Speedometer gear

[Husker Cuda]

Need your help!  My 'Cuda came factory with a 3 speed manual.  I changed it out for a A-833 4 speed and put the speedometer gear out of my 3 speed thinking my speedometer would be accurate since I kept the factory 3:23 gear gear.  Now that I know it obviously has a different ratio in the 4 speed, what gear do I need to make my speedometer accurate again?

thanks

[6packCuda]

Hey Husker, your inbox is full.

[Husker Cuda]

Sorry!, got it cleaned out now.

[ted]

it measures tail shaft speed, you dont need a  different gear.

[Chryco Psycho]

it depends on tire size but 32/ 33 tooth should be right

[MEK-Dangerfield]

it depends on tire size but 32/ 33 tooth should be right

   

The charts showed I needed a 33, but the 34 did the trick.   

[Husker Cuda]

My tires are P275-60 15 which show 28".  Mymopar site shows that I need 2838931(Green) which is a 31 tooth but they are showing this for a 3:21 ratio.  I would think this would be close?

thanks

[MEK-Dangerfield]

My tires are P275-60 15 which show 28".  Mymopar site shows that I need 2838931(Green) which is a 31 tooth but they are showing this for a 3:21 ratio.  I would think this would be close?

thanks

That's the problem I had. That chart showed a 33 for my car, but it was using a 3:21 ratio. My rear is a 3:23, so I needed a 34 tooth instead. I have a hunch you will need a 32, but 31 will be close...about 6 MPH fast at 60 MPH.

[Husker Cuda]

I think your hunch would be closer, I'll try the 32 and let you know how it works out.

thanks!

[wally426ci]

Anyone have a good chart to use? some use Tire size, some use Tire height....

[Changin Gears]

Anyone have a good chart to use? some use Tire size, some use Tire height....

This is from my previous post:

All you have to do calculate the number of teeth required is measure how far off your current speedo is, convert to percent, then get a new gear with the same percentage different teeth.  Example:

Hold your speed at 60mph between 2 mile markers, it requires 54 seconds to travel the distance instead of 60 (you could also use a GPS to get your true speed).  Your speedo is reading 10% low (your really going 66mph).  In this case, if your current gear had 30 teeth you would need one with 27 teeth (10% less) to speed the speedo up. 

This equation also works:

Number of Teeth = 259 * (axle ratio/tire diameter)

[wally426ci]

After reading the last response, I:

1. 

2. 

3. 

 

 

[MEK-Dangerfield]

Changin Gears must have majored in math.       

[Husker Cuda]

Ok, I have installed my new 32 (black) gear and went out with my GPS.  At 60 on the GPS I was running 45 on the speedometer!  15 MPH off, now what do you guys suggest.  Again I am running a 3:23 SG with P275 60 BFG's (28")

thanks,
Mike

[Chryco Psycho]

sounds like you are 30% low so add 11, so 43 tooth but that would be way off from my experience
 Duh went the wrong way 22 would be close , something else is wrong