2011 M8 secondary sheeves broke apart

[line8]

It looks like the 2 screws backed out and loosened. This caused the inside sheave to break away. Happened on a burst of throttle and I immediately stopped, it was like a blown belt.

What do I do about this one? Replace secondary and with what? No oil puddles and no chips or marks or anything I can see on the shaft.

Couple pics.....

 

[2010Catman]

Was the secondary taken apart recently? There's 3 screws per tower to the helix, to me seems like they were over torqued and caused them to shear under load. Hard for me to see that two of those screws backing out would cause the other 7 to shear off like that, yet alone to see them even back out? My 2 cents anyhow. Get a new secondary bdx or stock do alignment and ride.

 

[line8]

Not that I am aware of. I bought the sled last year. I only have about 4 rides on it-1400 miles after yesterday. Those 2 screws that came out were sheared at about 2 threads from the end of the screw. The rest are still in it, and I see what you mean about being over torqued.

 

[Hardass]

You can see the tower is still bolted on with that one screw as are the other 2 i say its something else besides a couple loose screws.is that tower with just the one screw still snugged up or real loose?

 

[line8]

You can see the tower is still bolted on with that one screw as are the other 2 i say its something else besides a couple loose screws.is that tower with just the one screw still snugged up or real loose?

It's loose, but not floppy loose. It will turn in about 1/4".

 

[IGBT]

Have you done the diamond drive mod/fix? It is possible your diamond drive locked up due to a grenaded bearing and the secondary sheared itself?

On my 2011 M8 I opened up the diamond drive housing after just 200 miles on the new sled. The problem bearing was already starting to come apart with pieces of the ball track loose in the bell housing cover. I machined down the shoulder to allow more clearance and used a Swiss made bearing instead of the Chinese one the factory uses. 1500 miles later I took it apart again and everything is pristine.

 

[line8]

Yeah, it's done and I did think of that. I did not open up the diamond drive as there wasn't really any indication of that being the problem. I think...Those 2 screws that appeared to have backed out of the inner sheave, which hold the helix to it are probably the cause. Why they would back out or not have been properly torqued is beyond me but thats what it would appear to be. The sheaves and broken helix are at the shop but the sled is still on the truck with me so I guess I should probably open that up to be sure it's all ok in there.

 

[IGBT]

Well that is good (that you have done the diamond drive mod). I change the oil every season by taking it apart so if you have not changed the oil in the DD it wouldn't be a horrible thing to do (if you have a spare gasket because the paper one always tears on me).

One quick thing to try first is to raise the track off the ground and try spinning it by hand. Mine spins easily when the belt is off the secondary. If it won't turn, binds, or you hear grinding in the DD, then maybe you have other issues.

Well, make sure you have the brake off

 

[line8]

It does spin freely without any weird noises for sure. I had to tow it out (with wife's Polaris And then had the joy of pushing it up the ramp to get it on the sled deck. Ratchet straps and pulley going into the truck from now on. I will say the snow bungie was a huge help.

 

[Bradywebb]

Pretty common to break helix. You probably felt the vibration on your left foot at higher rpm's before it went. If no sheave damage get a bdx helix since better than stock. Carrying an extra helix on a road trip is a good idea too. And helpful when another m in group to swap secondary and leap frog them out.

 

[line8]

I can't be sure about the vibration because I was in some deep snow and I was thinking the 2.6 track might have a bit of vibration. Maybe not! I was supposed to receive a new Helix yesterday via 2nd day air. But no luck so no ride this weekend. Good idea on the spare!

 

[diggerdown]

Center bushing may be shot which usually leads to broken rollers and helix,

 

[line8]

Center bushing may be shot which usually leads to broken rollers and helix,

Nothing seems outa the ordinary by just the looks of it. Rollers were good as well but going to put new ones in anyway.

 

[trappersnapper]

n

Diggerdown hit the nail on the head worn out bushing!

 

[line8]

How would that cause the 2 screws to back out of the tower of the helix where it attaches to the inside sheave? Or would you say there's 2 different issues here?

 

[diggerdown]

It puts un-even pressure on one leg of the helix. Slide the two sheaves together and see how much wobble you have....bet there is quite a bit play. Both the bushing and post wear quite quickly.

 

[line8]

So the screws didn't back out and then break. They broke off from stress. That makes more sense.
So I have a new helix, new rollers and a new spring. I guess a new bushing also from the sounds of this.
Thank you.

 

[diggerdown]

Once you determine if they are bad you can send them off to be rebuilt. I've only dealt with BDX but there are several different places that rebuild them by trueing up the center post and putting in a larger longer wearing bushing. I believe Mel's is one and I think racin station does them too. Maybe others.

 

[line8]

It's at Fastrax in Wa.
Full confidence with them.

 

[line8]

It puts un-even pressure on one leg of the helix. Slide the two sheaves together and see how much wobble you have....bet there is quite a bit play. Both the bushing and post wear quite quickly.

So when you say wear quite quickly. Is this based on type of riding? Is this based on just miles logged? Or both? I'm asking because I've had 2 M8's prior (07,08). Both were flawless, literally, with the only things needing replaced were fuel, oil and a belt each in a combined 4000 miles.
Earlier in this thread there was a comment on vibration, I assumed it was the track but now I'm thinking against that and pointing my finger at this secondary.