Clunky Commando

Long time listener, first time caller...

Ok, that last part is a blatant lie.

Short story to bring everyone up to speed before getting into the clunkiness. I've still been riding my Commando, to occasional club events or when I can get @Mike T to get out of the (Mighty) Garage. But I certainly haven't been working on it much. I've been wasting most of my time in the woods of the PNW (of the US, you dang Aussies) instead. And more recently I've been put on an unplanned sabbatical, more formally known as: I've been laid off of work. Only 23+ years at Nike and shown the door. But don't feel bad for me, it's happened to way better people than me.

So now I have more free time and will be haunting this place again. Sorry about that. I'm a wee too young to formally retire so I'll have to earn some money until I get as old as some of you farts. Ok, enough backstory...

I don't really ride on the freeways much, more just toddling along the backroads but the last couple times on the freeways at about 70mph indicated (probably more like 65 actual) there's a discernible clunking. Not enough for me to stop the bike and walk home but certainly a new sound. It feels like from the rear end, which means it's probably from the front.

So with the additional free time I've torn into it. And here's the story so far.

Victim/Patient: 1973 850 Interstate


We just had a ride to a museum (actually it was an awesome ride with an incredible turnout, video one of these days) and when I got to the start point (also an incredible location) I looked over the rear of the bike and noticed the nut holding on the rear brake arm had gone AWOL. Luckily our host has a substantial collection of random nuts and I was able to secure the arm down. Alas that was not the source of the clunking as I found out when we set off.


So back home the rear wheel came off for a better view. And to clean. Don't worry the rust prohibitor will reapply itself.


Stub axle moves around but that's normal. Strange but normal.


Chain guard is unfortunately broken which is a shame as that's a nice chain guard, aside from being broken now.


Relatively low miles on the speedo drive. The end doesn't spin but it wants to. Not sure if I'll be able to fix this. I swear these things have the life expectancy of a fruit fly. And this one was supposed to be the best quality out there.

New post as I think I'm limited on the number of images.

What's this? The rubber isolator bolt is hitting the swing arm? It's not hitting by much but it's definitely hitting.


My new favorite tool, a cordless die grinder. No more having to fire up the air compressor. Just lovely. Spins to like a billion rpm.


Within a couple minutes I removed about a tenth of an inch, which is plenty.



Clearance established. Not touching.

So I start grabbing the swingarm, looking for other sources of the clunk. At first I thought the swing arm is moving to the side, which would be surprising as it's been clamped. Upon more careful inspection I now think the play is in the rear isolastic.

Now I need to revise and remember if the rear iso can be addressed in the bike. I don't think it's the Mk3 type but I do recall buying a set of Mk3 isos for this bike with the grand intention of installing them on of these days. Maybe that day had come.

Anywhere else I should look for the clunk? I'll try to get a measurement of just how much the rear end is moving to the side later.

Chain looks dirty n' dry .
Good chance to regrease the double row hub bearing too .
Clunk could be a worn chain that hit the chainguard , breaking it .

My first thought were the cush drive buffers.
You have the wheel off, what are they like?

MichaelB said:

My first thought were the cush drive buffers.
You have the wheel off, what are they like?

Click to expand...

They look good. I think they got replaced recently enough.

Torontonian said:

Chain looks dirty n' dry .
Good chance to regrease the double row hub bearing too .
Clunk could be a worn chain that hit the chainguard , breaking it .

Click to expand...

Possibly, but it doesn't feel like a chain slap.

Wheel bearing maybe gone. Has the wheel got side play when bolted up? Mine disintegrated a few months ago. Clunk clunk. The spacer between the bearings was possibly not the right length causing side load on the bearings. Graham

velo54 said:

Wheel bearing maybe gone. Has the wheel got side play when bolted up? Mine disintegrated a few months ago. Clunk clunk. The spacer between the bearings was possibly not the right length causing side load on the bearings. Graham

Click to expand...

That is something I will definitely be checking. Although initially impressions are that the bearings are fine.