Need help with speedometer calibration

[Paul G]

My speedometer reads about 5 mph slow. I have a 36 tooth gear in the tranny. I checked the chart in the Year One book, that should be the right speedo gear for my 3.55 rear end with 295/50-15 tires. Tranny speedo gears come in one tooth increments smaller and larger than mine. Anyone know how many mph change I can expect when stepping down to the next smaller speedo gear.

[John_Kunkel]

The YO chart is incorrect, your combo calls for a 35 tooth pinion.

The difference in the speedo reading will be a little less than 3%, the actual mph difference will depend on the speed.

FWIW, the speedo pinion can only accurately calibrate the odometer reading, the speedometer isn't mechanically connected to the speedo cable so there can be errors in the speedo reading even though the odometer is right on.

[smokinrt]

The YO chart is incorrect, your combo calls for a 35 tooth pinion.

The difference in the speedo reading will be a little less than 3%, the actual mph difference will depend on the speed.

FWIW, the speedo pinion can only accurately calibrate the odometer reading, the speedometer isn't mechanically connected to the speedo cable so there can be errors in the speedo reading even though the odometer is right on.

John Kunkel,  I just read your discussion on the correct speedo cable to use and you've got my attension.  I thought that the speedo cable was a mechanical connection to the speedometer, shows what a beginner I am.  Anyway, I just installed my newly restored guages along with a new speedometer from Year One in my 69 charger.  The speedometer isn't working, but it was working before.  I just bought the 69 in Feb 06 and am getting around to fixing things.  That aside, what do you suggest I look for to begin correcting the problem???  I read in the restoration book that all 69 rt/se had cruse control, but my car doesn't have it, now that may be the start of one problem, another is that the tires are a size different,  but the speedometer should still work somewhat.

What do you think
smokinrt
Bryan

[John_Kunkel]

See my reply in your other thread.