The Dreaded Driveline Angle - Pirate4x4.Com : 4x4 and Off-Road Forum
 
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Old 05-08-2017, 07:15 PM   #1 (permalink)
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The Dreaded Driveline Angle

Hey All, new to the site here so be gentle. Been reading for 2 days now on hundreds of posts on driveline angle and can't seem to get the answer Im looking for.
Quick overview: 79 CJ7, dana 44 rear axle, SOA, T4 trans, dana 300 twin stick, propane injected.

THIS IS PURELY AN OFF ROAD RIG! Never sees the street, maybe goes 15 mph at the very most.

So i have bought this truck pretty much done, but having issues that I would like to fix. I like to build my own parts when possible, not buy complete (love fabrication).

My rear pinion is in direct line with the driveshaft (21 degrees). The transfer case is at 0 degrees (straight out, no tilt). I don't want to go with buying a whole new double cardan driveshaft. Im not really worried about driveline vibration cause I'm not going fast enough. U joints are rated at max about 10 degrees, anything over that its gonna break (from what i have read). I am going to tilt the motor up a bit to bring the angle down, but still think I'm going to need more.

Any ideas? Anyone custom fabbed something themselves? Open to any ideas. Pics would be great!
Thanks
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Old 05-09-2017, 07:29 AM   #2 (permalink)
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If you can weld, then just buy a good quality CV joint, cut down your existing driveshaft and weld it on.

Other ideas you can try. Drop the tail end of your transmission/t-case a few inches, and/or raise the engine, so that the tail tilts down a few degrees. The con here is your front driveshaft angle will increase. However, if you can clock the t-case, you'll solve some of the angle, but you'll also reduce the ground clearance a little.

Years ago I had a Ramcharger with 10 inches of suspension lift and a divorced 205 transfer case. The angle was about 25* after I dropped the t-case, so we tried an experimental set up where I had a Rzeppa joint welded onto my rear driveshaft instead of a standard double cardan joint. (A Rzeppa joint is the ball/groove style CV joint popularly used on FWD cars or called birfield joints on solid axled Toyotas) I never got a chance to try it because I eventually parted out the truck. The Rzeppa joint we used was a large unit found on the front axle half shafts of old V8 powered Eldorados and Toronados. Now that is at the extreme end of fabrication and theres no way to know for certain if it would hold up, but that was thinking way outside the box and it's something at the ragged edge, which might work for your off road only CJ7

Ed
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Old 05-09-2017, 07:43 AM   #3 (permalink)
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Thanks for the Info RXT. Would a CV joint allow for more angle without too much stress? U joints I know are only rated for max 10 degrees. Wondering if a CV would allow for more. After I lift the motor, if my math is correct, I should get my numbers down to around 13 to 15 degrees. Just not sure where to go from there.
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Old 05-09-2017, 08:10 AM   #4 (permalink)
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Your pinion will need to be pointed at the tcase output to run a double cardan joint. (CV) google it for illustration.
DC joint usually allows more angle and is pretty common in short wheelbase builds. Ive found in the 1310 flavor they come with and without a grease fitting for the center pin. Find a greasable one if at all possible.

Decreasing the angle via lowering the vehicle or drivetrain would be my first point of attack.

15mph or 100mph You will have seal, bearing and bushing problems if your drivelines are binding or out of round. If you can, then build it, if you dont have the tools to keep a driveline accurate, then your usually money ahead to have one made.
I have in the past on budget builds been able to source the ends i needed, DC and slip and had a local shop make a driveline and put a bearing and seal on the pin for around $150
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Old 05-09-2017, 08:13 AM   #5 (permalink)
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Quote:
Originally Posted by Frankenstein-CJ7 View Post
Thanks for the Info RXT. Would a CV joint allow for more angle without too much stress? U joints I know are only rated for max 10 degrees. Wondering if a CV would allow for more. After I lift the motor, if my math is correct, I should get my numbers down to around 13 to 15 degrees. Just not sure where to go from there.
Yes, a CV would allow for more angle and with less stress. Think of a CV as being two u-joints forever locked together. And BTW, they have a few advantages over a u-joint. For example, say you have a driveshaft with an operating angle of 20 degrees. This is beyond the range of a u-joint, but a CV joint will split the angular difference between the two crosses so that each cross will handle 10 degrees each.

You're also already set up to run a CV. You pointed the pinion up and inline with the driveshaft. For a CV, this is ideal. If you ran a u-joint at both ends, you'd need to run the pinion at the same output angle as the t-case which was zero degrees. Otherwise you'd have terrible vibration (even at low speed)

Finally there are a bunch of speciality CV joints out there. You can contact places like Tom Woods which has high angle joints available, or try and find an agricultural type CV joint, like those used on PTO equipment (like lawn mower implements)

Keep in mind that high angular operation will reduce the life span of any joint. This is because the joint has to swing back and forth rapidly and they contain very little grease, so they easily get hot, the more they have to swing.

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Last edited by RXT; 05-09-2017 at 08:16 AM.
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Old 05-09-2017, 08:36 AM   #6 (permalink)
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Might be some info in here you can use






http://www.pirate4x4.com/forum/chevy...p-dummies.html
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Old 05-09-2017, 01:12 PM   #7 (permalink)
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Tom woods superflex, offset u-joint. Low speed only.
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Old 05-10-2017, 10:10 AM   #8 (permalink)
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Thanks for all the info everyone. Im gonna lift the motor and see what that does to the angle. Im going to order the Tom Woods offset joints also. Hopefully that should be enough to make a U joint last more than 1 ride.
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Old 05-10-2017, 10:16 AM   #9 (permalink)
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How about a double drive shaft set up (3 u joints). I can build a hangar to hold
the center shaft. this way it would cut the angle of both U joints in half. Any comments?
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Old 05-10-2017, 10:21 AM   #10 (permalink)
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Originally Posted by Frankenstein-CJ7 View Post
Thanks for all the info everyone. Im gonna lift the motor and see what that does to the angle. Im going to order the Tom Woods offset joints also. Hopefully that should be enough to make a U joint last more than 1 ride.
Check for bind and grind yokes as needed for clearance and lower your pinion.
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Last edited by Beat95YJ; 05-10-2017 at 10:22 AM.
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Old 05-10-2017, 10:23 AM   #11 (permalink)
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Quote:
Originally Posted by Frankenstein-CJ7 View Post
How about a double drive shaft set up (3 u joints). I can build a hangar to hold
the center shaft. this way it would cut the angle of both U joints in half. Any comments?
I can't imagine you have room on the back of a cj7.
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Old 05-10-2017, 08:08 PM   #12 (permalink)
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Find an '01 or older Ford Explorer and pull the front driveshaft out of it. It's a double cardan shaft with the same 1310 ujoints that your CJ uses. Cut it down to size, add the correct rear output yoke and you have an inexpensive double cardan rear shaft.
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Old 05-17-2017, 02:02 PM   #13 (permalink)
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Quote:
Originally Posted by CSP View Post
Find an '01 or older Ford Explorer and pull the front driveshaft out of it. It's a double cardan shaft with the same 1310 ujoints that your CJ uses. Cut it down to size, add the correct rear output yoke and you have an inexpensive double cardan rear shaft.
^^
BillaVista driveshaft tech:
Pirate4x4.Com - Extreme Four Wheel Drive

DIY driveshaft shortening (the pics are long gone, but the text is still good)
http://www.pirate4x4.com/forum/gener...ing-101-a.html
I used OlBlueCJ7 write up and made three driveshafts (rear, rear spare, and front) for my Scout. All good with no vibrations. My pics still work:
http://www.pirate4x4.com/forum/31400810-post229.html
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Old 05-19-2017, 02:11 PM   #14 (permalink)
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Would not change anything until you break a joint.
Should build a spare driveshaft anyways.
make sure there is no bind on droop.
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Old 05-19-2017, 08:05 PM   #15 (permalink)
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I get 1310 cv driveshafts out of jeep cherokees for $25 at upullit. Cut and weld it yourself if it's truly off-road only. Or spend $100 and have it shortened. So $125 you could drive it on the road if you had too.
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Old 05-22-2017, 06:34 PM   #16 (permalink)
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Quote:
Originally Posted by Frankenstein-CJ7 View Post
How about a double drive shaft set up (3 u joints). I can build a hangar to hold
the center shaft. this way it would cut the angle of both U joints in half. Any comments?
Uh huh- stop monkeyfucking it. There are two ways to do it properly, parallel with a ujoint, or pointed at the tcase with a CV. Pointed at the tcase with a ujoint isn't one of those.

Is adding another shaft, hanger, and carrier bearing really easier than leaving everything right where it is and coming up with a CV shaft?
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