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Speedometer Disassembly

Steve L

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Dear CB750 Forum:

I have a 1971 CB that I am restoring. It was a little rough when I got it, but time and money can solve everything that is wrong with this bike. I want to tear the speedometer apart to restore the housing and to replace the speedometer face. I've removed the unit from my bike and removed the lower chrome bottom cover. When I look at the underside with the chrome cover removed, I don't see any clear way to remove the unit from the housing. I have a Chilton and a Haynes manual, but neither give any information on gauge disassembly.

Often, I can get stuff apart through intuition and maybe I can with this, too. Except some of you have certainly done this task already. Can anyone give me a few hints as to which screws to remove and how the internals pull out of the housing? I'm grateful for your wisdom.

Sincerely, Stevw
 
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Hi Steve,
hope you are having fun with your project. The gauges come factory sealed and can be accessed in two manners.

1- with a dremel cutoff wheel just cut the thin metal band which clamps the top and bottom together and rebuild using JB Weld to
hold the band when you re-assemble. Obviously the thinner the cutoff wheel, the less the gap will be when put back on.

2- with a thin screwdriver re-purposed as a prying device pry up the bottom lip of the metal band just enough to open the gauge,
and then re-crimp the band back onto the seam. This method is laborious and can deform the metal band if you are not meticulous and patient.

Once the band is removed the major issue you may face is the removal of the needle, these are usually very tight. The trick is to use two teaspoons as levers, one on either side of the needle. You place the tips of the spoons just under the round disc on the needle with the bowls of the spoons resting on the gauge face. You use the spoon bowls as a fulcrum to pry under the needle by pushing down on the spoon handles. Try to use even pressure and it WILL be tight. Then there are just two small phillips screws which hold the faceplate on.
Hope this makes sense.

Have you tested the gauges to see if they work and are accurate? It wouldn't make any sense rebuilding gauges which are not functioning well.


There are threads showing this procedure on the web just do a search, and I think there are replacement bands available on Ebay if you really mess them up.
good luck
 
Dear Daren:

I knew it! I knew that there would be people like you who know how to restore a K1 Speedometer. I must admit that I didn't imagine that I would have to slash & burn my way into this unit. Thank you very much for your wisdom. Now I have a reason to buy a dremel.

Sincerely, Steve
 
There's a few youtube vids on how to do it, just search. For a pretty penny you can send them away to cb750faces.com too. I did mine myself.
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Dear Mr. Grepper:

Very good advice!! I went to You Tube and found a guy who showed me how. He tightened a large hose clamp around the thin aluminum ring and then used a small standard screw driver to gently pry the bottom edge of the ring away from the housing. It only took a few minutes and the clamp kept the aluminum ring intact and reusable. The speedometer has a lot of rust and crap in the housing. I need to clean everything, but I'm not sure what chemical to use. Maybe some aerosol that is used to clean circuit boards. Does anyone have suggestions?

Sincerely Steve L
 
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