CiCiC3

I think I'd like to swap my blue 20 tooth speedo gear for a brown 18 tooth, seeing that I'm reading about 1.12 miles on the speedo for every mile I drive. Also I'm not really sure where to look on the tranny to change it. I have a Borg-Warner super T-10 4 speed on a '74 BB. Thanks for any guidance on this!

CiCiC3

Ok I see where that hooks into the tranny on the picture someone posted on another thread.

doorgunner

O.K. So......going to LESS teeth on the DRIVEN gear "slows the odometer down"?
I ask because my speedometer registers 90 mph when I'm actually doing 70 mph.

I'm wondering if I should go with more teeth or less teeth on the DRIVE gear that is located on the tailshaft, since there is such a large difference in actual speed/speedometer speed?

A/T shown (same principle though)......

CiCiC3

Well no maybe I should reverse that idea and go with more teeth to slow it down. Does that make better sense? Maybe that's it. 22 teeth would be a green I believe.

doorgunner

I have brain-lock....LOL! I understand larger diameter=more teeth=less rpm at connector..........BUT...does the DRIVE gear increase in diameter when more teeth are added---or.....are the teeth just spaced closer together in order to change the driven gear rpm?

thegazman

The drive gear stays the same diameter, just more or less teeth. And yes, more teeth on the driven gear slows the speedometer. However, be careful as a drive gear will only accept a limited number of different driven gear teeth before you also have to change the gear to more or less teeth. If you stay within a small range of number of teeth you shouldn't have any problem. If you try to correct a large problem, the drive and driven gears will not sync.