Weird speedometer problem

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webman94
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Weird speedometer problem

Post by webman94 » Mon Jul 03, 2017 6:40 pm

Hi everyone, I hope you have thoughts on this one. I have a '97 Seca II, which I've done a naked conversion on. I replaced the speedometer with one from Dime City, and it worked fine, for about 100 miles... the strange thing is that I don't think it's the speedometer that's the problem. I unscrewed the speedo cable at the wheel end, and put the end of the cable in my cordless drill, and pulled the trigger; the speedometer needle freely moved, every time I pulled the trigger.

I tried attaching and reattaching both ends of the cable several times, and tried riding the bike each time, with no success. This suggests the speedometer drive is either broken, or something else is wrong. I replaced the drive a few years ago, and haven't been able to ride the bike very much the last few years (probably less than 1,000 miles), so it would be surprising that the drive has gone bad, but you never know.

Is it possible that the aftermarket speedometer location is an issue? Is it possible that the internal part of the cable isn't engaging (or 'pops out' of the drive) for some reason? How could I test/diagnose this?

Any help would be greatly appreciated!

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Jimbo
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Re: Weird speedometer problem

Post by Jimbo » Fri Jul 07, 2017 7:45 am

You can check the speedometer wheel drive by removing the cable and with the front wheel off the ground, spin the wheel. Looking into the hole where the cable was, you should see the drive tab spinning. Next reinsert the speedo drive cable making sure the tab fits into the groove. It should then be spinning the cable and hopefully work.

If not, this can be verified by disconnecting the cable at the speedometer. Again spin the wheel and see if the cable end spins near the speedo. If it does, then you know the wheel drive and cable are connected correctly. Now match up the speedo cable to the speedometer tab. then screw on the cable securely. It should seat all the way on. It should now work.

I have had speedometer issues before when I replaced my cable and it was because I did not fully seat the cable at both ends to the drive tabs. Good luck.

webman94
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Re: Weird speedometer problem

Post by webman94 » Sat Jul 08, 2017 10:44 am

Thanks, Jimbo! This helps a lot! I'll try your techniques this weekend and report back.

webman94
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Re: Weird speedometer problem

Post by webman94 » Mon Jul 10, 2017 11:04 pm

Well, I tried your ideas, Jimbo, and got some weird results. At first, the speedometer cable didn't spin inside its housing when turning the wheel, so I removed the wheel and took the speedometer drive off. I made sure to align the grooves on the inside of the housing with the two "teeth" projecting from the ring (not sure what it's called) on the wheel. I noticed that the housing can be placed on the wheel in such a manner that it appears to be installed correctly, but isn't actually engaged with the two projecting teeth... lesson leaned.

Anyway, I buttoned everything back together, and attached the speedometer cable to the drive, but left it off of the speedometer, and then tried turning the wheel. The results were not what I expected; the inner cable didn't rotate when spinning the wheel, but then I tried spinning the wheel backwards, and then the inner cable did rotate! This made no sense to me, so I took everything apart again, double checked everything again, reassembled, and got exactly the same result! What is going on here? It looks like, based on the rotation, that something is installed backwards, but that doesn't make sense, since it was working properly at first. Any ideas?

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Re: Weird speedometer problem

Post by Jimbo » Tue Jul 11, 2017 5:30 am

Your right it does not make sense. When you got the cable to spin going backwards, did you try to spin it again going forward? Reason I am asking is, when you turned it backward it may have seated the cable to the drive. Just a thought. Also when you see it turn going backward, press lightly on the protruding cable end and see if it turns going forward. It may be coming unseated when you change directions. Cable should turn whether going forward or backwards. Hope it does now after you do this.

webman94
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Re: Weird speedometer problem

Post by webman94 » Wed Jul 12, 2017 5:27 pm

I'll check it again, but it wasn't spinning going forward at all. It stopped turning every time I changed the wheel direction. I'll try it again, and let you know. I don't recall pushing the cable back down again, after changing direction.

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Re: Weird speedometer problem

Post by Jimbo » Tue Jul 18, 2017 7:11 am

Just so you know the speedometer drive is simply a gear driven by the wheel rotation (tabs on the back side which fit into the wheel hub). This gear then turns a worm gear to translate the wheel rotation 90 degrees to now drive the speedometer cable. Very simple drive device with 2 moving parts but dependent on the parts (drive gear, worm gear and cable) making constant contact. I think when you rotate the wheel in reverse direction and it turns the cable, that is a result of the friction on the cable strands in the cable's sheath drawing the cable onto the tab keeping engagement. But when you rotate the wheel in the forward direction it does the opposite and pulls the cable slightly outward where it disengages the drive tab/slot connection. That is why I say to apply slight pressure on the cable when you rotate it to keep the cable engaged. Obviously when the speedometer is hooked up it supplies the pressure to keep the cable engaged. I hope this makes sense.

webman94
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Re: Weird speedometer problem

Post by webman94 » Tue Aug 01, 2017 3:01 pm

Well, I tried everything again, and it still doesn't work. It doesn't look like the drive is rebuildable, either. Strange that it quit working, given that it had less than 1,000 miles on it. Any thoughts on what could cause such an early failure? It was a factory part, bought new.

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Re: Weird speedometer problem

Post by Jimbo » Wed Aug 02, 2017 9:12 am

Lets back up a little. I stated originally:

"You can check the speedometer wheel drive by removing the cable and with the front wheel off the ground, spin the wheel. Looking into the hole where the cable was, you should see the drive tab spinning."

Is the internal mechanism turning when you spin the wheel? If it is, then your drive unit is OK. If not then it may not be seated correctly to engage the wheel hub or it is a bad drive. I have only seen a drive unit go bad if it got jammed and then the gear stripped the threads on worm drive to the cable. They are made of plastic.

Then install just the one end of the cable making sure it is seated in the speedometer drive unit only. Spin the wheel again and the cable should turn. If not then it is not seated into the drive unit.

If that works, then hook up the cable end to the speedometer from Dime City. Test if it works. Sometimes you can't see it function the speedometer until you ride as you need to spin the wheel pretty fast to fully register on the dial face.

Attack this issue methodically ruling out one component at a time. Its the only way to know where the problem lies.

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Re: Weird speedometer problem

Post by webman94 » Sun Aug 06, 2017 4:40 pm

Thanks, but I'm pretty sure the gear is shot. I spun the cable with it attached to the speedometer, using a drill, and it works. Then, I reattached the cable to the drive; no luck. Lifted the bike off the ground as described, unhooked the cable, and looked down the drive hole, and it appeared to be moving. I'll try re-checking to see if it moves when the wheel is moving forward; it was definitely moving, but I honestly don't remember if it moved in forward or reverse. The internal cable only moves when the wheel is in reverse, no matter how many times I've tried it. I tried pushing down on the speedo end of the cable as described, but this didn't change anything.

I ordered a new drive unit from Bike Bandit, but they're on backorder. What a pain, for something seemingly so simple!

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