Broke another Axle... (Video)

[NorthShoreBronco]

I like the limiting strap option but know nothing about how that kit would work with your set up…I would think they would need to longer with diff drop…

Would be easy enough to add a small spacer or make an extension with some thick flat bar. If I needed to. Could be interesting to test and play around with.

Sponsored

 

[Valhalla]

Would be easy enough to add a small spacer or make an extension with some thick flat bar. If I needed to. Could be interesting to test and play around with.

This is fine if you don't need it to articulate. Limiting straps and longer bumps tops reduce travel which can be hazardous on very broken and uneven terrain. Fine for crawling to the mall though.

 

[NorthShoreBronco]

This is fine if you don't need it to articulate. Limiting straps and longer bumps tops reduce travel which can be hazardous on very broken and uneven terrain. Fine for crawling to the mall though.

Wouldn't need bump stops, just the limiting straps for the excess droop. Wouldn't be too much. I mean, extra droop is no good if it Grenades your axle all over the trail......

I'd still have the same droop as someone with Sasquatch lets say. I just need it to not go past OEM specs...

 

[Valhalla]

I would have thought you gave up some up travel with the lift you have.

 

[NorthShoreBronco]

I would have thought you gave up some up travel with the lift you have.

Maybe? I don't think so but I'm not sure. I mostly need the height and not flex for my terrain. So it's a trade off I'm ok with.

 

[Snacktime]

Just easier to cut down the 5" spacer and add a perch collar lift to get the height back. This is pretty common failure for Rough Country lifts, at least on facebook.

 

[Valhalla]

Just easier to cut down the 5" spacer and add a perch collar lift to get the height back. This is pretty common failure for Rough Country lifts, at least on facebook.

Man those are just extreme operating angles. I had a '77 CJ7 that my rear driveshaft looked close to that with 10" of lift...

 

[NorthShoreBronco]

I think I have the cause figured out. I just need to have a look at a few more things before I post my theory. Obviously the operating angle is not ideal, but there's something else actually causing it.

 

[BigMeatsBronco]

having disassembled these, it seems obvious to me... the axle plunge is too short for the exter droop and the CV balls *and likely the race too) make contact with the retaining ring inside the CV bell...this causes the ring to deform, break, and/or dislodge...which then allows the CV balls to escape on the next suspension cycle, spitting them into the CV boot.

one solution would be slightly longer axle bars (shafts) AND adding a longer plunging spline to the INNER joint...so the splines slip inside the star ( like 930s and 934s do)....this could allow a longer slip-joint (when built correctly) and help alleviate the CV retaining ring getting pushed out.

I suggest the spicer joints with 32 spline...because they are BEEFY (1" balls) and have a larger diameter bell that allows more angle before the axle bare strikes the bell.

 

[BigMeatsBronco]

I think I have the cause figured out. I just need to have a look at a few more things before I post my theory. Obviously the operating angle is not ideal, but there's something else actually causing it.

how about pictures of the damage? are you doing the work yourself or hiring the repairs out?

 

[NorthShoreBronco]

how about pictures of the damage? are you doing the work yourself or hiring the repairs out?

I have it swapped out but haven't taken the boot apart. Busy week. I was thinking the same thing so I wanted to look for wear patterns on the side of the cage.

Solution could be a spacer on the stub shaft next to the hub. It would push the shaft back and line up the balls in the center of the cage.

The other issue I'm seeing is one of the clips that holds the sleeve between the thrust bearings isn't strong enough and gets pushed out, then the sleeve moves and the CV shaft can't lock in properly.

 

[87-Z28]

OEM CV plunge is probably not very good. Like BMB pointed out poor CV plunge can cause issues. There are also other geometry factors at play besides just CV angles especially with large diff drops and maintaining UCA/LCA pivot point geometry.

Diff drop is great to help with CV angles at full drop but very Large diff drop can quickly affect kinematics of CV motion and thus affect CV axle plunge. This is dictated by the arcs swept from both UCA and LCA pivot points. Just for awareness. Not sure what your setup has wrt this but if your CV plunge is not centered well near mid travel of the shocks you can quickly run out of plunge in either jounce or rebound.

visual example of CV plunge kinematics.​

 

[BigMeatsBronco]

The other issue I'm seeing is one of the clips that holds the sleeve between the thrust bearings isn't strong enough and gets pushed out, then the sleeve moves and the CV shaft can't lock in properly.

I think your referring to the stub shaft pulling out of the Diff? or the CV star is being pushed/pulled past the retaining ring on the axle bars?

either way I'm fairly certain your running out of plunge. the first ring to go is the big one on the bell on the inner CV, then it could pull the axle bar back through the outer CVs star, and OR pull the axle stub out of the diff....all of these are relative to axle length and plunge.

 

[87-Z28]

I suggest the spicer joints with 32 spline...because they are BEEFY (1" balls) and have a larger diameter bell that allows more angle before the axle bare strikes the bell.

Agreed. lots of benefits. Just improving CV plunge alone would make them worth it.

 

[Beach_Bum]

OEM CV plunge is probably not very good. Like BMB pointed out poor CV plunge can cause issues. There are also other geometry factors at play besides just CV angles especially with large diff drops and maintaining UCA/LCA pivot point geometry.

Diff drop is great to help with CV angles at full drop but very Large diff drop can quickly affect kinematics of CV motion and thus affect CV axle plunge. This is dictated by the arcs swept from both UCA and LCA pivot points. Just for awareness. Not sure what your setup has wrt this but if your CV plunge is not centered well near mid travel of the shocks you can quickly run out of plunge in either jounce or rebound.

​

visual example of CV plunge kinematics.​

Sponsored