UJoint Considerations for Axle Upgrade

Noble Woodsman

Noble Woodsman

New member
I know this is probably a dumb question, but I'm trying to understand how to properly size ujoints for a driveshaft after an axle upgrade. Should the ujoints on the front drive shaft be selected to match those on the new front axle shafts, or should they be one size smaller to allow failures to occur on the driveshaft ujoints instead of on parts that are more expensive or harder to repair in the field? I read somewhere that ujoints should be treated as the "fuse" in a driveline setup so that they would fail first. Is this correct? If the driveshaft ujoints are sized to match the front axle shaft ujoints, then would a driveline failure be more likely to cause damage to the transfer case and transmission?

To provide context, I'm planning an axle upgrade for my 2015 JKUR, and I'm strongly considering the Dynatrac Hard Core Plus XD60/XD60 axle package with ARB lockers and 4.88 gears. I plan to run 37" tires now and 40" tires later, and the use case is rock crawling. The entire drive train is currently stock. If I understand the Dynatrac website correctly, the XD60 uses 4140 series ujoints at the steering knuckles, and I presume the same size at the pinion yoke. Should I be looking for a driveshaft with 4140 series ujoints also (do they exist?), or should I step down to the 1350 ujoints for the driveshaft? Would the sizing for the rear driveshaft in this case be the same as for the front driveshaft?

Please go easy on me. I'm new to the forum and still in the planning stage on this build. Thanks!
 
First off... welcome. Jump to the wave section and say hi. It will go a long ways in getting some help here. Second... the XD60 front uses a 1550 ujoint. The 4140 you’re referring to is the grade of aluminum. That being said. The rear XD60 likely uses a 1410 u-joint at the yoke so, if it were me I’d stick with that for the rear at both ends. Front drive shaft I would go with whatever Dynatrac recommends which is likely a 1350, could be a 1410 but I highly doubt it.
 
RESURECTIONJK said:
First off... welcome. Jump to the wave section and say hi. It will go a long ways in getting some help here. Second... the XD60 front uses a 1550 ujoint. The 4140 you’re referring to is the grade of aluminum. That being said. The rear XD60 likely uses a 1410 u-joint at the yoke so, if it were me I’d stick with that for the rear at both ends. Front drive shaft I would go with whatever Dynatrac recommends which is likely a 1350, could be a 1410 but I highly doubt it.
Click to expand...

I have XD60’s on Brute...drive shafts are 1350’s...
 
RESURECTIONJK said:
First off... welcome. Jump to the wave section and say hi. It will go a long ways in getting some help here. Second... the XD60 front uses a 1550 ujoint. The 4140 you’re referring to is the grade of aluminum. That being said. The rear XD60 likely uses a 1410 u-joint at the yoke so, if it were me I’d stick with that for the rear at both ends. Front drive shaft I would go with whatever Dynatrac recommends which is likely a 1350, could be a 1410 but I highly doubt it.
Click to expand...

1410 with an 80. I doubt a 1410 would even fit in the front.


Sent from my iPhone using WAYALIFE mobile app
 
Ok, so it sounds like I should use the same size ujoints on both ends of a driveshaft, and I should size them to match the ujoints on the respective axle yokes. For the XD60 front driveshaft, it sounds like they should be 1350 series. Does this approach mean the driveshaft ujoints are/should be the weak link in the driveline, or am I thinking about this incorrectly? I read on another thread here that it's easier in the field to replace a front axle shaft with a broken ujoint vs. a driveshaft with a broken ujoint, which makes sense, so maybe the driveshaft ujoints should not be the weak links?

rubiDave

You probably wont be happy with 4.88, especially if there is a chance you'll put 40s on it. Would be between 5.13 and 5.38 if it were me.
Click to expand...

Thanks for the tip, rubiDave... I've been on the fence about choosing 4.88 vs. 5.13. I forgot to mention that this will be a DD while it's still on 37s, so that was why I was leaning toward 4.88s. I run about 2500 RPM at 70 MPH with stock wheels and 4.11s currently (auto transmission). According to the Tire Size vs. RPM chart at the prodigy performance website (https://prodigyperformance.com/blog/jeep-wrangler-gear-ratio-calculator/), I should expect similar RPM at 70 MPH with 37" tires. 5.13 gears with 37s would put my highway RPMs higher than they currently are, which I was hesitant about for fuel economy (I know, probably a bad argument considering it will be on 37s). Since it will be a DD when on 37s, do you still think 5.13 are the way to go?
 
Highway RPMs are only part of it. Big heavy tires take more torque to get going. Lower gearing will improve your acceleration and need to downshift on hills, etc at the price of highway fuel economy.
A lot of people run 4.88 with 37s and are OK with them, but 5.13 offers better performance.
I think 4.88 would be a poor choice if you're considering 40s and I would think about 5.38 in that case. Since your getting custom axles might as well get them built for your end plan.

Sent from my SM-G965U1 using WAYALIFE mobile app
 
Noble Woodsman said:
Ok, so it sounds like I should use the same size ujoints on both ends of a driveshaft, and I should size them to match the ujoints on the respective axle yokes. For the XD60 front driveshaft, it sounds like they should be 1350 series. Does this approach mean the driveshaft ujoints are/should be the weak link in the driveline, or am I thinking about this incorrectly? I read on another thread here that it's easier in the field to replace a front axle shaft with a broken ujoint vs. a driveshaft with a broken ujoint, which makes sense, so maybe the driveshaft ujoints should not be the weak links?
Click to expand...

1350 front is fine.

Yes, the axle U joints are bigger, but there is the added gear reduction in the differential to multiply the torque before it gets to them, so they need to be stronger.

Remember, each level of gear reduction brings a corresponding multiplication of torque, minus the friction of the gear.

Noble Woodsman said:
Thanks for the tip, rubiDave... I've been on the fence about choosing 4.88 vs. 5.13. I forgot to mention that this will be a DD while it's still on 37s, so that was why I was leaning toward 4.88s. I run about 2500 RPM at 70 MPH with stock wheels and 4.11s currently (auto transmission). According to the Tire Size vs. RPM chart at the prodigy performance website (https://prodigyperformance.com/blog/jeep-wrangler-gear-ratio-calculator/), I should expect similar RPM at 70 MPH with 37" tires. 5.13 gears with 37s would put my highway RPMs higher than they currently are, which I was hesitant about for fuel economy (I know, probably a bad argument considering it will be on 37s). Since it will be a DD when on 37s, do you still think 5.13 are the way to go?
Click to expand...

RPM is only part of the fuel economy calculation. You need the engine in a range to produce enough power to move you without lugging and struggling.

With 37's, you have more rolling resistance, as well as more wind resistance. This takes more power to overcome than stock tires, so the engine needs to be where it can make that amount of power easily. That's part of why 5.13 is a better choice for 37's. They also let you get to speed easier, so it is not a drag to drive.
 
Noble Woodsman said:
Ok, so it sounds like I should use the same size ujoints on both ends of a driveshaft, and I should size them to match the ujoints on the respective axle yokes. For the XD60 front driveshaft, it sounds like they should be 1350 series. Does this approach mean the driveshaft ujoints are/should be the weak link in the driveline, or am I thinking about this incorrectly? I read on another thread here that it's easier in the field to replace a front axle shaft with a broken ujoint vs. a driveshaft with a broken ujoint, which makes sense, so maybe the driveshaft ujoints should not be the weak links?



Thanks for the tip, rubiDave... I've been on the fence about choosing 4.88 vs. 5.13. I forgot to mention that this will be a DD while it's still on 37s, so that was why I was leaning toward 4.88s. I run about 2500 RPM at 70 MPH with stock wheels and 4.11s currently (auto transmission). According to the Tire Size vs. RPM chart at the prodigy performance website (https://prodigyperformance.com/blog/jeep-wrangler-gear-ratio-calculator/), I should expect similar RPM at 70 MPH with 37" tires. 5.13 gears with 37s would put my highway RPMs higher than they currently are, which I was hesitant about for fuel economy (I know, probably a bad argument considering it will be on 37s). Since it will be a DD when on 37s, do you still think 5.13 are the way to go?
Click to expand...

Like you I just installed the XD60s front/rear w/37s on my 2016 JKUR and replaced my stock Rubicon axles that had 4.10 gears. I went with 1350 drive shafts, which are working fine so far. As far as gears, I too, was concerned about 5.13s on the highway and my RPMs are close to 3k at 70 on the highway. However, with the added weight I am very glad I went with 5.13s and believe I would not be happy with the performance of 4.88s.


Sent from my iPhone using WAYALIFE mobile app
 
JJ151 said:
Like you I just installed the XD60s front/rear w/37s on my 2016 JKUR and replaced my stock Rubicon axles that had 4.10 gears. I went with 1350 drive shafts, which are working fine so far. As far as gears, I too, was concerned about 5.13s on the highway and my RPMs are close to 3k at 70 on the highway. However, with the added weight I am very glad I went with 5.13s and believe I would not be happy with the performance of 4.88s.


Sent from my iPhone using WAYALIFE mobile app
Click to expand...
That seems high..I was running almost 3k@ 75mph when I had my 35's and 5.13's now with 37's 2400 to 2500
 
Seahawkfan said:
That seems high..I was running almost 3k@ 75mph when I had my 35's and 5.13's now with 37's 2400 to 2500
Click to expand...

Gear ratio chart for 3.6L w/auto w/37s shows 2,708 at 70 mph. I’m a bit above that. I may need to recheck my Procal setting.

Even manual chart shows 2,600 rpm w/5.13 and 37s though.


Sent from my iPhone using WAYALIFE mobile app
 
This is all good info. I'm going to 37's and will need a regear. I've looked at the charts and was himming and hawing between 4:88's or 5:13's. I was set on 5:13's, but was beginning to second guess this being that I have a manual. I think I'm back to going with 5:13's. I plan on installing a 1350 front when I do the regear. Now to find the time to get those tires installed..haha. Also will be a good time to address the t-case front output shaft leak I just discovered. Pretty sure I just need to put some rtv on the t-case yoke. Looks to be a slow seep that slings onto the under carriage.

Sent from my 2PYB2 using WAYALIFE mobile app
 
This takes more power to overcome than stock tires, so the engine needs to be where it can make that amount of power easily
Click to expand...

This is a great point, which I had not considered. Thanks for helping me make this decision. Definitely ruling out the 4.88s based on everyone's feedback so far.

Yes, the axle U joints are bigger, but there is the added gear reduction in the differential to multiply the torque before it gets to them, so they need to be stronger.
Click to expand...

Ok, this is making sense now. I figured the gear reduction needed to be considered somehow. I seem to hear about ujoint failures on the axle shafts more often than on the driveshafts, and this logic also seems consistent with that observation.

JJ151, what wheels did you decide to go with for the XD60? It sounds like my build will have a similar drive train as yours.
 
jesse3638 said:
This is all good info. I'm going to 37's and will need a regear. I've looked at the charts and was himming and hawing between 4:88's or 5:13's. I was set on 5:13's, but was beginning to second guess this being that I have a manual. I think I'm back to going with 5:13's. I plan on installing a 1350 front when I do the regear. Now to find the time to get those tires installed..haha. Also will be a good time to address the t-case front output shaft leak I just discovered. Pretty sure I just need to put some rtv on the t-case yoke. Looks to be a slow seep that slings onto the under carriage.

Sent from my 2PYB2 using WAYALIFE mobile app
Click to expand...

I had a T-case leak after installing front 1350. Tried twice with the RTV ended up replacing the seal. Good to go. It was bitch finding the correct one. Some have a double seal and some single. Something like that. If I remember correct the color (Light Blue) of the seal ring had something to do with finding the right one. This was on non-Rubi 3.8
 
JJ151 said:
Gear ratio chart for 3.6L w/auto w/37s shows 2,708 at 70 mph. I’m a bit above that. I may need to recheck my Procal setting.

Even manual chart shows 2,600 rpm w/5.13 and 37s though.


Sent from my iPhone using WAYALIFE mobile app
Click to expand...

Yea I'm in a 3.8 w/ Superchip Programmer. I was actually amazed at the difference in RPM when I finally went to 37's . Oh MPG didn't change much at all.
 
jesse3638 said:
This is all good info. I'm going to 37's and will need a regear. I've looked at the charts and was himming and hawing between 4:88's or 5:13's. I was set on 5:13's, but was beginning to second guess this being that I have a manual. I think I'm back to going with 5:13's. I plan on installing a 1350 front when I do the regear. Now to find the time to get those tires installed..haha. Also will be a good time to address the t-case front output shaft leak I just discovered. Pretty sure I just need to put some rtv on the t-case yoke. Looks to be a slow seep that slings onto the under carriage.

Sent from my 2PYB2 using WAYALIFE mobile app
Click to expand...

You don’t hardly drive your Jeep, go 5.13’s. You will be able to hold the grade to mammoth in 5th gear at 80+ and accelerate going up it.


Sent from my iPad using WAYALIFE mobile app
 
JJ151, what wheels did you decide to go with for the XD60? It sounds like my build will have a similar drive train as yours.[/QUOTE]

I chose the Hutchinson Rock Monster beadlocks for several reasons. First, I wanted a wheel with a significant backspace to maximize my scrub radius and keep wheels tucked as much as possible. Second, I wanted a beadlocks wheel that I could more easily change. As these are a two piece wheel there is no need to force the tire over a bead of the rim. Third, I like the fact that it locks both the inner and outer bead.


Sent from my iPhone using WAYALIFE mobile app
 
OverlanderJK said:
You don’t hardly drive your Jeep, go 5.13’s. You will be able to hold the grade to mammoth in 5th gear at 80+ and accelerate going up it.


Sent from my iPad using WAYALIFE mobile app
Click to expand...
It gets driven more now that we have 3 licensed drivers in the house. Yeah I figured I'd benefit more from the lower (5:13) option considering my use. It's going to be going back and forth to Barstow a couple times a week now for my new job. It'll get at least 120 miles a week now..haha.

Sent from my 2PYB2 using WAYALIFE mobile app
 
You must log in or register to reply here.
Top Bottom