Toy inner shaft breakage...

[Vonski]

Greg and Skye, here's the deal with the broken inner shaft. First off, I think it was already weakened at the last UROC. The truck got worked hard. There was one obstacle on day 1 that had a climb nearly everyone had to winch (since it was damn near impossible). This section was nearly verticle and also undercut. I was spooling in the winch, under power @ 98:1, and turned to full lock all at the same time. My 15.5" wide SX's were at about 6 psi and getting smashed into this undercut wall. We new a stock birf would've blown, but with the Longfields we didn't know what to expect. If there was a situation that should've earned us broken parts, it was right then. Not only did we not break anything, but finished 4 more courses that day and 6 the next. One of the birfs started to make a little noise, but never failed. It later was replaced by Bobby Long since it was slightly deformed, but it never actually failed.
When the inner shaft broke, we were up in the Uintahs playing in a boulder field. I am much easier on the rig when not competing, so I was really surprised when it broke. From what I understand, they almost always break at the necked-down section just before the splines that enter the birf. Mine was no exception. I had extra shafts on hand and fixed it on the trail. BTW, Longfields simply rule! I wouldn't worry about breaking inner shafts unless you compete, forcing you to do things that are not normal on the trail.

 

[Skyetone]

Originally posted by Vonski
I wouldn't worry about breaking inner shafts unless you compete, forcing you to do things that are not normal on the trail.

I thought beer made me do things that weren't normal.
Did you just warp the cage then on the longfield?
Lets see winching and 96-1 thats like what 2000k pressure on the birf?

 

[spencurai]

Originally posted by Skyetone

I thought beer made me do things that weren't normal.
Did you just warp the cage then on the longfield?
Lets see winching and 96-1 thats like what 2000k pressure on the birf?

it was my understanding that a birf is stronger that a comparable u-joint in straight line scenarios but the u-joint maintains its strength pretty evenly when turned but birfields get weaker the more they are turned. is this a correct assumption.

 

[I Lean]

Originally posted by spencurai


it was my understanding that a birf is stronger that a comparable u-joint in straight line scenarios but the u-joint maintains its strength pretty evenly when turned but birfields get weaker the more they are turned. is this a correct assumption.

Nope, the U-joint is weakest when it's turned as well.

 

[spencurai]

Originally posted by I Lean


Nope, the U-joint is weakest when it's turned as well.

thank you for the clarification.

 

[Vonski]

Originally posted by Skyetone

I thought beer made me do things that weren't normal.
Did you just warp the cage then on the longfield?
Lets see winching and 96-1 thats like what 2000k pressure on the birf?

I'm kicking myself for not taking pictures of it, but I can explain. If you have seen a Longfield, it has the ring that has been added (by welding then machined down, of course). The material of this ring gets pretty thin as it wraps around the end and the balls will actually come in contact with it. If enough pressure is applied while turning, the balls can bend the ring slightly where it comes in contact with it. You end up with 6 "bumps" in this ring from the balls in the birf. When we heard it making noise, it must have been the slight amount of play the balls now had. I don't think there would ever be enough room for the balls to escape though. It technically didn't break, so Bobby really didn't have to replace it, but did it anyway with no hassle.

 

[Skyetone]

I have a pair so it is good to hear he is still putting out his warrentee