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post #1 of (permalink) Old 11-02-1999, 04:39 PM Thread Starter
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compound u-joint angles

i have about a 1 1/2 inch offset from my drive shaft to rear axle after swapping in a dana 44. what is the general rule for vertical and side angle combined?

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post #2 of (permalink) Old 11-02-1999, 05:22 PM
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Re: compound u-joint angles

You can't really combine the two to come up with a general rule. For 1.5" I wouldn't worry about the side to side angle. Both yokes are on the same plane (pointing front to rear and vice versa) and the angle is negligable. I would only be looking at the angle on the vertical plane. My '75 is about 1.75 inches off side to side right from the factory and with a CV joint and the pinion turned up I have absolutely zero driveline vibration.

post #3 of (permalink) Old 11-02-1999, 10:55 PM
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Re: compound u-joint angles

[img]/wwwthreads_images/icons/tongue.gif[/img] Will....think of it as a giant ice cube, with the transfer case yolk at the top corner of one end, and the differential yolk at the lower corner of the other end. As long as the sides of the cube are parallel(and the engine IS straight down the middle of the frame), it doesn't matter, as you can solve for that ONE angle that is made by the line between the two joints. It is only when you drop down and go off in another direction that you separate the men from the boys on setting up u-joints. THEN you have to worry about rotating the joints on the tube to get a slightly different cancelling relationship.[img]/wwwthreads_images/icons/wink.gif[/img]

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post #4 of (permalink) Old 11-03-1999, 09:41 AM Thread Starter
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Re: compound u-joint angles

thank you for the responses. i got the vertical angles within 3 degrees of each other and don't have any vibrations. i'm just curious how long my joints will last with a compound angle since the th400/quadratrac don't leave a very long driveshaft.

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post #5 of (permalink) Old 11-03-1999, 09:51 AM
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Re: compound u-joint angles

[img]/wwwthreads_images/icons/smile.gif[/img] Uh....Will...You don't HAVE a compound angle unless the rear axle is crooked with the Right Rear wheel lagging way behind the left. If you were a mouse and were clinging to the driveline, you would only see ONE angle...that angle does not necessarily have it's plane in the vertical, but....and listen close when the mouse tells you.....IT IS ONE ANGLE.....not two. You'll be fine. Take my word for it....there IS only one angle. Been there (engineering skool) done that...have TH400 W/ Quadra Trac.[img]/wwwthreads_images/icons/smile.gif[/img]

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post #6 of (permalink) Old 11-03-1999, 01:00 PM
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Re: compound u-joint angles

What model jeep did you do this swap on? I have a '76 that I swapped in the 44 and the same thing happend to me.

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post #7 of (permalink) Old 11-03-1999, 01:38 PM
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Re: compound u-joint angles

The reason that this happens with the 44 is because the pinion is not exactly centered beween the ends of the housing. The output of the transfer case is centered or is very close. Those of us with '72 to '75's have this right from the assembly line. It's not enough of a difference to cause a problem. The important thing to look at is that the output of the t-case is pointing directly at the rear and the yoke of the rear is pointing directly at the front. If a line is drawn through the respective output/input to the rear/front of the vehicle (not a line from the output to the input), these lines should be parallel to each other. If they are, the u-joints are in phase with each other. Problems occur when these lines are not parallel. Now if you are running a centered t-case to an offset diff or vice versa, you have big problems even if the lines are parallel. That would be too much for the u-joint to handle. It's all the same principals as looking at how much drop there is from the t-case to the pinion, just viewed from below (or above) instead of the side.

post #8 of (permalink) Old 11-03-1999, 04:21 PM Thread Starter
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Re: compound u-joint angles

thanks dave, i understand now. (sometimes engineers are the hardest ones to explaing things to.)

for matthew:
i swapped a 44 from a 70 wagoneer into a cj7 with a quadratrac. the 44 is a little offset and the quadratrac is more offset. one surprise i didn't think about is the 44 has a higher pinion position than the amc20 which helps with the driveshaft angle.

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post #9 of (permalink) Old 11-03-1999, 04:21 PM
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Re: compound u-joint angles

[img]/wwwthreads_images/icons/smile.gif[/img] You nearly had it SNOTOW.... you were right on track, except that when you have a lateral offset it STILL doesn't matter....the true angle plane is just tilted somewhat. There is still only one angle as you pointed out as long as the shafts are parallel. One could be on top of the tailgate as long as they are parallel. Very often, the angle to accomodate the drop is much greater than that portion needed to accomodate offset. Remember also, CV joints are a No-No if there is offset laterally, since there is no way to "bend" the pinion sideways.[img]/wwwthreads_images/icons/frown.gif[/img] and I'm sure that occasionally a Jeeper has vibration just because they have combined a single, transfer-case-end CV joint and a compound angle to an offset differential. [img]/wwwthreads_images/icons/wink.gif[/img]

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