RCVs and FAD eliminator

OneArmedSaint

OneArmedSaint

Member 2026
Over the next year, if I don't completely upgrade axles, I plan on putting in RCV front shafts. They have a one-piece option for the right side, eliminating the FAD. While I understand the point of the disconnect and all the ins and outs, want to hear what all you 'professionals' have to add to my cluttered thoughts.
Pros/cons?

All a thought exercise at this point but always like to hear input.
 
I highly recommend RCV shafts. The RCV joint allow freedom of rotation at any steering angle where a standard joint joint is very limited and and rotation is some what elliptical ( this causes the stress than breaks the joint). They are easy to service you will need a needle attachment for your grease gun and I recommend the RCV high molybdenum grease. I run them on my JKUR stock axle and they were running strong after 100,000 miles. Upgrading to the D60s I again ran RCV due to strength and articulation. The current Jeep has a set of RCV installed. I suspect that after this trip I will need to do some rebuilding but to no fault of the shafts. Note do not buy the top end M300 shafts, lots of $$$$ ad they are more fragile than the 4340shaft that are cheaper.

1 piece or 2. Debate rages on. With the 2 piece design you gain some fuel mileage and reduce some wear. One side will always be turning and so will the diff. The argument is this present a potential weak spot in the front axle. My feeling is if you drive it hard enough you can potential break the collar. Bounce the axle enough and you could break the tube at the FAD motor. this said we have a few JL/JTs in the club all running stock Rubicon front axles all seem to be running well even those who venture out into the deep end of the pool. @Fearless runs a one piece right side but she is on 40s and trailering.

Future build thoughts
What is the goal for upgrading? is there a founded concern or are the trails getting more challenging? Take into account you drive this rig to and from the trails, and weight is you enemy with a 3.6L motor. Good news is you have the 8 speed trans to help but highway speeds and a small motor weight is not your friend. Couple thoughts from Small$ to Large $$$ an future ways forward.

- Cheap way $ to to install a right-side one piece shaft. You still have the housing to dela with and that can be solved by a truss. Have a quality shop do the welding work and the axle will not come our curved. down side is you are turning the hole front axle assembly and drive shaft. Fuel mileage will drop.

- Option $$$ is to R&R the axle(s) one option is to go with an uprated 44 from ECGS/Currie/Dynatrac/Fusion. I would think about adding locking hubs to the build. This way you can still have the advantage of a free wheeling front end and stronger shafts and housing. This approach will necessitate new wheels to a 5 on 5.5 bolt pattern. Good news is you only have to swap axle shafts in the rear to a dual bolt pattern. Vehicle weight adds minimal.

- An alternate to the 44 upgrade is a semi float D60 upgrade$$$$$$. Currie and Dynatrac offer this option and they use the OEM knuckles and brakes. No need to buy new wheel as you can retain the same bolt pattern. Down side no locking hubs. Up side strong axles and housing with OEM bolt pattern. Weight will be added due to larger housings More weight but more strength.

- Next option $$$$$$$$$$$$$ R&R both axles for a set of full float Currie D60s. 8 bolt hubs will require new wheels and you can get either electric or air lockers installed. The best part is you can use you OEM Calipers. This is important because going to a 1 ton brake system the JT/JL/JK master doesn't have enough capacity to get that OEM brake feel back. these can be spec'd for RCVs as well. Down side is this adds about 800 to 1000LBS to the Jeep overall weight. Upside is they are bomb-proof with a 3.6L gas engine.

The options range from $3K to $25K.
 
I've seen a lot more discussion about FAD failures than actual FAD failures. Sure it is possible, but it doesn't seem all that common. And worst case, if your FAD motor fails you can buy a block off plate and lock in the FAD ring. If you are going hard enough to break the axle tube at the FAD connection, I would submit that a D44 is the wrong axle for you, FAD or no FAD.

It does seem more common that aftermarket front drive shafts with no-FAD has a castor limitation where you experience vibrations at highway speeds. I've read posts from a few people with no FAD (full time auto 4WD axle has no FAD) who can't run as much caster as they would like. I like how stable my Jeep is at highway speeds and I attribute that to running a decent amount of caster.

So until I've reached the point of running a 1 Ton axle with manual hubs, I want to keep my FAD. My vote would be to get the axle shafts that retain the FAD capability.
 
So... first, I had an FAD failure, BUT it was not the FAD internal device. It was the housing itself. The axle tube twisted/rotated in the FAD housing, letting the outer tube clock well over 16 degrees. I had to replace the axle.

Doing an FAD delete is good as far as having fewer parts to break, but you really need to have those tubes braced and welded. Also, keep in mind that the drive shaft is going to constantly spin. If your caster is not correct and if the u-joint angles are not perfect, you are going to smoke some very expensive differential and transfer case parts, along with some really annoying drive line vibration. If you have the FAD in place, none of that is a real concern.

As far as the RCV's go... I'm going to give it a hard no. I was using RCV's for awhile and had some serious problems with them.

Some folks may be bothered by having to lube them basically every oil change, but that wasn't a big deal. The big deal was grease spayed everywhere. All over the inner fenders. All over the side of the Jeep. All over my brakes, ball joints, and everything else in line of sight of the RCV joint.

The absolute worst part was, the boots are not a good seal. Every time I went offroad, I was cleaning water and dirt out of the joints when I got home. The last offroad trip I went on with the RCV's, one of the boots came loose. There was small pebbles ans sticks inside the boot. That joint got completely smoked in just 200 miles. The other side was clicking and banging away, too... but they were both biding up, making it had to steer.

I wanted to take them out to get them repaired under the lifetime warranty, and I was told it was going to be 2 to 3 months. There was no way I was going to wait 1/4 of a year to put my Jeep back on the road. We swapped the axles to something with 1350 u-joints and tossed the RCV's in the trash.

If I have a u-joint failure, I can fix it on the trail in an hour by swapping a $20 part, instead of waiting months or spending a stupid amount of money to replace a bad CV joint.
 
This former JL owner tried RCVs had a similar grease complaint as @Spaz. At the time, I believe there were no chromoly axle shafts that retained the FAD function. (The spicer shafts intend for you to disable the FAD and use a lock out plate) His solution was to machine the end of a spicer set of axels to allow for a brass bushing to be inserted. The bushing is necessary to keep the two spinning shafts alligned for when the FAD needs to engage. The stock shafts use a plastic busing. He combined this with the RCV inner shaft and RCV upgraded sliding FAD ring. I wish spicer offered this version of their axle shafts so one could keep the FAD and upgrade to chromoly.

I would be hesitant to run this exact solution as any breakage requires a machine shopt to modify a replacement part in order to fix it. This guy just carried a second set of axle shafts, which is outside my build plan.


IMG_20221006_175258.jpg
 
Like everything, ask three people for their opinion you will get 4 different answers. I have run 3 different sets of RCVs no grease blowing out all over the fenders, no boots coming off just straight performance. As @CookieMonster said "... a lot more discussion about FAD failures than actual FAD failures..."

You can stress a RCV joint out. the cage expands a bit and the joint clicks. Good news is it is a semi easy fix ( messy) and parts are available. Not sure if there is a 4 month wait but last I ordered a set as a spare it too two weeks to get. Under normal power and good judgment I have yet to see an RCV fail. I have seen some D60 throttle jockeys hammering away on their stuff and still the joint hold up. if the boot is cut grease get everywhere, if the boot is not installed properly the grease gets everywhere.

Stock 3.6 8 speed. you will likely want to keep the FAD system for fuel mileage and ease of driving. As you build get to that point where axles come into play start thinking about the motor or how you get from base to trail. Red Jeep had a mild hot rodded 3.6. D60 and STT pros of the 40 in size. towing my 800 trailer it was everything I could do to keep up with traffic. The Jeep weighed 7200# OEM is 4500#. if you go big think about the whole package.

If you do go big, standing by to wrench with ya. I will tell you this 450hp and 500 torques make these things a blast to drive on or off the road. But to get there takes some serious coin and and a holistic look at everything working together.

Cheers
 
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