Correcting the speedo drive gear

[CJAndy]

Good morning my American friends,

Anybody know how I can correct the gear drive for my speedo? I'm running 33's and Dana 300 with short output shaft. No idea where to get one from or even if you can get one for the short output.

Many thanks, English Andy

 

[hagar]

To know what you need, we first need to know what you have.
Could you post a picture of your Dana 300 rear output housing and where the speedometer cable attaches ?
The very early D300s used in CJ's (1980) used the same speedo gears as a Dana 20 Transfer Case (1979 and prior).
The drive gear is deep inside the Transfer Case .
The driven gear is removable quite easily where the speedo cable attaches.
To correct for axle ratio and/or tire change, you must first know the tooth count on the existing driven gear. remove it, count the teeth, and write down the Stewart-Warner (SW) part number on the gear.
You can go up or down in the tooth count of the driven gear, but you MUST remain within the SW series of gears that you currently are using.
You can't go nilly-willy here and just install any old driven gear; it has to be matched (series wise) to the driven gear.
Any incorrect gear, and you just strip the metal teeth right off the gear.
Typically any change in tooth count by just one number (up or down) will change the needle reading in the speedo head by 6-8 miles per hour.
So report on what you currently have, and folks here can figure it out.

If your Dana 300 is later than 1980, your rear output will use an entirely different speedo gear set-up, using nylon gears.

 

[CJAndy]

Thanks for the info hagar.

The Transfer Case is a 1980 model and has the steel driven gear not the nylon. I will check the number of teeth when I get home tonight and report back. Pleased it sounds like it can be corected.
I am stripping and rebuilding the Transfer Case soon anyway, just waiting for a rebuild kit to arrive from Novak.

Thanks

 

[Hedgehog]

There is another way. For really tricky or obsolete speedo problems you can have a .... oh I don't know what it is really called .... it's a small inline gear system that is customizable for your speedo needs. It goes directly in or on your speedometer cable between the Transfer Case drive and the speedometer itself. It isn't cheap or inexpensive, but it does work.

 

[CJAndy]

Thanks hedgehog, think I have heard of something like that before called an inline adapter.
Will try to obtain a driven gear first.

Took the driven gear out of the short output Dana 300 and the serial no. Is SW - 890239 and it has 15 teeth.

Any suggestions jeepster's? Oh I was told when I got the jeep that the axles are 4.1 gearing.

Thanks

 

[007]

These folks can sell or make whatever you might need if given the right info. They also make little speedo cable "transfer cases" that speed up or slow down the cable to make the speedo correct...

https://transmissioncenter.net

 

[hagar]

So is the speedometer reading too fast or too slow with your axle ratio/tire combination ?

SW-890238 14 tooth driven gear (faster)
SW-890240 16 tooth driven gear (slower)

Jeep P/N J5352813 for SW-890238 14 tooth
Jeep P/N J5352815 for SW-890240 16 tooth

Google search the numbers and something may pop up.
No new supply available other than NOS on the net.

Used can be obtained from 1979 and prior Jeeps, CJs, full size, Dana 20s and possibly Qtrac units as well.

 

[Torxhead]

Andy, I am currently running the Dana 300 Transfer Case with 4.10 gears in the axles and 33" tires. My speedo gear is a 36 tooth and is a bit slow on the speedometer reading but was good with a 35" tire that I used to run. So I figure a 33-34 tooth gear should do the job. Hope that helps.

 

[RevDrCueBall]

Andy, I am currently running the Dana 300 Transfer Case with 4.10 gears in the axles and 33" tires. My speedo gear is a 36 tooth and is a bit slow on the speedometer reading but was good with a 35" tire that I used to run. So I figure a 33-34 tooth gear should do the job. Hope that helps.

No, completely different set-up he has if he currently has steel gears and only 15 teeth.

 

[Lumpy Grits]

Have you called these guys?
Willys Jeep Parts Specialist | Jeep Parts & Accessories at Vintage Jeeps, Inc.

LG

 

[CJAndy]

No tried them lumpy, thanks for the link. Got the Transfer Case fully rebuilt now with a twin stick, it looks sweet! Seen some cool speedos at summit racing that use GPS and are accurate regardless of tyre size, might cosier one of those!

 

[007]

These folks can sell or make whatever you might need if given the right info. They also make little speedo cable "transfer cases" that speed up or slow down the cable to make the speedo correct...

https://transmissioncenter.net

These folks can help you...


Sent from my iPhone using Tapatalk

 

[JimsCJ5]

How far off is the speedometer? Use the GPS on your phone, figure out the percentage off and apply that same percentage to the number of teeth on your cable drive gear. Get the drive gear with the number of teeth closest to the calculated number and you are done.
On the off chance you can't get one (too high or too low) then you options are GPS speedo, in-line compensator, or crack the tranny open and change the driven gear which is not as hard as it sounds.