[topless lemans]

Had problems with it not reading right and needle jumping around. Bought one from someone here and pulled off my cable and made sure it was greased, reading 7mph higher when I'm doing 25mph, 17 mph faster at 55 mph. 14" tire size on it. Did have the 2 speed on it, now has TH350, red gear I do believe but not yet sure what is in the tail area

[Andre]

The problem is centered on the combination of rear gear and rear tire size. Once you are 100% certain of those, then you can get the correct pair of gears for the transmisson so your speedo will read correctly.
There is no adjustments or variations in the speedometers.

[jmt455]

Good info here:

http://www.wallaceracing.com/speedo.htm

[J.T.]

Here is another page with all you need to know.
http://chevelleengineer.home.comcast...eer/speedo.htm

[topless lemans]

Looked at those sites now finding the parts, have a green main drive and a orange speed drive. Might have to order the part in

[topless lemans]

Now do you have to change housings if your bumping up to 40 tooth size? If thats the case might just get a 39 tooth and see how it is

[Tim john]

Andre, What would cause the speedometer to jump around, with all else being untouched (orignal) The reason that I ask is the Sprint 6 is doing just that, jumping around, will stabilize for a few minutes then jump around again. Can I assume a dry cable ? or perhaps a broken tooth on the transmission plastic gear or the steel mating gear on the main shaft (manual transmission, 3 speed). Please advise when you have a free moment. Thank you.

Tim john---

[topless lemans]

I regreased mine and went away. Stayed 8 above but need a 41 tooth and a new housing, hard to find a 41 tooth. Went with 39 tooth and same housing might be a couple mph faster but I can live with that

[jmt455]

I had one recently that would not move smoothly, even after completely removing the cable from the housing to clean and re-lubricate it.

I had to replace the entire cable assembly; the cable had apparently worn through the inner liner of the sheath.

New cable, problem solved.

[Tim john]

Thnaks guy's I will look into lubricating the cable first and replace if deemed necessary. Thank You.

Tim john---

[Andre]

I didn't see this before, but lubricating the cable is the way to go. Ill bet your cable sheath has a bad spot and has let dirt get in and cake things up. Id remove cable and sheath, remove cable and inspect for damage. Clean inside of sheath to remove old grease and dirt. Relube generously and reinstall. If that fails, the speedometer head has gotten gunked up. On my 64 droptop the speedometer literally warms up, although the odometer works fine. That means my speedo has gone bad and must be replaced.

[Peter Serio]

The factory grease inside the speedometer does not last forever. It was designed to last for the normal life span of the car(s) in daily usage. But we are at least double or triple past that time frame now. At least once every 40 years all speedometers need torn down, inspected, cleaned and re-greased. After that the speedometer needs re-magnetized and then calibrated.

Delco made a special grease just for this and other spinning shafts. When you are going 60 MPH down the freeway your speedometer cable is turning the input shaft at the back of the speedometer 1,000 RPMs.