[derf]

http://www.klr650.net/forums/showthr...ghlight=melted

I'm on a round-the-US trip, and apparently, I forgot to put on the chain-side wheel spacer the last time I changed the tire. The bike made it 3500 miles, but on a 105 degree day, in the middle of the Texas desert, this happened:

Obviously, I need a new swingarm, and probably everything in the rear wheel as well. I'm spending a good bit of time tracking down used parts to replace everything with, but even buying used parts, and doing everything myself it's still going to be a $500 mistake, and it'll cost me a week of travel time. Don't neglect your spacers, apparently they're there for a reason!

Nah, it was definitely the heat that did it. The sprocket probably started rubbing on the swingarm after the bearing cap got hot enough to smush itself into the swingarm, and because the swingarm was so hot and soft, when the sprocket started contacting the swingarm, I think the force from that contact, combined with the tension from the chain, was enough to cause the swingarm to bend towards the front of the bike like a warm stick of butter. The rear wheel was smoking for a good five minutes after I stopped the bike. It was super-heated...

But I've been wondering, and maybe one of the more experienced people here can answer this question: why, exactly, would the loss of that spacer cause this to happen? A highly experienced motorcycle mechanic/drag racer named Mike Long of Odessa, TX took one look at it and told me that he bet it was missing a spacer, which made my heart sink because, well, I thought I remembered missing it, but I never really understood why that would cause this to happen. I remember eyeballing the sprockets/chain for alignment when I put it back together, and everything lined up, so I thought it was good. All the spacer'd do, it seems, would move the wheel about a half inch to the right, which doesn't seem like it'd be enough to make that much of a difference. Maybe because the wheel was misaligned, the tension from the chain would have been pulling the wheel to one side,which would put excess pressure on one side of the bearings, eventually causing the bearing to go kaput, create a ton of heat, and nuke my hub? And maybe, in more temperate climes, the excess heat from that slight misalignment would be dissipated, but maybe that 105 ambient Texas heat was just enough to push it over the edge into meltdown territory?

Karson, I'd gladly post a pic of that spacer, but it's about 2k miles away back in GA, probably rolling around somewhere on my driveway.

But if you want to check, just go look at the sprocket side of your rear wheel, and, if I remember correctly, you should see a dust cup that covers the bearing with a 1/2" or so spacer between that and the swingarm.

But why did it last 3500 miles before grenading? Hmmm... Actually, I tightened the chain the day before this happened, and I did put a little more torque on the axle nut than usual... guess that little bit of extra torque plus the heat might have been all it took to kaput the whole deal, which had been wearing away since I left home. What a stupid mistake!