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culcune
02-20-2014, 01:21 PM
I was just pulling out of my driveway at about 6:15 am this morning looking forward to another day of teaching inmates GED tips in the state prison where I work. Right at the end of my driveway, the bike stops moving as if something was in my rear wheel. I am thinking "great, another broken chain issue" but low and behold, my chain was not broken, but wrapped around the rear axle and stuck.

I loosen up the bolt of the axle, and both chain tensioners to loosen the rear wheel and release the stuck chain. The left chain tensioner bolt is kind of bent out of shape, but I could still tighten it up whenever I needed to tighten the chain. However, the metal cup-like item (rectangular shaped ) that is there for the nut to tighten up when you are tightening your chain was twisted sideways (it has been beaten up with the several broken chain issues that had to do with the aftermarket sprocket I used to have).

Anyway, I freed the chain, pulled the wheel back to desired place, tightened the axle nut, then both chain tensioners. However, both would not tighten, as if both were stripped. Sure enough, both were stripped. Stupidly, I tried my best to tighten them down, as well as the axle nut and bolt. Tried to ride, and bam! the chain was off once again.

Okay, so the inmates will have to do without me today, and I took the rear wheel off, and pulled out both chain tensioners. Sure enough, both bolts are stripped (and the left one is still beaten up).

Of course, no one carries them in Yuma, but one dealer had replacement bolts and nuts for $6. They said I should try "so and so" who can grind the weld off, remove the stripped bolts, and weld the new bolts on the old chain tensioners.

I figured I would save money and take both of them to a good friend of mine who owns a custom awning and upholstery business (he has just recently done some welding jobs for me in which I now have my engine welded straight to the frame thanks to ripped and torn off engine mounts, as well as welding my exhaust directly to my frame thanks to the exhaust bolts broken off, and him not wanting to weld it directly to the engine).

So, my question; could chain tensioners that don't tighten anymore cause one's chain to fall off? Shouldn't the axle nut and bolt at least be able to keep the wheel in place for a while? Will my reworked chain tensioners (I ordered two new replacement tensioners from Excalibur) "fix" this problem in the meantime (while waiting for the stock ones to come) if they are properly made with the new replacement bolts while I wait for the new ones to come? Or is there something more sinister going on when it involves rear wheels dropping chains?? I did check the sprocket, and it is tight on the rear wheel and the teeth are all there.

Killerbracing
02-20-2014, 10:07 PM
Too much torque will overpower the axle nuts. Competition grade bmx bikes now have chain tensioners.

Krasi_BG
02-21-2014, 07:05 AM
Generally "chain tensioners" are used only for aligning the wheel straight in respect to the swing arm. Wheel axle and nut hold it in place.

How much slack do you have on the chain?

Also, make sure the chain is stretched evenly and that you've checking the slack at the tightest and most stretched points. In other words, when checking the slack, take a measurement, move the bike a few feet forward or backward and check again. And then move another few feet in the same direction and check again.

culcune
02-21-2014, 07:48 PM
Thank you both! I think that since both tensioners had stripped bolts, and could not tighten down, the wheel was probably a little out of alignment. The TMEC distributor has brand new tensioners, but my friend is going to weld new bolts on the old tensioners which will allow both to properly tighten. If that works, then I might order them anyway to have new ones, or just get a new bike and keep this one for parts. It has been a good commuter for the past 15 months, and seeing all the little stuff occur, now I know what to look for from new.

david3921
02-21-2014, 09:56 PM
I noticed that you wrote that you tightened the axle nut and then the tensioners. It's the other way around, but I think you know that and mis-spoke (mis-wrote?). As Kasi wrote, the tensioners align and the axle and nut hold. I think you have an alignment problem. I make ajustments using a caliper. This also allows me to check to see of the marks on the swingarm match up to each other.

Krasi_BG
02-22-2014, 11:28 AM
And you can always use one of those cheap "laser" pointers, or distance gauges, to align it on the top of the chain and see if it's straight. Something like these:

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRkS1f4iqwwmWCmQR0RgLgPbA1F4PhzY woRICNwrj7kl1DZ_AJK

http://indysuperbike.com/img/MotionPro/chainalign.jpg

culcune
02-22-2014, 12:15 PM
And you can always use one of those cheap "laser" pointers, or distance gauges, to align it on the top of the chain and see if it's straight. Something like these:

https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcRkS1f4iqwwmWCmQR0RgLgPbA1F4PhzY woRICNwrj7kl1DZ_AJK

http://indysuperbike.com/img/MotionPro/chainalign.jpg

David, I don't know if the alignment is off or not, so I will try Krasi's suggestion. I may just bite the bullet and hope that Excalibur is parting out a TMEC and buy a new swingarm as it looks a little beat up on the left side.

culcune
02-24-2014, 08:18 PM
Well, had a friend grind off the threaded bolt and weld in brand new threaded bolts to the chain tensioner. Put it all back together, and it worked, or at least for today's commute. The chain was still tight and the bolts were tight when I got home.

SpudRider
02-25-2014, 05:58 AM
:tup: