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Speedo and diff gears

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Old Mar 7, 2007 | 06:50 PM
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Default Speedo and diff gears

I have changed the diff ratio from 3.08 to 3.70. Because of this my speedo, offcourse will be wrong.
How many toths should i have on the sprocket in the tranny to corect it.

i have a 73BB w\ a 400TH automatic.

I am also playing with the tought of changing the sprocket, so the speedo will show KMH instead of MPH. (live in norway, so all speed limits is in KMH) Anyone done this before? how many thets will i need to make this work with my 3.70 rear gears?
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Old Mar 7, 2007 | 08:13 PM
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Do a search, I think you need 22 teeth. ZIP Corvette Parts list a green gear and a silver gear, both with 22 teeth. That was for a Muncie. Not sure about your automatic. I am unsure which one I will need for my Muncie, and I haven't called the tech line yet. Anyone have any insight???
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Old Mar 7, 2007 | 08:53 PM
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do a search for speedo gears. There was a recent thread that had gear charts for a lot of years and tranny's including the TH400
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Old Mar 8, 2007 | 10:13 AM
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Originally Posted by gyopp
do a search for speedo gears. There was a recent thread that had gear charts for a lot of years and tranny's including the TH400
kayosnes, did you find the post? If not, PM me with your email address and I'll send the chart to you.
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Old Mar 8, 2007 | 10:45 AM
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Try this calculator:speedo gears
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Old Mar 8, 2007 | 02:49 PM
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Originally Posted by Duke94
kayosnes, did you find the post? If not, PM me with your email address and I'll send the chart to you.
Found it. works good for getting the speedo to work in mph.
But my primary goal is to get it to work in kmh. Goog info tough.
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Old Mar 19, 2007 | 04:09 PM
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KMH anyone????????
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Old Mar 19, 2007 | 04:22 PM
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hi,

I have a 79 which was originally imported in Belgium, so it did have the export speedo (kmh). From what I could see, the gear on the trans is the same, but its the gear inside the speedo that are different. Seems more or less logical i would think
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Old Mar 20, 2007 | 04:19 PM
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Originally Posted by Belgian1979vette
hi,

I have a 79 which was originally imported in Belgium, so it did have the export speedo (kmh). From what I could see, the gear on the trans is the same, but its the gear inside the speedo that are different. Seems more or less logical i would think

Logical??

it is easyer to change the gears in the tranny. if there exist one w\ the correct nr of teeths.
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