Off Road Suspension Guide

Tech Article – Off-Road Suspension Tuning Guide

Never minded how camber, toe or shocks effect your vehicle handling ? Suspension tuning is one of the most important way to decrease your lap time. Maybe you’re fast, but with a good setup, you’ll be faster. Here’s few good tips to set up your vehicle.

Note: Be sure there is no loose or bending in the suspension or in the steering components before attempting to tune your vehicle.

Camber

Description: When you look at the front of the rear of your vehicle, camber represents the vertical angle of your tires. If the top of the tires are leaning toward the chassis (like the letter A), this is negative camber. On the opposite, if the top of the tires are leaning away the chassis (like the letter V) , this is positive camber. Camber is used to adjust the contact patch of the tires. Why adjust the camber ?? Simply because when entering a corner, the inner tires are leaning toward the chassis while the external tires are leaning away the chassis. By tweaking the camber, you can adjust your wheels to have more contact on the track surface and then have more traction. More the suspension is stiff, less camber you’ll need.

Typical settings:
Front: -2 to 0 degrees
Rear:
-2 to 0 degrees
Never use positive camber (0+ degree)

Negative camber Positive camber
Front: Increases steeringRear:Increases traction when entering corners

Makes the vehicle more forgiving

Front:Decreases steeringRear: Decreases traction when entering corners

 

 

Toe-in / Toe-out

Description: Toe represents the horizontal angle of the tires. If the tires are pointing in, this is toe-in. If the tires are pointing out, this is toe-out.

Typical settings:
Front: -1 (toe-in) to 2 (toe-out) degrees
Rear: -3 (toe-in) to 0 degrees

Less toe (toe-out) More toe (toe-in)
Front: Decreases straight line stabilityIncreases cornering when exiting cornersRear: This is not recommended to use toe-out Front: Increases straight line stabilityIncreases initial corneringRear:

Increases rear end stability on power

Makes the rear end feel more “tight”

Increases rear end traction

Decreases steering

 

Caster

Description: Caster is the angle of the king pin or the steering block when viewed from the side of the vehicle. If the top of the king pin or steering block leans toward the rear, this is positive caster. In the opposite, if the king pin or steering block leans forward the vehicle, this is negative caster.
More negative caster More positive caster
Increases off power steeringDecreases on power steeringDecreases straight line stability Increases on power steeringIncreases straight line stabilityDecreases off power steering

 

Shock oil

Description: Shock oil affect damping speed. The thicker the oil is, the slower the shock piston moves inside the shock body. If the shock can’t move fast enough, the tire will loose contact with the ground and by consequence, lose traction. On the opposite, if shock oil is too thin, the shock will not absorb sufficient bumps and can make your vehicle bottom out after landing jumps. Don’t forget that the shock oil also influences the weight transfer when turning, accelerating and braking.Shock oil and shock springs work together, when you drastically change shock oil, don’t forget to replace shock springs according to the oil used. See Shock spring section for more information.
Lighter shock oil Heavier shock oil
Front:Increases front traction on bumpy surfaceIncreases body roll on high traction surface 

Rear:

Increases rear traction on bumpy surface

Increases body roll on high traction surface

Front:Decreases front traction on bumpy surfaceDecreases body roll on high traction surfaceWill make the vehicle less prone to bottoming out

Can make the vehicle jumps better and higher

Rear:

Decreases rear traction on bumpy surface

Decreases body roll on high traction surface

Will make vehicle less prone to  bottoming out

Decreases the rear end to squat under hard acceleration

Can make the vehicle jumps better and higher

 

Shock spring

Description: Shock springs are paired with shock oil used. If you use thicker oil, you should normally use firmer springs and vice versa. The shock spring should be firm enough to fully extend the shock when fully compressed in a reasonable amount of time. This means that if you use thick oil and the spring is not firmer enough, the spring will have not enough time to fully extend the shock before the next shock compression. On another hand, a shock with thin oil and firm spring will make your vehicle looks like a pogo stick.Shock springs and shock oil work together, this is important to have springs that work with your oil selection. See Shock oil section for more information.
Stiffer shock spring Softer shock spring
Front: Decreases traction and steering on bumpy surfacesDecreases body roll on high traction surfacesCan make the vehicle jumps better and higher

Rear:

Decreases rear traction

Decreases rear squat effect

Can make the vehicle jumps better and higher

Front: Increases traction and  steering on bumpy surfacesIncreases body roll on high traction surfacesRear:

Increases rear traction

Increases rear squat effect

 

Shock piston

Description: By changing the shock piston you will delay or activate the damping action. This is similar to use thicker or thinner shock oil. Basically, the smaller the piston’s holes are, the slower the damping will be because less oil will pass thru the piston.This option is used when you can’t find the right oil density. Ex,: When 40wt oil is too thin and 45wt oil is to thick. The solution is to use 40wt with smaller piston holes or 45wt with larger piston holes.
More or bigger holes Less or smaller holes
Front:Increases front traction on bumpy surfaceIncreases body roll on high traction surfaceRear:

Increases rear traction on bumpy surface

Increases body roll on high traction surface

Front:Decreases front traction on bumpy surfaceDecreases body roll on high traction surfaceWill make the vehicle less prone to bottoming out

Can make the vehicle jumps better and higher

Rear:

Decreases rear traction on bumpy surface

Decreases body roll on high traction surface

Will make vehicle less prone to  bottoming out

Decreases the rear end to squat under hard acceleration

Can make the vehicle jumps better and higher

 

Shock position

Description: Shock position is the angle of the shock. You can adjust the shock position by changing the shock location on the shock tower and/or the a-arm.Changing the shock position can be helpful when you can’t find the correct shock spring/oil combo.Don’t forget, by changing shock position, you’ll alter the suspension damping and maybe you’ll have to fine tune shock spring/oil according to your new shock position. Ride height is also affected by the shock position.
Less inclined shock position More inclined shock position
Front or rear: Makes the initial shock damping stifferDecreases lateral tractionMakes the vehicle more responsive

Makes the vehicle less forgiving and less stable

Front or rear: Softens initial shock dampingMakes shocks more progressiveMakes the vehicle more stable

Makes the vehicle more forgiving

Increases lateral traction

 

Ride height

Description: The ride height is the distance between the vehicle and the ground. For off-road, a good starting point is the adjust the suspension to “bone level” which means that the a-arm, the CVD and the ground are parallel. Ride height dramatically modifies weight transfer. If you bash, you can set the ride height higher to prevent chassis bottoming. For racing, you better keep things low for better cornering and lower CG.
Higher ride height Lower ride height
Front: Decreases steeringIncreases rear tractionIncreases CG and chassis roll

Increases weight transfer

Rear:

Decreases rear traction

Increases steering

Increases CG and chassis roll

Increases weight transfer

Front: Increases steeringDecreases rear tractionDecreases CG and chassis roll

Decreases weight transfer

Rear:

Increases rear traction

Decreases steering

Decreases CG and chassis roll

Decreases weight transfer

 

Wheelbase

Description: Wheelbase represents the length between the front axles and the rear axles.
Shorter wheelbase Longer wheelbase
Shorter wheelbase makes the vehicle good in tight turns but decreases stability on bumpy surfaces. Will also increase weight transfer when accelerating or braking. Longer wheelbase makes the vehicle more stable on bumpy surfaces but will decrease cornering. Will also decrease weight transfer when accelerating or braking.

 

Anti-squat

Description: Anti-squat is visible when the vehicle accelerates or breaks. When accelerating, all the weight of the vehicle is transferred to the rear end causing the rear to lower. This also transfers traction to the rear tires.
More anti-squat Less anti-squat
Makes the vehicle more sensitive to throttle inputsIncreases rear tires traction because more weight is transferred under acceleratingDecreases steering under acceleration Increases rear traction while accelerating on loose surfaceIncreases side-biteMakes the vehicle accelerate faster through bumpy surface 

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