Wild Wolf keeps breaking RR axles

[racerone3]

Last night I headed out for a solo night ride. The tank trainer isn't proven yet and the Bigfoot is LOUD to be playing on someone's property at night, so I hopped in the Wolf. Other than the pesky axle issue, that machine is super reliable. Had a great ride and started for home when sure enough, it snapped another RR axle (#11 in 2 years) I had the tool/ parts bag with me, so I was able to run a short chain from the T-20 down to the middle axle and limp it home. they all break inside the sprocket tube at the through bolt. I know that this is the weak point in an axle, but I've never broken an axle in any of my other machines, or in any other position on the Wild Wolf. I have thought I had the problem found or fixed several times. my next thought is to find another sprocket/ tube and try that... although I can't imagine what could be wrong with the tube to cause it. my other idea was to drop from a 3/8 to a 5/16 bolt in hopes that the bolt would break before the axle (like all the others do).
anyone have any ideas on this one???

[amphibious drew]

No idea's, but I am pretty sure its not the sprocket and tube assembly because I have the same luck with the same axle on the tomahawk and i replaced that sprocket and still broke the axle you gave me at busco. Are you using 4140? I was thinking about upgrading to splinned once the colt is done and sold and funds are available.

[thebuggyman1]

I'm not familiar with how the attex chains wrap around, but I'm guessing this is the closest to the trans sprocket?????? My theory: As the chain "pulls" to the trans, it is putting the most stress on this axle flexing it at the weak spot (bolt hole). I'd try a custom sprocket tube. One that was much thicker walled and was as wide as possible. Spreading the force as close to the bearings as possible.

[amphibious drew]

Buggyman is correct as to the location to. the t20 when pulling. i have an inch thick wall on my sprocket and still have issues. what about another shear bolt 90degrees from the original a few inches down the tube. this would cut the stress on the week point in half. the only downside would be an additional week point in the axle.

[thebuggyman1]

The worst place for the "weak spot" is centered between the bearings. Put it as close as possible to a bearing. Maybe even a smaller thru bolt/hole in addition to a keyway or clamp collar (one half welded to the tube)????

[LarryW]

Im not sure 100% but it seems that I was told By Don that attex(superchief for sure maybe others) had a rear axle different then the rest of the axles. He said it wasn't always the case and wasn't sure why. I pretty sure it was the pin location that was different. I cant remember what side either but the right does sound right. Is that axle the same identical as the others? I wonder if maybe its different and the pin further away from the bearing like Buggyman stated. But for all I know is that may have just been a 3rd gen machine issue. Now changing them as much as you did might eliminate that problem or you would at least know about it unless you are just machining a new one to match the old one. Let us know, I'm real curious now.

[chris davison]

Is it possible to bolt in another bearing right next to the sprocket to give additional resistance to flexing. Or back to back bearings with the frame in between?

[LarryW]

Is it possible to bolt in another bearing right next to the sprocket to give additional resistance to flexing. Or back to back bearings with the frame in between?

Hmm, It would be like internal bearing extensions. Like the older max had with the cage and double bearings. I dont think there is enough room though unless you get bigger bearings that the sprocket tube fits in. That might work.

[lewis]

It sounds like it is time for two Argo axles and sprockets to be installed into the 2 rear positions. My thought is that it is annealing at that location. Tension, more right hand turns. The chain on the Crush seems to stretch a little more on the right side, why i don't know, it may be i just pull harder because i am right handed or what, but i must keep a eye on that side chain. Others can answer if they seem to have to keep the RR chain adjusted more. I will start getting parts together for you if you want me to.

Lewis

[amphibious drew]

George,

Could you or another left handed attex driver chime in about the chain stretch. If yours stretches faster on the left side, then we know lewis is on to something. Just a note, my right side broke when I first got my machine two years ago. I had an axle made for me government work style using some crazy military grade aluminum or stainless and it was great. It eventually made its way over to the left rear. Can't for the life of me remember the logic on it getting there, but it's still turning and looks brand new. Wish my buddy still had that job or at least remembered the specs on the stuff he used.

[jerseybigfoot]

Ok, here is my 2bits. The axle is being torqued by the drive bolt and the reaction load is from the axle to the tire. The drive tube can either help the strength of the axle if the tube clearance is minimal and the bolt fit is accurate .If the bolt is sloppy in the axle the bolt will act as a stress point to shear the axle from the outside to the center. The trick is to ream the axle bolt hole to fit the bolt so that the bolt acts as part of the axle not part of the tube.
As the Attex axles are 1" a 3/8 drive pin does not allow much material in the axle. I would drop the drive pin size down or increase the strength of the axle. I have some exotic material for my Attex 1" axles and so far so good. I also use 5/16" shoulder bolts.

[LarryW]

What about weld the sprocket tubes on. It would be like a scrambler. The tube would help strengthen it. You could take the axle out from the inside by taking the inside bearing out and sliding it in. Or maybe the taking the outer bearing off and slide the axle out so you can remove the axle from the inside bearing and pull up and in. If my 1st generation axles didn't have the 1" step down to 24mm I would weld the hubs on. But then there is the issue of heat weakening the axles.

[chris davison]

When welding a tube to a shaft dont weld around the shaft at the end of tube, this is where the shaft will break. Go as close to the center of the tube as you can drill a 1/2" or 5/8" hole and plug weld the tube to the shaft, preferably in several spots. The weakened by heat spot is small and supported by the tube. Let it cool by itself dont cool it off with water. Most times this weld can be removed with the same drill bit for dissassembly.

[JoeMeg]

Quoting jerseybigfoot "If the bolt is sloppy in the axle the bolt will act as a stress point to shear the axle from the outside to the center. The trick is to ream the axle bolt hole to fit the bolt so that the bolt acts as part of the axle not part of the tube." This is my opinion on pinned axle design also.

Joe.

[Dan Grover]

I had an Attex 400 Chief as a kid in 1975 and it was uncanny how many right rear axles I broke. It is still an inside joke today with a buddy that used to help me fix the axle. Back then I thought of things mentioned so far like a smaller diameter axle pin. One possible solution is when it breaks again, drill the axle hole closer to the inner or outer bearing. You will have to have cup washers and weld them in the new spot. Just a thought. Lastly you can try not to bounce or get airbourn. I found that difficult with that 399 JLO.