# How many teeth for Drive Gear in 69 Lemans 5.7 V8 TH-350???



## shimelhoch (Dec 9, 2009)

Hello Everyone,

I am trying to determine the correct drive gear for my 1969 Pontiac Lemans. The car's speedometer is overstating actual speed by 5 mph. The car has the original TH-350 and is a 5.7l V8. Not sure the gear ratio but I am comfortable that it is whatever was stock with the engine/tranny configuration. Any help would be appreciated. 

Thank you,

Scott


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## ALKYGTO (Mar 29, 2010)

5 mph at what speed? Tire size can throw it off by that much.


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## shimelhoch (Dec 9, 2009)

*14" tires on stock rally II rims*

I've noticed it at 50 mph. Any idea on the number of drive teeth? I figure for $16 it's a cheap way to eliminate one item from the equation. Plus I have a small leak at the speedo cable so again, its a cheep way to eliminate a possible contributor to the problem. Thanks.


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## BearGFR (Aug 25, 2008)

Fire up your favorite internet search tool and look for "speedometer calcuator" or similar terms. You should find several on-line tools that will help you figure out what size gear(s) you need. (You'll have to know what gear it has in it now to start off with, but you can also find on-line instructions on how to get to it.)

Bear


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## GTO JUDGE (May 14, 2005)

Here are 3 links for you to research, your answer will be found in at least one:
You should be able to order one here, I did, I had the same issue I was 18 mph over at 50 mph with 4:10's and 14x7.

I changed out the 4:10's to 3:55 and I am now spot on until 60mph and am only off by 2mph.

I am running 45 teeth, light green. (TH400) On your speedo driven housing it should state the highest gear you can run with the set up you have, as long as the internal gear was not changed. My gear when I purchased it was like 3.50- 4.50 in that range. that was in 2010. Hope this helps you.

Speedo Gear Selection

Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

Speedometer gear charts


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