gear calculations..

[blackbrains7]

can any1 help me with how to do gear calculations...wat r the variables...etc..

[blackbrains7]

can any1 help me with how to do gear calculations...wat r the variables...etc..

[Dan Lentsch]

I think that I can help you out here.. I have a spread sheet that does all the work for you.. email me @ daniel.lentsch@mu.edu if you want it. Either which way the variables are (in this order): engine speed (RPM), primary drive ratio, individual gear ratios (1-5 or 1-6), final drive ratio (engine sprocket to the sprocket on your rear diff), and last the tire circumfrance (which you can find using the diameter of the tire.. my spread sheet uses 21 in for the dia.) that should do it.. if anyone else wants the spread sheet let me know..

[Drew Price]

Just to be clear, do you mean gear RATIO calculations? More information in your question will likely generate more informative responses, which is really what you want from the board, not necessarily just a spreadsheet (but a very nice gesture on Dan's part).

Best,
Drew

[Wesley]

I think with something this simple, if you're looking for the answers, making a spreadsheet will be the most informative thing you can do. You gain a lot of knowledge by making the numbers work in a spreadsheet (or on paper, for that matter.)

Plotting engine RPM versus engine speed in various gears is something you could do in Jr. High, I slapped one together in 15 minutes or so on the way to California, so I'd have it later to play with.

Then, using a dyno graph you can get rough estimates of your accelerations throughout the gears and RPM range, and if you have tire data, can use that and weight transfer calculations to plot how much power you put down vs. how much you CAN put down, figure out your theoretical ET and total thrust available at any point, and use that to make your car go fast.

Then you can take that, and factor in other things like drivability, where do you spend more time in the RPM range, driver preference, and establish a final drive (unless you can muck about inside the transmission and modify ratios) that satisfies those in the best way.

If thats what I think you mean. Or, you take your drive gear teeth, divide by the driven teeth, and get your gear ratio. like 14/35, or something like that. But I hope thats not what you mean. http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[drivetrainUW-Platt]

Since you asked such an open ended question, heres my answer: count the teeth.

[Chris Allbee]

measure the chain, then divide by the circumference of the tire. Take this in inverse ratio with respect to your Ackerman setting and multiply by the valve clearance of the exhaust valve on the third cylinder. Oh, and normalize according to vehicle mass. Toss in a fourier transform or two...

[Wesley]

Chris, don't be so cruel to strangers. They don't know that you're being completely serious.

[Luke_Morrow]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Chris Allbee:
measure the chain, then divide by the circumference of the tire. Take this in inverse ratio with respect to your Ackerman setting and multiply by the valve clearance of the exhaust valve on the third cylinder. Oh, and normalize according to vehicle mass. Toss in a fourier transform or two... </div></BLOCKQUOTE>

What about a single cylinder engine?

If you go by firing order (1, 1, 1, 1, 1, ...) it would therefore be cylinder 1!

[Diablo_niterider]

hey Dan it could be grt if u could send me that sheet

[Dan Lentsch]

sent

[Diablo_niterider]

thanx so much , i will be sending u the tips and experiences with air intake and exhaust design in some time

[Dan Lentsch]

awesome! thanks