The way a car behaves can be changed dramatically through the steering and geometry setup. While our Kyosho Lazers don’t have all the options that newer racing cars have, we’re going to dig a bit deeper in how you can change how your car drives and fix some handing issues or handling traits you want to work with.
We will focus on the list of things you can adjust on your car first, and then check out some of the main issues you may come across and what you can do to fix them – while also zooming out on some general setup approaches.
Understanding the effects by going through these lists and cross-referencing what a certain adjustment does, will also show you the general effects. To give an easy example: lowering your car will give you less roll, but you will of course get less ground clearance which may have an effect on how it soaks up bumps or how it jumps and lands. But that’s part of the fun – you’ll end up experimenting with (in this example) the shocks and find out how oil viscosity and spring rates interact with each other.
Oh… don’t do a list of dramatic changes all at once. While it may be good to change one single thing dramatically to instantly see the effect it creates, it’s often a better idea to change small things one at a time. That’s until you really get the hang of it and understand how all things interact and have different side-effects. There’s often more than one way to change certain behaviour, it’s understanding what else it will do that is the secret to enjoying your car.
As always, there’s a balance to be struck. While the tips below hold true, a lot is dependent on the track you drive. While you will be able to maintain higher speed on a rough track using softer shocks, you will be able to drive faster on a smooth grippy track using a stiffer setup. And while we may say that more camber adds to the grip, this may change when you go over a certain point.
Shock absorbers: oil viscosity and pistons
A thinner oil will give less damping effect to the shock (you will be able to push them in quicker), which means they will react with larger strokes and the car will be more springy.
Softer damping
Smoother over uneven / bumpy surface but also more likely for the chassis to hit the ground (eg. jumps). More grip and traction. Softer damping will allow greater suspension movement and make the transition effects slower. There’s also less controlled body movement on weight transfer (steering / changing speed). This makes the car a bit easier to drive / a bit lazier and less precise in its reactions. So your choice will also depend on your driving skill.
- Front: More grip and braking and traction, resulting in more steering response and more steering. Less understeer / more oversteer due to the higher grip at the front.
- Rear: More grip and braking and traction, more steering response and more steering. More understeer / less oversteer due to the higher grip at the rear.
Pistons (‘pack’)
More holes with the same size or equal amount of holes with larger size will give you softer damping. Thin pistons have less friction against the shock sidewalls which makes the movement more consistent. Thin pistons will also have shallow holes, again offering you softer damping.
For a piston that is not flat on one side, you need to have the contoured / tapered side facing downwards. It will rebound (go back to its original position after compression) more easily. This is a wanted effect because for the rebound you only have the springs working and not helped by the weight of the car.
There is in fact also a difference in behaviour of the shocks if you choose smaller holes or larger holes. Even if your total ‘surface’ of the holes is the same (number of holes and size of holes results in the same total hole size), the piston with the smaller holes will be a bit stiffer.
Springs: stiffness
Stiffer springs will, like stiffer damping, result in less grip. The car will respond more reactively to inputs and environment. Take note that ‘stiffer springs’ are not achieved by moving the spring clamp or threaded collar.
Stiffer springs
Like other settings, there is a balance to be struck. Stiffer springs will generally require harder damping. Stiffer springs will keep the car more in line with the track surface and less sensitive to mass transfer. On smooth surfaces you want a stiff car which will increase the grip and thus speed in corners, while on more uneven and bumpy tracks you want a softer setup for more stability and have the car float over the surface a bit more. Find the balance between soaking up the track but keeping the car lively and responsive.
Stiffer springs will give you more response (also to steering), decrease grip and traction, you’ll get less chassis roll so more speed possible in corners, but react more to a bumpy surface making the car less stable and in touch with the surface. For bigger jumps you will want a stiffer setup so the car can still soak it all up.
- Front: more responsive steering, more steering under braking, less steering after the initial response
- Rear: less grip, more steering after the initial response
Springs are always progressive! Although some are less progressive. 🙂 You will see springs that have a lot of winds / coils close together. These springs are more linear / less progressive which means that there is not much difference in there reaction when they are extended or compressed. Springs with less winds are more progressive which means they become stiffer quickly when being compressed. Progressive springs will allow the car to behave soft when going over small bumps, while resisting larger compression like jumps.
Shock position
Top and bottom position
Moving the shocks more to the center of the car also make the car softer (lever effect).
Laying down the shocks
If you lay down the shocks more (less vertical shocks) you will get a more progressive feel on the shocks. This means it will be softer initially, but get stiffer the more it gets compressed.
- Softer, less response, less roll
When changing the position, always check ride height and you may have to change springs and oil to adapt to the different feel.
Camber
Camber is the angle of the wheel with regards to the surface. Negative camber means the top of the wheel will sit closer to the car’s center than the bottom of the wheel. It’s measured in degrees of angle. The camber plays a role in traction and grip. If you keep your camber at 0° then you will have the largest contact patch possible when driving straight, meaning it will result in the best traction (best acceleration and braking). But in corners, you want to counteract the change in the geometry, the flex of tires, the digging into loose dirt,… etcetera so tipping the wheels inwards at the top (negative camber) will get you a better grip around corners. Mostly your camber will be between -1 and -2.
- Negative camber: less traction, more grip, more agressive steering effect.
- Tune balance: add more front negative camber for more grip (less understeer / more oversteer), add more rear negative camber for more grip (less oversteer, less understeer)
On the Lazer, the length of your top suspension link can be changed to change camber. Make it shorter (disconnect the ball ends or directly change it if your car has turnbuckles like OTW-11 / OTW-12 / OTW-13) to have more negative camber. Use a camber gauge (angle measurement tool).
Camber gain
You can tune your suspension geometry to have the camber change through the suspension’s throw.
To have more camber gain (more negative):
- Bring the connection of the upper suspension link to a lower position on the shock stay.
- Bring the connection of the upper suspension link to a higher position on the hub.
- Bring the connection of the upper suspension link to a more outwards position on the shock stay.
- Bring the connection of the upper suspension link to a more inwards position on the hub.
If your lower arm and upper camber link are the exact same length and perfectly parallel, your camber gain will be zero.
Mostly you will tune camber in a dynamic environment however, which means the camber will also be affected by your car rolling in a corner. Pur your car on the ground, twist it around its length and see how the chassis roll affects the camber. If you want your camber to become more negative when going around corners (with the car rolling) then you have to take this into account.
Toe-in and toe-out
Toe-in (or positive toe) is where the wheels of your car will point to each other. It’s like when your steering, but both wheels of an axle are steering towards each other. It’s measured in the angle degrees of one wheel.
You can change the toe at the front by changing the length of the steering links. At the rear on the Lazer it is done by changing from one rear suspensoin toe bracket (LA-30) to another. The number marked on the bracket is the number of degrees of toe it introduces (1 or 2 degrees).
- More front toe-in: more steering when accelerating, more responsive
- More front toe-out: more steering when decellerating, smoother,
- More rear toe-in: less traction when accelerating, more stable in a straight line, less steering
- More rear toe-out: more traction when accelerating, less stable in a straight line, more steering
As noted before: there is a balance to be struck. In this case, increasing toe-in by too much will also make you break the grip more quickly beyond a certain point. So while more toe-in at the rear will make the car more docile and stable while it is gripping, it will suddenly swing into oversteer when breaking that grip.
Roll center
The roll center is a virtual point around the center of the car. You get to it by taking the lines of your suspension top link and bottom arms, continuing them to where they meet on the other side of the car, then draw a line from that point to the contact patch of the tire on the other (initial) side again. The roll center is on that line, at the middle of the car. It may be below ground level (very low roll center) or it may be above it (higher roll center). You will notice that the roll center is thus defined by your suspension geometry (position of the ball studs on the shock towers, hub,…), but also ride height, length of your shocks (so it changes when driving),…
- Low roll center: more roll, more side grip, more response
- High roll center: less roll, less side grip, less response
I am run my Lazer on flat carpet sometimes and I choose to make it a bit lazy and lower the effect of the very high grip by running a low roll center. In these conditions also have spacers inside the shocks to limit droop and use stiff springs and hard oil – ride height is only about 6mm so I have these 6mm to work with in terms of suspension travel.
