CV/U-Joint Question

Kugellager · **Posted:** Wed Aug 13, 2008 11:13 am

Here is a question (maybe a naive one) for some of the drive-line/axle/CV experts around here.

Would it be possible to replace our front CV half-shafts with an one having two Double Cardan u-joint CV's? Would there be enough play in this type of shaft to eliminate binding issues?

Maybe you could modify a doner CV shaft and replace the ball-bearing CV's with the U-joints parts.

It seems like you can have axles made in just about any size. This would solve the problems of torn boots and make them much more easy to rebuild. I would guess that it would be stronger too. One other thing I forgot to add. I believe this modification could allow the center section of the shaft to be slightly longer thereby reducing the joint angles.

John
];')

tjkj2002 · **Posted:** Wed Aug 13, 2008 8:03 pm

You can,the older Vettes are IRS and use u-joint shafts from the diff to the wheels.

But.....................

How much money do you want to spend?

Kugellager · **Posted:** Thu Aug 14, 2008 9:28 am

Well I have already had to change out my CV's once and was lucky to get the barley used pair from TED. I only have 14k miles on mine - lifts and wheeling are hard on them. The way I look at it, if the U-joint CV's are only a little more expensive that the ball-bearing CV's and they last longer AND are easier to maintain then it would not be a trade off in money. Plus, from what I have looked at as far as getting parts to have something like this made, Spicer seems to have all the parts and I saved the bad CV's from my swap so I alread have a donor pair.

SFA would be much more expensive.

I need to do more research on CV angles and such. Finding a double cardan that bends in the 45 degree range is easy from what I have seen online - there are many available. I have also measured the angles of CV's from several photos on this site and have so far found a maximum at-rest angle of 23 degrees for standard 2.5" lifts. Just need to pull the JKS disconnects and jack mine up to see what angle is at full droop to find maximum.

RE: Corvettes. That is only the rear suspension. The front suspension will have another degree of motion - The turning of the wheels. That is probably about a 30 degree bend.

Like I said...more research needed.

John
];')

Jeep4me99 · **Posted:** Thu Aug 14, 2008 9:34 am

your avitar scares me

Kugellager · **Posted:** Thu Aug 14, 2008 9:35 am

Jeep4me99 wrote:

your avitar scares me

BOO!!!

Guest · **Posted:** Thu Aug 14, 2008 5:27 pm

Kugellager wrote:

RE: Corvettes. That is only the rear suspension. The front suspension will have another degree of motion - The turning of the wheels. That is probably about a 30 degree bend.

Not to mention the Vette doesn't flex nearly as much as any 4x4. Double cardan joints I could see...but that would require a sliding axle. Couldn't just throw the U joints on the end of the shaft and call it a day. U joints would be as taxed (or moreso than) the CV, and you've also got space at a premium. I'm not staring at my KJ right now, but might the LCA interfere with a double cardan joint?

Kugellager · **Posted:** Thu Aug 14, 2008 6:10 pm

Well the theory I have on it is that you have one double cardan at each location where the current ball-bearing CV's are now. The housing and boot is about 4" in diameter with about 1/2" to spare over the LBJ. There are cardans in the proper size range from what I have seen.

Why would you need a sliding axle? The current CV's don't have them. The U-joints would just replace the ball-bearing CV"s and provide a flex similar to what is current there.

Besides, Flex in the front is limited by the a-arms anyway. I suppose a sliding axle could provide a a small amout of extra flex...but not that much IMO.

John
];')

tjkj2002 · **Posted:** Thu Aug 14, 2008 6:12 pm

You would need a slip joint built in.The inner CV's are a floating CV,it can move in/out about 3.5"-4".

Kugellager · **Posted:** Thu Aug 14, 2008 6:21 pm

tjkj2002 wrote:

You would need a slip joint built in.The inner CV's are a floating CV,it can move in/out about 3.5"-4".

I did not know that...very interesting. So does the inner cup slide in and out? What exactly slides in the inner CV?

John
];')

tjkj2002 · **Posted:** Thu Aug 14, 2008 6:27 pm

Kugellager wrote:

tjkj2002 wrote:

You would need a slip joint built in.The inner CV's are a floating CV,it can move in/out about 3.5"-4".

I did not know that...very interesting. So does the inner cup slide in and out? What exactly slides in the inner CV?

John
];')

The CV cup does not move it's the rest of the joint,all internal,that moves in/out.There is a retaining clip on the inside of the CV cup to prevent the joint from comming apart.That's why cutting off the inner CV cup,like for JBA's 4" and 6" lift,is a bad idea since the joint could pull itself apart.

Jeep Dawg · **Posted:** Thu Aug 14, 2008 9:18 pm

If this forum was not censored I would have a really bad potty mouth about the CV's !

Tonight I had a few drinks while looking over my KJ and I have a 5 gallon gas can and a lighter. Lucky for the KJ the 5 gallons of gas cost too much to torch it!

DryBones · **Posted:** Thu Aug 14, 2008 9:40 pm

it's that bullbar/tow hook combo...it just ain't natural! Either that or those spark plugs that are causing all your bad mojo! :lol:

j/k, hope you get it worked out soon

Jeep Dawg · **Posted:** Fri Aug 15, 2008 10:46 am

one way or another something will work or sonner or later.
which ever happends first, I just want it to happen....

Kugellager · **Posted:** Fri Aug 15, 2008 10:50 am

Here is something interesting I found today. They have a 35 degree angle with only two U-joints an no Double Cardans.

http://www.driveshaftsuperstore.com/ <---see the front drive axles. Would probably want the 1350 one ton axles.

If we could weld flange plates to modified (cut down) CV housings then we could use something like these. They even have a 9" stroke.

Of course there would have to be some detailed measurements taken of the current CV's and the suspension geometry to make sure the axles were perfect. But thats is not too difficult.

By the way the diameter of the 1350 one-ton u-joints (based on what the Spicer website says) is just under 3.9".

By the way, I took some measurements off my old pair of CV's which I will post tonight. The stroke was the same for both and was about 3". I will post exact measurements later.

John
];')

Kugellager · **Posted:** Sat Aug 16, 2008 9:28 am

Here is what I measured off of the old pair of CV's

Long CV Joint
Minimum Length - 37 7/8"
Maximum Length - 40 3/4"
Stroke - 2 7/8"

Short CV Joint
Minimum Length - 24 1/2"
Maximum Length - 27 3/8"
Stroke - 2 7/8"

CV cup housing diameter - 3 3/4" to 4"+ if you include the boot.

John
];')

Kugellager · **Posted:** Fri Oct 30, 2009 4:48 pm

Bumped a real old thread here.

See the "Bad Boy JR 60 degree CV" Driveshaft to get a picture of what I am talking about as a model for a replacement for our front CV half-shaft joints maybe using Spicer 1350 (or stronger) parts..

http://www.driveshaftsuperstore.com/bad ... shafts.htm

Still need to look into this more.

John
];')

BugginKJ · **Joined:** Mon Jul 06, 2009 7:35 pm **Posts:** 4576

Kugellager wrote:

Bumped a real old thread here.

See the "Bad Boy JR 60 degree CV" Driveshaft to get a picture of what I am talking about as a model for a replacement for our front CV half-shaft joints maybe using Spicer 1350 (or stronger) parts..

http://www.driveshaftsuperstore.com/bad ... shafts.htm

Still need to look into this more.

John
];')

I looked into this here localy because I work with a driveshaft shop that makes a lot of stuff for us. They said sure we can make them but it is the cost that made me wince......anywhere between $500 and $1,000 PER shaft, probably closer to $1,000 he said :shock:

! The same pricing in the link you provided basicaly.

CV/U-Joint Question

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