Speedometer Failure?

[Foozle]

Folks:

So, I'm catching a little leisurely wind on our local bypass when suddenly the speedometer needle falls to zero.  I suspect the cable, and when I get home - sure enough:  the plastic piece which attaches to the gear box (and is prone to failure if over tightened) is, indeed, broken. 

Since the cable is pretty old (1998 Standard), I write if off to age/wear and order a Motion Pro replacement.  The new cable installs uneventfully. I go for a quick ride around the block, and nothing.  No speed, no odometer, no trip meter.

The speedometer gear box is good, since the cable rotates when the front tire is spun.  Similarly, the speedo needle will "blip" when I manually spin the cable at the tire end.  However, once everything is put back together and connected - it's dead as a door nail.

I did a search our our tech archives and found a post by Hubcapsc (Mike) who indicated a stuck trip meter may be the culprit.  I rotated this back to zero several times, but to no avail.  I can't recall from past experience:  Should the reset knob pull out and push in?  Mine doesn't seem to.

Any ideas?  If I have to, I'll lay out the cash for another speedo unit, but I've never heard of these things failing very often.  In short, I'm perplexed.

In advance, thanks for any advice or ideas you may have.

Terry
Lexington, KY
VRCC 22179

[sandy]

The reset knob is screwed in with a TINY screw; instrument phillips driver. Try disconnecting the back of the speedo and rotate the wheel (on a lift). See if the cable spins going into the speedo.
BTW: I have a speedo you can have cheap if you end up needing it.

[Foozle]

Hi, Sandy.

Thanks for the reply.

Yes, everything (when disassembled) works as it's supposed to:  the cable spins when the front wheel is rotated - and the needle moves slightly when the cable (disconnected at the gear box) is spun by hand.

I've tried installing things in opposite order (the gear box followed by the speedometer and vice versa) - each time verifying that the cable and the gear box are working.  The issue appears to be with the gauge itself, although why I can get the needle to "blip" by spinning the cable is inexplicable.

I even went so far as to double-check the model number to make sure the vendor sent the correct one (they did).  Interestingly, however, it's about 1" longer than the same version I had on the bike earlier.  I guess this doesn't really matter as long as the inner cable and outer sleeve are matched.

Whatever the problem is, it seems to be occurring when the cable is connected to the gauge.  Q: Is there something in the speedometer linkage that exerts slight downward force on the inner cable - keeping it engaged with the gear box?  Or is this merely held in place by gravity?

To illustrate, if you disconnect the cable and hold it by the upper end, the inner wire simply drops out.  If it's free to move upward (pushing the inner wire further into the speedometer), it's possible the cable is not staying engaged with the gear box.  I feel like I'm perhaps missing some small but essential piece (perhaps literally) to this installation.

Terry

[sandy]

Remove the speedo and take the housing off. When you remove the instrument size phillips, do it over a solid colored towel to prevent bouncing. Rehook it to the cable and observe the innards working (or not) to see what might be wrong.

[indybobm]

You said the outer housing is 1 inch longer? Does that make the inner cable 1 inch too short?

[Foozle]

You said the outer housing is 1 inch longer? Does that make the inner cable 1 inch too short?

No, the inner cable seems to extend proportionally to the one it replaced.  The entire assembly is simply ~1" longer.

I'm sure I kept the stock OEM cable that I removed after installing the earlier Motion Pro stainless version.  If I can locate it, I'll do a little experimentation.

Terry

[Foozle]

Remove the speedo and take the housing off. When you remove the instrument size phillips, do it over a solid colored towel to prevent bouncing. Rehook it to the cable and observe the innards working (or not) to see what might be wrong.

Thanks, Sandy.

I'll give this a shot tomorrow and report back.  Given my mechanical aptitude (or lack thereof), I'm fearful that my experimentation will create progressively larger problems where they didn't previously exist.  If I don't need a whole new speedo unit now, I may after I remove the housing to "observe the innards." 

Terry

[Foozle]

Okay, a somewhat long-winded update on the mysterious speedometer cable issue.

First off, the speedometer unit itself is fully functional.  I chucked up the end of the old cable in a cordless drill and "slowly" rotated it in reverse (causing the cable to turn in a clockwise direction).  The needle and the odometer both advanced.

Second, despite what I reported earlier, the new cable is EXACTLY the same as the old one in terms of length. I should know better than to take any measurements after 7:00 pm or so.

Third, the speedometer gear box on the front wheel is correctly positioned and fully functional.

The problem (I'm convinced) is that the square, inner "twist" cabling that actually rotates and allows speed to be displayed is not being properly positioned between the speedometer and the gear box.  That is, there is insufficient adjustment on the gauge end to limit the cable play "upward" into the  speedometer connection.  So, free to move backwards into the speedometer, the mating of the opposite end of the cable with the drive box gear must rely solely on gravity (which is evidently inadequate).  As a result, the cable is simply failing to stay engaged with the gear.

Since lengthening the inner cable or shortening the outer cable isn't an option (nor is extending the threads on the gauge connection nut), I ended up inserting a ~3/8" long cylindrical shim of approximately the same diameter (into the speedometer end - just above the inner cabling).  Without exerting any downward pressure (to avoid friction or binding), it limits the upward travel of the inner cable - keeping it engaged with the gear box.

This isn't the most half-assed, "Mickey Mouse" solution I've ever concocted - but it's close. Why it's even necessary continues to baffle me.  One thing I neglected to mention (and am not sure is relevant) is that to keep the stainless braid from turning brown over time, I sprayed a coat of clear UV protector over the outer cable (I had read about rubbing on sun block, but didn't have any handy).  It is possible this coating somehow affected or limited the pliability of the cable and, subsequently, the fit of the inner connector from the gauge to the gear box?

Anyhow, I now have a functional speedometer - though I'm sure when it comes time to replace the cable again, the shim falling freely out of the speedometer unit will warrant a giant face palm.

I'd sure like to hear others' thoughts on this.  I've exhausted all my theories (but at least I can ride again). 

Terry

[The emperor has no clothes]

If I'm understanding this correctly, it sounds like the cable wasn't made to spec. Doesn't seem like a 1/2 assed concoction at all. It works. 

[Foozle]

OK, guys - final update.  I think a resolution has been found:  The connector spline on the speedometer gear box was broken off - probably when the plastic mount on the cable fractured and it fell out of alignment while riding.

Not having ever looked at the inside of a Valkyrie speedometer gear, I wasn't sure how far it should extend out from the unit.  As it turns out, it should be long enough to fit almost fully into the female cable end (~3/4" of an inch?).

My shop lighting isn't good (nor are my eyes), but I could see a slotted connection that turned when the tire was rotated.  Moreover, when it apparently sheared off, it left enough of a nub that it looked reasonable and was able to sporadically engage the cable.

When I was able to get a good look at a new unit on the Internet, the problem was obvious.  I just pulled the front tire, and will be ordering a new speedo gear shortly.

Thanks to everyone who shared their advice.  Hopefully, this experience will assist someone else in troubleshooting what was, in the end, a pretty straightforward problem.

Terry
Lexington, KY
VRCC #22179

[sandy]

Check your private messages. I have a drive gear for you.