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Developmental/Alpha - Ride Height & Crossweight calculator


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#1 JPM

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Posted 13 June 2013 - 11:03 PM

EDIT: Version 5 is available. Better instructions.

Here's a Screen Shot of version 4 (version 5 is very similar):

version4fullss.jpg



Hello All,

I thought I would share a calculator/spreadsheet that I'm working on to get some constructive feedback and recommendations. It's not a calculator moreso than a methodology so I'm looking for advice on how to improve it. I hope it will help new racers (like myself) come to grips with building our own setups. I'm not a programmer but I'm sure someone out there (alot smarter than I) could turn this into a working app without too much trouble. If you are one of them, feel free to do with it as you will and share it with the greater community. I'm also not an engineer so this is designed without complex physics computations. I wouldn't have the patience to reverse engineer iRacing's physic engine at any rate.  I used Excel because I've had some rudimentary training with it. I'm a big fan of the KISS principle..(keep it simple stupid!)

Quick background info on the project:

I started building this spreadsheet based on a methodology described by Bob Bolles in an article from CircleTrack. You can find the article here: http://www.circletra...ht/viewall.html. His article does a pretty good job explaining his method for setting ride heights and cross weights in layman's terms.

EDIT:
I re-evaluated the process/methodology. It simplifies things when I think of CW% as a horizontal plane with 4 corners. Initially, to keep the crossweight where you want it, you have to move (raise/lower) all 4 corners equally so that all your ride heights are within the allowable range for your chosen car.

Once you have the ride heights set, you can use the CW calculator to tweak your crossweight with minimal effect on your ride heights. **You can also use the CW calculator to help you get your CW set at the beginning of the ride height section.


My current method of making a setup:

**Over the last 4 weeks, I've been watching video's, reading articles, examining matrix's, cheat sheets, guides, examining other racer's setups and making build after build after build, in an attempt to learn how to make a car handle the way I like it and hopefully get around the track quicker. After 4 weeks of banging my head on the desk, this is what I've gotten comfortable with when building a setup from scratch---

1. Set my spring rates and sway bars based on the type of setup I'm shooting for (Aero or Mechanical). I start with the fixed setup provided by iRacing, drive some laps, make an adjustment, drive some more laps, etc until the car feels comfortable. All the while trying to keep an eye on ride heights and crossweight as much as possible.

2. Then I move to truck arms, nose ballast, and shocks to dial it in for more consistant laps and stable handling. I try to leave the track bars, crossweight, and tires alone until I'm comfortable with my basic chassis settings. My intent is to get a baseline setup that I can tweak from day to day or season to season with track bar, wedge and tires.

Thats my two step plan..lol. So, Step 1 is why I am attempting to make this calculator.

The goal of the calculator

Why bother? Well, with my limited racing experience and knowledge, each week I've been experimenting with different types of setups (Aero vs. Mechanical)

I try to get through Step 1 for a - Left Front Coil Bound, Right Front Coil Bound, and old-skool mechanical. Whichever feels the best, I take to Step 2 and then go racing.

However, the more I experiment, the more I find myself spending time on ride heights and minimizing cross-weight changes. For example, lets say I'm working on a Right Front Coil Bound. To keep it as a RFCB, I might reach a limit on my Spring Perch Offset or my crossweight moves into a % range that is too loose or too tight. This might mean a truck arm change which then affects my ride heights and crossweight again. It seems a viscious cycle and I've been spending too many hours chasing my tail.

So thats why I started this.

The Bottom Line-- What I hope to accomplish: make a tool that quickly finds the desired ride heights and crossweight for a specific Spring Package.

 



#2 JPM

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Posted 18 June 2013 - 12:18 AM

new version available

 

pm me here or pick it up at: http://members.iraci...st/3197280.page



#3 JPM

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Posted 19 June 2013 - 08:56 PM

Version 4:

I elaborated on the steps and tried to organize the process to be easier to follow. Changed the colors some for easier reading and eliminated one or two unnecessary formulas. All the ride height formulas are gone, so its important to go step by step when trying to get your ride heights within the range allowed by iRacing. It will not fix ride heights that are beyond their limits. If you have your configuration such that the front is below minimum ride heights and the rear is above their max, you have to give somewhere. All crossweights may not be achieveable easily.

P.S. The spreadsheet does not attempt to calculate anything other than changes made to spring rates. (Truck arms, sway bar, preloads, camber, tire psi, etc.. are beyond the scope of the assistant.) These items have to be changed as you test your car and make adjustments. When the ride heights and crossweight exceed your goals, the process can help fix them.



#4 JPM

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Posted 20 June 2013 - 06:51 PM

Version 5:

Against my KISS principle, I expanded the instructions. Hopefully making it easier to understand.






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