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FE Power Forums => Non-FE Discussion Forum => Topic started by: hwoods on March 22, 2025, 10:42:46 PM

Title: transmission gear ratios
Post by: hwoods on March 22, 2025, 10:42:46 PM

anyone have a formula to determine transmission gear ratios for a drag car?  5 speed trans   Thanks

Title: Re: transmission gear ratios
Post by: cleandan on March 29, 2025, 10:59:35 PM

Sorry, no specific formula to determine literal "best" gears.

But I do the math using differential gear ratio, rear tire diameter, and engine rpm to help choose the most useful transmission gears available from the transmission maker.

I recently did this for a 5spd install on a 1965 GT350.
It was a lot of various inputs to figure the results, but it was not too boring or troubling.

It was worth the investment in time because the car was nicely transformed into a much better performing and driving vehicle.

Be sure to ask the transmission supplier what they have available for transmission gears to be certain you know what you have to work with.

Title: Re: transmission gear ratios
Post by: Gaugster on March 30, 2025, 02:46:15 PM

I found this calculator to be very helpful with overall shift points, mph etc. Need to figure out what results are needed for optimized drag racing. One constraint will be making to the end of the race without having to shift into an overdrive gear.

https://www.blocklayer.com/rpm-gear

Title: Re: transmission gear ratios
Post by: hwoods on April 01, 2025, 07:11:31 AM

Thank You for the replies