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Old 03-15-2004, 02:41 PM   #1
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Default roll out help

before i get flamed for this i know about the search but with 56k dail i could spend all day looking for a simple answer........how do u figure out what the final gear ratio of the diffs on a car....i've looked at a few sites that have the roll out Calculator on them but none of them have my car........the spur ans pinion are easy the tire diameter is easy but the tranny ratio has got me stuck.............also most stock motors are about the same rpms right so what would be a good avarage rpm to Calculate in
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Old 03-15-2004, 04:38 PM   #2
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Default

it would help if you would tell us what car you have.
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Old 03-15-2004, 05:25 PM   #3
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Default Internal Drive Ratio

To figure the internal drive ratio of your car you divide the number of teeth on the diff gear by the number of teeth on the drive pulley.

Example: 32 teeth on diff gear divided by 18 teeth on the drive pulley. 32/18 = 1.77 internal drive ratio

Final drive ratio is spur gear divided by pinion times internal drive ratio.

Example: 128/32*1.77 = 7.08

Rollout is tire diameter times Pi(3.14) divided by final drive ratio.

Example: 2.28*3.14/7.08 = 1.01

Hope this helps,

Later,
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Old 03-15-2004, 09:22 PM   #4
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Default Re: Internal Drive Ratio

Quote:
Originally posted by CRASH
To figure the internal drive ratio of your car you divide the number of teeth on the diff gear by the number of teeth on the drive pulley.

Example: 32 teeth on diff gear divided by 18 teeth on the drive pulley. 32/18 = 1.77 internal drive ratio

Final drive ratio is spur gear divided by pinion times internal drive ratio.

Example: 128/32*1.77 = 7.08

Rollout is tire diameter times Pi(3.14) divided by final drive ratio.

Example: 2.28*3.14/7.08 = 1.01

Hope this helps,

Later,

thanks that is exactly what i needed .......it's a tech racing voggard by the way
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