If ya have an extra 1k burning hole in your wallet get some RCV's... other wise.. its not really a big deal to most of us.. at least it has never been an issue on the dozen or so jeeps I have owned... but its your jeep do what makes you happy...

 

X2
RCV is the only brand I know of. This won't help the bind but tacking the caps helps prevent failure.

 

That's not the full reason for the 'funny' steering.... Part of it is that ALL of the tires are turning at different speeds. And some of them are trying to make others turn at the same speed they are........ I agree, U-joints are not the smoothest transfer of motion, but i believe that more of what you feel is the difference in speed between tires.......

 

Yeah, I suspect there's more to it than just the axle U-joints, but several off-road magazines have evaluated the CV joints and noted a significant difference in steering, smoothness, steer wheel back drive, less vibration, etc.

Front wheel drive cars use CV joints and they don't have the rear wheels connected to the front wheels like conventional 4WD does. That strongly suggests a problem with U-joints themselves.

 

I would think the likelihood of longer life and zero maintenance and also most FWD vehicles having open differentials (so no binding issues).

Also thinking that FWD vehicles are more sensitive to variations of steering from U-joints being non-constant velocity...


Edited: Sorry about still going on the why or why not for CVs or U-joints..... No, i have not used CVs and don't know anyone who has......

 

Subscribed...

 

CV's are used on a lot of hardcore and competition rigs. I think it was four wheeler magazine just did a build with them. If you look at a lot of high end built rigs you will see RCV's under there. I have no personal experience with them, but it seems to be a curious choice for a stock rig. The benefits will certainly be there, but it may be that you could better spend a few thousand dollars elsewhere. OP it is your rig, do with it what you want.

 

Not sure I get the point, the problem you feel isn't related to part time 4x4 system the Wrangler has ?

To solve your

'funny' steering when making turns in 4WD

, you would need an AWD transfer case, like my old Cherokee XJ had, AKA

Sometimes I miss it in winter...

 

Not sure I get the point, the problem you feel isn't related to part time 4x4 system the Wrangler has ?

Depends on if you have u-joints or CVs on the front axles.

I feel if there is not a problem with u-joints on front axles, we would see FWD cars with u-joints instead of the more expensive CV joints.

Again, U-joints are not constant velocity joints - that means the wheels are driven at different speeds than the axle - that causes wheel scuffing.

When a u-joint is in a turn, i.e. transferring power at an angle, the output shaft, i.e. the wheel goes through acceleration and deceleration due to the mechanics of a u-joint. If a wheel is accelerating or decelerating faster (or slower) than the vehicle requires, that would mean the wheel has to break traction and scuff.

This phenomenon will happen with front wheel drive only vehicles. That's why ALL front wheel drive vehicles use a constant velocity joint - that's why it's called a CV. In this sense, constant velocity means the output shaft, i.e. the wheel, turns at exactly the same velocity as the input shaft regardless of angle.

A u-joint doesn't do that.

...To solve your , you would need an AWD transfer case, like my old Cherokee XJ had, AKA

The characteristic non-constant velocity of a u-joint would still occur with the third differential of a AWD vehicle. The AWD does not change the behavior of the U-joint.

 

I think we are starting to beat a dead horse. You cant compare a FWD car to a Wrangler with Part Time 4WD Transfer case, apples and oranges. I doubt too many people have upgraded to RCV shafts to avoid binding when driving on a surface that probably doesn't need 4WD to begin with. Good luck in getting the answer you desire.

 

Front wheel drive vehicles WITHOUT Live axles must have cv joints. The design of a cv is to allow movement in almost all directions. A u joint cant provide that where as a live axle only needs to turn right and left and not up and down. The reason why scrubbing occurs on a 4wd drive is again due to the rear end being connect thru the transfer case. My cherokee has the 242 transfer(best snow tcase i have ever driven imho) dosent scrub when in full time but it sure does when in part time. I wish jeep offered that tcase in wranglers
Cameron

 

yes, beating a dead horse indeed. I believe this is what OP is trying to describe.

https://www.youtube.com/watch?v=T4P75ZQvpws

 

Awesome demo!

.

 

Wow, this debate is still going on? The second post was the best answer. RCV axles are nice and make turning in 4wd easier and don't tend to break as often (run by several in my club) but will set you back $1000 or more. Can buy a lot of u-joints for that, but if you have extra money and want RCV axles I say go for it.

 

indeed. the problem with RCV's is that you want your axle shafts to be the weak link, and if you are running a dana 30 or 44 with RCV's your axle shaft is absolutely not the weak link.

 

I upgraded to RCV's this Spring. LOVE them!!! Very smooth turning in 4WD even if I'm locked up front almost to the point you forget you are locked.
I push my rig hard off road, I've taken lines that have cost other guys ujoints...not a single issue. Ran me about $1K.

 

The 4x shop that I go to had / has a set of factory refurbished RCV's for sale they were down
To $500 no takers to date that I know of.......

 

I have a stock, i.e. no lift, 2014 Wrangler Unlimited and have been thinking about replacing the front axles with CV (constant velocity) axles.

Because if you are running RCV surely you are not still running stock drive shafts.

Fwiw

 

This has been very educational. As a DD, it is unnerving to go in 2 wheel mode as fishtail is inevitable in snow/ice. 4x4 offers stability in traction at the expense of steer-ability. RCV seems to offer a compromise that would allow better steering during longer stints in 4x4 mode. I will definitely look into this. Thanks for posting it.

My guess is Subaru must certainly use this...

 

Go drive a short bed IFS 4x4 pickup in 4x4 and get back to me. This isn't going to do what you think it is going to do.

 

Can you explain this? Will it still bind?

 

On snow/ice even, my 2014 JKURX binds "a lot". More than my old F150. Some people here have said the binding is significantly reduced with RCV. It has to be a little better, isn't it? It doesn't take that much of a turn or that dry a pavement before the lurching starts.

 

I dunno. I could be wrong. But it seems to me my 2007 silverado with 119 wb bound up about as much as my jku.

 

It seems there are two different issues being discussed.
Binding in a dry or high traction turn is a trait of all Wranglers and most 4x4. RCVs will not stop the drive train from binding in this situation. The tires WILL turn at different speeds, either they will scrub or something will break.
As for feedback resulting from the elliptical motion of the axle ujoint, if the roads are bad enough to require constant use of 4wd you shouldn't be traveling fast enough that the ujoint is an issue.
I had RCVs on a previous TJ and they are great shafts, however I don't feel they are worth the $ to solve the perceived issues being discussed in this thread. That's my 2¢'
Why do fwd cars have CV shafts? It is for the same reason most IFS trucks have them, the joint is required to move in multiple directions at once as was mentioned above. I have worked on a LOT of vehicles and have never seen a factory live axle with CV joints. Now someone will post up the exception that proves the rule lol.

 

I've been thinking about getting some CV axles, and stumbled upon this post. Some background:

I am... ummm..... a "spirited" winter driver. As long as its in a safe environment, getting a little sideways = fun. However, I have definitely noticed that when I am on the throttle fairly hard and my front wheels are turned significantly (lets say more than 2/3 of the way to full turn), my steering wheel often times shakes. Keep in mind, this is on low traction surfaces (snow/ice), so this shaking is not from the front and rear wheels traveling at different speeds, especially since the wheels aren't traveling at the same speed as the ground anyways.

It is THIS sort of binding that I believe can be remedied by a CV axle. A U joint does not transmit power well (linearly), and at increased turning angles and on the throttle, this can quite noticeable from the steering wheel shaking.

HOWEVER, (and i'm just basing this off my knowledge of how the world works, not firsthand A/B experience) a CV does not slip any more than a U joint does. Therefore, if you are in 4WD and turning on a high traction surface, the drivetrain is going to bind. Granted, that binding might manifest itself in a slightly more linear way (like one tire constantly breaking traction slightly, as opposed to the "bucking" you sometimes feel with a U joint). In the end, I dont think CVs would help much in this situation.

 

Just a different perspective on this discussion. Is a CV superior to a u-joint? Beyond a doubt. Will a CV make a 4wheel drive behave and handle like an All wheel drive? A resounding NO? For people that buy a JEEP and then want AWD.......you screwed up by not knowing the difference!

 

Exctly

 

U-joints certainly work, but when turning, the output shaft, i.e. the one driving the wheel, accelerates and decelerates even if the axle is rotating at a constant speed.

The biggest misconception here is that the above does not apply to JK. There reason is, this acceleration and deceleration only occurs on a garden variety single joint, but if you look under JK, you'll find a double U-joint: two of them together. The joints are oriented relatively each other so they compensate this acceleration and deceleration.

The reasons why such double U-joint is used are primarily reliability and torque, as well as cost. The reason why FWD cars use CVs is that a double U-joint requires the driveshaft to be supported near the joint. The live axle provides this necessary support.

BTW, most powerful of Russian 6x6 trucks used to come with an interesting hybrid, which, IMHO, is worst of both worlds. The hub and shaft have cuts in them, into which a disc is inserted, like a spline. The disc transmits the torque in the same way balls do it in conventional CV joints. The idea was that it can transmit more than a CV of the same size and weight. However, such joint requires outside protection and so they had a spherical housing with gaskets. Obviously that thing leaked all the blessed time.

 

The biggest misconception here is that the above does not apply to JK. There reason is, this acceleration and deceleration only occurs on a garden variety single joint, but if you look under JK, you'll find a double U-joint: two of them together. The joints are oriented relatively each other so they compensate this acceleration and deceleration.

I've watched the axle replacement videos that detail the install of the RCV CV axle. Each drive axle (front left and front right) has only one U-joint. Are you referring to the main U-joint by the transfer case?

Any pictures might be helpful since I am not following well

 

Anyone concerned about their Jk's handling should go drive an old 60's solid axle 4x4 pickup for a few months and they will come back appreciating their JK immensely. Like a slot car I tell ya.

 

There is only one ujoint per axle shaft. Some drive shafts have double cardan joints which utilize two ujoints.

 

Double cardan joint.

 

Great picture!