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Setup Guide for R/C off road racing

Look for this article on the RC Monster Truck Forum

This is a 'Quick Reference' setup guide, a cheat sheet.
You can print it down for your convenience.

This setup guide assumes you have some sort of 'standard setup' to begin with. One should come with your kit. You can also find standard setups on manufacturers' websites.
It also assumes your car is in perfect working order. (Bearings spinning freely, nothing dragging the ground, no binding in the suspension etc...)

Differential Settings
---------------------
Differential's are used to allow the wheels on the same end of the car to rotate at different speeds during cornering. If diff's are set to tight or are "locked" the tires will fight each other as the car is turning.

Front Diff
Thinner
Increases steering into corners (off-power)
If oil is too thin the steering may become inconsistent, especially it can lose forward traction (and steering) during acceleration out of corners
Thicker
Increases stability into corners during braking
Increases steering on-power at corner exit

Center Diff
Thinner
Front wheels unload more during acceleration
Decreases on-power steering (reduces overseer)
Easier to drive on rough tracks
If a high-power engine is used you could waste too much power and sometime "cook" the oil in the center differential because it "overloads"
Thicker
More all-wheel drive effect
Better acceleration
Increases on-power steering (reduces under steer)
Better suited on high-bite, smooth tracks
Car can be more nervous to drive especially if a high power engine is used - you might need to be smooth on the throttle

Rear Diff
Thinner
Increases cornering traction
Increases steering into corner
Thicker
Decreases rear traction while cornering
Reduces wheel spin

Front Diff Looser than Rear Diff
Steering response increases
If rear diff is to tight, the car will under steer into the corner, and will cause loss rear end sliding out of the corner.
Could cause overseer while entering the corner (depending on other settings)

Rear Diff Looser than Front Diff
Steering response decreases, stability in turns in increased
Could cause under steer or "push" while entering the corner (depending on other settings)

Springs

The purpose of the springs is to control wheel movement and keep the tire in contact with the road over bumps and irregularities. Stiffening the springs front and rear will reduce body roll and make handling more responsive, but cause a loss of traction over bumpy surfaces. Likewise, softening all of the springs will give more grip on bumpy tracks, but increase roll and reduce responsiveness. You can also use the springs to affect the car balance. You can reduce overseer by stiffening the front springs or softening the rear. Likewise, you can reduce under steer by softening the front springs or stiffening the rear. However, be advised that changing just one end also affects fore/aft weight transfer. By softening the front springs, you'll also get more dive under braking. Softening the rear will give you more rear weight transfer under acceleration, which can give you more traction on the rear wheels in straight-line acceleration. Read and understand about "anti-roll bars" before you come to the conclusion that you need to change your springs, springs should be one of the last, if not the last thing you should change to effect how the car handles other than during a bump condition.

Stiffer springs make the car feel more responsive, more direct.
They also help the car jump a little better and higher.
Stiff springs are suited for high-traction tracks, which aren't too bumpy.

Softer springs are better for (mildly) bumpy tracks.
They can also make the car feel as if it has a little more traction in low-grip conditions.

Using Harder Front Springs
Less steering
Faster steering response
Used on flat tracks
Minimum 'diving' under braking
Used more for large fast tracks

Using Softer Front Springs
More steering
Slower steering response
Used on bumpy tracks
More 'diving' under braking
Used more for tight technical tracks

Using Harder Rear Springs
Less traction out of the corner
Faster steering response
Used on flat tracks
Minimum front lift under acceleration
Used more for large fast tracks

Using Softer Rear Springs
More traction out of the corner
Slower steering response
Used on bumpy tracks
More front lift under acceleration
Used more for tight technical tracks

The purpose of the shock absorbers is to dampen the oscillation of the springs. The dampers not only dampen spring oscillations, but they also affect handling during transient conditions (such as the entry and exit of turns), but not steady-state conditions.

More Dampening
Slower shock action = could be unstable on bumpy tracks
Slower chassis weight transfer
Generally less traction

Less Dampening
Faster shock action = less chance of tire leaving the ground on bumpy tracks
Faster chassis weight transfer
Generally more traction

Damping should always be adapted to the spring ratio; the suspension should never feel too 'springy' or too slow.

The turn radius is wider, but smoother. The car doesn't 'hook' suddenly.
The car is easier to drive, and high-speed steering feels very nice.

Feels very easy to drive, the car can be 'thrown' into turns.
More rear traction while accelerating.

If one end of the car has slightly heavier damping than the other, then that end will feel as if it has the most consistent traction and the most stable when turning in and exiting corners.
A car with slightly heavier rear damping, or slightly lighter front damping will feel very stable turning into corners on bumps or whoops sections. It won't feel 'touchy' at all.

Caster is the angle to which the steering pivot axis is tilted forward or rearward from vertical, as viewed from the side. If the pivot axis is tilted backward (that is, the top pivot is positioned farther rearward than the bottom pivot), then the caster is positive; if it's vertical to the lower pivot point then the caster is zero.

More Caster (laid back more)
Less steering into the corner
More ON POWER steering out of the corner
More straight-line stability

Benefits of castor: (more positive castor/laid back more)

Maximizes tire contact patch during roll, braking, and acceleration
Improves turn-in response
Increase directional stability
Improved steering "feel" and self-center
Increases dynamic negative camber during turn in

Less Castor (vertical = 0 castor)
More OFF POWER steering into the corner
Less steering out of the corner
Less straight-line stability

A lower ride height lowers the center of gravity, which reduces weight transfer during cornering, acceleration, and braking. The reduced weight transfer improves cornering. A lower ride height also lowers drag at high speed because you are presenting a smaller frontal profile to the airstream. Also, by lowering the front end and raising the rear, you can improve high speed stability and increase down force by preventing high-pressure air from building up underneath the nose of the car. If the car is too low, it can bottom out, though this can be eliminated by stiffening the springs (which could cause problems elsewhere).

The car feels better in bumps, and jumps better.
It can feel tipsy, or even flip over in high-grip conditions.

The car feels more direct, and it can potentially corner a bit faster.
It's also harder to flip the car over.

Lowering one end of the car, or putting the other end higher up, gives a little more grip at the lowest end, but try to avoid big differences in ride height between the front and the rear.

Wheelbase

A short wheelbase makes the car feel very nimble, and good in tight turns.
This is a good idea for very small and tight tracks, without big jumps or bumps.

With a long wheelbase the car becomes a lot more stable, and better in wide, high-speed turns.
This is good on wide-open tracks.

More anti-squat generally makes the rear of the car more sensitive to throttle input.
The car has more steering while braking, and also a little more powering out of corners.
On high-traction tracks, it may feel as if the car momentarily has more rear traction accelerating out of corners.
A car with more anti-squat can also jump a little higher and further, and it will soak up bumps a little better, off-power.
A lot of anti-squat (4° or more) can make the car spin out in turns, and make the rear end break loose when accelerating.

Less anti-squat gives more rear traction while accelerating on a slippery or dusty track.
It also gives more side-bite.
Less anti-squat will make the car accelerate better and faster through bumpy sections.
Very little anti-squat (0° or 1°) makes the rear end feel very stable. It also makes power sliding a lot easier.

Note that anti-squat only works when you're accelerating or braking, it does absolutely nothing when you're coasting through turns.
The harder you brake or accelerate, the bigger the effect of anti-squat.

The assumption is made that if pistons are changed, the viscosity of the oil is also adapted...to give the same static feel (Same low-speed damping)

Smaller holes mean more 'pack'. Pack means the damping gets very stiff, or almost locks up, over sharp bumps, ruts, or landing off jumps.
Small holes are good for smooth tracks, with big jumps or crummy jumps with harsh landings.

Bigger holes mean less pack. The point at which the damping gets stiff (where the shock 'packs up') occurs a lot later, at higher shock shaft speeds.
Big holes are very good for bumpy tracks. The car is more stable and has more traction in the bumpy sections. It won't be thrown up over sharp bumps, the suspension will soak them up a lot better.

Smaller holes in front makes the car jumps very nicely, a little more nose-up.
It feels easy to drive.

Bigger holes in front can give a subtle feel of more steering and more consistent front end grip if the track isn't perfectly smooth.

Always use the same, or about the same shock pistons front and rear. Big differences in pistons make the car feel inconsistent, and not very smooth.

Bear in mind that changing the lower shock mounting location changes the lever arm of the shocks on the wheels.
So mounting the shocks more inward makes the suspension softer at the wheel, and mounting the shocks more towards the outside makes the suspension stiffer.

Makes the car soak up bumps a little better, and can make the car corner a bit faster.
Can be good for bumpy, low-grip tracks, but general stability is greatly reduced.

Upper Shock Mounting Location

More direct feel;
Less lateral grip. (side-bite)
generally a bit better for jumps and harsh landings.

Steering feels very smooth.
A little more mid-corner steering.
Mounting the rear shocks very upright can result in the rear end sliding in the middle of the turn, especially in high-speed turns.

Feels aggressive turning in.
The car has a lot of side traction in the rear, and the turn radius isn't very tight.

A long link gives a lot of body roll in turns.
It feels as is the body is willing to keep on rolling, until in the end, the springs prevent it from rolling any further.
The car has more grip in corners, especially the middle part.

A short link makes that the body doesn't roll as far, its tendency to roll drops off as it rolls.
This can stabilize a car in bumps and curved sections.
It feels as is the car generates a little less grip.

A parallel link gives a little more roll than an angled one.
It feels very smooth, and consistent as the body rolls in turns.

An angled link makes it feel as if the car has a tendency to center itself (level, no roll), other than through the springs or anti-roll bar.
It gives a little more initial grip, steering into corners. It makes it very easy to 'throw' the car.
The body rolls a little less than with parallel links.
On bumpy tracks, it could be possible to use softer settings for damping and spring rate than with parallel links, without destabilizing the car.

Beware that you should always keep an eye on the balance of your car; large differences in roll center front vs. rear will make the car feel less consistent and less confidence-inspiring.

The front rolls and dives more in turns.
Lots of steering in mid-corner.
Could make the car hook.

The front feels very stable.
A little more turn-in, but less steering in mid-corner.

More rear traction in turns, and coming out of them.
Rear end slide is very progressive, not unpredictable at all.
Make sure that there's enough rear camber though, or you could lose rear traction in turns.

The rear feels very stable. It breaks out later and more suddenly, but if it does, the slide is more controllable.
It makes the front dive a little more, which results in more steering, especially when braking.

Turn-in is very aggressive.
The front feels as if it wants to roll less than the rear.

Camber is best set so the tires' contact patch is as big as possible at all times. So with a stiff suspension you'll need less camber than with a soft one.
If the tires wear evenly across their contact patches, camber is about right. On really bumpy tracks, adding a little more negative camber (2 to 3 degrees) can help traction and reduce the chances of catching a rut and flipping over. Camber is the angle the tires make with the road and is measured in degrees. Tire grip varies with the camber angle, and ideally is maximum when the angle is zero. However, the maximum grip is found with a small amount of negative camber because of tire sidewall deflection (when the top of the tire is tilted inward it is called negative camber. Also, as the body rolls in a turn, the suspension movements themselves causes some adverse camber change. These combined effects mean that for maximum cornering power you need to have some amount of negative camber. However, too much camber will cause you to lose grip because the outside edge of the tire is being lifted off of the pavement, reducing the contact patch. So to summarize, as the camber angle increases from zero, cornering grip improves to a point, then falls off.

-2 deg. ~ -1 deg. Front Camber
Quicker steering response
More overall side traction
Less chance of traction rolling

-1 deg. ~ 0 deg. Front Camber
Less quick steering response
Less overall side traction
More chance of traction rolling

-2 deg. ~ -1 deg. Rear Camber
More overall side traction
More traction under braking
Less chance of traction rolling

-1 deg. ~ 0 deg. Rear Camber
Less overall side traction
Less traction under breaking
More chance of traction rolling

Toe is the angle (inwards or outwards) that the tires point when the wheel is straight ahead. Toe-in means the front of the tires point inward, and toe-out means they point outward. Zero toe means the tires are parallel to each other. The biggest effect toe has on the handling of the car is on stability. When a car hits a bump or enters a corner, forces on the tires act to steer the car off to one side, making the car unstable and difficult to control. Toe-in counteracts this, improving stability. Toe-in also causes under steer during initial corner entry. Interestingly, toe on the rear wheels has the same effect on handling as toe on the front. Toe on the rear wheels is useful for tuning the handling of the car as it is exiting corners.

Front Toe "IN"
Slower steering response
More straight-line stability
Too much will cause greater wear at the outboard edges of the tires

Front Zero Toe
Medium steering response
Minimum power loss
Minimum tire wear

Stabilizes the car in the straights, and coming out of turns.
It smoothes out the steering response, making the car very easy to drive

Front Toe "OUT"
Quicker steering response
Less straight-line stability
Too much will cause greater wear at the inboard edges of the tires

Increases turn-in steering a lot.
But can make the car wandery on the straights;
Never use more than 2 degrees of front toe-out!

Less Rear Toe "IN"
Less straight-line stability
Less traction out of the corner
More steering
Higher top speed

Intermediate Rear Toe "IN"
Intermediate straight-line stability
Intermediate traction out of the corner
Intermediate steering
Intermediate top speed

More Rear Toe "IN"
More straight-line stability
More traction out of the corner
Less steering
Less top speed

Rear Toe "IN" Stabilizes the car greatly. It makes the rear end 'stick', but more toe-in makes the difference between sticking and breaking loose bigger.

Anti-roll bars are best used on smooth, and high-traction tracks only.
If you must use one on a bumpy track, try to use a very thin one.

Adding an anti-roll bar, or stiffening it, reduces traction at that end of the car. So it feels like the opposite end has more grip.
If the track is smooth enough, it also makes the grip level feel more consistent.
Anti-roll bars reduce body roll in turns, so they make the car feel more direct, and make it change direction quicker.

An anti-roll bar at the front of the car reduces low-speed steering. The turning radius will be larger, but very consistent.
It reduces 'hooking' by preventing front end roll.
The car will have more rear traction in turns.

Adding an anti-roll bar to the rear of the car gives more steering. the car steers tighter, also at low speeds.
On a very smooth track, it can make power sliding easier. It can also make powering out of turns and lining up for jumps a little easier.

More Ackerman makes the steering more consistent, and smoother.
It just feels right, also at low speeds and in tight turns.

Less
(Smaller, or no difference in steering
angle between the two font wheels)

Less Ackerman makes the steering more aggressive at high speeds.
The car turns in more aggressively.
It doesn't work well when either traction or cornering speeds are low.

The car changes direction faster, and corners flatter. It feels generally more responsive.
Adding a lot of travel limiters is only advisable on smooth tracks.

Visit our Youtube channel

Setup Guide for R/C off road racing

Wheelbase

A short wheelbase makes the car feel very nimble, and good in tight turns. This is a good idea for very small and tight tracks, without big jumps or bumps.

With a long wheelbase the car becomes a lot more stable, and better in wide, high-speed turns. This is good on wide-open tracks.

Upper Shock Mounting Location

A short wheelbase makes the car feel very nimble, and good in tight turns.
This is a good idea for very small and tight tracks, without big jumps or bumps.

With a long wheelbase the car becomes a lot more stable, and better in wide, high-speed turns.
This is good on wide-open tracks.