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If we put the free calcs from him on this site it would save having to put a link up everytime someon needed a gear calc.
 

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so what ever happened with this????? its a good idea i was just curious if it was still an idea???
 

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I have a spreadsheet I made up in MS Excel (2000) that will calculate final drive mph and rpm for several different gear ratios. Inputs are tire size, trans type (manual, auto lock-up, or auto non-lockup). Can you use it?

It's not every day or even week, but at least 2 to 3 times a month I see a question asking "what rpm would I turn with xx" size tire an x.xx gears?"

It would be nice to just have the program accessable for others, rather than me emailing it to interested parties. Just a thought...

-Aaron
 

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if I can just get the forumals, with the info for particular items, like trans ratios, how much the torque convertor multiplys, etc, then I can build it easy.

Maybe someone should post on the open board to help obtain all this data. We could do everything, like crawl ratio, gear ratio, metric tire conversion, etc.
 

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Ahh. Mine only compares several different gear ratios in final drive, so you can see what your rpms (or mph's) are on the highway for a given tire size.

More of a "how many rpm's would I be turning on the highway with this gear and tire?" spreadsheet.

-SM
 

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So what's happening with this? It's a good idea.
 

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Nothing happening with this yet? I'd like to see it and if anyone has any ideas on where I could look for this Info I'd be happy to do the searching for it.
Mid_Evil_thymz
 

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mid_evil_thymz said:
Nothing happening with this yet? I'd like to see it and if anyone has any ideas on where I could look for this Info I'd be happy to do the searching for it.
Mid_Evil_thymz
www.4lo.com has the calcs
 

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Here are a few formulas I have:

Metric tire size to actual diameter-
Tire Dia= 2 x [(Width x aspect ratio) / 2540] + Rim Diameter

Engine RPM thru gear ratio and MPH:
rpm =(mph x gear ratio x 336)/ tire diameter

Equivalent ratio (gear ratio to use when changing tire size):
Equivalent Ratio = (New tire diameter / Old tire diameter) x original ratio

Effective ratio (what your gear ratio is like after changing tire size):
Effective ratio= (old tire dia. / new tire dia.) x gear ratio

I have a book with a bunch more useful stuff in it- but nothing having to do with torque converters.
 

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I finished the metric tire conversion, I will finish the rest later when I have time.  I am making it so there is only 1 submit button for all of the convertors.  So they can get answers from 1, any or all of the convertors at the same time.  I am putting checks in there to so if they leave a required field blank, etc it will let them know.
 

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Yeah, the tire conversion is just mm to inches.
Those formula's are perfect for picking a new gear set when changing tire sizes.
One thing I forgot to mention about the Equivalent Ratio; the stock gear ratio AND tire size of the vehicle MUST be known and correct, or the result will be incorrect for the specific application. If your truck has 3.92 gears stock, you can't plug in 3.92 and 29" tires and get something close. It'll give you the equivalent for that SPECIFIC combonation of tires/gears. From what I understand our trucks came with 28.8" tires stock.
Also, if the result is in between gear sizes, pick the next size higher. It leaves more room for tire growth, which is pretty important with us wheelers! ;)

I'm still trying to find the book I've got with the formulas in it. It has a lot more information that is useful to our area of intrest- like finding actual speed thru indicated speed (good for those using a lower gearset from stock or one lower than the equivalent ratio).

The book is called Auto Math, if anyone else has it maybe they can supply some of the formulas on pages 88-102 (there's also 2 pics of an RC wheeling in the tire section).
 
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