Repaired Speedo Drive Assembly

[luvmy40]

I wish I had thought to take some pics during the the process but I didn't think I'd have any luck fixing this so...

Has anyone repaired a bad speedo drive gear assembly? My speedo has been defunct since I bought the bike. I put a new gauge cluster in as the speedometer it's self was actually damaged beyond repair. I knew that the speedo cable was not spinning but it took me a while to make the time to look into it.

I pulled the front wheel today and sure enough found the speedo drive froze. The drive cog would not turn at all. The wheel was good(recesses for drive cog look square and tight) and the drive cog was not visibly damaged., but it was immovable.

I disassembled the gear assembly and found the spiral shaft(?) was caked with grime and looked like a smooth shaft. It cleaned up nicely and did not look worn at all. On the back side of the drive cog the tabs that interface with the main gear were worn down to half thickness and would not engage at all. I peened the ears in with a punch till they made good engagement. This is not a permanent fix but it should work for a while.

Everything cleaned up nice. I used a good bit of PB Blaster to get the gear assembly clean and rotating freely. But here's my question. Are there supposed to be ball bearings(tiny ones) between the drive cog and the main gear assembly?

I ask because when I first took it apart I found what looked like a single, tiny ball bearing in there. I picked it out with a needle nose pliers but could not find it later to inspect.

BTW after re-assembling everything with a little synthetic grease, the speedo is right as rain!

[WilliamGLX81]

Good to know! I think mine may be similarly seized, so this may be in my future.

[chuck hahn]

Yes....do the following and in this order so you don't ruin anything else.

Look in where the cable goes into the gear drive. See in the back there is a plate with 4 notches in it. make something that will grip in those notches and unscrew the retainer...then remove that worm gear the cable rides on.

Next heat the gear drive with a torch for maybe 2 minutes. This softens the rubber seal on the grease seal that goes over the axle when its on the bike. Take a flat screw driver and pry under the edge and work it out of the housing.

Now you can remove the big worn gear and clean everything up and pack with new grease. Just reassemble and press in the grease seal. I finger start it and seat it with a big socket and a few taps with a hammer.

[chuck hahn]

No bearings..the speedo drive engages between the wheel with the washer with the two ears on it.

[luvmy40]

Thanks chuck,

I did re pack the assy. with synthetic grease. I'm not worried about that. I may have to get a new "drive cog"( the eared washer) eventually as my hammer and punch repair may not last long.

I just wasn't sure if there was supposed to be bearings or not. It looks like the inside of the aluminum case might have been shaped as a race.

[jermee47]

"drive cog" tab repair

"drive cog the tabs that interface with the main gear were worn down to half thickness and would not engage at all"

THE SAME THING HAPPEND TO MY DRIVE COG, SO I HAD THE TAB BRAZED USING A GAS TORCH AND FLUX AND BRAZING WIRE.... THE BRAZING LEFT A NICE PILE OF METAL TO GRIND AND FILE BACK DOWN TO REFORM THE DAMAGED TABS....

I DID NOT HAVE PICS, BUT THE BRAZING METAL SEEMED TO ME A HARDER METAL THAN THE STEEL COG ITSELF.....

I HAVE NOT HAD A CHANCE TO INSTALL BACK ONTO THE BIKE, BECAUSE THIS ALL OCCURED TODAY.

THE TABS ENGAGED WELL AND THE UNIT TURNED AS SHOULD AFTER THOUROUGH CLEANING AND GREASE PACKING.

CERTAINLY A CHEAPER FIX THAN A USED CABLE DRIVE ASSEMBLY AND WAY EASIER THAN TRYING TO FIND A REPLACEMENT COG..... ALL SITES I HAVE VISITED DO NOT SELL REPLACEMENT PIECES TO SERVICE THE CABLE DRIVE ASSEMBLY