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Discussion Starter · #1 ·
Hello all, got a new sound that started a week or so ago with an '81 GL500. As I decelerate and clutch into neutral, engine rpms drop enough that I can hear a mechanical "moaning" sound whose pitch drops with the speed of the bike. As I stop, it disappears. This is a new sound, one that I hadn't heard before. It's not possible to describe the sound except in this manner. Does anyone out there have any idea what might be causing this? All fluids are fresh and full. Outside temps have been in the 30's and 40's, but I've ridden in those temps before without this sound.
 

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Rear end? Tires? Wheel bearings?



Is the noise present when running the bike on the center stand?
 

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Noises are tough to diagnose over the internet so without being right there I'll relate a "moan" that I had.



Moan could be the speedometer gear down at the front wheel axle. Put the bike on the center stand and prop it up so front wheel is off the ground. Spin the wheel by hand. On my '81 GL500, that little gear mechanism got bunged up. Was able to get one from ebay and moan issue was solved.
 

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Discussion Starter · #4 ·
Noises are tough to diagnose over the internet so without being right there I'll relate a "moan" that I had.



Moan could be the speedometer gear down at the front wheel axle. Put the bike on the center stand and prop it up so front wheel is off the ground. Spin the wheel by hand. On my '81 GL500, that little gear mechanism got bunged up. Was able to get on from ebay and moan issue was solved.


I know, it's really tough to diagnose a sound online. Just describing it so it makes sense is near impossible. Speedo makes sense, though. It seems to be coming from the front end. I'll try to center stand it today and see what I find. Is there a lube requirement for it?
 

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I don't know what the lubrication requirement is for that axle speedometer gear but mine that went bad was full of grease. It was good looking clean grease too and completely full but somehow, the mechanism just got tight. I could actually feel it dragging if I pushed the bike without the motor being on.
 

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Discussion Starter · #6 ·
I have a copy of the owners manual. Well, a pdf version anyway. It has a lubrication points page that indicates you should lube the speedometer gears, pointing at the axle, and the speedometer cable, pointing at the dashboard area. What's the procedure for lubing the speedometer gears? I'm assuming the cable is literally removing the cable from the housing and getting some cable lube on it and re-inserting. Anyone out there have specific information on this? Thanks!
 

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Here's my nebulous 2 cents worth. Speedometer cables should have grease on them full length but shouldn't be jammed full of grease. Both the axle speedometer gear assembly that went bad and the new one I got from ebay were completely full of grease. It'll be obvious to you if you remove it from the axle.
 

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Discussion Starter · #8 ·
Well, it is the speedometer box at the wheel. I did pull the cable and lubed it with some chain/cable lube. Also tried to shoot some into the speedo box without removing it from the bike. It helped, but not completely. Speedometer needle is now swinging pretty wildly. The moan is off and on and getting louder when it's on. I'll be looking to get another speedo box and replace it when I can. Might be a good winter project.
 

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Well, it is the speedometer box at the wheel. I did pull the cable and lubed it with some chain/cable lube. Also tried to shoot some into the speedo box without removing it from the bike. It helped, but not completely. Speedometer needle is now swinging pretty wildly. The moan is off and on and getting louder when it's on. I'll be looking to get another speedo box and replace it when I can. Might be a good winter project.


Pull the speedo drive and service it. You do not need to remove the front wheel, but you do need to pull the axle out far enough to remove the drive. Clean and lubricate should help, unless the gears are broken/worn out. 15 minute job.
 

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Discussion Starter · #10 ·
Pull the speedo drive and service it. You do not need to remove the front wheel, but you do need to pull the axle out far enough to remove the drive. Clean and lubricate should help, unless the gears are broken/worn out. 15 minute job.


Nice to know I don't have to completely remove the wheel. I got a "new" speedometer gear box. Cost about $15 shipped. Got some other things to attend to today, but hoping I'll be able to carve out a little bit of time to work on it.
 
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