Go Back  R/C Tech Forums > General Forums > Electric Off-Road
Anti squat calculator for rc? >

Anti squat calculator for rc?

Like Tree11Likes

Anti squat calculator for rc?

Old 10-15-2021, 08:15 PM
  #1  
Tech Apprentice
Thread Starter
 
Join Date: Sep 2019
Posts: 54
Default Anti squat calculator for rc?

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?
dpiRC is offline  
Old 10-15-2021, 08:38 PM
  #2  
Tech Champion
 
Sir 51D3WAYS's Avatar
 
Join Date: Jun 2011
Location: Stuck in urban hell
Posts: 5,068
Default

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.
Sir 51D3WAYS is offline  
Old 10-16-2021, 12:16 AM
  #3  
Tech Apprentice
Thread Starter
 
Join Date: Sep 2019
Posts: 54
Default

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.
dpiRC is offline  
Old 10-16-2021, 01:48 AM
  #4  
Tech Lord
 
Roelof's Avatar
 
Join Date: Aug 2007
Location: Holland
Posts: 10,220
Default

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.
Roelof is offline  
Old 10-16-2021, 05:18 AM
  #5  
Tech Apprentice
 
Join Date: Dec 2020
Posts: 54
Default

Yes. The same guys that make So Dialed app makes a pill Calculator app.
Jurassic579 is offline  
Old 10-16-2021, 08:06 AM
  #6  
Tech Adept
iTrader: (3)
 
Join Date: Aug 2005
Location: Detroit Metro
Posts: 211
Trader Rating: 3 (100%+)
Default

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

Last edited by Khan48; 10-16-2021 at 06:12 PM.
Khan48 is online now  
Old 10-16-2021, 11:43 AM
  #7  
Tech Apprentice
Thread Starter
 
Join Date: Sep 2019
Posts: 54
Default

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.
dpiRC is offline  
Old 10-16-2021, 07:18 PM
  #8  
Tech Rookie
 
Join Date: Aug 2021
Location: NorCal
Posts: 11
Default

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?
BRabbit is offline  
Old 10-16-2021, 07:20 PM
  #9  
Tech Champion
 
Sir 51D3WAYS's Avatar
 
Join Date: Jun 2011
Location: Stuck in urban hell
Posts: 5,068
Default

I don't understand exactly what you are looking for.... Anti-squat is a relatively simple concept.
What exactly are you trying to calculate?
Sir 51D3WAYS is offline  
Old 10-17-2021, 10:38 AM
  #10  
Tech Addict
iTrader: (2)
 
Alexv2024's Avatar
 
Join Date: Dec 2017
Location: Ohio
Posts: 748
Trader Rating: 2 (100%+)
Default

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.
Alexv2024 is offline  
Old 10-17-2021, 04:43 PM
  #11  
Tech Apprentice
Thread Starter
 
Join Date: Sep 2019
Posts: 54
Default

Originally Posted by Alexv2024 View Post
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.
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.
dpiRC is offline  
Old 10-17-2021, 05:37 PM
  #12  
Tech Rookie
 
Join Date: Aug 2021
Location: NorCal
Posts: 11
Default

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?
BRabbit is offline  
Old 10-17-2021, 06:16 PM
  #13  
Tech Lord
iTrader: (24)
 
wingracer's Avatar
 
Join Date: Nov 2007
Posts: 13,418
Trader Rating: 24 (100%+)
Default

Originally Posted by dpiRC View Post
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.
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:
wingracer is offline  
Old 10-17-2021, 10:54 PM
  #14  
Tech Elite
iTrader: (4)
 
ray_munday's Avatar
 
Join Date: Apr 2006
Location: Melbourne, Australia
Posts: 2,784
Trader Rating: 4 (100%+)
Default

Originally Posted by dpiRC View Post
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?
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, RogerM, gwhiz and 4 others like this.
ray_munday is offline  
Old 10-18-2021, 11:57 AM
  #15  
Tech Champion
 
Mason's Avatar
 
Join Date: Oct 2004
Location: Ocala, Florida
Posts: 5,350
Default

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".

Mason is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.