Aisin Hub Dial Failure (1 Viewer)

[SmokingRocks]

1993 part time converted fzj, locked and modded (see signature for full deets)

So in June 2022 I completed the part time conversion, Aisin Gold Hubs, spool etc. I believed I had/have the shorter earlier birfields so I thought everything was fine. Anyway this last Sunday we wheeled Spring Creek outside of Idaho Springs which has some particularly challenging lines, and me being me I was trying all of them.

Well in addition to bending an LCA and landing on my rear driveshaft yoke hard enough to subsequently grenade my rear diff I also broke a front hub. I think it happened when I was trying to turn around and forgot to unlock, but I can't be sure. Anyway, I pulled it apart tonight and was surprised to see that the cams on the control dial had broken off. I degreased everything and glued the pieces back together to try and understand what happened.

It looks like the C clip had been driven into the cams, you can see the gouging. Is this the failure that would happen if you ran these hubs with the later longer birfs? does this mean I've got the longer birfs in my rig and I had no idea? Also what do I need to do to stop this from happening again?

 

[MANUCHAO]

Here is a pic for reference...on inner axle shaft.

 

[SmokingRocks]

So this is what happens when you just assume that the birfields that came with your 1993 rig were original when in reality they were replaced over the years with the longer ones. Somehow it made it over a year before popping...

I pulled the other side's dial to check it and noticed the witness mark on the face of the cams from the C clip riding on it. It was just blind luck that kept this one from breaking.

The key takeaway is to never assume you have the shorter shafts just because you have a pre-4/94 rig, I should've known better.

Oh, and another fun note about this whole situation is that the birfield decided to exit the chat the same moment the hub dial did...

 

[Kernal]

Looks like a cascade of events, did the star, cage, spindle bushing/bearing fail causing the hub dial to fracture or ---?? (which failed first)?

 

[SmokingRocks]

Idk what failed first. The spindle bushing was fine other than being peppered by the shrapnel from the exploding birfield. I am scratching my head on how loading the system by turning a 3 point turn with the lockers on could have caused movement past what the physical limits of the system.

Idk

 

[Squeegee]

Cool

 

[Kernal]

Are there chunks out of the star or did the cage fracture?

 

[SmokingRocks]

cage fractured

 

[Kernal]

So sounds like the cage may have went first and all the wobbling of the birf coming apart put too much pressure on the hub dial fracturing it??