I have a 57 up, red, 19 tooth speedometer gear. With a 380 to 1 rear end I'm seeng a 10mph high reading at 30-40mph. What gear would you guys recommend to bring it in line? Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

That much error % could only be corrected with speedometer repair/calibration. Also, if your axle ratio/tire diameter is much changed from stock, you will be handicaped by the limited selection of speedo gears/teeth that fits your trans.

If you can come up with the correct RPM/MPH #s for your specific equipment, a good speedo shop can calibrate for accuracy at most traveled/enforced speed.

6 VOLTS/POS. GRD. NW INDIANA

Is the speedometer showing the same 10 mph error in reading at 60 mph or is the error twice as much?  If you can time your vehicle between some mile markers and let us know exactly what speed the speedometer is showing along with the minutes and/or seconds between mile markers, then the percent error can be more accurately determined.  And with that information, along with knowing that you've got a 19 tooth gear, it might be possible to get you a speedo gear that may correct the error.  Doing it this way takes the tire diameter out of the equation.  As it stands right now, you'll need a speedo gear with more teeth to slow down the reading.  Each tooth increase will slow the speedometer reading down approximately 5% but you'll need some more specific numbers at higher speeds in order to be accurate.  And it's possible the gear that slides over the output shaft will also need to be changed depending upon how far off you are.

And as Daniel suggested, your speedometer itself may be the problem.

Lorena, Texas (South of Waco)

Speedometer was NOS. I'm sure the change of rearend ratio's is the problem. Looks like I need a 21 or 22 tooth gear. How many teeth do the FordO tailshafts have?

Ted did you get my message on the compression test? Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Chuck,  I sent you a response back on your compression stuff this morning.  Regarding the tailshaft gear, I don't have that information handy on those particular gears that I can look up.  Maybe someone else?

Lorena, Texas (South of Waco)

Chuck:

Your FOM should have an 8 tooth drive gear on the output shaft.  I thought you were going to go to an AOD.  Is that still your plan?  Did you get the fuel pump and carburetor secondary problems worked out yet?

John

John - "The Hoosier Hurricane"

I'm still waiting for the AOD and have everything to install it. While still running the FOD I wanted to get the Speedo a bit closer to correct.

Since Ted replaced the mashed floats with the plastic ones its been running pretty good. I still don't get any launch even with the 3.80:1 gears. I'm starting to wonder about advancing the cam 4 degress to see if that helps.  It has never seemed to pull well above 4500rpm so I worry about advancing the cam. I don't have the specs right now but I'll send them to you. The plugs read good, all medium brown and clean. I did a compression test but didn't have the carb at WOT so the numbers are probably off. I'll do it again as soon as the rain stops. I had a high of 170 and low of 119 with the rest around 140.

I'll try the WOT method and then read again with a squirt of oil and see what happens. I'll be in touch.

I guess I'm now looking for a 21 or 22 tooth 57up speedo gear!

Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire