
Outline
The Real-time 4WD-Dual Pump System model has a hydraulic clutch and a differential mechanism in the rear differential assembly. Under normal conditions, the vehicle is driven by the front wheels. However, depending on to the driving force of the front wheels and the road conditions, the system instantly transmits appropriate driving force to the rear wheels without requiring the driver to switch between 2WD (front wheel drive) and 4WD (four wheel drive). The switching mechanism between 2WD and 4WD is integrated into the rear differential assembly to make the system light and compact.
In addition, the dual-pump system switches off the rear-wheel drive force when braking in a forward gear. This allows the braking system to work properly on models equipped with an Anti-lock Braking System ABS).
Construction
The rear differential assembly consists of the torque control differential case assembly and the rear differential carrier assembly. The torque control differential case assembly consists of the differential clutch assembly, the companion flange, and the oil pump body assembly. The rear differential carrier assembly consists of the differential mechanism. The differential drive and driven gears are hypoid gears.
The oil pump body assembly consists of the front oil pump, the rear oil pump, the hydraulic control mechanism, and the clutch piston. The clutch piston has a disc spring that constantly provides the differential clutch assembly with a preset torque to prevent abnormal sound.
The clutch guide in the differential clutch assembly is connected to the propeller shaft via the companion flange, and it receives the driving force from the transfer assembly. The clutch guide rotates the clutch plate and the front oil pump in the oil pump body.
The clutch hub in the differential clutch assembly has a clutch disc that is splined with the hypoid drive pinion gear. The hypoid drive gear drives the rear oil pump.
The front and rear oil pumps are trochoidal pumps. The rear oil pump capacity is 2.5 percent larger that the front oil pump to handle the rotation difference between the front and rear wheels caused by worn front tires and tight corner braking. The oil pumps are designed so the fluid intake works as a fluid discharge when the oil pumps rotate in reverse. Genuine Honda CVT fluid is used instead of differential fluid.
Operation
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 engages the differential clutch, and drive force from the transfer assembly is applied to the rear wheels.
The hydraulic pressure control mechanism in the oil pump body selects 4WD mode when the vehicle is started abruptly, or when accelerating in a forward or reverse gear (causing rotation difference between the front and rear wheels), or when braking in reverse gear (when decelerating). It switches to 2WD mode when the vehicle is driven at a constant speed in forward or reverse gear (when there is no rotation difference between the front and rear wheels), or when braking in a forward gear (when decelerating).
To protect the system, the differential clutch assembly is lubricated by hydraulic pressure generated by the oil pumps in both 4WD and 2WD modes. Also, the thermal switch relieves the hydraulic pressure on the clutch piston and cancels 4WD mode if the temperature of the differential fluid rises above normal.
HYDRAULIC FLOW
Forward Start and Acceleration (4WD)
During a forward start and forward acceleration, the dual pump system can engage four wheel drive. If the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front pump draws fluid through check valve B and discharges it. Some of the discharged fluid is drawn in the by the rear oil pump. The remaining fluid will pass through check valve E into the clutch piston. There, hydraulic pressure is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston pushes the plates and discs of the clutch together to form a connection. The engaged clutch then passes driving force from the transfer assembly to the rear wheels, producing 4WD.
Forward Driving at Constant Speed (2WD)
When driving forward at a constant speed (cruising), the dual pump system functions in two wheel drive mode. The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same. Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. Because there is no pressure built up at the clutch piston, the clutch does not engage, and the vehicle remains in 2WD (front wheel drive).
Forward Deceleration (2WD)
During forward deceleration, the dual pump system functions in two wheel drive mode.
Because of braking characteristics, the speed of the rear wheels may exceed the speed of the front wheels during deceleration. If so, the rear oil pump spins faster than the front oil pump.
Fluid discharged by the rear oil pump is simply drawn in again by the rear pump and recirculated. Because there is no pressure built up at the clutch piston, the clutch piston does not engage, and the vehicle remains in 2WD (front wheel drive).
Reverse Start and Acceleration (4WD)
During reverse start and reverse acceleration, the dual pump system can engage four wheel drive.
If the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front oil pump draws in fluid through check valve A and discharges it. (Note that in reverse, the direction of the pumps is the opposite of that during forward driving.)
Some of the fluid that is discharged by the front oil pump is drawn in by the rear oil pump. The remaining fluid passes through check valve F into the cylinder of the clutch piston, where it is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a connection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
Reverse Driving at Constant Speed (2WD)
When driving in reverse at a constant speed, the dual pump system functions in two wheel drive mode.
The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same. Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. But, because the there is a difference in the capacity between the two pumps, fluid flows through check valve E, and then through orifices. This fluid lubricates and cools the clutch assembly and bearings.
Is this condition, only a low pressure is built up at the clutch piston. Therefore the clutch does not engage, and the vehicle remains in 2WD (front wheel drive).
Reverse Deceleration (4WD)
During reverse deceleration, the dual pump system can engage four wheel drive.
When decelerating in reverse direction, the speed of the rear wheels may exceed the speed of the front wheels (due to engine braking). In this condition, the rear oil pump draws fluid through check valves B and C. Fluid discharged from the rear oil pump then flows through check valve E to the clutch piston. There, pressure is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a connection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
Thermal Switch Operation (2WD)
During 4WD operation, pressure-regulated fluid is in contact with the clutch piston and the thermal switch.
If the temperature of the fluid in the differential goes too high, the thermal switch pushes open the relief valve R. This causes the pressure in the clutch piston to drop, and 4WD mode is disengaged.
Relief Valve Operation
When the fluid pressure goes higher than the relief valve spring force, check valve R opens. Pressure applied at the clutch piston is held constant. This feature adds stability by preventing the rear wheel drive system from experiencing excessive torque.
Description and Operation
DESCRIPTION
REAR DIFFERENTIAL
Outline
The Real-time 4WD-Dual Pump System model has a hydraulic clutch and a differential mechanism in the rear differential assembly. Under normal conditions, the vehicle is driven by the front wheels. However, depending on to the driving force of the front wheels and the road conditions, the system instantly transmits appropriate driving force to the rear wheels without requiring the driver to switch between 2WD (front wheel drive) and 4WD (four wheel drive). The switching mechanism between 2WD and 4WD is integrated into the rear differential assembly to make the system light and compact.
In addition, the dual-pump system switches off the rear-wheel drive force when braking in a forward gear. This allows the braking system to work properly on models equipped with an Anti-lock Braking System ABS).
Construction
The rear differential assembly consists of the torque control differential case assembly and the rear differential carrier assembly. The torque control differential case assembly consists of the differential clutch assembly, the companion flange, and the oil pump body assembly. The rear differential carrier assembly consists of the differential mechanism. The differential drive and driven gears are hypoid gears.
The oil pump body assembly consists of the front oil pump, the rear oil pump, the hydraulic control mechanism, and the clutch piston. The clutch piston has a disc spring that constantly provides the differential clutch assembly with a preset torque to prevent abnormal sound.
The clutch guide in the differential clutch assembly is connected to the propeller shaft via the companion flange, and it receives the driving force from the transfer assembly. The clutch guide rotates the clutch plate and the front oil pump in the oil pump body.
The clutch hub in the differential clutch assembly has a clutch disc that is splined with the hypoid drive pinion gear. The hypoid drive gear drives the rear oil pump.
The front and rear oil pumps are trochoidal pumps. The rear oil pump capacity is 2.5 percent larger that the front oil pump to handle the rotation difference between the front and rear wheels caused by worn front tires and tight corner braking. The oil pumps are designed so the fluid intake works as a fluid discharge when the oil pumps rotate in reverse. Genuine Honda CVT fluid is used instead of differential fluid.
Operation
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 engages the differential clutch, and drive force from the transfer assembly is applied to the rear wheels.
The hydraulic pressure control mechanism in the oil pump body selects 4WD mode when the vehicle is started abruptly, or when accelerating in a forward or reverse gear (causing rotation difference between the front and rear wheels), or when braking in reverse gear (when decelerating). It switches to 2WD mode when the vehicle is driven at a constant speed in forward or reverse gear (when there is no rotation difference between the front and rear wheels), or when braking in a forward gear (when decelerating).
To protect the system, the differential clutch assembly is lubricated by hydraulic pressure generated by the oil pumps in both 4WD and 2WD modes. Also, the thermal switch relieves the hydraulic pressure on the clutch piston and cancels 4WD mode if the temperature of the differential fluid rises above normal.
HYDRAULIC FLOW
Forward Start and Acceleration (4WD)
During a forward start and forward acceleration, the dual pump system can engage four wheel drive. If the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front pump draws fluid through check valve B and discharges it. Some of the discharged fluid is drawn in the by the rear oil pump. The remaining fluid will pass through check valve E into the clutch piston. There, hydraulic pressure is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston pushes the plates and discs of the clutch together to form a connection. The engaged clutch then passes driving force from the transfer assembly to the rear wheels, producing 4WD.
Forward Driving at Constant Speed (2WD)
When driving forward at a constant speed (cruising), the dual pump system functions in two wheel drive mode. The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same. Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. Because there is no pressure built up at the clutch piston, the clutch does not engage, and the vehicle remains in 2WD (front wheel drive).
Forward Deceleration (2WD)
During forward deceleration, the dual pump system functions in two wheel drive mode.
Because of braking characteristics, the speed of the rear wheels may exceed the speed of the front wheels during deceleration. If so, the rear oil pump spins faster than the front oil pump.
Fluid discharged by the rear oil pump is simply drawn in again by the rear pump and recirculated. Because there is no pressure built up at the clutch piston, the clutch piston does not engage, and the vehicle remains in 2WD (front wheel drive).
Reverse Start and Acceleration (4WD)
During reverse start and reverse acceleration, the dual pump system can engage four wheel drive.
If the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front oil pump draws in fluid through check valve A and discharges it. (Note that in reverse, the direction of the pumps is the opposite of that during forward driving.)
Some of the fluid that is discharged by the front oil pump is drawn in by the rear oil pump. The remaining fluid passes through check valve F into the cylinder of the clutch piston, where it is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a connection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
Reverse Driving at Constant Speed (2WD)
When driving in reverse at a constant speed, the dual pump system functions in two wheel drive mode.
The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same. Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. But, because the there is a difference in the capacity between the two pumps, fluid flows through check valve E, and then through orifices. This fluid lubricates and cools the clutch assembly and bearings.
Is this condition, only a low pressure is built up at the clutch piston. Therefore the clutch does not engage, and the vehicle remains in 2WD (front wheel drive).
Reverse Deceleration (4WD)
During reverse deceleration, the dual pump system can engage four wheel drive.
When decelerating in reverse direction, the speed of the rear wheels may exceed the speed of the front wheels (due to engine braking). In this condition, the rear oil pump draws fluid through check valves B and C. Fluid discharged from the rear oil pump then flows through check valve E to the clutch piston. There, pressure is regulated by two orifices.
The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a connection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
Thermal Switch Operation (2WD)
During 4WD operation, pressure-regulated fluid is in contact with the clutch piston and the thermal switch.
If the temperature of the fluid in the differential goes too high, the thermal switch pushes open the relief valve R. This causes the pressure in the clutch piston to drop, and 4WD mode is disengaged.
Relief Valve Operation
When the fluid pressure goes higher than the relief valve spring force, check valve R opens. Pressure applied at the clutch piston is held constant. This feature adds stability by preventing the rear wheel drive system from experiencing excessive torque.