M1009 Speedometer Calibration

[jacksmad1]

Just got my M1009 a week ago and the speedo was not working. The driven gear in the transfer case was broken. It was a 41 tooth gear so I replaced it with a 41 tooth. Wrong. I am running stock 31x10.5x15 tires and this gear was causing the speedo to indicate 50 mph when I was actually running 62 per my GPS. Also the external gear unit that mounts inline with the speedo cable was missing. I located a friendly transmission shop that had a lot of used driven gears and also the inline units. After several mix and match attempts I was able to come up with a setup that is dead on accurate (well at least < 1 mph ). I am using a 34 tooth driven gear with a 1.050 inline speedo overdrive. The transmission guy also told me and I was able to verify that 1 tooth on the driven gear equals about 1.5 mph on the speedo. Hope this info might help others.

 

[Barrman]

The inline gear box is just on the M1009. That way, all the gears for the other CUCV trucks are the same in the tcase. Because the M1009 has the 3.08:1 axles, it needs the convertor box.

Thanks for posting what you found.

 

[wallew]

It's funny, my M1009 was showing 10 mph SLOWER than the correct MPH.

My M1028A2 was showing 10 mph FASTER than the correct MPH.

I've had both of my speedo's rebuilt and calibrated and they are literally dead bang on. I've tested it with both GPS, radar (buddy of mine is a cop) and running next to my wife's car which is a Subaru that is also right on the money.

Good for you. Going the extra effort had to be much cheaper than the route I went. And now YOU know exactly what's what with your speedo, cable, gears, etc. EXCELLENT INFO for you to share.

Thank you very much.

 

[DrJekl]

You can buy the right gear and install it rather than using the gear box. Just go to a GM parts counter and order it. The Jeep catalogs have a good reference chart for the speedo gears for a 208 case. Or, you can find a chart online. They give you a tire size and gear ratio and you line them up for the tooth count and gear color. The gears are easy to find and cheap on ebay too.

 

[jacksmad1]

According to the transmission shop, with the standard drive gear having 15 teeth and the driven gear with the smallest tooth count is 34. So unless you change the drive gear, which is a major PITA, if you are using the standard size tires, there is not a gear combo that will work without the external adapter.....

 

[DrJekl]

The drive gear just slides over the tail shaft on the transfer case. It is not too difficult if you do have to change it. The online charts list the drive gear color combos. I think the one inside the CUCV 208 is blue if I remember correctly.

 

[blowe]

Can any one help me figure out what gear i need in my m1009? I bought it and the person who had it before me put m1008 axles under it and I'm trying to figure out what tooth gear i need, i'm also looking for a m1008 i can just get the gear from and try. Hoping that'll fix it. ??

 

[ehuppert]

Go to the attached link and look for the Excel application. This is probably the best program I've seen for determining drive/driven gears. Also keep in mind GM has discontinued numerous speedo gears. Guess the TH 400 and 350's are obsolete???

Performance Automatic - SPEEDOMETER GEARS

 

[blowe]

thanks, ill check it out.

 

[Iceman3005]

here is another link for speedo gears and a formula for figuring out what gear/s you need.
Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

 

[shaker]

I am also having speedometer troubles. My speedometer was not reading right and kind of jumpy so I replaced the cable hoping that would cure the problem.... no such luck, so I looked at the driven gear in the transfer case and noticed that the yellow 41 tooth gear was kind of wallowed out where the cable goes into the housing. After countless searching I found the correct tooth size gear from PATC it cost me $19.00 shipped to my door overnight. After installing the new gear the speedometer quit jumping around but it still does not read correct. I found out that the m1009 had some sort of adapter that hooked into the transfer case ans as my luck goes my truck does not have this adapter on the transfer case. I have done some researching and was told a 1.3000 ratio adapter is what is should have. My question is where in the world can I get one and I searched ebay with no luck. Please anyone who can help point me in the right direction I thank them kindly. I am running everything stock and 33-35 psi on tires

 

[jacksmad1]

I found one at a local transmission shop. A lot of the older shops will have parts stored away they have scavenged from previous work. That is where I was able to pick one up. My speedo cable was bad and it caused too much resistance and made the transfer case eat my newly replaced driven gear so in the process of replacing the speedo cable I also took another approach to totally eliminate the adapter. My understanding is that the adapter was used for some of the CUCV's so the transfer cases could all have the same gears in them for parts commonality. The M1009 had to have the adapter so the speedo would be correct with the standard transfer case setup. So if you just want to be bone stock, you have to find an adapter. I am currently running mine without the adapter on stock tires and I have a 34 tooth gear also from PATC and mine is doing fine. I don't remember for sure but you may have to get a new gear retainer (I forget the technical name) but the housing that holds the gear into the transfer case as they are different sizes depending on the number of teeth on the gear. The housings work for a range of driven gears i.e. 34-37, 38-42, etc. PATC has them also. Good luck.

 

[epitts]

Check out this thread http://www.steelsoldiers.com/showthread.php?70087-Speedometer-Adapter-Assy-(6)-M1009