BrotatoChip

Hello everyone. This is going to be some info on K AWD swaps for the DC5/EM2/EP3/ES1, in my case the EM2. I first heard about AWD swaps like 5 years ago and was instantly intrigued. Making 800 HP is cool, but lots of wheel spin even when running massive tires up front is definitely not. I've been researching ever since with dreams of converting my '02 Civic to AWD some day (still hasn't happened). An AWD swap on this chassis actually isn't too difficult (in relative terms). Currently my EM2 has a 6 speed AWD transmission and CRV subframe. Nothing else has been added yet since 200 WHP isn't enough to need it. I plan on finishing the rest after turboing. Here are some basics:

Pre-requirements?
-K swapped, if not stock K.
-5 lug swap, if not stock.

What parts are needed?
For the specific chassis I mentioned, you will be sourcing parts from the CRV/Element along with some other custom fabrication. The basic list includes:
-Transmission
-Front subframe
-Driveshaft
-Rear differential
-Rear axles
-Rear control arms/hubs

How does the AWD system work in the CRV/Element?
The CRV/Element 5 speed is essentially the same to other K series transmissions with the obvious exception of the transfer case sticking off the back. The transfer case is driven off and additional drive gear on the differential. The differential is special to the AWD transmissions as well. In FWD transmissions the final drive is bolted to the differential. In the AWD transmissions the bolts run through the differential, then through the final drive, finally threading into the transfer drive gear. So, the driveshaft is always spinning at the same speed as the differential/final drive. The rear differential is where the slipping occurs (to avoid binding). The rear differential has a dual pump assembly. When the input from the driveshaft spins faster than the output to the rear wheels, the pump begins engaging clutch packs to send power to the rear. Once the input/output speeds match, the clutch packs are disengaged. This is far from ideal from a performance perspective but it does function (more to come).

How much power can the AWD system hold?
Depends. The transmission should be just as strong as all other K series transmissions. So, somewhere in the neighborhood of 400-500 whp without upgrades (if driven correctly). The rear differential I've heard can handle even more, but you'll never get that much through the stock dual pump system. After some upgrades I'll talk about more below, I believe it can handle upwards of 800 whp.




Now, for some more detailed information.



What transmission?
You have two basic choices, '02-'06 CRV or '03-'08/'09 Element (conflicting sources for final year). Both are 5 speeds with slightly different gear ratios. Both use a 4.7 final drive and an open front differential. The major difference between the two is the VSS. The CRV uses the low frequency, differential driven type found in the EP3 and the '02-'04 RSX. The Element uses the high frequency, third gear type found in the '05-'06 RSX and '06+ Civic Si.

The outer case is compatible with other transmissions as well, it's just the clutch case that is different. For instance, you can take just the clutch case and put an RSX 6 speed case on the end. No issues as long as you have the VSS sorted (low frequency type needs the proper clutch case, high frequency type needs the proper outer case).

This also means you can use any K series gearset you desire. The only thing to note is the countershaft bearing size is different between the 4.3 final drive and the CRV/Element's stock 4.7 final. I currently am using a '03 CRV transmission with '03 RSX 6 speed internals (except for the differential).

All CRV 5 speeds are AWD. The Element on the other hand was also offered with a 5 speed and FWD. The FWD 5 speed transmission uses the same clutch case but is missing other parts. You could covert it to AWD by adding a transfer case (has a plate covering the mount location), an AWD differential, and transfer case drive gear.



Here you can see the difference between the FWD and AWD transmissions. CRV AWD 5 speed on top, RSX-S on bottom.

Which subframe?
Again, your pick between the CRV and Element. Both will bolt up to the chassis in question. The auto and manual subframes are the same for each model. The rear transmission mount will interfere with the firewall (at least on the EM2). I have heard you can use the Hasport rear mount and it clears. I took the alternative route and beat the firewall with a hammer until it fit. It really doesn't take too much. The front engine/transmission mount is the same. All suspension will bolt up to the new frame without issue.



Here you can see the difference in sub frames (don't mind the control arm I had to cut off afterwards). Left is RSX-S, right is a repainted CRV subframe.



Same two subframes from another view. Almost identical except for the rear cross bar. On the CRV is is much flatter and further back to accommodate the AWD transmission.

Rear differential?
Any will work. They are all very similar. Some of the later CRV ('07+ I believe) have a quicker ramping clutch system so power is sent more quickly. I believe the Crosstour rear differential can also work. You will have to research which is best for your build.

Mounting will require some custom fabrication. There are a handful of kits available. These utilize the rearward control arm mounting holes. Swap out for a longer bolt to hold a rear mount for the differential. A mount for the front of the differential usually uses sandwich plates through the body sheeting at the front of the spare wheel "tub". Ideal? No. But it works.

Rear control arms and hubs?
The CRV/Element AWD control arms/hubs will bolt up to this chassis. The top camber mount will look a little wonky but you can make it work. The ride height will be off afterwards so you will need coilovers to fix this. Ideally, this would be as simple as swapping just the knuckles/hubs. But, the mounting tabs on the control arm do not match between the two.

Swapping to the CRV/Element hubs also means a 5 lug conversion. If you are still running 4 lug (EM2/ES1 and early years EP3) you will need to convert. I was able to find a set of 4 lug AWD hubs from FCS Race. These are supposed to use the CRV knuckles, accept the stock axle, and stay 4 lug. They don't appear to sell them anymore and I have not tested them yet.

Another item to note, the CRV/Element use a different style of wheel speed sensor that isn't compatible with this chassis. If you have ABS and want to keep it you will need to work around this. The rear axles can be modified to have to stock style tone ring. A custom mount bracket is needed for the wheel speed sensor.

Rear axles?
You'll use stock CRV rear axles. I believe the first gen CRV is what you want to use if trying to keep ABS, they will have the proper tone ring. Left/right are different lengths, I believe you must use two of the shorter axles. I can't remember which side that is.

Rear brakes?
I don't have much info on this. You can use the stock CRV/Element setup. They have rear disc/drum hybrid style brakes. Disc for regular braking, drum for the parking brake. I also know you can use the regular EP3/DC5 disc brakes but I can't confirm how this is done.

Fuel Tank?
The differential cannot mount inside the fuel tank (for obvious reasons), it will have to be removed. What most people do is install a fuel cell in the trunk. You could also design/built a custom aluminum fuel tank still using the stock mounting holes. Another guy cutout the entire back seat seating on an RSX and installed a fuel tank from a '16 AWD Honda N-box from Japan. Whichever route you go it will inevitable be smaller than the stock ~13 gallon tank (maybe around 8-10 gallons).

Which driveshaft?
I have seen some reports of the stock Element driveshaft working, it is slightly shorter than the CRV. More than likely it will require shortening by a specialized shop. The middle carrier bearing will require a custom mount, that is simple though. The other thing to note here is the exhaust tunnel (now used for a driveshaft) has to be extended all the way back. Cut the sheet metal so it can be bent up and out of the way. Then weld in some additional pieces to seal it back up. There is also a brace in the tunnel that has to be removed.

Front sway bar?
The stock sway bar will interfere with the driveshaft. I tested with the stock CRV sway bar on my EM2. The end to end length is longer than the stock bars but I was able to make it work. Puts a funky angle on the sway bar links but nothing too serious.

Exhaust?
The exhaust will interfere with the transfer case and drive shaft. You will have to do something custom here. I see lots of people using oval/flattened tube to avoid scraping. I have seen some examples of tucking the exhaust in the tunnel with the driveshaft.

Limited slip differentials?
There are some front AWD LSDs available for purchase (I am using Wavetrac). This is just the front differential, only affecting the front wheels. Some will have extra holes, one set of threaded holes for FWD applications and one set of pass thru holes for AWD. I believe some stock FWD LSDs can also be modified to work with AWD but I don't have this information. For the rear differential, I'm not aware of many options. Gear-X sells one but I cannot find much info.




So, the stock AWD system isn't good enough, what's next?
The stock AWD system is FWD with active 4WD. You still have to spin the front wheels before anything happens in the rear. With an upgraded dual pump system in an '07 CRV rear differential the best split you can get is around 60:40 front to rear. No numbers for stock but this is drastically better. Even so, there is still room for improvement.

The common upgrade is to pin the rear differential clutch packs, locking in the rear wheels. This will cause binding though. When turning the front wheels are spinning at a different speed than the rear. Only having the pinned clutch packs will snap axles, destroy differentials, etc. To fix this you replace the driveshaft with a viscous coupler shaft from a Land Rover Freelander (early 2000's I believe). The viscous coupler allows for slight front/rear speed changes at slow speeds while still transferring lots of power at higher speeds. This is referred to as the poor mans wagovan differential. Using the viscous coupler you can achieve 50:50 split front to rear.

In other chassis the popular choice for the rear differential is from the wagovan. Instead of the dual pump system it uses a viscous coupler like mentioned above. With the price of a wagovan differential these days being $2k+, the freelander driveshaft is a much more economical solution.




Links?
Here are some links below where you can find tons of info. This is definitely more involved than a simple engine swap so do your research.

Pirate Garage on Youtube. Lots of videos showing AWD swapping an EM2. Channel is not active anymore (now Gravy Built). So much good information in the videos, this is where most of my information comes from.
https://www.youtube.com/c/PirateGarage
https://www.youtube.com/c/GravyBuilt
There are also a few K AWD groups on Facebook, lots of good discussions there.


This is all the info I have to share at the moment. I can update the thread in the future when something notable comes up. I may also add some more pictures if I can find anything useful on my phone. If anyone has anything to add, feel free to comment.

D17VTECPOWER

iTrader: (1)

Outstanding job, by far the best information I have seen! This is something I'd eventually like to do also. Really looking forward to seeing more on this project.

In Japan and possibly other markets, there were actually models of 7th gen Civics that came with 4WD. Not sure how many of those parts would be useful for K swaps though, perhaps the gas tank? It's 11.8 gallons instead of 13.2 but still a good size and presumably a bolt on swap.

BrotatoChip

That's a good thought. I wonder if someone could get one over here.