Speedometer Gear Teeth Number

I don't think my speedometer is reading correctly. I will confirm tonight with GPS in my phone. In preparation for by assumptions being correct I'd like to know a couple things. My CJ-6 is stock as far as I know. I had my axels rebuilt and I suppose it's possible the gears where changed by Northstar Willys.

Here is where I stand now: NOS speedo (appears to be functioning properly), new speedo cable, stock wheels and tire size, D18 T case. My axle ratios at 4.27:1 according to the tag. I believe they should be 4.27:1 based on this information posed by Oldtime. (my serial number is 57747 24088) http://cj3b.info/Photos/Tech/ServiceBulletins/SB601AxleRatio.JPG. If my axles were rebuilt to 5.38:1 but my tcase speedo gear is set for 4.27:1 would by speedo be reading slow or fast?

I'd like to know the correct speedo gear sets (driven gear and drive gear) for both the 5.38:1 and the 4.27:1 so I can try and figure this out and get it fixed.

 

There are a variety of speedo gear combinations. The most common are listed below, from parts catalog W 1195 R1:
4:27 axle 6 tooth drive gear #910086, 18 tooth driven gear #910087
4:27 axle 6 tooth drive gear #910086( assumed) 20 tooth driven gear #910088 for use with 6.70-15 tire
5:38 axle 4 tooth drive gear #A-1511, 15 tooth driven gear #A-5707
5:38 axle 6 tooth drive gear #910086, 22 tooth driven gear #910089
I hope this helps answer you question.
-Donny

 

Thanks Donny! Now, where to find them...

Anyone have an idea? I'll post up in the classified ads but if anyone knows of a source, please let me know.

 

The first thing I would do is see what you have now for speedo drive gears, and start from there. You may already have what's supposed to be in there.
-Donny

 

If my Dana 18 output shaft endplay is to much could that cause the drive gear to slip some?

 

Crown is apparently starting to reproduce the driven gears.
Try a google search for "jeep speedometer gear"
I authored an article here many moons ago that showed the conversion in part numbers from Jeep to Stewart-Warner.
You can't go nilly-willy on this; the driven gears have to be matched by series to the drive gear.
As already mentioned, you need to pull your existing driven gear and count the teeth and record the SW number on that gear and go from there.
One tooth was usually good for 6-7 mph difference.

 

If you want to get crazy there are places that can rig up a gear box to correct almost any off speed speedometer. not cheap

Speedometer Services | Portland, OR is one such place in Portland OR.

 

I wound up getting a correct set for 4.27 gears from Willysjeepparts.com despite the reputation I've heard. I got them in a timely fashion and as described. Installed and everything works great now.

 

This product will allow you to reduce or advance your speedometer in small percentage increments...
*GM / Dodge / Ford, Ratio Adapter, Select Speed Up Rate, #54RA2

it doesnt say Jeep but I called them and they verified it would work with my 71 CJ5...eh.

good luck,
willie