Odometer works, speedometer doesn't

[Kerry]

To say the least, I've "been away for a while".... 

A couple summers ago, I took a week off and rode my 1999 GS500E about 2000 miles in a big "circle" to Yellowstone, Custer's Last Stand, Devil's Tower, Mt Rushmore and Rocky Mountain Nat'l Park before re-entering Utah.  I guess I owe you some pics! 

A couple months before that, my company closed the little office that was just over a mile from home, and turned me and my coworkers into telecommuters.  Things were pretty hectic w/work, so without a commute my bike just sat ... out on my driveway. 

Last summer I got the bike out from under its cover and rode it up and down the street, doing starts and stops to scrape some of the rust off the brake rotors before getting it inspected / registered.  One last, big stop ... and the bike died and would not start again.  Wha...?!  I goofed with it for a minute or two, then decided I "didn't have time for this" and pushed it back to the driveway and covered it again.  Bad Idea.

Several weeks ago (a year later)  I decided to give it another try.  Using my multimeter, I found a quirky connection to the clutch interlock switch.  Sure enough, I pulled the switch and found that it was pretty much shot.  If only I had done that little bit of troubleshooting last year! 

After 2 years of sitting, the bike had a whole list of things that needed doing - from cleaning the carburetors to cleaning the fuel tank.  (Yeah, I had less than 2 gallons sitting in there for 2 years.  Ouch!)  I slowly knocked out most of the tasks, one at a time.  Today I finished the last "big" task of cleaning the tank.  It's not totally clean, and I'll probably want to etch and re-coat it at some point, but if I waited for that to get done I might never get it inspected and registered.

Anyway, I put a couple gallons in the tank and rode it to the nearest gas station to fill it up, then rode to my usual inspection place on the off-chance that they were open on Memorial Day.  They weren't.  But that might be OK, because I noticed that

the odometer works but the speedometer doesn't

(Whew!  He finally got to the point!  )

Couple items:

1) One of the things I did was to lubricate both the tach and speedo cables, which I had never done before.  (I actually removed both cables from their outer coverings and made sure they got lubed from end to end.)  Since the odometer is working, I don't think I messed up the "reconnect".

2) When I left for the gas station today, the tach wasn't working either.  That has happened several times over the life of the bike.  The "fix" has always been to rev the engine way up and "break 'er loose" ... which worked again today.  But my speedo has always worked in the past.

I'm guessing that the two years of sitting has caused some kind of grease packing to harden up, and that if I were to ride the bike really fast the speedo might "break loose" too.  But I'd rather not ride out to a suitable venue with a 2-years-expired registration ... know what I mean?

So!  Does anyone have any experience with the innards of the speedo?  I found some cool pics that starwalt posted a few years ago (is he still around?) but not much info in the way of actual inner gauge maintenance.

The bike is (obviously) 12+ years old.  It has about 43,000 miles on it.  But I think the problem is more due to its sitting for 2 years than anything else.

All feedback / brainstorms / ideas are welcome!

   

[comradeiggy]

Give it a good rev and smack that Buddha Loves You really good with your hand. My tach sticks sometimes when I first start her up and that always does the trick.

[Dizzledan]

It's surreal to actually be posting in one of your threads after having seen so many of your topics and that valve shim video (thanks for that by the way).

I've taken apart the tachometer to clean up the gauge face, and I've got some pics I can post up of the inner workings.



The needle itself sits freely on the pin that travels down to the spring and the weight on the bottom. I cant say for sure, but I believe the cable spins a mechanism inside the weight that meets the tension of the spring at 0 RPM and increases to accurately reflect the RPM of the engine. By no means am I an expert, just speculating.

I'd pull your cable off all together and make sure it isn't broken or seized, and then hook it up to the tach and see if you can spin it to rule out any problems with the cable.

[Jared]

I have pics  of one  apart- just sent you an email.

Pics:

   

Started my first  edit as you posted evidently...

The speedometer needle is driven magnetically - the cup tries to keep up with the rotating magnet - the hair spring  keeps it in check...

[comradeiggy]

I see a few areas where you could have problems. The wheel, the cable, and the speedo. Pull the cable from the speedo and spin the front wheel and see if the cable spins with it. If it doesn't, then pull the cable from the wheel also and try and spin it by hand. If you can spin it by hand then that indicates the problem is coming from the part attached to the wheel. If the cable does spin when you spin the wheel then that indicates that it's actually the speedo that's the problem. There's a magnet inside the metal half sphere that spins. The cable hooks up to that magnet. When the magnet spins it creates eddy currents in the metal bell that cause it to twist. The spring tension acts in the opposite direction, and the needle moves until the force from the spring and the force from the magnet are equal. There is no physical connection between the needle and the cable.  Move the needle and see if it effects the spring and the metal bell(or vice versa.) If they are both moving, then the problem could be the magnet.

[Kerry]

Thanks for the cool pics guys ... especially the one showing the worm gear that advances the odometer. 

As I mentioned, the odometer (and trip meter) are working fine.  It's hard to tell from the pics, so Question: Do you recall seeing any "disconnect" between whatever drives the odometer worm gear and whatever spins the magnet under the speedometer cup?

The pics from starwalt that I found earlier were of the tachometer, but here is what really interested me (red highlighting added):

The output needle of the speedo has two sources of resistance to the spinning magnet turned by the front wheel. The primary source is the spring.
[...]
The secondary source that I have noticed after taking them apart is, for the lack of a better term, clear viscous goop. The goop is between the top plate in the following pic and the larger diameter shaft insert between the spring and the top plate. The goop is glommed all over the shaft. Here are pics of the tachometer. The speedometer has the same mechanism in addition to the odometer.
[...]
I think the goop dampens the movement somewhat. It sure is sticky.

One idea that I had right after hitting "Post" before was to hook the bottom end of the speedo cable up to a Dremel tool (or similar) and see if I could break anything loose that way.  I haven't tried it yet (I wanted to see what the group would come up with) but if I end up pulling the cable again that's one thing I plan to try.

Thanks again!

Kerry

[ivany]

You may have some luck breaking it with a dremel tool or similar. When my tach got sticky, I had no choice but to take it apart. But I noticed that after "flicking" the needle a few times and letting it settle back down, it seemed much smoother. Maybe using a drill or a dremel could reproduce this without having to crack open the unit. I don't know what the "goop" is - some kind of factory grease, both to keep it lubed and to dampen the response?

[Jared]

The gears all seems locked on the shaft -am sure it's a press-never to come off- Ther's so little resistance I doubt it could ever be broken free - I've had a few gauges be sticky after sitting  for long periods- try the dremel thing (like the drill thing I said in email )- or even the tach cable as Dizzledan said ( good idea )  and thump it to see if it gets it moving.

Off to work- Good luck.

[Kerry]

As I said to Jared in an email today...

I hooked up my Dremel and let 'er rip, but no joy.  The odometer was moving at more than 1/10 mile per second, but the speedo needle never budged.

Am I correct to assume that if the odometer is moving, then the magnet under the cup is also spinning?  (Is there any way for one to happen without the other?)

If my thinking is correct, then the cup must be "stuck" somehow.  If my thinking is NOT correct, then something might be keeping the magnet from spinning, even though the worm gear for the odometer is turning.  Right?

[Kerry]

GOOD NEWS / BAD NEWS!

I wasn't sure if a working speedometer was necessary to pass a safety inspection, but I decided to chance it.  It passed just fine, and on the way home THE SPEEDOMETER STARTED WORKING! 

Unfortunately, when I went online to complete the county registration, I was told that I would have to go down to the DMV.  (No doubt because my registration expired over a year ago.)  This was at about 5:20 PM today (Friday), and of course the DMV is only open

           Mon-Fri, 8:00 AM - 5:00 PM

Grrrrr!  I was hoping to go for a long-overdue ride tomorrow....   

[Kerry]

UPDATE:  The speedometer has been starting just about every ride in "nonfunctional" mode, but before long it starts working and is fine for the rest of the ride.

[Bonus: I had to go to the DMV because of the lapse in my registration.  That was a drag, but one side effect is that my new registration expires at the end of June instead of the end of March.  That actually works out much better for me.  Yay!  ]

[sledge]

I know of an old trick that may help, cant say I have ever tried it myself though. You suspend the clock over a tray of petrol for a day or two so that the fumes can enter the rear side of the casing through the cable-drive and bulb holes. The idea being that if there is any dirt or hardened lube in there the vapour might soften it off.

[Kerry]

Thanks for the idea.  I've been trying to think of non-invasive ways to effect a permanent fix, so this is worth a shot.

It seems like such a "softening" process might reverse itself over time, but even if it only worked for a few months it would be nice.  (And, one assumes, repeatable.)

Before I try it though ... any insight on what petrol fumes might do the cluster case and lenses?