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Discussion Starter #1
Okay, got a quick question. Swapping to an AOD and I decided to go with a 3.73 rear ratio. Only problem is I havent found a 3.73 for the 8 inch rear, only 3.8. No big deal except which speedo gear do I use. I had it figured out for the 3.73, but the Calculator I was using was on a 5.0 site and has no provision for the 3.80. Anyone know of a good speedo gear calculator or which gear I should use for this setup. The tires are 205/75 R 14 (overall diameter 26.11 inches). Any help is appreciated.
 

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Discussion Starter #2
found some info

Well, I did find a calculator and the best I can tell is I'll need the 21 tooth gear (Actually, it said like 20.55 teeth).
 

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Re: found some info

Hmmm.. Doesn't sound right. The AOD has an 8 tooth output which means you'd need a 24 tooth gear (based on 45 mph correction which is more accurate). You could use a 23 tooth but you'd be off by about 3mph at 60. 21 tooth would be for a 7 tooth output. Good luck finding one of those in an AOD.

You can get a 23 tooth from most aftermarket suppliers such as STEEDA but it's not guaranteed since it has the wrong pitch. You're best off going to a speedometer shop and having a convertor box put inline.


Bill

kirkm76 said:
Well, I did find a calculator and the best I can tell is I'll need the 21 tooth gear (Actually, it said like 20.55 teeth).
 

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Discussion Starter #4
I have seen both 7 and 8 tooth for the AOD. Would they be interchangable? I know it's a pain to change.
 
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