This is what the bare speedo looks like. This is a shovel NOS one, but from what I can make out they are the same. You can see there are several screws that will enable it to be dismantled, if you wish to!

 

Sorry, but I don't have anything else for you. I have an 89 and when my speedo was acting up I had to replace the broken cable. Looking at the pictures you attached I would say the only way you can take it apart it to pry off the clear cover (thus the sealed unit), which if I was doing that I would surely break it. If it was working and then not after you pulled the cable again I would think something didn't go back together right, as there is a little play and if you don't get it back into the speedo right it will not work.

 

Mine was from an '86 and it looked just like the pic from grbrown. It all comes apart. When I replaced mine (a few years ago) it wasn't that expensive. They were made the same to around '90-91. You might even get the HD part # and google it or look on ebay. A lot of people have old new stock.
Mark

 

On the one I have, right beside me as I wrote earlier, off an '87 I think, dismantles easily. It is held together with screws and should dismantle without any problems. No I am not about to do that to mine just for the sake of science!

The clear cover is held on by four screws, the speedo, tacho, fuel guage and other contents are all held in with screws through the back of the blue housing. Simples! (You need to see UK adverts to fully appreciate that!)

 

i was going out to sturgis in1990 and then to yellowstone. the speedo drive on the front wheel went out about 700 miles from sturgis and about 1100 from yellowstone. i rode it like that (not working) for 9 years. i would drive the same speed as the traffic i was in. i'm, not suggesting you do that, i'm just saying that's what i did.

 

i found just the speedo part at a swap meet and paid $4 for it.

 

Get a new mechanic ....... soon.

 

schooner, do you know if the cable spins when you ride the bike? that's the first thing to find out.

 

chicken!!! ;-)

 

Kind of an old thread but we had this exact problem in Montana with our FLHTC. The speedo started howling like a siren when we left East Glacier and the needle was bouncing all over hell, and many times read either zero or 80 mph. When we got home I searched the board to see if other folks had had it happen to them. I pulled the outer fairing and removed the instrument cluster and speedometer.

It is NOT a sealed unit, and is fully serviceable. And I believe they are the same from about 1984 to 1991 or so. It is a simple affair with a spring dampened drum attached to the speedo needle. Inside the drum is a rotating magnet that creates "drag" on the drum and makes the needle go up and give a higher reading, the faster the magnet turns. The magnet is driven by the cable. It also has some gears that drive the odometer drums.

All that was wrong with it was that the shaft and bushings on the magnet had gotten dry with age and the howling or "whining" was caused by a high-frequency vibration of the shaft in the bushings because they were dry. I put some grease in the end of the speedo shaft where the cable attaches, and "packed" it like you would a wheel bearing by forcing the grease into it with my finger. After I got it to turn smooth again I cleaned the excess grease out of it with some tissue paper, lubed the cable (it comes right out the top of the cable sleeve) and put it all back together. Works like a charm again and no howling or "whining" noise.

I found the telltale sign that the shaft and bushings are getting dry is the fact that your speedo needle bounces a little, indicates about 5 mph high, and ours did that for the previous 10,000 miles before it suddenly started howling. After lubing it the speedo needle is now dead steady with no bouncing, and indicated speed agrees perfectly with GPS speed, +/- about 2 mph.

As a side note, the lights in the speedo and tach had all burned out on our bike. As long as I had it apart I decided to put in new bulbs, but could not find the little A12V3.4W bulbs for it at NAPA. I put in Wagner 1873's and they work fine and our speedo and tach is lit again at night.