speedo erratic

[mjb765]

The speedo in my 69 'Bee is doing something weird. From 0-60 it is perfect and smooth. Over 60 it does something weird--out of no where it jumps to 70 and stays there for a sec, then goes back to the original speed--usually around 60-62mph. Doing 70 it jumps up to 80 and then goes back down just as fast. Already replaced the speedo head and the cable. Don't really think it's the gear since it works fine below 60. It's even accurate according to my GPS! I replaced the speedo because the first one was not working at all. When the replacement started doing this I called and had another one sent under warranty and it does the same thing. I can't believe I got 2 bad brand new speedos.

 

[mjb765]

Nobody has any ideas???

 

[RustyRatRod]

Remove the cable from the back of the speedometer head. Slide the inner cable out completely, clean it up real good, dry it off completely and then lube it up with powdered graphite and reassemble.

 

[tpodwdog]

speedo gear in tranny maybe?...looks like you covered everything else!

 

[lyndondb]

The speedometer gear in the transmission is plastic. When it gets worn could cause this.

 

[mjb765]

I thought about the gear. Wouldn't the speedo go down if the gear is worn and slipping??? My speedo jumps up almost 10 MPH. ALso thought about the cable binding, but that should also make registered the speedo go down and not up.

 

[RustyRatRod]

Ok. How long will it take to lubricate the cable? 10 minutes? You gotta start somewhere. Arguing about it here aint gonna get it fixed.

 

[mjb765]

Ok. How long will it take to lubricate the cable? 10 minutes? You gotta start somewhere. Arguing about it here aint gonna get it fixed.

Hope you didn't take my comment as an argument....was not meant that way. Just trying to make some sense out of this.

And the cable is new and lubed when I installed it

 

[tpodwdog]

there are only 3 parts to that system....speedo itself.....the tranny gear....and the cable and casing.......

youve replaced the speedo 2wice....right?..... go for lubing the cable like the rat said....the only thing left is the tranny gear....theyre not that hard to replace....and all are different with number of teeth and color....pull it out and replace it . youll see a number circled on it and the color...if this is screwed up.....EBAY has them all over the place !

 

[mjb765]

That was my guess...just scratching my head about why it goes up in speed.....but I will pull the gear.

Thanks

 

[RustyRatRod]

It's going up in speed because the cable is binding then releasing. It's nothing more than a big spring, essentially. If you lube it with powdered graphite, it will stop. Some folks use grease and it overheats and dries out. With the speedometer gear, either it works or it does not. All I meant by the arguin comment was....go out there and grab hold of it and start somewhere...cause it aint gonna get fixed in here. lol It may not be the cable, but IMO that's the easiest and best place to begin. ;)

 

[mjb765]

It's going up in speed because the cable is binding then releasing. It's nothing more than a big spring, essentially. If you lube it with powdered graphite, it will stop. Some folks use grease and it overheats and dries out. With the speedometer gear, either it works or it does not. All I meant by the arguin comment was....go out there and grab hold of it and start somewhere...cause it aint gonna get fixed in here. lol It may not be the cable, but IMO that's the easiest and best place to begin. ;)

I was just looking for ideas.....Now that I think about it the way you explained it, It makes sense!!! I will start there before I pull the gear.

Thanks

 

[RustyRatRod]

I was just looking for ideas.....Now that I think about it the way you explained it, It makes sense!!! I will start there before I pull the gear.

Thanks

You're certainly welcome. Keep us posted. I may well be wrong as hell, but the cable is something you dont have to get under the car for and takes literally less than 15 minutes.