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gear ratio with a th400

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Old Oct 15, 2015 | 12:03 PM
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Slo_balt's Avatar
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Default gear ratio with a th400

The car was previously a 6 speed car with a 9 inch with a set of 4.30s. But I just got a th400 with a rmvb and was wondering what gear to run. The car has a nine inch and I run a 28" tall tire. The motor is ly6 with 243 heads and and a fast 102 intake. I'm running a 235/244 620/596 on a 113 lsa cam. The car is going to be half track half street car. I was considering running either a 3.25 or a 3.50, what are your guys opinions
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Old Oct 15, 2015 | 02:21 PM
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Depends on what you want. You may find out that the current gear ratio may be ideal for drag racing but not so much fun cruising at highway speeds. If you are considering the 3.25 gear ratio it seems you are worried more about street driving than drag racing.

My suggestion is make some passes and see what the rpm's are going through the traps. Testing is going to give you the best data for gear ratio's.
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Old Oct 15, 2015 | 02:54 PM
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Well my current ratio is a 4.30 and that is too big. Honestly I want it to perform decent on the street and the track. I know I can't put a bigger gear in there that performs great at the track and expect good gas mileage on the street and vice versa . I'm just looking for a happy median. I'm also wanting to get my gear set ordered so I know what stall to run
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Old Oct 15, 2015 | 03:43 PM
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I'd try some online calculators and see what you come up with. You'll need a little more info to get a better guess on ratio.
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