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Discussion Starter · #1 ·
Hey All,

thanks for taking the time to read. Pulled my forks ('72 CL350) apart yesterday for inspection, clean-up, new oil, etc. My left fork leg damping rod does not want to expand.

IMG_2198.jpg

Closer inspection of the lower oil hole suggests it was compressed to heavily.

IMG_2197.jpg

I'm guessing the compressed metal is pinching the internals from expanding. Any thoughts on how to remedy??

Cheers
 

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I think internal corrosion or some coagulated goo may be your problem. Try soaking it in some solvent for awhile and try to work it free.
 

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The one that is out the furthest almost looks too long. When the spring is in place it should be just a bit longer than the rod as you have to compress the spring to put the cap on.

I've never seen that much difference in any that I've taken apart.
 

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Discussion Starter · #6 ·
Thanks Boomer. Yeah, it really extends and there doesn’t feel like there is any spring in it. This is my first experience with these type of damping rods so am not sure what to expect.

Are they supposed to be “springy”?
 

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I know on the end of the rod there's a piston, and I think there's a small spring either above or below it.
 

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Discussion Starter · #8 ·
On the rod that's moving there sounds like a piston/plunger action going on. However, if there is supposed to be some spring action happening, there's none. After soaking the stuck rod for two days in PB Blaster it still won't budge. Might try to 'uncrimp' it - I'm thinking that the piston/plunger may be pinched at the bottom by the compressed metal.

I'm really unsure of how they are to function out of the forks.
 

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I have a old one cut up that I could post a pic if you're interested. I'm thinking there's not a spring involved. At least not above the piston. I don't think they able to be easily disassembled. If the pipe is kinked out of round the piston will be stuck hard to fix. Maybe try threading some nuts on the rod and use a crescent wrench as a slap hammer to free it up.
 

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Discussion Starter · #10 ·
Thanks very much Lefty - if it’s not too much trouble I’d really appreciate an idea of what’s going on in there. I’ll give your idea a try to free it up as well.
Cheers!
 

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Here shows the piston construction. When compressed oil easily flows through the holes, displacing and flowing by the thin washers located by the groove. During the rebound, the washers block the flow(except for a tiny cutout), providing more damping.
IMG_0898.JPG
I think the steel cylinder may be threaded onto the aluminum base, but it's hard to tell. Can anyone confirm?
 

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Discussion Starter · #12 ·
Thanks very much Lefty for posting that. It explains a lot. So no spring in it then? I’m surprised that I couldn’t find a cut away anywhere to show how it’s made up.

It does look like it is possibly screwed together like you said. Going to work on it Sunday to see if I can free it up.

Much appreciated!
Cheers
 

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Hey I ran into the same issue. Big thanks to Lefty for that cut view. Helped a ton.

I inserted a steel drift into the bottom bolt hole of the damper assembly (the bolt hole near the wheel axle) and knocked it loose.

I didn’t experience this when I rebuilt the left side... so this was a head scratcher for me. the rod gets gummed up at the top and very bottom end of the total rod travel. I think the inner wall of the damper assembly gathered some gunk over the years... the top and bottom end of travel probably didn’t see much action and it accumulated. That’s my best guess. I’ll make sure both forks feel the same once it’s all reassembled.

thanks,

jronfr
 

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. . . So no spring in it then? I’m surprised that I couldn’t find a cut away anywhere to show how it’s made up.

It does look like it is possibly screwed together like you said. Going to work on it Sunday to see if I can free it up.
Here you go:





It's interesting that you posted this. I didn't even realize that Honda used this damper rod suspension, but I had a Honda FSM that showed it. By coincidence, I have a pair of 1968 BSA 650 Lightning forks apart right now on my workbench. They used damper rods from 1966 through 1968. The pair I have were far nastier than what you found, and the replacement parts are expensive to say the least -- as in more than this old bike is worth. Yet, I may be stupid enough to pursue it.

Ray
 
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