ONR RoadRunner - Damping Formula

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1

Greetings Community!
Need a little help tuning your damping settings?
Hopefully with the use of my formula, you’ll be able to quickly get some settings which work for you!

Damping Formula(s):
Front and Rear Rebound = ((WB% (LBS) * 9.8) / (LSR * RH^2)) + 1
Front and Rear Bump = ((WB% (LBS) * 9.8) / (USR * RH^2)) + 1

abbreviation meanings:
WD = Weight Distribution
LBS = Weight of car in pounds (Only pounds!)
USR = Upper-Spring-Rate (Maximum stiffness the spring(s) can go)
LSR = Lower-Spring-Rate (Minimum stiffness the spring(s) can go)
RH = Ride Height
9.8 is a constant which must NOT be changed!

Note[/h]
When finding Front Rebound or Bump, use Front Weight Distribution and Front Ride Height
When finding Rear Rebound or Bump, use Rear Weight Distribution and Rear Ride Height
Example:
In this example I will use a 2013 Lotus E21 (F1 car) just because it’s light.
Weight Distribution: Front - 46% / Rear - 54%
Weight: 1422 lbs
Upper-Spring-Rate: 589.3 lb/in
Lower-Spring-Rate: 73.7 lb/in
Ride Height: Front - 3.5 in / Rear - 3.1 in
Once you have got your values substitute them into the formula…
Front Rebound: ((46% (1422) * 9.8) / (73.7 * 3.5^2)) + 1 = 8.1 (to 3 significant figures)
Rear Rebound: ((54% (1422) * 9.8) / (73.7 * 3.1^2)) + 1 = 11.6 (to 3 significant figures)
Front Bump: ((46% (1422) * 9.8) / (589.3 * 3.5^2)) + 1 = 1.9 (to 3 significant figures)
Rear Bump: ((54% (1422) * 9.8) / (589.3 * 3.1^2)) + 1 = 2.3 (to 3 significant figures)
Taking Mathematics to the game!
“The true sign of intelligence is not knowledge but imagination” - Albert Einstein
For my open source tunes please click ‘here’
Hope this helps!
Enjoy,
RR

7 Likes
2

The ^ symbol. What does that represent - To the power of? e.g 3.5 to the power of 2?

3

got it. 3.5 * 3.5 * 3.5.

cool

4

is there a formula for the roll bars ?

5

This means to the power of 2
Example:
If the ride height is 4.5, put it to the power of 2 so - 4.5^2 = 4.5 * 4.5

I have one but it needs tweaking. Been using the same formula for years. But you have to remember that the anti-roll bars are mainly a tailor tuning aspect…

RR

6

Can u do a spring and diff. formula?

7

The Diff and springs are tailor tuning aspects. How you drive makes the tune!

8

Doesn’t seem to work on my E21 but awesome job might be better for lower classes

9

All of a sudden, I regret leaving school at 15.

3 Likes
10

You sure… I tried it on my F1 tune and took off 0.2 seconds.

I’m 17 so not a big difference =P

11

Haha exactly. You still remember school. Is a distant memory for me hahah

12

yea i couldn’t get it to work i would try to take turns like i normally do especially for some high speed turns and it will lose it, i think unless there was a way to include aero because that adds weight and maybe the individual spring rates that are already tuned it would be more accurate in giving a basic damper setting, but i’m no mathematician

13

thanx for this post. i am working on a tuning spreadsheet in xcel. i will try this out and add the math to my spreadsheet.

14

Thanks for posting this, the damping is my ugh problem child. Are you using the actual curb weight of the vehicle or what you have figured the sprung weight would be? I have a ARB formula and a second way I figure them also and sometimes you just wing it LOL. Question at the end of your calculations you had this “(to 3 significant figures)” can you explain? Is that meaning constraint of up or down only by 3 from original answer or something else?

15

“Are you using the actual curb weight of the vehicle or what you have figured the sprung weight would be?”

I’m using a bit of both…

Three significant figures: This means 3 consecutive numbers which doesn’t start with a ‘0.’
Example:
If you had:
i) 15467.2 = 154|67.2 (Round up) = 15500.0 (to 3 s.f)
ii) 0.0010234 = 0.00102|34 (Round down) = 0.0010200 (to 3 s.f)
Hopefully you get what I mean…
RR

16

What can I say? This formula is terrific. With Damping & Tire pressure dialed in based off your 2 formulas, that took my car to a different level. Great work!

17

I see what you mean… for the Mazda 787B and F1 car, maybe some others, high bump rates and lower rebound rates ate better =/ I might have to do some tweaking… Thanks for the info!
RR

Thanks gangrel!
RR

18

At the risk of sounding dumb, how can i figure out my lower spring rate?

19

How exactly do i find my lower spring rates

20

Lower spring rate is the minimum rate the springs can go…
Go to your tuning setup > go to springs > and put one of your springs value all the way to the bottom and remember it > then put it back to the value it first was…

RR