Disclaimer, I'm no world class pro but I want one thing with this thread, that every racer achieves a better setup. I'm no authority in Physics or whatever but I did a fair amount of research on the matter of suspension and most of the stuff that happens in our cars and translated that to a spreadsheet that helps understand what is happening mathematically.
Moderators, if this thread doesn't belong here please contact me.
About the service
per se:
The suspension frequency spreadsheet is aimed at knowing your car's front to back balance regarding springs, shock pistons and roll stiffness. Every measurement is SI, millimeters and grams mostly.
Using the suspension frequency spreadsheet:
-I've included a sample of my personal JQ The Car setup. The input is the first sheet of the spreadsheet, you'll need a caliper to measure accurately and a scale (preferably 4 equal scales, the ones from e-bay that measure up to 1kg are sufficient up to 1/8th buggies). All measurements taken from center of screw or shaft.
Step 1 - lift the buggy (fig. 1) and drop it (fig. 2), try to not disturb the buggy when taking measurements, in the photo you see it sideways but that's because it doesn't fit in the bench facing me. Let's start front side first.
Step 2 - measure the distance between center of the upper shock mounting screws (fig. 3), input the number in the sheet.
Step 3 - measure the distance between center of the lower shock mounting screws (fig.4), input the number in the sheet.
Step 4 - measure shock length (fig. 5)
Then do the same for the rear end.
Now use an online spring K calculator like
this, choose "ASTM 228 music wire" option and retrieve yours spring K using
metric data (times 10 because it's not the correct unit used in the spreadsheet's equations).
The kickup is chassis kickup +/- A-B plate bushings, so let's say 10* of chassis kickup + +1 degree of bushings combo=11*. If 10* chassis kickup - -1 degree bushings combo=9*. Didn't make an anti squat ACF because it's of negligible effect on suspension frequency.
Weight each end of the car RTR, divide by two to have corner weight. Boom done.
Post your spreadsheet as a attachment or PM. I'll look at it and show how to improve your setup/driving
I'll update this post with all the spreadsheets I'll make. Stay tuned(no pun intended).
V2.1 - Now includes weight bias and track width and it's stored in google drive.
V2.2 - Added piston hole diameter recommendation!
V2.5a - A bunch of shock calculations and roll stiffness calculation, improved piston hole diameter starting recommendation. Corrected.
V2.6 - Added shock oil prediction for a balanced setup. Cleaned up the not so useful calculations and visuals.
V2.7 - Added Total tire load transfer equation. Tomorrow if I'm not at the track I'll break side to side load transfer in front and rear bias.
V2.8 - Removed the various line to input different shock tower hole and arm hole, now input your current setup and see if they are balanced. Gray areas are user input, green are results.
V2.81 - Corrected a mistake.
V2.9 - Expanded the load transfer equations and shuffled things a bit.
V3.0 - Visual tweaks and organization, place to enter tires used in the setup.
V3.2 - Roll stiffness and shock piston starting setup improved.
V3.3 - Added a roll angle estimation and discolouring for neatness.
V4.0 - Made weight transfer more visual and grouped on a new sheet, cleaned the layout and made it a little smaller. Important update.
V4.1 - Added a few pointers.
V4.2 - Cleaned up and changed shock angle measurement thanks to Morgoth.
V4.3 - Added spring recommendation!
V4.5 - Added graph to see your options regarding spring balance front to rear
V5.0 - Damping ratio graphs now available.
Lite v1.1 - A new condensed spreadsheet, some stuff was expanded and other corrected or deleted. Fixed suspension frequency error!
Lite V1.2 - Added spring converter from most manufacturers claims and improved CG height calc.
Lite v1.3 - Cleared some concepts and corrected some calculations.
Lite v1.4 - The return of roll angle. See if your car should be over or under steering.
Lite v1.7 - Sway bar equations added! Sorry for having sway bars with SAE units but will convert them visually if it causes trouble to you. Internally it's all good.
Lite V2 - That's it folks, has everything working properly and can't think of new features to add.
Lite V3! Cleaned up the weight transfer page and used the standard weight transfer bias layout. Shock hole diameter is more precise.
TODO:
-video of my cars running over ruts and uneven terrain, the track has no flood control so it gets very rutted, should be a great way to show how my cars work - done.
Sources:
Wikipedia
http://white-smoke.wikifoundry.com/ and it's sub links.
www.f1technical.net
http://www.rctech.net/forum/electric...t-results.html