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Discussion Starter · #1 · (Edited)
Maybe a little over a year ago the plastic part of my speedo drive cracked. It was the second to do so in a few months. User error? Incorrect install? Not sure.
I ended up replacing the unit with one from a gl500, which is completely metal. I got maybe 10k+ on it, and then one random Friday my speedo stopped working. Turns out the worm wheel and drive jammed and busted the metal retainer in the wheel. After thorough cleaning through the grease and inspection, looks like the worm gear is all worn out and the extra play causes it to bind after a few revolutions.
Any thoughts on this?
 

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Is this on your 350? I've never personally seen a speedo drive worn out, but after all these years I guess anything's possible. You may end up getting a complete used drive assembly, individual parts for them are probably unavailable anymore
 

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Discussion Starter · #3 ·
Hey tom
It's an 83 cb450sc nighthawk.
At first I thought it was debris that jammed everything up, but after a good clean it still binds. The worm wheel looks okay, but the worm gear has been worn pretty sharp.
The original speedo unit had maybe 50k on the clock when I picked it up.
My nighthawk has about the same, 50k.
No issues with the 350s, fortunately! Different guts.
 

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Well, I guess it's not something you can be disappointed by anyway - 50k is a bunch of miles. It deserved to be worn out! :D
 

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Discussion Starter · #5 ·
Maybe! I just pulled out an old busted drive unit with plastic worm wheel, and the worm gear appears to be in the same condition as the gl500 one, so it doesn't seem to be the issue?
I'll try installing the 500 wheel in the 450 unit and see how it goes.
How's your 450, tom?
I haven't touched mine. Barely ridden the 350. Just today worked on the moped, moving from points to Cdi and bigger aftermarket carb, and finding places to mount everything.
 

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It's a few weeks or so away from re-assembly, the head is off and I'm swapping cams while it's apart for the head gasket oil leak, and the frame is almost ready to go back to the powdercoat shop. Got a few other small things to get done and then put the pieces back together. Gotta get it done by the end of March when my cousin visits. Looking forward to you getting started on your 450.
 
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