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Homemade rear CV shaft: Almost there!

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Blazer79

1/2 ton status
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Guatemala, Central America
Well guys, I'm very proud to tell you I'm almost finished building a rear driveshaft with a CV-joint for a 14bolt axle /forums/images/graemlins/cool.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/thumb.gif . I did all this with the help of a guy who owns the best Chevy & Ford only junkyard in the country. Here's what we did:

The starting point was my stock driveshaft that was between my NP203 and a 12bolt axle. This had the slip yoke close to the transfer case.

He found me a new slip yoke from a longbed Chevy truck. I saw when they removed it from the old driveshaft. This driveshaft had like a support bearing and a U joint around the middle of the bed of the truck. The slip yoke I'm talking about was grabbing this U joint. We just slipped the old yoke out and put the new one in. It fits perfectly on the 14 bolt. Now this means the driveshaft is now backwards.

He then found me a CV joint out of a front transmission. I'm guessing it came from a 208 or something like that because it still had the yoke from the transfer case and it appeared to be a slip yoke (not sure about this). All I had to do was unbolt the straps from the old yoke and that left me with a U joint that was held on two ends by the CV joint and the other two ends fit perfectly on my NP203. It was the perfect size U joint. This CV joint is different from my current front driveshaft one. Mine ends with a circle with four bolts on it, this one has no circle, just a yoke with straps.

All I had to do now was remove the old U joint end (12 bolt side) from my driveshaft and weld the CV joint. He sent me to a shop that did the welding nicely and in about 3 hours I had my driveshaft ready to bolt on.

I arrived home to test fit it, and there's one little detail I found out I missed. On the NP203 side, the U joint fits perfectly, but the holes for the strap bolts on the CV joint do not align with the holes on my NP203's yoke. /forums/images/graemlins/angryfire.gif

So what should I do now? I think I have 2 options here. I'm going back to the junkyard tomorrow and take a closer look at the yoke we removed from the CV joint. I think I counted twenty something splines on it. Does anybody know how many splines on a 203 yoke? Maybe all I have to do now is remove my NP203's yoke and install the other one. If that yoke is not compatible with my NP203, then I'm thinking maybe I can cut off the little ears on the CV joint and use those little U Bolts bolting the U joint to the Tcase's yoke.

Now to prove this poor guy from the Guatemala is not making this up, and just trying to build the best Blazer in the country while saving a few bucks, here are the pics.

This is how the driveshaft looks after installing the new driveshaft and welding the CV joint:
ds01.jpg


This is a closer look to the CV joint side:
ds02.jpg


This is the 14 bolt side with the truck slip yoke installed:
ds03.jpg


No problems on the 14 bolt side. Perfect fit!!
ds04.jpg


Here's the problem. When he showed me the CV joint I only noticed if the U joint fit, I didn't notice the misaligned bolt holes.
ds05.jpg


All comments, ideas, flames, etc. are welcome. /forums/images/graemlins/laugh.gif
 
Right on, thats exactly how I made my first one, with a front CV! Sweet job, it looks good. I had the same problem with the bolt holes not lining up. What I did was build a bead of weld on each side of the CV flange, fill in the holes, then drill and tap new holes and runs studs in the CV rather than running bolts through. A few nuts on the TCase side and your fixed. You will want to take the CV apart to do this and remove the centering ball bushings so when your welding you dont burn them up.
 
Borrego:

I think I'm going that route too. Do you know if I need any special weld for this?

Also, did you ever break something in this kind of shaft? Why did you change it? I'll be running 36" with 4.11, which is actually softer to move than my current 31" with 3.07s
 
I used steel flux core to build up the edges and it never failed. There were 2 reasons I had to step up to the High Angle 1350 CV and 1410 yolk. The 1st was due to my 415ci and its ability to 'twist up' anything between it and the ground. It was a constant factor in wearing out the smaller U-Joints. The 2nd was the operating angle of the CV was near its limits even with the tabs trimmed down on it. I was getting more and more rear end flex and could hear it binding on full droop. The 1350 CV cured both of these issues. It worked great for around town with an occational pinion U-Joint replacement.
 
Not to be an ace-holyo, but thats not a CV joint. That is called a double cardigan joint. You will still have vibration because usually the front and rear joints cancel each other out, yet the DC joint will cancel out the one joint having the other create the vibs. A Constant Velocity joint is designed totally different and does not utilize u-joints. /forums/images/graemlins/burb.gif
 
So I guess it won't hold much with my 454 then /forums/images/graemlins/frown.gif

I thought I had something good going here, it seems it will just be a temporary solution. The problem is I can't afford a high angle driveshaft, especially with high taxes and heavy shipping costs.
 
BigBurban, then what does a real CV joint looks like? I thought the High angle ones were similar only larger and with the proper cavities to allow higher angles.
 
You might be surprised at how long the one you made will last. Give it a shot, you've come this far. You might want to safety hoop it so that if you do bust a weld or throw a U-Joint that the shaft doesn't wipe out your exhaust or open up the floor.

BigBurban is correct, it is technically a Double Cardigan joint as opposed to Constant Velocity, the term has crossed over to driveline shops who have dubbed them the same because their characteristics are nearly identical . Constant Velocity joints typically use large ball bearings as opposed to U-Joints. I disagree with the two DC U-Joints not canceling each other out though. The locating ball in the center forces each U-joint to split the overall angle equally. Were you could pick up vibes remains only from the opposite end of the shaft at the pinion where only one u-joint exists if that should gain any angle, perhaps this is what he meant. CV shafts in cars typically have them at both ends so that problem doesn't exist. Trucks with excessive lifts and bad driveline angles sometimes run a DC at both ends in order to become perfectly vibe free.
 
Uh, I think you guys are talking about a double Cardan joint. Not a Cardigan sweater. /forums/images/graemlins/wink.gif A double Cardan is considered to be a type of constant velocity joint, since the shaft on either side isn't speeding up and slowing down with each revolution of the shaft, as is the case when a single u-joint is working at an angle.

I think the one you're thinking about that uses the ball and cage arrangement is called a Rzeppa joint, which is another variation of a constant velocity design. There are several different designs, with various names and configurations, but they all accomplish the same task.

To properly use any type of CV joint on a driveshaft, the other end of the shaft needs to have a near-zero degree working angle (or another CV joint). Otherwise the u-joint at that end of the shaft will induce the speeding up and slowing down on each revolution effect and create vibrations. The reason that you don't feel the vibrations on a stock truck driveshaft is that the driveshaft is designed so that the angle at each end of the driveshaft offsets the angle at the other end, thus cancelling each other out. In essence, it could be considered a constant velocity joint with a very long center support. /forums/images/graemlins/shocked.gif
 
Can you use a Cardigan on both ends of the shaft? I've heard somewhere that you can but I have never seen it done.
 
</font><blockquote><font class="small">In reply to:</font><hr />
Can you use a Cardigan on both ends of the shaft?

[/ QUOTE ]

No, it'll be far too hot with two sweaters /forums/images/graemlins/rolleyes.gif installed on it! /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/rotfl.gif
 
Hahah - I thought I had it wrong all along with cardan when BigBurban350 posted(although I was thinking cardian) .. I think I like the CV acronym better!! /forums/images/graemlins/ignore.gif
 
Interesting info you found there, Harry. I've seen those Rzeppa joints on my mother's Caravan. Pretty fragile in those transaxles. Imagine them on a Blazer.
 
The centering pins in each CV would keep it from flopping around with CV's at both ends. I've seen this done before. So, whats the status.. are you going to build up the edges or... ?
 
Yes, I have to finish it all the way, since I can't afford a new one.

I'm currently looking for a shop that has such advanced kind of welding. Everyone here just talks about electric (stick) or gas (acetylene) welds. I've just found a few that have MIG and TIG. I was also told about a shop that fixes wheels that should be able to fix this. I'm guessing they have all types of weld.

I still want to look in that junkyard again maybe there's an output yoke for my 203, or maybe it could be easier for the shops here to cut my current yoke and put the ears of another one?
 
I'm not sure you'll find a yolk to match which will fit the rear output shaft and still fit the U-Joint.. but its definately worth looking into. A stick or Mig should do the trick to build it out.. I never had a failure at the mounting if that helps.
 
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