Driveshaft question, CV and single U joint?

[Motorcitydak]

I am not quite there yet but I was thinking about my rear drive shaft. My transfer case is from a Cadillac STS and uses a cupped 6 bolt flange to attach to the CV joint driveshaft. The rear axle is a ford 9 inch, I have a few u joint flanges I can use on that. Can I run a driveshaft with a CV on one side and a single U joint on the other? I know that the U joint will change speeds as it rotates but is it really that necessary to address? My truck had a CV joint at the transfer case and a single U joint at the axle but that was for IFS and, well, a truck. This is a different application and obviously I do not want any problems from the driveshaft. This does seem like a rather easy solution to join the two, but that does not mean that it is a good idea.



I showed the transfer case yoke to a machinist who said that he could do something so that I could get a U joint flange on the output. I also know that I could get a flat flange for the 9 inch and have him make a cup of some sort to fit the CV joint into. Should a CV shaft be attached to a live axle tho? Or should I stick to the good ole tried and true U joint setup and have the t case output adapted to hold one? The rear shaft will not be very long, I would guess around 3 feet at the most.

[Kenova]

Stick with the CV/u-joint combo. Your drive shaft will be less prone to vibration due to differing work angles.
Andrew B. used such a combo on his drive shaft to successfully eliminate a persistent vibration.

Ken

[Motorcitydak]

Ok, thanks! So keep the CV joint at the transfer case, U joint at the axle. I figure I can have the telescoping part at the axle side, just get the shaft welded into the end of the driveshaft I have now

[zombiekiller]

You'll end up with a cv at the t-case, a slip yoke and a u-joint at the axle.

The only thing that you'll want to be mindful of is that a slip yoke may have an inherent vibration based on its design at speeds over 100mph of so.

Make sure that you're greasing the slip yoke at regular intervals with high quality, heavy grease to minimize wear on it.

If we're talking high ponies and torque, you may want to find a beefier slip yoke than is generally found on 1/2 ton trucks. The beefier the slip yoke, the larger the axle side u-joint will need to be.

[Motorcitydak]

Good advise, thanks. I was planning on using a 1350 u joint with one of the yokes I have. I can pick up a slip yoke shaft from some kind of pick up that uses the same size tube that the CV shaft I have now is, then have those 2 welded together

[CTX-SLPR]

Subscribing as I have a slip yoke at the center of my 2 piece shaft in my Riviera.

Where does one get a heavier duty slip yoke, Inland Empire?

[andrewb70]

Here is the driveshaft that was made for me by The Driveshaft Shop:



Technically, it is not proper to run a CV on one side and a u-joint on the other side because you need u-joints on both sides to cancel out the vibrations. However, in practical terms, there are no issues. What you must keep in mind is that the operating angle for the u-joint must be kept as small as possible, but not zero. In my case, I run about a .5 degree working angle with the pinion down, so that under load the pinion cycles from about -.5 to +.5 degrees. This keeps the u-joint lubricated and makes it work without vibrations even at high driveshaft speeds.

Alternatively, you can run a CV at the pinion on your 9" rear. Hollinger Engineering in Australia makes a CV pinion yoke for Ford 9" rear ends that accept a CV (not sure what size, but most likely the popular 108mm, like on my driveshaft). The yoke is a little expensive, but this would be the slickest and most vibration free solution.

Andrew