Topic: Keep blowing axle joints

[stan98tj]

Last 2 times i hit the trail, blew the driver side axle joint with the locker engaged which in turn shreaded the ears on the shaft. Now I know I'm not running any upgraded joints and I have stock shafts, but the joints I blew were both 3 months old. I got a buddy who busted 2 really old joints and he's locked up front as well. When I went wheeling a few weeks ago I blew the driver side joint and my buddy lent me his shaft with a 3 month old joint...took it out the other day for the first time and blew it 10 min into the trail. The weird thing is I've been through this trail a ton of times and I just started popping the joints recently, and it's always the same one and it's never on anything particularly hard. So I'm wondering if it's just a coincidence and this is all cause i'm running a locker now and it's stock parts and my buddy never blew any cause he was just lucky....or could something else be causing this?

Oh, one more thing, I'm not just popping the joints as in the top caps breaking..i'm grenading these things, literally breaking them clean down the middle and stuff. AND I went to Rausch Creek in July when I came home from sea, the Jeep hadn't moved in 4 months. I used the Jeep for about 5 min-locker engaged- and then realized I had a bad leak so I parked it for the rest of the trip. Went home and found I had cracked the head of the driver side joint-that's when I swapped in the "upgraded" autozone joints in..which I end up blowing a few weeks ago. So pretty much 3 driver side joints in pretty much the last 3 times I used the locker on the trail without doing anything really difficult.
Feel free to call me out if I'm being foolish and worrying for nothing. My temporary plan is to go up to Spicer joints on stock shafts-I can't drop serious coin right now cause the bank is combing my statements to approve my mortgage-and then upgrade the shafts.

[neale_rs]

It sounds like the u-joints are just too weak.  The Spicer joints should do much better especially if you tack weld them.  The other big factor is driving style, maybe just too much throttle, letting the tires get spinning fast or engaging the clutch when it is revved up.

Kind of a long shot, but if you always break on the same side: Is the locker locking both sides or just the side that breaks?

[stan98tj]

It sounds like the u-joints are just too weak.  The Spicer joints should do much better especially if you tack weld them.  The other big factor is driving style, maybe just too much throttle, letting the tires get spinning fast or engaging the clutch when it is revved up.

Kind of a long shot, but if you always break on the same side: Is the locker locking both sides or just the side that breaks?

The fact that I'm blowing just one side made me wonder if it's an issue. The locker seems to work fine as both wheels spin when engaged. I have an auto, so no clutch work for me. Also, I'm pretty light on the throttle.

[neale_rs]

Well, I've read that the short axle side tends to break more because the longer shaft can twist more and this softens the blow on that side to some extent.  With an auto the shock loads are not as great so it is probably just the brand of u-joints.  IIRC, jagular7 on this forum runs stock shafts with Spicer u-joints (also auto with front and rear lockers) and rarely breaks them so it should also work for you.

Another thing is that with locked front and open rear if a rear tire is spinning and only one front tire has traction, all the torque will be on that front tire with traction. This could be avoided by running a rear locker too.  The default ARB wiring for dual lockers allows the front locker to be used only if the rear is already activated, probably to avoid this type of loading of the front axle.

[sharpxmen]

from what i read in the first post the locker is selectable (if i got it right, he says somewhere "with the locker engaged") so both left/right will be locked regardless unless there's a blown spider gear.

[stan98tj]

Well, I've read that the short axle side tends to break more because the longer shaft can twist more and this softens the blow on that side to some extent.  With an auto the shock loads are not as great so it is probably just the brand of u-joints.  IIRC, jagular7 on this forum runs stock shafts with Spicer u-joints (also auto with front and rear lockers) and rarely breaks them so it should also work for you.

Another thing is that with locked front and open rear if a rear tire is spinning and only one front tire has traction, all the torque will be on that front tire with traction. This could be avoided by running a rear locker too.  The default ARB wiring for dual lockers allows the front locker to be used only if the rear is already activated, probably to avoid this type of loading of the front axle.

My buddy has a front Aussie locker and open rear. He's never blown joints and runs 33s as i do. He's actually the one who brought up this concern. Im pretty certain the locker is functioning as required. Wouldn't I hear a blown spider gear? I know the stock joints are flimsy, I know that the Autozone "upgrades" are flimsy esp when put up against a locked front, but my concern was based on a comparison to a similarly built Jeep and the fact the same joint keeps blowing and the ease at which it blows. I could just be paranoid, but I don't want to "mask" the problem by upgrading parts if it will end up in me blowing something more expensive. And i repeat, I could just be paranoid...

[neale_rs]

It's most likely just the u-joints. 

You might want to see if it is hard to turn the tire by hand on the side that breaks with the steering in extreme positions.  Maybe the u-joint "bend point" does not match with the steering knuckle bend point (outer stub shaft is too far in or too far out).  Just throwing things out there.

[Jeffy]

Could be bent ears on the axle shaft.  If they're tweaked, you'll be eating up U-Joints.

[stan98tj]

Could be bent ears on the axle shaft.  If they're tweaked, you'll be eating up U-Joints.

everytime i grenaded the joint, the ears bound up and tore off as well.

[sharpxmen]

i'm sure it's not the case but i'll ask anyway

you replaced the whole shaft (including the hub portion) after the first blown u-joint, right?

[stan98tj]

i'm sure it's not the case but i'll ask anyway

you replaced the whole shaft (including the hub portion) after the first blown u-joint, right?

The first time the u-joint cracked (just the cap) i didn't replace the hub. Hub was good and shafts were good. When I grenaded the joint, I ended up eating up the ears on the shaft ends so they were useless. I swapped in my buddy's good shafts and hub...i blew that u joint the other day and tore off the ears from those shafts too. So no, the hub hasn't been the same throughout

[sharpxmen]

The first time the u-joint cracked (just the cap) i didn't replace the hub. Hub was good and shafts were good. When I grenaded the joint, I ended up eating up the ears on the shaft ends so they were useless. I swapped in my buddy's good shafts and hub...i blew that u joint the other day and tore off the ears from those shafts too. So no, the hub hasn't been the same throughout

was a long shot, i was just thinking if it was the same could have been the reason but obviously not the case.

[stan98tj]

I swapped in Spicer u-joints today. Running the stock shafts for now, until I upgrade to RCVs.  Oh, and my neighbors above me are super loud. Just figured I'd complain about that as well.

[jagular7]

I would suggest you take a look at your turning radius of the knuckles. You can put the yokes/joint into a bind that creates fatigue. See if you have the proper operating angles on them. I'm betting you are bending the steering stop enough that you put the yokes into a bind. To get an idea of the binding force, take a look at this video. Replace the bolt stops with new ones. Fine thread and lock down with a nut. Put washers or spacer between the head of the bolt and the stop nut.

Then check to make sure your unit bearing nut is tight to keep the pressure of the stub onto the back of the unit bearing. And the unit bearing knuckle bolts are tight. Then check the pull/push of the axle by prying the back side of the inner shaft yoke against the inner C. When you turn, due to the nut on the end of the stub shaft, the inner axle is push/pulled in/out of the housing.

I adjusted my axles and was breaking joints/yokes due to not changing them on a frequent basis. If you wheel 2 or more weekends/month, locked, larger tires, etc. best to replace the joints 9-12 months depending on terrain, how you drive, etc. etc. etc.

BTW, I'm now wheeling in RCVs in my D30R (high pinion from a XJ). Trans is burned out (auto). Wheeling in a stock YJ on 225s for the time being....

[stan98tj]

I would suggest you take a look at your turning radius of the knuckles. You can put the yokes/joint into a bind that creates fatigue. See if you have the proper operating angles on them. I'm betting you are bending the steering stop enough that you put the yokes into a bind. To get an idea of the binding force, take a look at this video. Replace the bolt stops with new ones. Fine thread and lock down with a nut. Put washers or spacer between the head of the bolt and the stop nut.

Then check to make sure your unit bearing nut is tight to keep the pressure of the stub onto the back of the unit bearing. And the unit bearing knuckle bolts are tight. Then check the pull/push of the axle by prying the back side of the inner shaft yoke against the inner C. When you turn, due to the nut on the end of the stub shaft, the inner axle is push/pulled in/out of the housing.

I adjusted my axles and was breaking joints/yokes due to not changing them on a frequent basis. If you wheel 2 or more weekends/month, locked, larger tires, etc. best to replace the joints 9-12 months depending on terrain, how you drive, etc. etc. etc.

BTW, I'm now wheeling in RCVs in my D30R (high pinion from a XJ). Trans is burned out (auto). Wheeling in a stock YJ on 225s for the time being....

Very interesting video. I'm planning on running RCV shafts as well. I'll check the operating angles i currently have as you suggested. I wheeled on the Spicer joints yesterday, no issues.