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Double Cardan Vs. Cv Drive Shaft

59K views 41 replies 22 participants last post by  biffgnar 
#1 ·
WHICH DRIVE SHAFT IS STRONGER FOR THE REAR OF 97' TJ? DOUBLE CARDAN STYLE OR A CV STYLE? TRYING TO DECIDE ON SYE STYLE. HACK AND TAP OR OTHER.:confused:
 
#6 ·
those are actually some very strong axles and can operate at some very steep angles. theres a company building axle shafts for TJ's now but i dont remember the name of the company.

a lot of people call the double Cardan drive shaft a CV shaft so when you bring up this subject most people will say they are the same. when you get to specifics they arent the same at all. dippert gave a perfect example of a cv shaft.

IMO id go with the SYE and double Cardan drive shaft. the hack and tap just seems like too much work for an inferior setup. i believe the new input shaft you get with the SYE kit is stronger than the stock one so the hack and tap job isnt as strong.
 
#5 ·
They're basically the same thing. I think ONLY Double Cardan shafts are made for Jeeps. But I seriously wonder why a true CV shaft (ball type) isn't used or preferred in 4x4 applications. Serviceability maybe? Cost? I know it's not power reasons because I've seen some of those shafts handle 800HP or more. It just seems like they could handle some extreme angles.

Any thoughts on that?
 
#8 ·
They can be built to handle the angles, but their typical failure is they can't handle the higher RPM's the driveshaft needs to turn. The driveshaft turns an average of 4 times faster than the wheels do. That's a big increase in surface feet per minute that the bearings get subjected to.
 
#13 ·
I know this thread is a few months old, but I've been recently dealing with similar issues. I found a great writeup on pirate4x4.com

It explains not only how to do your universals, but also offers a disgustingly in-depth explanation so when you're done reading it, not only is your brain made of driveshaft goo, but you can replace/repair a driveshaft and/or joint while you are drunk, asleep and have your eyes closed. It will also teach you how to match up angles correctly and explain what Glidecote, Phasing and a Trunnion all are.

The four-part writeup is found here.
 
#16 ·
I'm not a JK guy, but don't JKs have CV joint (ball type) rear driveshafts, rather than ujoints? I thought I saw that somewhere.

Pete
Don't think so. Most in the Jeep community use the terms double cardan and CV to mean the same thing. They are really refering to the double cardan style shaft with two u-joints and a centering ball on the transfer case end and a single u-joint on the differential end.
 
#19 ·
You were right. Hmm! I had crawled around under on and didn't notice it. I was paying more attention to the suspension and obviously didn't pay enough attention to the drive shaft.
 
#23 · (Edited)
if i ever have to install another ds, i'm going with Cornay. i assume price has something to do with me not hearing much about them on any of the forums.
They list a maximum and operating RPM's. operating RPM of their CVX joint is only 2200, but maximum is 5000. Might want to ask them what would happen if you drive for sustained periods over 2200 RPM. Even w/ my OD (0.72ish:1) i still go over 2200 RPM on the highway.

Cornay® - Welcome
I don't know what you define a 'CV' joint as. But to me it is a Constant Velocity joint and much like a TV (television) it can come in many different shapes, sizes, and designs.

I believe the joint in the pictures you posted is called a Rzeppa joint.
Both the Rzeppa joint and Double-Cardan joint are what I consider to be CV joints.

Luke.
DC, Rzeppa (which i posted animations of), Tripod, Thompson couplings. They are all CV joints of varying sorts. A lot of car people think of Rzeppa styles when we say 'CV' joint. Is that a Rzeppa on the stock JK?
If you feel the need to jump on me about this, why don't you call them what they really are? Rzeppa and DC joints. Just calling it a CV might confuse somebody. Obviously the OP was confused about the difference.

Double Cardan Joint


Rzeppa Joint


Tripod Joint


Thompson Coupling
 
#20 ·
Like I said -- I didn't remember, had to go find that. Maybe they've stopped using them, as it was considered a weak point? I have no idea. Man, JK's been in production almost 4 years already. Yikes, time flies!

Pete
 
#24 ·
This is an old thread but since it has been revived, driveshaft expert Tom Wood considers a double-Cardan and a CV joint to be the same thing. His opinion is good enough for me and I'll continue to use the terms interchangeably.

In all of his technical writeups, Tom uses the two terms interchangeably and even places one in parenthesis following the other like where he says "The real benefit to a C. V. (double cardan) drive shaft is smoother operation at higher operating angles and longer life. The C.V. assembly works by intersecting the joint angles at the center pivot point and delivering a smooth rotational power flow or surface velocity through the drive line." at Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist on his Driveline Geometry 101 tech page.

That above animation is cool but that's not the only form of CV joint, the driveshaft industry widely categorizes a double-Cardan (two u-joints with a centering joint) and many other types as a CV (constant velocity) style joints as well. :)
 
#26 ·
a rectangle is a square but a square isn't a rectangle.
but for the purposes of Jeepforum, and jeeps in general, CV and DC joints are the same object. but in the world of joints, they aren't always interchangable. hence TW using parenthesis to specify which CV joint he's talking about.
 
#27 ·
This is like DeJaVu...

They are all types of CV joints.

Double cardan type CV joint - the kind most Jeeps use on the drive shafts, utilizing two U-joints

RZeppa type CV joint - the "ball type" you usually see on front wheel drive imports

Tripod style - a plunger type, resembles a three ended u-joint inside of a machined housing (sometimes also of FWD car axles)

Birfield joint - another style of "ball type" CV joint, theses are the ones people are usually talking about when they refer to older Toyota front axle shafts

So yes, a double cardan joint is a CV joint. But no, a CV joint isn't nescessarily a double cardan joint.

So you can't ask if a DC joint or a CV joint is better. That's like asking "Which is better - oil or lubricant?"!

BTW - CV joint means constant velocity joint, meaning that it theoratically does not change speed as it rotates through it's range of motion when operated at an angle...
 
#30 ·
Is anyone making a drive shaft with a thompson coupling?

A shaft with two couplings one on each end would pretty much allow the transfercase vs differential to be at just about any angles...
Eliminating the need to install adjustable control arms etc.
I doubt it, I believe that is a fairly new design...

Looks like a high tech variation of a double cardan joint.

Probably pretty expensive!
 
#35 ·
So I had to go look at the TCVJ website tonight. (Awesome post though! What a great looking product...)

Found this:

V-Series
Constant velocity variable angle Joints - shaft angles to 40 degrees
Reduces energy loss by reducing friction, heat and vibration, especially in applications where motors and devices have angular misalignment as well as compound angular misalignment.
Applications
• Steel and paper rolling mills
• Diesel motors and pumps
• Electric motors and pumps
• Helicopter propeller shafts
• Large industrial off-Road vehicles
• Marine drive lines

Looks like they are all ready making them for off-road industrial applications. I'm assuming this means skidders, logging skids, ect. I like the setup, but it looks very complex... it would be a great upgrade if you could put a big boot over it to keep gunk out. I can just imagine a stone making it's way inside and destroying the guts to that thing.

Give it another year and I bet they will produce them in a size small enough for passenger vehicles... especially if they are as amazing as they claim to be... [almost] no friction when bent?... with everyone screaming about fuel economy, that's sure to get some kind of response!
 
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