Please critique me gentlemen.

[Typicray@rainmans]

My school is having me do a project called make math mine. It has to be a project that takes time, uses math, and can be beneficial to you in the future. I decided to make a toolbox guide for R/C tuning. I have a good grasp on how each change makes a car "feel" but I have a hard time with the technical aspect of things. Here is the start of my guide, please tell me where you guys think I need to change, omit, or add. The finished product will have pictures.



Ray's pocket guide to setup and tuning
This guide will go through every aspect of setting up an off road R/C vehicle. As I learn more about setup, this handbook will evolve. There are many setup tips that are more opinion based rather than performance based. What works for one driver/car may not work for another. Through each setup change, I will go through the way it makes the car feel and the physics behind what the change will do. I will examine many different credited sources and make sure they are properly cited. I make no claim to being a professional, but I have a great grasp on tuning and the mechanics of an off road R/C car.

Table of contents
When to review a setup
Camber
Front toe
Camber link lengths
Bearing size
Unsprung weight
Rigidity vs. durability
Suspension
Piston size
Oil weight
Limiters
Shock length
Mounting
Spring rate
Ride height
Tire size and diameter
Rear toe and kick up
Gear ratios
Motor turns
Esc tuning
Batteries
Rims
Tire balancing
Tread pattern
Compounds
Foam inserts
Old school mods
Sweat the small stuff
Ride height
Gravity
Roll center
Scrubbing weight
Adding weight
Caster



When to review a setup
Before tuning the car, make sure to identify what is wrong with it. Take a few practice laps around the track and see what is needed out of the car. If the car is spinning out right before every corner, it needs more traction. If the car is hitting the inside pipe every corner, a little less aggressive turn in is needed. If it is not cornering well, suspension needs to be gone through. Everything that is wrong with a car around the track can be fixed through tuning. Do not tune a car without knowing what it needs around the track. A well running car that does everything the operator needs it to will not benefit from setup changes.

Camber
Camber is the angle of the tire when it is on the ground. Positive camber has the top of the tire leaning outward while negative camber has it facing inward. Camber is one of the most overlooked steps in tuning an R/C car. It is vital to make sure it is properly set in order to produce a consistent car. A good way to check camber when a gauge is not around is to put an aluminum soda can next to the tire and see what part of the sidewall hits it.

The contact patch between the tire and the running surface is changed as camber is changed. The largest contact patch in a straight line is at 0 degrees. This provides the most forward traction. The most lateral grip is found from negative 2-3 degrees of camber. On most cars, anything over negative three degrees or positive camber will make the contact patch smaller on both lateral grip and straight line grip. A car should never need positive camber.

Front toe angle
Toe angle is the direction a tire is facing in relation to the other. Toe out, or positive, toe has the back of the tires facing inward while toe in, or negative toe, has them facing outward. Toe is the best way to tune the way a car turns.
Toe out is the best way to get a car to have more aggressive turn in. If the car has plenty of grip, but pushes hard transitioning into corners, toe out makes the car much faster. Toe out makes the inside tire turn farther then the outside tire. This makes the car turn in faster. It is a large trade off though. It makes the car less stable in a straight line and results in a kind of twitchy feel. The front tires will be pushing against each other so acceleration will be reduced.
Toe in allows the car to track better in a straight line. This option is especially good for a buggy with way too much turn in. If a car needs to be less aggressive in the turns, toe in makes the car more consistent and predictable. Using toe in makes lap times more consistent. If a car is producing one really fast lap then two slower laps and feels really aggressive, it needs to have a more consistent turn in response.
It is a good idea to only use toe angles on tracks that have a very low tire wear surface. On high wear tracks, toe in or out will tear through sets of tires; make sure to have 0 degrees of toe. When using toe, a little goes a long way. Never will a car need more than 2 and a half degrees of toe either way.

Camber links
The camber links on an R/C car control the roll center and stiffness of the car. Adjusting the roll center allows the driver to fine tune the way the car transitions weight. there are two ways to adjust the length of a camber link. The first way is to change the hole the ball stud is located. The other way is to raise the ball stud by putting washers underneath it. Moving the ball stud location is a far more dramatic change then raising it.
There are several places that the camber links can be located. The front camber links go from the shock tower to the caster block. On the shock tower, the holes are numbered one and two. Number one is the inner hole. On the caster block, the holes are normally labeled a,b, and c. A is the inner hole and c is the outer hole. On most tracks, the car will do best if the camber link is in the number one slot on the shock tower and the a slot on the caster block. If the track is really loose and loamy, the car could benefit from using the b slot on the caster block. Using the b slot makes the car have less turn in and better on power steering exiting the corner.

[Sixtysixdeuce]

Explaining how the changes affect the vehicle's handling is useful to the driver, but does not seem to meet your class requirement. If you do not understand geometry and physics, you should probably choose a more elementary subject; knowing how one thing affects another is wholly different than knowing why.

Toe angle is the direction a tire is facing in relation to the other. Toe out, or positive, toe has the back of the tires facing inward while toe in, or negative toe, has them facing outward.

Backwards. Positive toe, front side of the tires pointing inward, is "toed in".

Now, on my previous point, to see if you grasp the mathematical side of this, do you understand why positive toe helps a vehicle track straight while negative toe makes them squirrely?

Not trying to be harsh, but you did ask for critique. If you really want to do this, I'll be happy to help you, but understand that you have chosen a subject that, while it seems somewhat simple prima facie, is actually very complex-especially if you wish to attack every item in your "table of contents". Also, you need to organize that table into groupings, and if you intend to be so encompassing, should include nitro information. Know that everything you have listed there, explained concisely but properly, will comprise a book, not a short math project.

[Typicray@rainmans]

You got it! Thank you for your help sixty six deuce. On the toe angle I was using the back of the tires as a reference point. That's a good thing to point out. I would like to end up with a book and, at the end of writing it, obtain a better grasp of Tuning in general. The "table of contents" is more my wish list then anything else.

[Typicray@rainmans]

Backwards. Positive toe, front side of the tires pointing inward, is "toed in".

Great catch!!!