Double Cardan Rear Propellor Shaft

So I am working on my trans-model CJ3A.
Modified with Dana 20 and a center flanged D44 rear axle.
I really wanted to use a standard 2 joint rear propellor shaft. However the short length and steep angle made that a no go
So I tilted the differential upward and then installed a double cardan constant velocity yoke right at the transfer case.
I started my engine today for the first time and spun the complete drivetrain. Everything was perfect except the rear propellor shaft assembly,
It wobbles around like crazy when spinning,
How does a modern JK Jeep get by with such a floppy double cardan joint.
IMHO it’s just pathetic.
Now I have to rethink and change much of the drivetrain in order to go back to a typical 2 joint propellor shaft.

Only 2 options I can think of…

1) Lengthen frame 20” so I can install a long 2 joint rear propellor shaft.
That means I need to stretch the body tub, brake tubes, the exhaust pipe and wiring harness too.

2) Switch to an offset flanged D44 rear axle and the D18. But I had wanted this jeep to be as quiet operating as possible.

Custom built D20 TL 3.15 IH twin sticks and Jeep factory park brake:


Front view:
Rear view:
Right view:
Left view:

 

Shouldn't there be a centering deal on the double and the diff be more centered?

I'm all for converting to dual rear output. Then you can use this axle for a powered trailer.

 

If properly assembled, those double cardan joints DO NOT WOBBLE. I think you need to disassemble it and make sure all the parts are in there. That last photo is not normal.

 

Right the double cardan yoke has nothing to keep
it on center. So I’m not sure what is missing.
Some kinda centering ball assembly like the inside of a bendix joint ?
The double yoke is a Spicer C2 - 26 - 309

 

You are missing the centering ball....
I believe you need this part for your coupling flange side.

 

https://4xshaft.com/collections/jeep-cj-products

Call Tom Woods.

 

It may be this one that you need......
https://www.dennysdriveshaft.com/p4...easeable_flat_flange_style_cv_centering_.html

 

Looks like a double cardan attached to a stock flange. From Tom Woods....Features a Greaseable CV center ball.

 

I had to set this jeep build aside for the past year and just got back started on it today,
Guys I really appreciate the help with all this “modern” stuff.
As you can see I simply tied the outer double yoke to the stock standard flanges on both ends.

So is there a male and a female or is it just one centering yoke that’s required ?

 

You would need to check that the the bolt centers match to your D18 flange. When I had called Woods, they said I needed to use a splined yoke on a Dana 18
to use the double cardan. I am not sure if the correct yokes are not available or the price is through the roof for them. I would call Shawn Woods {really cool guy}
with any questions seeing as you have a special application. You are attempting to to use the parking brake and can only use a flanged centering yoke to match.

 

Ken, you have nothing to center the joint assembled that way. You need something similar to this: https://www.summitracing.com/parts/...MIwN2Xivag_wIVchN9Ch0NsAn6EAQYBCABEgLawvD_BwE

There should be all sorts of video online as how to assemble those.

 

Not the best photo for this, but this is the driveshaft for my 3B which connects to a 1310 CV yoke on the D18. Those yokes are specific to double cardan joints have through holes for the bolts into the centering "yoke" and are machined flat for the bolt heads.

 

Here's some diagrams on how a double cardan goes together and works with the centering ball:




You'll need a new top end on the driveshaft too. As others have noted, contacting a driveline shop with your needs and having them make you a new proper double cardan shaft is the way to go.

 

This is going to hurt your wallet a little more, but I’d highly recommend a double cardan at the axle end too. You’ve got a fair amount of sideways misalignment, and even if the pinion is pointing at the same angle as the driveshaft, the standard single cardan joint at the pinion won’t have an equal/opposing joint to cancel out its sideways misalignment, and it will vibrate noticeably. With two double cardans, any misalignments are ok if they’re within the joints’ specs.

How bad are the u-joint angles if running standard joints and equal opposing angles at the t-case and pinion? If running two standard u-joints, the sideways misalignment isn’t an issue if the angles match.

 

X2. All of this.

 

Vtxtasy, yes the park brake requires the early 2 x 2.375 bolt pattern,

John, thanks for the pic. Mines is not much if any longer. Yes I also wanna run the typical 1310 joints.

Fireball, yep I was thinking it will need a special end for the slip yoke too. Thanks for confirming that.

itlksez, thanks for the “2/double cardan” propellor shaft suggestion; Yes I understand the reason. I was very surprised to see so much sideways misalignment between the center flanged D44 axle pinion and the D20 transfer case companion flange.

All in all it looks like the only way to make this work properly is to have a custom rear propellor shaft fabricated with double cardan crosses at both ends.

Now I Kinda wish I woulda just stretched the wheelbase by 20”. Long propellor shaft with single “U” joints and problem is solved. I may rethink this build design since I have lots of parts for other options like stretching the wheelbase or installing a D18 with offset flanged axles.
If I go to the D18 and offset flanged then the 2 differentials will be more “in line” for the short wheelbase.
On the other hand I have wanted a 100” wheelbased Jeep ever since the late 1970’s when I read Jack Jackson thoughts on “extreme duty expedition rigs”.

 

I'm betting Tom Woods would be very helpful.

 

Yep. The people that built my driveshaft. It was too short for their decal

 

If that's what you've always wanted...
What are you doing for a top?

 

I have 3 different tops to work with:
A new Black 3A Tigertop
Complete original framework and door frames for a 3A canvas top.
A NOS (still in original box) Kelly half cab to fit a 3A.

Right now I’m leaning toward re-arranging everything and use the D20 and associated narrow track center flanged axle under a 116” wheelbased pickup,
The pickup will have a 3A front end and use up the NOS Kelly half cab.
I have s Bantam trailer tub to use for the 6’ bed.
It will end up being a narrow 3A pickup with a lockable cab.
Of course it will be Dauntless powered using the factory mounts.
That way I can go back to using a normal jointed propellor shaft.
Besides I already have extra 3A frames to easily stretch an otherwise standard frame.
I’ve had all these parts for years not knowing which way I might go.
Love a good Jeep and also a good pickup. Best of both worlds.