dpiRC

Does one exist? I've seen 4 link calculators for cars, but I've never seen and cannot find any video that tells you exactly how to calculate your anti squat percentage on say, a 2wd buggy.

Does it exist?

Sir 51D3WAYS

Not that I know of, maybe RC Crew Chief.

Normally anti-squat is pre-determined by pill inserts nowadays and a lookup chart/table in the manual.

Anti-squat is measured in degrees.

dpiRC

Yeah.. that doesn't actually tell you anything, heh. That's the annoying part. There's calculations to get an actual anti squat value... and degrees on pills is a scratch on the surface.

Roelof

Looks to me if you have a full size calculator it can be used on a scale model as wel.

I know there is a calculator called SUSPROG to calculate and simulate suspensions.

Jurassic579

Yes. The same guys that make So Dialed app makes a pill Calculator app.

Khan48

iTrader: (3)

Most kits should have a table that tells you to the anti squat based on your pill or suspension hanger spacers

dpiRC

Rc crew chief sounds like it might do what I'm looking for.. but you have to pay for it. I was hoping there would be a suspension guru on here that knew the calculations, that could just easily tell my how to classify the rear for spit? Susprog could probably do it, but looking for something rc related.. and that one is super expensive lol

Again, pills don't tell you anti squat.. They're just one piece in a complex puzzle.

BRabbit

Antisquat is calculated off of your sprung mass center of gravity height. So its both active and different from brand to brand. Even in full scale cars it’s difficult to calculate without lots of CAD modeling or an elaborate weighing process. What are you trying to gain by getting an actual percentage?

Sir 51D3WAYS

I don't understand exactly what you are looking for.... Anti-squat is a relatively simple concept.
What exactly are you trying to calculate?

Alexv2024

iTrader: (2)

Well real cars need more precise adjustments, and have more ability to change singular aspects of the setup.

RC cars are much smaller so some aspects can't be adjusted. Also its quite different from solid axle dynamics so its not going to be the same anyway.

In my racing experience simply adjusting within the range given on modern cars is plenty effective enough for anything you need to do.

dpiRC

That's what I'm looking for.. how the rear end calculation differs, tbh. I know everything else.. just not the specifics of the rear end and how it relates to a 4 link. I'm sure someone in the universe knows.

BRabbit

To be clear… you’re trying to compare the antisquat percentage (definitive number) of a 4-link solid axle setup to an a-arm configurations percentage?

wingracer

iTrader: (24)

You will never get the crazy high antisquat percentages on a wishbone car you can get from a 4 link like drag cars running 400%. If you can handle the Indian accent, here's an ok introduction to it:

ray_munday

iTrader: (4)

The calculations for a 2wd are pretty simple (more complex for 4wd as it depends on torque distribution which depends on tyre traction, centre diff tuning etc).

With an independent suspension rear wheel drive car, you basically draw a line from the ground contact point of the rear tyre at the same angle as the anti-squat angle of the rear arms. You then compare the height of this line at the centre of gravity of the car with the height of the centre of gravity. The ratio of the height of the 'line of force' to the height of the centre of gravity gives you percentage of anti-squat. If there is no squat built into the suspension, the line follows along the ground giving 0% squat. If the line angles up steep enough to meet the centre of gravity, you get 100% anti-squat.

If you want to calculate it, you can use the following simple equation:

Anti-squat percentage = Anti-squat force height @ cg / centre of gravity height x 100
= [anti-squat angle x 3.14/180 x wheelbase x Frt weight bias / Centre of gravity Height] x 100

Anti-squat force height at cg = (distance from rear tyres to centre of gravity x position) x sin (anti-squat angle)
distance from rear tyres to centre of gravity x position= (weight distribution frt %) x wheelbase
sin (anti-squat angle) = anti-squat angle x 3.14/180 (using radian conversion for small angles)

Using some typical values for a B6.3:
Cg height = 45mm
Wheelbase = 280mm
Weight Bias = 40% front
Anti-squat = 2 deg

-> 8.6% of anti-squat.

Hope this helps.

Ray

Mason

Great stuff Ray. Thanks for take a couple minutes to educate us.
This is what the forums are for. Not the "you shouldn't do this, you shouldn't do that". It's for "this is how this works, learn, utilize, create".