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i have a 66 cpe, c-4, 2.80 gears, 225/60/15's and 8 tooth drive gear. after doing the math i show i need an 18 tooth speedo driven gear. currently i have a 16 tooth but i am told the more teeth the slower the speedo will show and they don't make one with less than 16 teeth. what do you think i should do? thanks
 

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More teeth on the driven gear will make the speedo read even slower. The number of teeth on the driven grear equals how many teeth from the drive gear must engage with the driven gear to get your cable to turn around once.

So if 16 is the lowest count you can get, then you need to increase the number of teeth on the *drive* gear. (or have the speedometer adjusted)

How accurate is the mileage count on the odometer? i.e., if you drive past one mile of "mile markers" on the highway, how many tenths of a mile does your odometer show you've driven?

If the odometer is *accurate* as is, then you actually do need to have the speedometer adjusted, if the odometer is inaccurate then you need to change the gearing.

John Harvey
 

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Change the drive gear then, the speedometer probably doesn't need adjustment becasue both the odometer and speedometer are reading slow.

Drive gears are more difficult to change, but it sounds like that is your only option.

John Harvey
 

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Might be more satisfying to change the rear end gears instead...just something to think about. You'd be a lot quicker with something like 3.25s in place of the 2.80s.

Regards,
MrFreeze
 

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When I changed mine, I just found a city speed display, removed the clear plastic piece from the dash pod and then rotated the speedo needle until it was right. Took a couple of drives past the display but it's been ok for 12 years or so. I don't really care about the odometer -- and this was free! I did it when I did the T5 conversion and before the right gear was available.
 

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That's a damn good idea. I'm going to have to try that one when the weather warms up.
 

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That is only correct at the one speed, it will be off proportioninally more the farther you are away from the set speed.

John Harvey
 

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That is only correct at the one speed, it will be off proportioninally more the farther you are away from the set speed.

John Harvey
That's how I thought it would be, but for some reason, it isn't.
 

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When I changed mine, I just found a city speed display, removed the clear plastic piece from the dash pod and then rotated the speedo needle until it was right. Took a couple of drives past the display but it's been ok for 12 years or so. I don't really care about the odometer -- and this was free! I did it when I did the T5 conversion and before the right gear was available.
I'm sorry, but that just doesn't make any sense at all.
 

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1. find a place where you can see the real speed, like the afore mentioned display (most cities have them and the local PD's will tell you where they are in my experience if you tell them why you want to know;
2. note how far off your speedo is;
3. rotate the speedo needle above or below "0" as needed (it rotates on the spindle)
4. go past the display to check it at least twice
5. reassemble.

Hope this helps; it has worked for me for a long time...if the idea does not appeal to you, buy a new gear, they don't cost much. Me? Old rodders like me love this kinda stuff and are willing to share it. Let's let this threat die; there is not much more I can say about it.....
 
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