A new spreadsheet and other info....

[Sumner]

Not sure if this post should be here, in the tech section or in the GearSplit section.  Jon I could not tell if the GearSplit software is still available or not.  If not maybe move this there or copy it to there as this post will soon disappear down the page.

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After our screw up with ordering the wrong gears for Hooley's Stude thinking we had a different Input Drive/Cluster Gear combination than what we really had I modified one of my old "RPM/Speed in Gear" spread sheets.  If  you have a transmission, such as a Gerico/G-Force/Tex where you can change the Input drive gears and the individual gears this spreadsheet will allow you to enter all of those by their tooth count.  It will then show you speeds at any rpm in any gear and also the drop in rpm shifting to the next higher gear.  Here is a direct link that will allow you to download the spreadsheet in Excel format....

http://purplesagetradingpost.com/sumner/bvillecar/101%20Transmission-Master.xls

I also have numerous other spreadsheets related to land speed racing that deal with air inlet area design, HP needed to run a certain speed,  drag calculations, intercooler ice water tank sizing and some others.

Also more RPM/Speed in different gears for car 3,4,5, and 6 speed transmissions and motorcycles with multiple gears (4-5-6 speeds).  These are explained a little better below but all of the spreadsheets can be found here....

http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html

Below are a couple of screen shots of the spread sheets from above, one for a car 4 speed transmission and one for a 5 speed motorcycle.



Above is the car 4-speed spread sheet. You enter the tire size, rear-end gear, and the ratios in each gear. To the right of that is a small table showing speeds at fixed rpm's in each gear.

The main feature of the spread sheet is explained next.



Above we are looking at one section of the spreadsheet. We can pick any rpm shift point in any gear and see the mph there and also the rpm drop between that gear and the next higher gear.

For instance if you were to shift from 1st to 2nd at about 6800 your speed there would be 105 and you would drop to 5100 in 2nd, a drop of 1744 rpm. Likewise if you made the 2-3 shift at 6800 again you would be going 140 and be turning 5300 in 3rd. Again if you made the last shift also at 6800 at 180 you would be turning 5340 in 4th. Since the above is a screen shot of the spreadsheet it doesn't show your final speeds in 4th. You would just scroll down to see them.

The Spreadsheet could be a big help in selecting gears that will work with your motor/cam so that you don't fall out of the power band on shifts.

Next is one of the motorcycle spread sheets. You can input tire diameter, primary gear ratios, ratios in each gear and also different sprockets with different tooth counts.



It will show you speeds at different rpms and rpm drops between gears for the primary sprockets you choose and final gear speeds for other sprocket combinations,

Sum

[peterdallan]

Thank you very much, extremely useful.

We fitted a 5 speed cluster into our pre-unit box for flexibility, but we now think the original 4 speed cluster might have been better.

The spreadsheet will help us determine if we can shift and maintain the RPM's we need to keep the bike on the cam.

Cheers

Peter

[hotrod]

Sum:

Just an idle observation it might be useful to add a tire slippage factor to that sheet (I don't see one but could have missed it).
Might help someone sync up their trap speed data with the spread sheet output for better precision of real trap speeds.

[Milwaukee Midget]

VERY early on in my build, I downloaded Sumner's spreadsheet.  That's when I started putting together the combination that I have and helped me make the decision to go with the close ratio box. 

It served as a point of reference as to what I needed for a HP band, my tire size and my diff gearing.

It's fast and easy to use.

And thanks to Sumner, so was the car!

[Sumner]

Sum:

Just an idle observation it might be useful to add a tire slippage factor to that sheet (I don't see one but could have missed it).
Might help someone sync up their trap speed data with the spread sheet output for better precision of real trap speeds.

What I've done is change the tire size slightly to make up for that.  I used the sheet for my license runs and it was right on the money or at least as close as I could observe the tach ( + or - a hundred RPM) while driving.

My A license pass was way off, over 23 mph over what I ran.  So that got me checking the transmission at home and found out that we had ordered and put in the wrong overdrive 4th gear.  Once I put in the right gear info the sheet matched the exit speed withing 1 mph.  Without the sheet and the data logging and my memory we might of gone back for World Finals and not had any luck since the new 4th overdrive was not as much overdrive as what we took out (.960 vs the .93 we had) we thought it was a .865 (what we wanted).

So the spreadsheet and data logging saved us hundreds of dollars in expense that we would of spent going back with the wrong gears in the car.

One nice thing about them is that users can still modify them and use them as a starting point for what they need,

Sum

[SCAATY]

     
   Like Milwaukee Midget, we downloaded Sumner's spreadsheet early in our build.  We were able to figure the ratios we needed when we ordered  our G-Force transmission.  Working with the RPM drops between the gears will help figure our shift points to keep our motor in the power band.  I think Sum proved how well this spread sheet works during his licensing runs.  You made it look easy Sumner !!!   Congratulations to you and Hooley on the first runs with the "new" car.  Can't wait to see what you guys do in October.
   
     SCAATY