Gear Charts

[bjstark19]

I need to find a gear chart calculator like Hewlands, but that allows gear sets that are no longer sold by them. It appears that the Hewland site only allows you to select gears that they currently sell. The gear boxes are FT200 and FG400. Any help is greatly appreciated.
Thanks,
Brian Stark

[Rick Kirchner]

you can modify both as required

[Robert J. Alder]

Really nice Excel work!!

[bjstark19]

Both are very nice, but not for a 5 speed. I guess could just worry about 2nd thru 5th......

[Becker Motorsports]

I like to use Ratio's which is sold by Pegasus. It allows me to enter any gear ratio, diff ratio and set up min and max rpm ranges, and shows you RPM drop's and MPH It can be used on 4 or 5 speed gear box's

[LFFR]

Brian,

I have an Excel spreadsheet for the FT-200 using the old gearset ratios. Drop me your e-mail and I'll send you a copy. lffr@hotmail.com
John Mihalich, Jr.

[Rick Kirchner]

i didn't write them, but i did modify them for my specific ratios (these are the originals) should be easy enough to make a 5-speed version. Just show the formulas and cruise over to the areas where they are located, add columns, copy the formulas, and modify the ranges on the plots.

[TimH]

Thanks, Rick. Really useful.

[kea]

I'm still using a DOS based program Hewland gave out years ago. Any ratio, CWP, drop gears, etc.
I see what you mean about their new offering though.

[gerhard_k]

I have found this calculator very handy: http://www.csgnetwork.com/rearendgearcalc.html

Besides finding your max. speed in a gear at your max. rpm, you can also find the rpm-drop between gears: Input the gear ratio of, say, 3rd gear and try different rpm's until the calculated speed matches the 2nd gear top speed.

For a preliminary check on the spacing between gears, I look at the "tooth difference" between adjacent gears: e.g., 18/33 2nd to 21/29 3rd is 21-18=3 + 33-29=4 =>7 total tooth difference. You want the TD to be smaller as you get into the upper gears, for a smaller rpm drop.
My current MK4 ratios in my LeGrand Mk.2 Fiat/PBS H-mod are 15/37, 18/33, 21/29, 24/27, 26/25, so the TD is 7, 7, 5, 4, and the calculated next-gear rpm (for a 7500 rpm max.) is 5570 (1>2), 5650 (2>3), 6090 (3>4) and 6410 (4>5). Seems nicely progressive to me.

Of course, once you get to the course, you will most likely find that you need to tweak one of the ratios to better suit some specific corner...

HTH - Gerhard