Rear driveshaft and U joints - JeepForum.com
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post #1 of 19 Old 03-30-2020, 08:22 AM Thread Starter
Waternut
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Rear driveshaft and U joints

As mods have been made to my Jeep, the rear driveshaft is becoming a little less trail worthy. Originally my Adams double cardan driveshaft was perfect. Now it's a little short but not a deal breaker under normal flexing and driving.

However, if I turtle and let both rear shocks fully extend, I have two problems. First is that the driveshaft will actually separate so it needs to be longer...no question about that. The second issue is that the double cardan joint exceeds the angle that it can take. I ground down a little of the double cardan joint and got maybe 5-6 extra degrees but it's on the limit and if I turtle, I'm sure that will wreck something. I could probably grind a little more but looking at other options....

So here is my dilemma.... I could lengthen my driveshaft and grind the double cardan joint a little more and be in the clear. However, this wasn't the extreme duty driveshaft from Adam's and I've now got a 5.3 LS engine so it makes me wonder if this driveshaft is strong enough and valid as a primary solution. I could possible upgrade the TC output flange to a 1350 as well as change the 8.8 drive flange to a 1350 but then I'm probably $500 deep in a driveshaft change/upgrade. I'd also be guessing on the proper pinion preload due to the crush washer on the 8.8. Would a 1350 give more angle or would I have to grind that joint as well?

Other opinions?



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post #2 of 19 Old 03-30-2020, 08:33 AM
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limit strap on the rear at the center. still will flex just wont go to full droop on both sides. one idea....

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post #3 of 19 Old 03-30-2020, 08:43 AM Thread Starter
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Originally Posted by 222Doc View Post
limit strap on the rear at the center. still will flex just wont go to full droop on both sides. one idea....
Actually I did have one but accidentally melted it welding nearby... I guess I could put one back on although it's not as easy as bolting a new on.


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post #4 of 19 Old 03-30-2020, 09:21 AM
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There's a company that makes u-joint yokes that have more clearance in them to allow for more droop. Up to 30° if I remember right.

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post #5 of 19 Old 03-30-2020, 09:34 AM
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It might be time consider moving the rear axle back a few inches Water. It would relax the drive line angles quite a bit.

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post #6 of 19 Old 03-30-2020, 10:02 AM Thread Starter
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Originally Posted by shaggyjim View Post
It might be time consider moving the rear axle back a few inches Water. It would relax the drive line angles quite a bit.
I'm barely touching the gas tank skid at full bump. Only way to go further back is to run a fuel cell or one of the crazy expensive genright tanks both of which I'm trying to avoid.


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post #7 of 19 Old 03-30-2020, 10:34 AM
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Quote:
Originally Posted by Waternut View Post
I'm barely touching the gas tank skid at full bump. Only way to go further back is to run a fuel cell or one of the crazy expensive genright tanks both of which I'm trying to avoid.
I have a piece of 2x4 steel across the back of my frame as part of my bumper/tire carrier. I have not done it yet but with that in place it would be pretty easy to notch out the tin rear cross member and move the tank back.

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post #8 of 19 Old 03-30-2020, 10:46 AM
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1350 because of the cross dimension would give less angle.


Are you running 1310 now ?


1350 parts will lengthen the DS simply because they are bigger parts. The opposite of what you want. The 8.8 from flange to yoke would also be a slight step backwards.


Have you broken anything ? Seems the best course would be to limit the droop and lengthen what you have.


With little exception the DS companies are using off the shelf Spicer parts. You could build your own for a fraction of the price.
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post #9 of 19 Old 03-30-2020, 11:02 AM Thread Starter
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Originally Posted by jbolty View Post
I have a piece of 2x4 steel across the back of my frame as part of my bumper/tire carrier. I have not done it yet but with that in place it would be pretty easy to notch out the tin rear cross member and move the tank back.
Interesting concept... Maybe I need to spend some more time laying under the Jeep.


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post #10 of 19 Old 03-30-2020, 01:49 PM Thread Starter
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Quote:
Originally Posted by jsawduste View Post
1350 because of the cross dimension would give less angle.


Are you running 1310 now ?


1350 parts will lengthen the DS simply because they are bigger parts. The opposite of what you want. The 8.8 from flange to yoke would also be a slight step backwards.


Have you broken anything ? Seems the best course would be to limit the droop and lengthen what you have.


With little exception the DS companies are using off the shelf Spicer parts. You could build your own for a fraction of the price.

Yes, I'm currently running greaseable 1310 u-joints on my driveshafts.

Interesting info on the 1350...hadn't really considered that. I just figured the joints would be bigger allowing more angle but I found a chart that shows 30° for 1310 joints, 20° for 1330 and 1350, but then the biggest 1410 gives 40° which makes absolutely no sense to me.

I'm already converting the 8.8 flange to a yoke... I was thinking by running a yoke attached directly to the pinion instead of a yoke attached to the flange, it might reduce the overall length of the axle mounting point thereby increasing the necessary length of the driveshaft which would reduce the angle at droop.

I have not broken driveshaft u-joints except when failing something else first. I think you're right in that the smart decision is to limit axle droop and run what I've got with a little extra length. It does also make some sense to have the driveshaft u-joints as the fuse and carry a spare. Just wanted to cover my bases before pulling the trigger.
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post #11 of 19 Old 03-30-2020, 02:00 PM
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Consider Spicer SPL non greaseable. They are not hollow and are heat treat a bit harder. Little more carbon in the mixc so they aren’t brittle. If you look on the DanaExpert site you’ll find a load rating chart.

Not sure if your running a yoke or a flange at the TC. Tom Woods has a flange Mount that features a grease fitting for the center ball. Something Spicer does not in their flange mount.

They (it) can be purchased separately and retrofitted if that’s your desire.
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post #12 of 19 Old 03-30-2020, 02:14 PM Thread Starter
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Originally Posted by jsawduste View Post
Consider Spicer SPL non greaseable. They are not hollow and are heat treat a bit harder. Little more carbon in the mixc so they aren’t brittle. If you look on the DanaExpert site you’ll find a load rating chart.

Not sure if your running a yoke or a flange at the TC. Tom Woods has a flange Mount that features a grease fitting for the center ball. Something Spicer does not in their flange mount.

They (it) can be purchased separately and retrofitted if that’s your desire.
It's a flange at the TC and I'm running a regular SYE and not a super short.


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post #13 of 19 Old 03-31-2020, 09:12 AM
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Step 1... Get that center limit strap in there to keep what you have alive.

Step 2... find a superduty front CV shaft. They have 1350's and it will be cheaper to have shortened, or shorten yourself, than buying a new Adams.

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post #14 of 19 Old 03-31-2020, 10:26 AM Thread Starter
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Originally Posted by daddyjeep87 View Post
Step 1... Get that center limit strap in there to keep what you have alive.

Step 2... find a superduty front CV shaft. They have 1350's and it will be cheaper to have shortened, or shorten yourself, than buying a new Adams.
I definitely need to get step 1 accomplished. Interesting on the superduty front driveshaft but after looking a little harder, it's far from having enough travel to work. At the moment, I'm using over 4" of driveshaft slip but maybe limiting the center chunk would bring that more in line as well and one of the higher slip SD driveshafts would work.


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post #15 of 19 Old 03-31-2020, 11:32 AM
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Quote:
Originally Posted by Waternut View Post
I definitely need to get step 1 accomplished. Interesting on the superduty front driveshaft but after looking a little harder, it's far from having enough travel to work. At the moment, I'm using over 4" of driveshaft slip but maybe limiting the center chunk would bring that more in line as well and one of the higher slip SD driveshafts would work.
Wow... I'm not using anywhere near that much slip. My frame side link mounts are very close to the t-case output so everything moves on the same arc.

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