So, I've been pondering on how to more readily engage the awd system on the 2nd gen crvs, something more substantial than just waiting for the front wheels to slip. I wish we had an actual selector, but, that's neither here nor there. I did come across some guys essentially locking the differentials for their boosted civics though, by basically "pinning" the clutch packs together, thereby making it full-time awd. They remove the dual pump as it no longer really serves a function, and swap in a driveshaft with a viscous coupler. So far I've only seen this done on boosted civics but it got me wondering, has anyone actually just tried it on the crv(or element) itself? What are the potential ramifications of this down the line? I'm sure it would put some kind of extra wear on the tranny/transfer case, being engaged all the time, but substantial enough to do any real damage? I know for sure gas mileage would drop. I guess it only really seems worth it if you're hitting trails often, or live in constant snow. Doesn't seem like it'd be beneficial for daily city driving. I'm somewhat considering diving into this though, as it seemed pretty straight forward, and not at all difficult. I don't know, what do you guys think?

 

You're basically describing a Subaru. Open front diff, viscous coupling in the "transfer case", and open/LSD in the rear. Only downside to the Subaru setup is you can ruin the viscous coupling quite easily (towing on one axle, severely mismatched tires). Mode of death for the coupling is overheating. They keep it inside the transmission which helps a lot. If you tried to use an external viscous coupling as a retrofit, I don't think would be a very robust solution.
Locking the front diff is stupid for anything except a drag strip car. If you could replace the dual pump system on the CRV with a viscous clutch it would basically be the same thing as a Subaru, just with the coupling at the other end of the driveshaft. Not sure what the benefit would be aside from marginally quicker response time on the torque transfer.

 

I know that it's basically a Subaru set up, but on a Honda. That's kind of what I'm looking for though, the responsiveness of the subie, with the reliability of my Honda. Except I was under the impression subarus had a center diff as well to account for the wheel spin, in place of a viscous coupler. The older awd Civic wagons used to run full-time awd with a viscous coupler driveshaft and had no problems aside from sourcing fluid for a rebuild 30+ years later. Honda scrapped it in favor of the real time Awd set up, I'm assuming in favor of fuel efficiency, since its now fwd, until wheel slippage. As far as the problems you mentioned that may arise with running this set up, the crvs already suffer from the mismatched tires/towing on one axle problem, except it burns the dual pump out instead. It's my understanding that the whole dual pump set up is already a viscous clutch differential system, where when the front wheels slip, torque is applied, the pump spins the fluid and locks the clutch packs together, thereby giving the all wheel drive. But the delay doesn't really do any good for trail riding, since the cars are kind of lacking in any power., And depend more on momentum to climb. So at that point, if the wheels are spinning on a grade, probably not going to make it up waiting for the rears to kick in, whereas if all wheels were spinning from the start, it'd be a little less dramatic lol. Don't get me wrong, I'm not trying to turn this thing into a rock crawler, I know it's capabilities and it's limitations. The proposed idea is merely to lock the clutches in the rear together, nothing done up front to the transmission or the diff there, except swapping in a driveshaft with a middle coupler. Which from what the drag guys are saying, is more or less to help asorb the initial punch from their launches. I've also seen people running a straight drive shaft set up in their drag cars for this, and they're all using the crv/element diffs for it, so it's not like apples and oranges or anything. One guy converted his boosted crx to rear wheel drive with it. I'm not doubting the downsides you mentioned, I'm just more or less looking to see if there's downsides that we don't already suffer from. Thank you though.

 

alot of work to put design on to another car. Hope this turns out well for you though.

 

You're right, the Subaru system is more like a VLSD between the front and rear axles. It's the same principal as a viscous coupler in the driveshaft, just runs at way lower speed than the driveshaft. If all you want to do is lock up the clutch in the rear diff and add an external viscous coupling/driveshaft, it might not be too expensive to just try out. Get a used rear differential and driveshaft. Weld up the clutch in the diff, and then add your viscous coupling to the driveshaft and see what happens. Make sure you spec the viscous coupling correctly, if its too aggressive it will overheat and if too weak you won't be impressed with it. I think Volvo used to use a driveshaft like that in the 90's? Might be worth looking at if they had roughly the same final drive ratio as the CRV.

 

Just a small correction. The older wagons were considered “real-time”. They aren’t full time awd. They are the same basic principle as the crvs, fwd till the front wheels are going a different speed than the rears. then the coupler engages and locks rears until wheel speeds match.

Imho, the viscous coupler system works way better than the pump system in the crv. Engages considerably faster. Plus you can install a lsd in the rear differential. Something that can’t be done with the newer systems. However, from what I gather, both designs are prone to overheating during prolonged use. So not sure putting in a viscous coupler and disengagement of the pump system would net you the desired result.

As you likely know, a lot of people use the rear diff from the later elements to get faster rear diff engagement. I have one waiting, but have been slacking on getting it installed. I kind of want a snow day to do it for instant gratification to feel the differences.

FYI, the awd wagons were in production in Japan from 1987 to whenever the crv was released in what 1996? The later year wagons had the dual pump system, and iirc, there was a button on the dash that did something with the rear diff, but I can’t remember exactly what it did.

you mentioned the wagon was underpowered, it is, but my wagon will kick the **** out of my 00 crv in every way but ground clearance and interior creature comforts. Can’t speak for the newer crvs though.

I wish i could find it, but I read an article about the drag racers finding a way to “lock” the rear diff hydraulically. To me, that is the ideal solution. Only locked for when you need it. Not sure if that’s realistic for long term use due to overheating, but would be great for those areas where the crv lacks off-road, off camber stuff.

 

That's pretty much the method. They drill the clutches in the rear diff and weld pins in to lock them together, and I believe they're using a viscous shaft from a Range Rover freelander? The just fab up the ends to mate with the transfer case and the rear diff. As I've only seen them being used for drag cars, I'm not sure if the coupler would hold up for daily driving, as you said with the potential overheating. Definitely something I'm doing plenty of research on before I make any moves.

 

Ah, thank you for the correction! I was under the impression that the wagons were full-time. I'm not sure where I've read that but I've seen it a few times. As for the wagons power, I was referring to the crvs lacking. I have no real experience with the wagons themselves and wouldn't be able to speak on their behalf, but it would makes sense as they are lighter than the bricks that are the crvs. I have seen the later model element diff swap and am still considering that too as I believe it will drop in to my gen with no modifications necessary. I believe I've seen the lsd swap on the second gen diffs as well. I don't remember who manufactured it, I'll have to check again. Id love to see a hydro lock set up, but I can't fathom how that'd work considering the differentials contain no electrical components whatsoever (that I'm aware of anyway lol). Only way I could imagine is some kind of modifying transmission side, somehow applying more torque to the transfer case? It'd definitely be interesting, but I'm sure also very costly. Controlled engagement on the crv would made the vehicle damn near perfect.

 

^^^ the lsd swap is only doable in the 4th gen rt4wds. Possibly the 3rd gens as they use the same basic system, if I don’t know much about them. I stick to the 4th gen civics. You can use any dseries lsd in the 4th gen diffs, but all of them require some shimming.

Im still pissed I can’t find that article about hydro locking the rear diff. I have 2 buddies with 1000 HP+ awd civics. I was hoping one of them would dial it in so I could just ride the coattails, lol.

no electrical stuff would be needed, basically you’d need an onboard air system like the rock crawler crowds do to engage and keep their lockers engaged with air. Iirc, it would work the same way. Since the hydro pump activates the clutches with more fluid the air would keep the fluid engaging the clutches until it was turned off. basically just replacing what the pump does when it senses wheel speeds between front and back.

Once I swap out my diff for the element setup I’m going to take the stocker down to a buddies speed shop and pitch the idea to those guys and see if they can figure it out. They are just finishing up a kswapped awd 4th hatch that would likely benefit from the idea. If I make progress, I’ll report back.

another thing that we know works in the crv diffs is shimming the clutches. Member turbo2cam did it with his rear diff and he said it definitely made a difference, but swapping in the element rear diff is going to net the same results. I guess it just depends on how much you like tinkering, lol. His build thread goes into more detail if you wanted to mess with the concept.

 

Have any of you played with a CR-V that has that ramp clutch in the rear diff? The 05-06 CR-V. That locks up immediately, WAY faster than the RT Wagon with a brand new viscous coupler. Was playing on a wet grass hill, RT Wagon on BFG all-terrains would just spin the front, had to really spin hard to get it to move enough power to the rear. CR-V on highway tires would maybe get 1/10th of a rotation on the front before the rear locked up and started pushing.

Where are you getting your information on the Element rear diff? In the manual transmissions the Element rear end is unchanged from 2003-2010 (2011 was automatic only), same part number for all years. It is the same rear end as the 02-04 CR-V. The Dual pump assembly is 41011-PNZ-307. The 05-06 CR-V (last of the manual transmission) uses a ramp clutch inside the dual pump. This has a part number of 41011-RRL-030.

Check out Automotive Koncepts. They are making shims and ceramic clutch packs for the dual pump rear ends.
https://automotiveknd.com/shop/advan...l-system-dpqs/

 

I completely forgot air lockers exist. Now that would be something! And yes please do, the more options the better! Haha

 

Ive seen that! Actually came across it on the same YouTube channel that I got the idea for pinning the clutch packs together. Pirate garage I believe? That dude is a Honda genius. One of the guys in the H/T lifted thread said he was going to try out the quick spool but I don't know what ever became of that, I was thinking about that as well, but still haven't seen too many people post results for it.

 

^^^ well just talked with one of my buddies and he said that you cant run full time awd in any of the realtime vehicles cause the rear diff is geared differently than the front. If you did go that route youd burn stuff up. either way, im still pursuing the hydro-locker for off road use. no idea if it can be done, but we are going to investigate further. in the meantime, I was referred to this vid:
might be something to try for quicker engagement.

Im guessing theres still issues with that rt if its taking that long to engage. what sized tires were on it? the bfg at's weigh twice as much as a stock sized tire on the rt's. maybe that has something to do with it. ive been dicking with the rt's since 02 and all mine have engaged immediately in slickery conditions like that. snow, mud, and ice etc, but sometimes it is delayed on pavement like at the autoxs. however, imho, it was a good thing. when diving into a corner the car will push. with just a sec of delay before the rears would engage it was just enough to initiate oversteer. wasn't always the fastest, but was always the funnest.

I am intrigued with the ramp clutch setup you speak of. ill have to look into that further. forgive my newb. up until recently, all first gen crvs were to me were donor cars and ive not even driven any of the newer crv's.

same buddy with the awd eg has had all the different diffs apart. he couldn't remember the exact years, but he said 09-10ish element diffs had larger clutch pads and a bigger spring (like in the vid above). but ive heard from a few other sources other than my friend that the later element diffs were an upgrade for the older crv's and elements. either way, that's why im waiting for a snow day to swap the one I have in cause I want to see if it actually makes a difference and only way to tell is back to back in the same conditions.

^^^ buyer beware with that dude. been told to stay clear. apparently he has ripped off quite a few folks. no first hand experience, but was told not to do business with that company. apparently another company still offers the kit that was referenced in the video above to help the diffs engage quicker with the thicker spacers and beefed up spring. if he sends me that company name, ill post it up.

 

Yeah I had a bit of a time getting my parts from Automotive Koncepts. Took nearly 3 months of excuses.

So part numbers for rear diff 03-11 Element manual and auto are all the exact same. I don't think there is a single difference. Dual pump unit is 41011-PNZ-307 and the diff is 41010-P6R-345 for all years and trims on the Element.

RT works as expected, will stall instantly with the viscous test outlined in the manual. Manages deep soft sand no issue, performs excellent in the snow. Pushes like crazy in the wet, too tight. Full lock in the dry you have to throttle through the binding. Just not as responsive as the dual pump with ramp.

 

In that youtube video he is disassembling an 05 CR-V rear end, says so right at the the start. That is a dual pump WITH ramp. They had bigger bearings in them than the non ramp.

ALSO DO NOT DRILL THE OIL ORIFICE! That is a to release pressure off the clutch pack not allow more oil into the clutch pack! If you drill those the clutch will respond slower as it bleeds more oil off.

https://automotiveknd.com/dual-pump-...-installation/

Also in that, how to lock up your clutch pack with compressed gasses.

 

Was just going off what my buddy told me who had both a early and late model diff disassembled in front of him. Regardless, the engagement of my 00 stock diff is pathetic. Must just be worn out cause all the 98 crv stuff I put in my first rt worked a hell of a lot better.

appreciate the heads up on the drilling. Will be a while before I consider any mods though. Projects, I have to many and not enough moola for any of them.

 

Can someone explain to my why the front and rear differential ratios are different? Are the dual-pumps different displacements or something?
Edit: I think I figured it out. Its because the ratio from the differential transfer gear, and the bevel gearset in the "transfer case" are not 1:1.

 

Yes but also in the pre 05 CR-V the rear end is driven at 1:1 to the front. In the later 05+ CR-V the rear end ratio very slightly taller making the rear end under driven. Was an economy thing and Honda added the ramp clutch to compensate for engagement speed. This is only true for the dual pump with ramp clutch rear ends.

 

So for a pre-05, I don't see why you couldn't weld the rear clutch and use a viscous coupling in the driveshaft. Still not sure it would be valuable, but you could do it. Since the driveshaft is driven directly off of the ring gear in the front diff, you'd at worst still have a 1.5WD (one front tire and whatever the viscous coupling can apply to one rear tire) because front and rear diffs are open.

 

I think the dual pump rear end in good condition can transfer more power than a viscous coupling. That is until you get the coupling into hump mode where there is so much heat the plates inside act more like clutch plates than fluid dynamic plates. But then it cools off and returns to open until heat builds up to that condition again. Hence the term hump mode.

A rebuilt dual pump with shims and an aggressive clutch pack will probably be as close to 4x4 as one can get.