cv/u-joint strength

[bj-666]

why hasn't anyone come out with a cv joint for the xj. What are the pros and cons of both u-joint and cv joints. i know the basics that a cv joint is designed to keep every part spinning at the same speed as where a u-joint is always accelerating/slowing . which type is stronger. o yea i'm speaking about the front axle shafts.

[DDCxj]

There is no point in having a cv joint in the front axle where it is a solid axle. All of the cars/trucks you see cv joints on have independent suspension and therefore need to run axles with cv joints. The axles in your jeep dont moves seperate from eachother, its just a straigh line across at all times. The only time the joint moves is for steering.

Dean

[bj-666]

but what about the strength issues of cv vs u-joint.

[DDCxj]

I'm not really sure on this but I don't think there is much of a difference. At the shop I work at, we probably replace just as many cv axles as we do u-joints. But, in an application that uses a cv joint, it does twice as much work as a u-joint does. If you could put a cv joint in a solid axle truck it might be stronger because its only doing half as much work as its made to do, but thats just in theory.

Dean

[XJ_ranger]

teh new WJ's have cv's instead of u-joints...

and they arent 1/2 as strong... honda's run CV's, f-250's run D60's with u-joints... what do we want? honda strength or 3/4 ton truck strength?

[Citat3962]

A CV is used when you need to bend on two planes vertical and horizontal.. Suspension compression and steering..

I would think the angles encountered in either plane will cause different wear on different parts of the bearings inside the CV. So you would likely have similar service life for a CV in a solid axle as it would in an IFS setup..

Strength concerns aside I'd much rather go through replacing a broken U Joint $$ and simplicity wise than I would replace a CV. The CV would be bought shaft and all ($$$) You can replace a bad Ujoint (Before it breaks) and use your original shafts.

FWD cars only have CV's because they have to to turn and compress the suspension and deliver power all at the same time and smoothly and silently..

U joints only turn on one plane and have a solid axle housing to muffle any noises.

CV's are also quite a bit bigger than U Joints so it could be an issue of fitting the CV inside the axle housing.

[CRASH]

There is so much mis-information in this thread I'm thinking of deleting it to save NAXJA's reputation.

All who have posted thus far, please go do some research and return with good information and apologies.

CRASH

[poomba]

There is so much mis-information in this thread I'm thinking of deleting it to save NAXJA's reputation.

All who have posted thus far, please go do some research and return with good information and apologies.

CRASH

You called 'em on it, throw the true info up there for 'em. Tease :P

[CRASH]

You called 'em on it, throw the true info up there for 'em. Tease :P


This is like college.

I'm the professor.

I tell you that you are an idiot.

It's your job to figure out why.

CRASH

[Dirk Pitt]

There is no point in having a cv joint in the front axle where it is a solid axle. All of the cars/trucks you see cv joints on have independent suspension and therefore need to run axles with cv joints. The axles in your jeep dont moves seperate from eachother, its just a straigh line across at all times. The only time the joint moves is for steering.

Dean

Well, for one thing, your axles most certainly move separate from each other. That's what your open/unlocked differential allows them to do.

As already stated, some solid axle vehicles run CV joints.

have a solid axle housing to muffle any noises

How can an axle housing conceal any noise from a u-joint when the u-joint is not inside the axle housing but rather open in the inner knuckle?

[poomba]

This is like college.

I'm the professor.

I tell you that you are an idiot.

It's your job to figure out why.

CRASH
I'd cry cop-out, but yer right. Applying for student aid, send me a check :P
Right now, I'll staring at my ujoint strap/bolts (ushaped) that are bent into a purty pretzel, and thinking..if these were stronger, I coulda made it up that..and then again, I might have a driveshaft that looks like a candy cane. If something's gonna give, I'd rather it be 5 bucks in parts rather than getting the shaft...cough. I did figure they's be stronger than the regular straps though. Spending my birthday under the jeep figuring out what really went wrong, cuz it wasn't much of an obstacle, and I wasn't hopping the jeep. I'll be under the jeep studying for my web wheelers degree, if ya need me..zzzzzzzz

[DDCxj]

[QUOTE=Dirk Pitt]Well, for one thing, your axles most certainly move separate from each other. That's what your open/unlocked differential allows them to do.

As already stated, some solid axle vehicles run CV joints.QUOTE]

Thats not what I was trying to say. What I meant was that a truck with a solid axle does not articulate at all like a truck with indepent suspension with cv axles. I know that a solid axles have multiple shafts that make up the axle as a whole. As said before, solid axles on move need the joint to move on one plane but independent needs the joint on two planes.

What solid axles have been mentioned that have cv joints? Not trying to start an argument but I didnt see it anywhere in this thread and I have never seen one.

Comparing the two is like comparing apples and oranges, they are completely different applications.

CRASH: please enlighten us. I have searched the internet and come up with nothing. Got a link or something we can learn from?

Dean

[RCP Phx]

[QUOTE=Dirk Pitt]Well, for one thing, your axles most certainly move separate from each other. That's what your open/unlocked differential allows them to do.

As already stated, some solid axle vehicles run CV joints.QUOTE]

Thats not what I was trying to say. What I meant was that a truck with a solid axle does not articulate at all like a truck with indepent suspension with cv axles. I know that a solid axles have multiple shafts that make up the axle as a whole. As said before, solid axles on move need the joint to move on one plane but independent needs the joint on two planes.

What solid axles have been mentioned that have cv joints? Not trying to start an argument but I didnt see it anywhere in this thread and I have never seen one.

Comparing the two is like comparing apples and oranges, they are completely different applications.

CRASH: please enlighten us. I have searched the internet and come up with nothing. Got a link or something we can learn from?

Dean

ZJ's and WJ's Both used CV's on the D30!
Sorry,forgot to include the obvious "XJ"

[PeterBuilt]

Everyone who is reading these posts are now dumber because of it. I award you no points and have god have mercy on your soul.

:wave: :wave:

Pete

[DDCxj]

I stand corrected. I knew the new WJ's had them but I never noticed on the old ones and the ZJ's.

Dean

[RCP Phx]

[QUOTE=Dirk Pitt]What solid axles have been mentioned that have cv joints? Not trying to start an argument but I didnt see it anywhere in this thread and I have never seen one.CRASH: please enlighten us. I have searched the internet and come up with nothing. Got a link or something we can learn from?

Dean
I knew the new WJ's had them
Hmmm???

[DDCxj]

What are you trying to get at?

The new WJs have independent suspension, not solid axles.

I have seen plenty of cv joints, just never hit me that I have seen them in any solid axles, which obviously they do,but I still dont understand why they would be in a solid axle set up.

I never said I was a professional or that I know everything about anything and I'll be happy to admit when I'm wrong....well, maybe not happy, but I certainly will admit it as I did.

So why doesn't someone that knows everything there is to know post something so that this thread doesn't continue to be so useless. Why would Grand Cherokees have CV joints in the front D30 as opossed to u-joints? I assume there is a reason but I'm not seeing it.

Dean

[kewlkatdady]

If it means anything....the new Grand Cherokees with IFS are called WK's

not WJ's anymore

[DDCxj]

That would mean something. It would mean that Im confusing myself and probably many others.

"Yeah, I'm retarded"-Tommy Boy

So, ZJs have CVs up front and obviously WK's do too. And I guess WJs also have them......so what I am going to do right now is stop thinking cause my head is starting to hurt and I will just accept that for some reason unseen to me, CV joints are used in solid axles. But if someone could shed some lights as to why, it would make this process a whole lot less painless.

Dean

[kubtastic]

Why would Grand Cherokees have CV joints in the front D30 as opossed to u-joints? I assume there is a reason but I'm not seeing it.
Dean

-Longevity, fewer seals. You might replace just as many CV's, but those are on IFS. You've never seen a solid axle with CV's... go figure.

A CV is used when you need to bend on two planes vertical and horizontal.. Suspension compression and steering..

-Correct answer but you fail geometry. When two lines intersect they define a single plane.

IFS uses CV's because they constantly see non-zero operating angle: the differential is tucked up against the belly of the vehicle. Suspension movement also affects the angle. Meanwhile, on a solid axle, only turning creates an angle, and usually the higher the angle the slower you're moving.

[DDCxj]

-Longevity, fewer seals. You might replace just as many CV's, but those are on IFS. You've never seen a solid axle with CV's... go figure.



-Correct answer but you fail geometry. When two lines intersect they define a single plane.

IFS uses CV's because they constantly see non-zero operating angle: the differential is tucked up against the belly of the vehicle. Suspension movement also affects the angle. Meanwhile, on a solid axle, only turning creates an angle, and usually the higher the angle the slower you're moving.

Thank you.

After thinking long and hard I can only come up with a few times in the last 5 years that I can remember replacing cv shafts on a solid axle and yes, all of those were on ZJs.

So longevity and fewer parts is the only reason to put CV Shafts in a solid axle? Still sounds stupid since you can't just replace the joint but have to replace the entire shaft. They would have to last at least 3 times as long as a u-joint to just to break even in cost. Doesn't seem worth it but oh well.

Dean

[Storydude]

My 84 D30 Command trac had CV axles.
My 86 d30 Selectrac has u-joints.

Only difference I noticed was not as much "Hunting" in 4wd at full lock.

As for strength, the u-joints AND the CV's in the d30(260X joints) are about the same in torque strength.

Only bad thing is the Boots rip on CV's and then they are toast in 100 miles.

[RCP Phx]

What solid axles have been mentioned that have cv joints?
I knew the new WJ's had them
I have never seen one.
The new WJs have independent suspension, not solid axles.
I have seen plenty of cv joints, just never hit me that I have seen them in any solid axles
I never said I was a professional or that I know everything about anything
So, ZJs have CVs up front and obviously WK's do too. And I guess WJs also have them......so what I am going to do right now is stop thinking cause my head is starting to hurt and I will just accept that for some reason unseen to me, CV joints are used in solid axles

After thinking long and hard I can only come up with a few times in the last 5 years that I can remember replacing cv shafts on a solid axle and yes, all of those were on ZJs.Dean
Are you still trying to tread water!

[DDCxj]

not at all, just a very long day, but it does seem like it when you put it like that. Maybe the concussion I got today has something to do with it. I probably shouls have just stayed in bed.

I think I'm done now, I'll be back tomorrow in a less conussed state to post more intelligent things.

Dean

[explorer]

There is so much mis-information in this thread I'm thinking of deleting it to save NAXJA's reputation.

All who have posted thus far, please go do some research and return with good information and apologies.

CRASH

I agree.


The main difference between u-joints and c/v joints is the constant velocity nature of the cv, hence its name. A universal, or "cardan" joint, creates a speed fluctuation on the output side twice every revolution. This is the reason that single cardan shafts need to have the joints phased properly to get smooth running. Even then, the shaft between the joints still has to accel and decel twice every revolution. At excessive angles, this setup can give vibration even if the joints are phased properly and at equal angles and the shaft is properly balanced. Same concept with a "double cardan" which is improperly referred to as a "cv" joint. The H-yoke between the two joints sees this same speed variation.

There are different types of cv joints to further confuse people. Some are made to accomodate plunge in the joint, serving the same purpose as a slip yoke on a conventional propshaft. They are typically used on the inner joint of FWD halfshafts. Another common application in the Jeep line is for the axle end of the front driveshaft. It was commonly used on Quadratrac models from around 96 ZJ's and into WJ's and KJ's regardless of t-case option. Fixed type cv's, without plunge capability, are typically used on the outer joint of FWD halfshafts, and this is the type used on solid frt. axle applications in the Jeep line. They were used from the beginning of the XJ when equipped with Selectrac and in various Jeeps since then. Quadratrac Grand's use nothing but cv's, and depending on the year, many Selectracs also use them.

As far as strength is concerned, you have to watch what you compare. Does the OEM cv equal the strength of a CTM or OX joint, or something similar? Probably not. Does it equal the strength of the standard 297 joint. In my opinion, yes. In theory, its used in applications with the most power (ie:V8 Grands,including 5.9's) which also happen to be largely fulltime 4wd models, meaning they are %100 duty cycle, as opposed to what, maybe %20 at best on a part time model. Now, there are cv's being engineered for the same application as the super u-joints out there. They are no doubt better than the standard versions, and the little info out there suggests that they can equal the strength of the bigger, better u-joints out there. One inherent advantage is the consant velocity output. U-joints often break when operating at an angle. The accel and decel transfered to the wheel assy. is partly to blame for this. It creates a shock load to the entire driveline.

I believe cv joints are a superior design. And I don't just have this opinion with nothing to back it up. I run them (OEM) in my TJ's frt. axle. This with 4.10's, a Lockright, and 32" Swampers. That combination scares a lot of people before even mentioning the cv's. But in practice, it has proven just as strong, and more durable. I don't wheel rocks that much, but i do wheel the Jeep hard. I've broken one. Binds up the steering, but virtually no chance of seperating the knuckle from the axle hsg., which is not uncommon when a u-joint breaks. I have a friend running 35's with the same joints and 4.56/ Lockright also, so far he hasn't broken it. It was installed after he broke a 297 joint. I will continue running them with the 36's I'm soon getting, and when the frt. gets a 44, I'll be looking into some custom cv shafts.

[CRASH]

:yelclap:

Thank you, Explorer.

CRASH

P.S. One other related advantage. Each joint in the CV only sees half of the operating angle for a given turning angle as a standard U-joint.

Still not convinced teh stock CV's in XJ's/ZJ's/WJ's are better than a 297/760, but I have limited experience with them (saw a couple break in a rather easy spot).

I agree.


The main difference between u-joints and c/v joints is the constant velocity nature of the cv, hence its name. A universal, or "cardan" joint, creates a speed fluctuation on the output side twice every revolution. This is the reason that single cardan shafts need to have the joints phased properly to get smooth running. Even then, the shaft between the joints still has to accel and decel twice every revolution. At excessive angles, this setup can give vibration even if the joints are phased properly and at equal angles and the shaft is properly balanced. Same concept with a "double cardan" which is improperly referred to as a "cv" joint. The H-yoke between the two joints sees this same speed variation.

There are different types of cv joints to further confuse people. Some are made to accomodate plunge in the joint, serving the same purpose as a slip yoke on a conventional propshaft. They are typically used on the inner joint of FWD halfshafts. Another common application in the Jeep line is for the axle end of the front driveshaft. It was commonly used on Quadratrac models from around 96 ZJ's and into WJ's and KJ's regardless of t-case option. Fixed type cv's, without plunge capability, are typically used on the outer joint of FWD halfshafts, and this is the type used on solid frt. axle applications in the Jeep line. They were used from the beginning of the XJ when equipped with Selectrac and in various Jeeps since then. Quadratrac Grand's use nothing but cv's, and depending on the year, many Selectracs also use them.

As far as strength is concerned, you have to watch what you compare. Does the OEM cv equal the strength of a CTM or OX joint, or something similar? Probably not. Does it equal the strength of the standard 297 joint. In my opinion, yes. In theory, its used in applications with the most power (ie:V8 Grands,including 5.9's) which also happen to be largely fulltime 4wd models, meaning they are %100 duty cycle, as opposed to what, maybe %20 at best on a part time model. Now, there are cv's being engineered for the same application as the super u-joints out there. They are no doubt better than the standard versions, and the little info out there suggests that they can equal the strength of the bigger, better u-joints out there. One inherent advantage is the consant velocity output. U-joints often break when operating at an angle. The accel and decel transfered to the wheel assy. is partly to blame for this. It creates a shock load to the entire driveline.

I believe cv joints are a superior design. And I don't just have this opinion with nothing to back it up. I run them (OEM) in my TJ's frt. axle. This with 4.10's, a Lockright, and 32" Swampers. That combination scares a lot of people before even mentioning the cv's. But in practice, it has proven just as strong, and more durable. I don't wheel rocks that much, but i do wheel the Jeep hard. I've broken one. Binds up the steering, but virtually no chance of seperating the knuckle from the axle hsg., which is not uncommon when a u-joint breaks. I have a friend running 35's with the same joints and 4.56/ Lockright also, so far he hasn't broken it. It was installed after he broke a 297 joint. I will continue running them with the 36's I'm soon getting, and when the frt. gets a 44, I'll be looking into some custom cv shafts.

[explorer]

:yelclap:

Thank you, Explorer.

CRASH

P.S. One other related advantage. Each joint in the CV only sees half of the operating angle for a given turning angle as a standard U-joint.

Still not convinced teh stock CV's in XJ's/ZJ's/WJ's are better than a 297/760, but I have limited experience with them (saw a couple break in a rather easy spot).

As far as ultimate strength with zero operating angle, the u-joint might win. This due to the smaller diameter of the shaft where it mates with the inner race of the cv joint. I have seen a few broken at the shaft, but these were vehicles that rarely if ever went off road. Both of them however had bad viscous couplers in the Quadratrac case which meant they had been driving around for who nows how long with the Jeep binding and jumping around every turn. When I broke mine, it was under very little load, strapping someone backwards off a rock. I wish I would have saved all the pieces, but I left them on a rock for someone else to laugh at. I believe it was fatigued from heat. Prior to actually breaking it, I have strapped people in reverse where the frt. suspension was squatted to the bumpstops and under scary loads, hopping the rr. off the ground. The morning that it broke, I had made numerous attempts at a hilll crest that I was high centering on. I eventually made it, but it took lots of throttle, and lots of wheelspeed on the slippery hill. I was strg. lock to lock under those conditions, something I'm sure would have damaged or broken a u-joint. I think this is what eventually caused the failure, but I subjected it to the same abuse many times before without a problem. When running the u-joints, I would have never even have put them through that much abuse due to the violent shaking that it causes.

[DDCxj]

Thank you CRASH and Explorer, I now feel edumicated......and a helluva lot less dizzy. Wow, I made no sense.

-Dean aka "The concussed idiot"

[XJ_ranger]

just some pictures to prove straight axle rigs come with CV's (sometimes)

here is an XJ (note the grill, d30 diff cover, and u-joint)
this is a 1992 with ABS and 297 u-joints
http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/thumbs/tIMG_3438.jpg (http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/images/IMG_3438.jpg)

http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/thumbs/tIMG_3439.jpg (http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/images/IMG_3439.jpg)

This is a 2003 WJ with ABS and a CV joint
notice the d30 diff cover again and the solid axle

http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/thumbs/tIMG_3440.jpg (http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/images/IMG_3440.jpg)

http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/thumbs/tIMG_3441.jpg (http://www.opiebennett.com/images/Jeep/WJ-d30-XJ/images/IMG_3441.jpg)

all images are clickable for a larger size...

just for refrence...

[bj-666]

i'm not here for less than 24hrs and my post goes to hell :lecture: . Thanx to explorer and Crash, the two people that actually provided some real info.

i would realy like to see some some pics/experiences about cv's.

i must request that anyone else who posts on this thread only post if they have factual info or at least some decent questions.
not just bickering hasta they came in a zj no a wj no an xj. yea that's it

[Yucca-Man]

This is like college.

I'm the professor.

I tell you that you are an idiot.

It's your job to figure out why.

CRASHI'm currently in college - most of the professors ARE idiots. Your turn! :laugh3: But I liked the rest of the thread...

[explorer]

Here are some pics of nothing really. But it gives a frame of reference anyway.

http://tinypic.com/5ds3s4 (http://%5BIMG%5Dhttp://tinypic.com/5ds3s4%5B/IMG%5D)
http://tinypic.com/5ds3zo (http://%5BIMG%5Dhttp://tinypic.com/5ds3zo%5B/IMG%5D)
http://tinypic.com/5ds83t (%5BIMG%5Dhttp://tinypic.com/5ds83t%5B/IMG%5D)
First, my friends TJ with 35 MTR's at the time, now running 37 MTR's. When the frt. tire dropped over the end of that big slab of rock, the rock wedged between the frt and rr. tires hard enough to almost make contact with both rims. That put enough force to bend the tie rod, and break the u-joint. Note that this happened at a speed of almost zero. The yokes on both inner and outer stub were damaged beyond being usable. I removed the inner shaft, stuffed a rag in the tube to attempt to keep oil in. He made the 3hr. trip home like that and a few days later, I installed a cv shaft in that side, which so far has given no trouble. We'll see how it lasts with the 37's now.

http://tinypic.com/5ds49l (http://%5BIMG%5Dhttp://tinypic.com/5ds49l%5B/IMG%5D)
http://tinypic.com/5ds7s0 (%5BIMG%5Dhttp://tinypic.com/5ds7s0%5B/IMG%5D)
The other two pics are my TJ showing the cv's in the original TJ frt. hsg. Cv shafts from a ZJ Grand are a direct swap to TJ or later XJ hsg. and knuckles. Earlier XJ's I believe too. WJ shafts are different lengths, but may work if you used the knuckle and hub from the WJ.

[Lawn Cher']

Everyone who is reading these posts are now dumber because of it. I award you no points and have god have mercy on your soul.

:wave: :wave:

Pete

Serve it up, Pete! :D

Thanks to CRASH and Explorer for saving this thread from inclusion in The Idiots Guide to Jeeps.

[Ivan]

Despite the "safety tire" being there just in case, this pic scares the crap out of me.... I just don't trust Hi-lifts enough to crawl under a rig in this situation...

http://tinypic.com/5ds83t

[Storydude]

http://tinypic.com/5ds83t

Wow.....Just WOW. You don't like Life much do you?????

I'd at LEAST have the tire pushed under that thing.

Because we ALL know Hi-Lifts don't slip, or fail.......

[explorer]

Ivan, and Story, I figured that pic would get some peoples attention. I'm fully aware of how high lifts operate and their dangers. The wheels were blocked, brakes locked. The high lift was also in a reciever hitch, and strapped to the bumper to keep it from leaving the reciever. I tried pushing the Jeep around and could not knock it off. I'm was a professional mechanic for @10 yrs., and in that time had no injuries other than some cuts and scrapes.

With all that being said, that isn't me in the picture. Its the Jeeps owner. All my work was performed sitting outside of the frt. fender with enough room between me and the Jeep that even if it did fall, I wasn't going to be under it. I don't know what he was doing under there.

For those who don't know better, don't let that pic be your example of how to work on your broken Jeep.

[hillbilly_jeeper]

Im quite happy running my 297x joints, but i was thinking, What might the strengh improvemnet be to the factory CV joints by having them frozen like they do toyota birfields? Dont know what the cost would be, but seems if they can make the birfields stronger by freezing them, then why not the jeep CV's?

[Boghog1]

I can tell you one good reason to run CV's vs U-Joints. I can pick CV axles for my XJ at any parts store and stores like VIP, Advanced Auto, Pep Boys and Auto Zone normally they come with a lifetime warranty, I pay about the same as an axle assembly from Quadratec but I only need to do it once.

I think if I was running bigger tires I may go the u-joint route because I can get alloy shafts. but since there are some on here running 35+ I may hold off.

Kurt

[XJ_ranger]

I can tell you one good reason to run CV's vs U-Joints. I can pick CV axles for my XJ at any parts store and stores like VIP, Advanced Auto, Pep Boys and Auto Zone normally they come with a lifetime warranty, I pay about the same as an axle assembly from Quadratec but I only need to do it once.

I think if I was running bigger tires I may go the u-joint route because I can get alloy shafts. but since there are some on here running 35+ I may hold off.

Kurt
35+ on a d30? you need more than a CV joint or an alloy shaft to keep us from laughing at you...

[BrettM]

well I see that this thread has been somewhat resolved, but CRASH sent me the link a few days ago and I was gone for several days and just read it; I have no further input except these very cool pictures:


http://img170.echo.cx/img170/9131/dana60cv018fn.jpg (http://www.imageshack.us)

http://img170.echo.cx/img170/6655/dana60cv052yd.jpg (http://www.imageshack.us)

[explorer]

Dont know what the cost would be, but seems if they can make the birfields stronger by freezing them, then why not the jeep CV's?

I talked to Bobby Longfield about this a while ago. He can do the same process, and I believe he told me @$65 a piece. He was actually surprised to learn that Jeeps use cv joints.