Speedometer Correction is it Possible

[gadawg31]

I have been seeing the Jeep speedometer gears from Morris 4x4 and it looks pretty simple. Has anyone done this? If so, what type of project scale would you give it? I just put the tub back on my jeep, so I would have to come from underneath the jeep. I would like to get as close as possible to actual speed reading, but a +or- 3 to 5 mph would be just fine. Any thoughts. Thanks.

JD

 

[PaRenegade]

It's a pretty simple procedure you can do from underneath. First figure out what new speedo gear you need. You can do that here. Speedometer Gear Applet
Then get the gear. You may also need a new housing for it depending on which one you now have. They make two, one for 21-25 tooth gear group and one that fits the other 3 groups 26-31, 32-38, & 39-45 tooth. You just rotate the housing to the correct lock groove’s.

Here's where it's located, but you probably know that.

Here's a place to get both, as well as the o-rings that you should replace while your doing the change, to keep any leaks at bay.
Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4
Click on the Dodge / Jeep link at the top.

 

[gadawg31]

Thanks PaRenegade! I have been searching all over the web and have found all sorts of ratio adapters and gears, but I just have not seen a lot of them refer to the jeeps. This was mainly why I asked the question. From some of the research, it made it sound like I needed a special adapter built. The jury is still out of this one. I need to wait until I get home, since I can't see all of your pics here at work. These gov't computers won't load certain pics. I will review the post again, when I get home and go from there. Thanks for the input.

JD

 

[hagar]

If indeed your Jeep is a 1979 and if indeed you still have the Dana 20 Transfer Case , the above information does not apply to your Jeep. That is for a Dana 300 Transfer Case , not a Dana 20 Transfer Case .
The gears are not interchangeable between the two units.

You will have to search for the proper driven gear to match to your Dana 20 drive gear.

In my opinion, one tooth is worth about 6-8 MPH with this type of gear set-up.

 

[PaRenegade]

Yes, my oversight. The info I posted applies to the Dana 300 Transfer Case . I'm not familiar with the Dana 20 's speedo. Sorry

They may be able to still help in some way if you call them.
"Call Kerry at 1-888-8771008 with your needs."

 

[gadawg31]

Copy that. I will have to get under there and get the numbers off the Transmission and Transfer Case , but I believe they are a BW-T-150 Transmission and Dana 20 Transfer Case . So, would a ratio converter work. I have been reading a lot of info about these items or am I stuck because of the type of Transfer Case I have? Thanks

JD

 

[wm69]

Yep, you'll have to get an adapter if you have a Dana 20 . That said, the same website listed above
Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

has a ratio adapter. They aren't cheap, but it should work. I've got to get one for my 83 GMC truck.

As for the long shaft gears that are used in the 80-86 Dana 300 's, they're cheap on ebay. Just search for "mopar speedometer gear" or "dodge speedometer gear"

 

[BusaDave9]

Yep, you can't get the Dana 20 gears anymore. I gave up long ago. As already stated you need a speedometer ratio adapter.

These things have gears inside that can be matched up for the speedometer correction you need.