M1009 Speedometer Cable Replacement?

[Sharecropper]

OK, using the time-tested formula of "# of Drive Gear teeth X axle ratio X (20168 divided by tire diameter) divided by 1001 = # of Driven Gear teeth to use", I determined this: 15 (drive gear teeth) X 3.73 (M1009 rear axle ratio) x 616.99 (20168 divided by your tire diameter of 32.6875) divided by 1001 = 34.48. Or put more simply 15 X 3.73 X 616.99 divided by 1001 = 34.48 required teeth on driven gear for accurate speedometer output.

So you will need to use a light green 34-tooth driven gear GM 9774413 or an orange 35-tooth driven gear GM 9780387. You will also need the GM25512340 sleeve with either of these driven gears. All this is readily available on Ebay. PM me and I will send you a link because the SS website police don't like for us to post links to active Ebay auctions (so dumb).

 

[Sharecropper]

OK, using the time-tested formula of "# of Drive Gear teeth X axle ratio X (20168 divided by tire diameter) divided by 1001 = # of Driven Gear teeth to use", I determined this: 15 (drive gear teeth) X 3.73 (M1009 rear axle ratio) x 616.99 (20168 divided by your tire diameter of 32.6875) divided by 1001 = 34.48. Or put more simply 15 X 3.73 X 616.99 divided by 1001 = 34.48 required teeth on driven gear for accurate speedometer output.

So you will need to use a light green 34-tooth driven gear GM 9774413 or an orange 35-tooth driven gear GM 9780387. You will also need the GM25512340 sleeve with either of these driven gears. All this is readily available on Ebay. PM me and I will send you a link because the SS website police don't like for us to post links to active Ebay auctions (so dumb).

I just looked and I have a new 25512340 sleeve in my spare parts bin which you are welcome to if you want it. All you will need will be the driven gear. If you plan to keep running your same tires & wheels I would get the light green 9774413 driven gear. If you change to larger tires in the future, it is a simple calculation to determine which driven gear to use with that specific tire circumference.

 

[HelluvaEngineer]

Didn't the M1009 have 3.08 axle ratios? As a spot check, unless the stock gear was way off, if using the adapter, I can do the ratio of the tire diameters and apply that to the gear ratios I would think, since that's a simple linear ratio. That gives me 38.9.

 

[Sharecropper]

Didn't the M1009 have 3.08 axle ratios?

Dang. Good catch. I stand corrected. Let me re-work the calculations. For some reason I was thinking the M1009's were running 3.73 gears.

 

[Sharecropper]

Holy Mackrel. Using 3.08 gears in the equation, you would need a Yellow 28 tooth driven gear without the reducer adapter that you removed. Is that what you said you had? If so, try using the Yellow driven gear without the reducer adapter and see how the speedometer reads. If you do not have the Yellow 28-tooth driven gear, I just looked and there are several on Ebay. Just search "yellow 28 tooth driven gear".

 

[Sharecropper]

Just following up on this. What sleeve do you have? The Yellow 28-tooth driven gear will require the GM 25512340 sleeve. As previously stated, I have one of these sleeves in my spare parts bin which you are welcome to if needed. It is new in the GM box. Let me know.

 

[HelluvaEngineer]

It has the stock grey sleeve. I'm still waiting on the order of the gear and carrier that I posted above. I'm still planning to try it with the adapter so I don't have to open the case. It may be the weekend before I can follow up.