Any guesses as to what caused this?

[barelycompetent]

The shop its at is closed today so I cant bug them for any answers lol, but I will be stopping by to check on it tomorrow for sure. My buddy wanted to straighten the shock out, he said you'll never know. I looked at him like he had two heads. BULLS**T I said, all new suspension for me, Im not taking any chances with a bent shock. New progressive shocks ordered up and on the way. Once that back end is figured out I am fingers crossed good to go.

 

[5twins]

Those look like the $79 cheapo shocks from Mike's anyway (I can't believe people buy that shit). Bending one was probably the best thing you could do to it, lol.

 

[barelycompetent]

Damn you are good 5twins, it was the cheapo's from Mikes. Not anymore though, got a set of progressive 13.5 shocks on the way.

 

[angus67]

A while ago, My axle shifted taking off from my drive, low speed still a wtf moment. I had tightened to spec(105ft/lbs) Chewed up my chain adjs, and chewed up the heads on my sprocket bolts. Turns out, the cheap as mikes adjusters had wrong size hole thru smaller of the shouldered side, making it seem tight, that also wrecked the threads on the axle.
so I die grind them a tad bigger, replaced with a axle from a 75, tightened it, fine since then.
Mikes adj went on fine in hand, but in action, the smaller hole ran up against the shoulder end of threads on the axle.
Just thinking out loud. You have real adjusters, so prolly not the issue, but worth a thought?

 

[Uncle Bryan]

Don't know if this will help but here's the axle from my 81.

I measured the axle from the inside of the head...

To the end of the axle and it comes out to 10 3/4 inches.

Also, here's what it looks like when the axle nut is bottomed out. Note that the top of the castle lugs are well below the cotter pin holes and there are 4~5 threads showing. Yours doesn't look like its bottomed out, compared to mine.

Hope that helps.

 

[FrkyMnky]

A while ago, My axle shifted taking off from my drive, low speed still a wtf moment. I had tightened to spec(105ft/lbs) Chewed up my chain adjs, and chewed up the heads on my sprocket bolts. Turns out, the cheap as mikes adjusters had wrong size hole thru smaller of the shouldered side, making it seem tight, that also wrecked the threads on the axle.
so I die grind them a tad bigger, replaced with a axle from a 75, tightened it, fine since then.
Mikes adj went on fine in hand, but in action, the smaller hole ran up against the shoulder end of threads on the axle.
Just thinking out loud. You have real adjusters, so prolly not the issue, but worth a thought?

Thats how they are stock as far as I know. It is done that way so the adjuster is pulling from both sides equally since the axle tapers down. If it wasn't done that way, you would only be pulling from the inside while the outside had a slight gap between the adjuster and the axle.

 

[TwoManyXS1Bs]

If you get the 'rear wheel' parts lists from http://www.biker.net for all the models, you'll notice that the axle adjusters for the 70-73 models are the same, while the later 74-on models show a specific right and left adjuster part number. The adjuster nearest the axle nut will have a smaller hole for the axle threads.

Some older Hondas had this setup, and we had to watch for adjuster mix/match/swapouts/flipovers and wrong axles.

Amazing how some of these XS threads drag up long-lost memories...

 

[Uncle Bryan]

I didn't know that the adjusters are right and left sets. Learn something new every day, eh?

So here's a couple new pics that may be more relevant.

Nut bottomed out with the adjuster on the axle.
That's an incredibly short torque range with only about 1-1/2 threads showing.

And the new measurement with the adjuster installed, is 9-3/4" as measured from the inside of the axle head to the inside of the outer adjuster.

Now I can see how easy it would be to have the nut torqued but still have the axle loose.

@ barelycompetent:
From what you have said, and looking at your pictures, I'm guessing (read guessing) that is what happened to you (adjuster bottomed out on the axle) and prevented you from truly tightening the axle.
If I was going to run my stock swing arm I would open up the adjuster to about .790" to ensure the axle was getting tight.

On a funny side note, in the Clymer manual, step 2 is to tighten the axle nut to 108.5 ft/lbs, step 5 is to adjust the chain tension

 

[TwoManyXS1Bs]

Good pics and explaination there, Uncle Bryan! This should go into a 'trivia tech' section...

 

[barelycompetent]

Thanks Uncle Bryan that is the conclusion I am coming too as well. The pics really are helpful too. I am stopping by the shop today after work to see if there is anymore progress or damage internally, after the hit it took I dont really trust the bearings anymore so I am going to see about replacing those as well.

 

[5twins]

Bearings are easily checked. Just stick your finger in one and turn it. It should rotate smoothly without any rough spots. Also try wiggling the inner race. There should be very little slop between it and the outer. Bearings are pretty dependable (as long as they are greased). Yes, I have found a few in need of replacement but most are fine with just some fresh grease added.

 

[jetmechmarty]

If I'm reading this right, a bolt backed out of the rear sprocket and broke stuff on its way around. Correct?

The same thing happened to me. I took the bajillion spoke rear wheel off my SK and put on a cast wheel off of an '81. I then rode the length of the Blue Ridge Parkway. On the return I hear "CLACK CLACK CLACK". WTH!? One of the bolts is backing out of the rear sprocket and making contact on each rotation. I had to stop and tighten it two or three more times before I got home. A second one had begun to loosen as well.

I replaced the bolt, the sprockets, and the chain. This appears to have solved the problem. It has been almost four years since.

 

[barelycompetent]

Jetmech, that bolt backing out of the sprocket was the first time the bike tried to kill me. I had a new bolt put in, and a new to me adjuster put on. Two days later I put everything back together, and thought I had properly torqued my axle down, but it is starting to appear that I had actually bottomed out the nut on the shoulder of the axle and didnt have it tight. It shifted on me while riding and bent my shock, broke the chain adjuster(again) and slammed the wheel to the right against the brake stay and rubbed it down. The shop did say that my chain and sprockets were worn, havent heard about the wheel bearings yet.

 

[jetmechmarty]

Based on my own experience, replace the chain and sprockets. Be sure to get proper torque on the axle nut before it bottoms. I think that will do it.

Before I got a proper fix on mine, I also knocked the wheel out of alignment and wrecked the tire sidewall. The axle is fine.

 

[barelycompetent]

Yup that is on the list of things to replace. Hopefully this is the last time this particular bike tries to kill me lol, I really like this bike too!

 

[barelycompetent]

Ok so final update. The bike is fixed. Bearings, shocks, sprockets, and chain all replaced and good. The verdict, I had bottomed out on the shoulder of the axle instead of actually tightening the axle down. The chain adjuster would not allow the axle to come far enough through for all of the threads to engage and lock down. Like Uncle Bryan pointed out. The adjuster had to be opened up slightly to lock down properly. So the moral of this story here, is if you take your rear wheel off, make sure you seat the axle properly, or else you might end up like my bike did. Maybe this should be a sticky in the tech section to serve as a warning to others.

 

[Uncle Bryan]

Dig it, I don’t want to be “that guy” that pulls the fire alarm just because some kid is smoking in the boys room, but I think this could be a serious safety issue that we should all be aware of. The next time you are doing a “walk around” on your post 1973 bike, take a look at the rear axle nut. If the axle has more than one (1) thread showing you should be suspicious about whether your axle is properly tightened or not.

As we have seen, if the left hand chain tension adjuster has bottomed out on the shoulder of the axle, all sorts of bad things can happen. These include, but are not limited to, high speed wobble, sudden shifting of the rear wheel alignment, sticking brakes, sudden lock-up of the rear wheel, general loss of joy-joy feelings, cats sleeping with dogs (okay, that was over the top) but you get the idea.

Of course there are always manufacture tolerances that blow this out of the water, but lets error on the side of safety and spread the word to be on the look-out for this.

I hope that some of the more experienced members will chime in on how to diagnose this problem without all of us running around with our hair on fire and having to tear down the rear end just to verify that the problem doesn’t exist.

 

[barelycompetent]

If it helps some one learn from my mistakes, and avoid the same problem, then Im all for spreading the word.

 

[retiredgentleman]

Dig it, I don't want to be "that guy"that pulls the fire alarm just because some kid is smoking in the boys room, but I think this could be a serious safety issue that we should all be aware of. The next time you are doing a "walk around"on your post 1973 bike, take a look at the rear axle nut. If the axle has more than one (1) thread showing you should be suspicious about whether your axle is properly tightened or not.

As we have seen, if the left hand chain tension adjuster has bottomed out on the shoulder of the axle, all sorts of bad things can happen. These include, but are not limited to, high speed wobble, sudden shifting of the rear wheel alignment, sticking brakes, sudden lock-up of the rear wheel, general loss of joy-joy feelings, cats sleeping with dogs (okay, that was over the top) but you get the idea.

Of course there are always manufacture tolerances that blow this out of the water, but lets error on the side of safety and spread the word to be on the look-out for this.

I hope that some of the more experienced members will chime in on how to diagnose this problem without all of us running around with our hair on fire and having to tear down the rear end just to verify that the problem doesn't exist.

Yes, only one thread should be showing. The fact that barelycompetent had to have the chain adjuster opened up, to prevent hitting the axle shoulder, tells me that his bike has the wrong size axle spacers, or wrong size bearings. The combination of spacers, bearings and dust covers is too narrow, meaning the axle nut has to be threaded further inward than normal.

 

[jetmechmarty]

When mine threw the sprocket bolt, it certainly wasn't because of an improperly installed axle. My incident was 2010. The axle is fine. It was fine, installed IAW the FSM.