I have a 2003 Fatboy. About a year ago me and the wife were riding up to our local Wally World when all of a sudden we here a clank and I can no longer accelerate. I pull over to the side of the road and look to see the Rear drive pulley totally sheared the bolts from my rim. I have asked other people on what could cause that and I always get the same reply, "I never heard of that happening before". Well I fixed it, extracted the bolts remounted the pulley, reinstalled new bolts and to be extra sure that the bolts wouldn't somehow vibrate loose I red locktighted them.
Well this weekend I was up at the Tomahawk Fall Ride Bike Rally in Tomahawk, Wi. when all of a sudden it happened again. Exact same thing the bolts were sheared off and my pulley was just hanging there. (Maybe you saw my bike up there on Hwy. L) Any info that anyone has would be very much appreciated. It cost me alot of money I didn't have, to get my bike back home 250+ miles. I don't want this to happen again.
PS. Both times I was riding at less than 35 mph.

 

Well that sucks, where did you get the replacement bolts from? I wonder if they were bottoming out and not truely tight on the pulley. If they were even the slightest bit loose, they will shear off like that.
Think its time to upgrade to some grade 5 or 8 bolts that are long enough to get the job done and still not bottom out.

BTW Using locktight on them will not stop them from shearing, only coming loose.
Then they can get sheared off from the play loose bolts allow.

 

I used the exact same size bolts but upgraded to a grade 8. I also ran a tap through the threads before reinstalling.

 

When you tighten them down, do not over torque them... the top of the bolt will twist and weaken... hence the reason for "torque wrenches"

 

Then I haven't a clue why it would do that. Unless like I said the boltswere never really holding the pulley but bottoming out. If there is ANY slippage between the pulley and the wheel hub it will give the pulley a kind of running start at the bolts that will eventually pound them till they shear off at the hub. Or like handyhoward said they were over tightened,got twistedand weakened that way.

BTW I'm not surprised that it broke at a lower speed, lower speeds means lower gears and the lower the gear the greater the torque multiplication. If the ratio is 3 to one in gear X it means that the pulley is being hit with 3 times the torque pressure of the crankshaft everytime a cylinder fires that it gets in 5th gear that's only 1 to 1.

 

Ok, that's freakin' scary!!! That's the kind of stuff that should never... ever... happen. I agree with Handy though, given you're using the correct strength and length bolts, the proper torque amount should ALWAYS be adhered for this mission-critical connection point.. If grossly over-torqued, those tops might have popped right off, rather than just sheering off. Probably totally not-related, but I'd check your wheel alignment also, just for sh45s and giggles.

 

I can tell you exactly how it happens. I have repaired two rear wheels for friends with the same problem. You're not going to like the answer, but you needa new rear wheel. It has become conical. Maybe not enough to feel, but certainly enough to make a difference in the torque specifications. Most dealerships that doreplacementwheelwork will not assume responsibilty on any wheels other than HD wheels. Some aftermarket wheels have a week aluminum hub. Sorry to break it to you, but thats the deal...
If they are HD wheels, then demand that they assume responsibility.