Ohlins Tuning Guide
Overview: What this guide covers
This guide pertains to Öhlins ‘Road and Track’ kits, Öhlins ‘Dedicated Track’ kits, and 3DM Motorsport ‘TrackDay Series’ kits.
Suspensions are VERY complex. Please note this guide is intended to be a BASIC tuning guide and covers information at a relatively high level. Just like there are several ways to brew coffee, there are several ways to setup suspensions. It is ultimately the drivers responsibility to figure out what works best for them.
Understanding how the dampers work
Setting up ride height
Adjusting the clicker knobs
Documenting your setup and changes
Understanding How the Dampers work
It is important to understand WHAT the shocks (dampers) are doing in order to understand how to make changes to the handling characteristics of your car.
Dampers create force to control the springs and the dynamics of the suspension/chassis. When the suspension moves we measure it by velocity. When the suspension compresses it is called “Bump” and when the suspension droops it is called “Rebound”. Turning causes the car to roll (outside tire compresses and the inside tire droops) and this is typically a low velocity occurrence of the suspension (aka low speed). Hitting a bump or curb is typically a high velocity occurrence (high speed).
So the more adjustment knobs the better right? The tendency is to want a damper that has a knob for every function… low speed rebound, low speed compression, and high speed rebound/compression so we can fine tune but unfortunately its not that easy. We see it over and over and over again where people install complex dampers, get lost with knob turning and end up NEVER adjusting them ever again. The best laid plans get derailed by complexity. Its important to keep it simple and keep good notes.
Öhlins dampers are competitive, not complicated. They are setup out of the box with force curves oriented to YOUR car and towards performance driving. The clicker predominantly adjusts low speed rebound (the most important) and low speed compression is matched as necessary. This low speed adjustment helps dial in the “dynamic balance” of the car, in other words, how the car reacts when you turn. It also helps dial in grip through the turn by keeping the tire contact patch optimal over small undulations and ripples in the pavement. The Dual Flow Valve (DFV) replaces the need for high speed adjustments, it allows the damper to soak up bumps without upsetting the car and lets the tire return to the ground quickly.
What about range of adjustment? There are typically two different use cases for aftermarket dampers and their adjustments: combo street/track cars, and dedicated track cars. It sounds enticing to buy a damper that can control a large range of spring rates to encompass multiple use cases but this approach is a major compromise. They typically end up with a small adjustment range for the springs you settle on limiting your adjustability and tuning capabilities from track to track. Everyone is a little bit different, or perhaps a lot different, which is why Öhlins offers two distinct kits, the ‘Road and Track’ and ‘Dedicated Track’, each of which are capable of handling a window of spring rates for their particular use case. No need to have your dampers re-valved if you want to make spring changes to suit your driving style or car setup. ‘Road and Track’ and ‘Dedicated Track’ are based off the same damper technology and can be converted back and forth. Custom applications are also available.
Setting up the Ride Height
When installing an aftermarket suspension, one of the bonuses is the ability to lower the car. This is good because it lowers the center of gravity (CG) and ultimately creates a better handling car. However, it is not that simple, especially with a MacPherson strut car. It is a two fold problem…
First, the balance of the car is determined by the roll resistance between the front and the rear. Roll resistance is created via springs, ant roll bars, dampers, and roll moment. Roll moment is a part of the geometry equation where it is the distance between the center of gravity (CG) and the roll center (RC). On MacPherson strut cars, the roll moment typically gets exponentially larger the more you lower the car. Therefore the more you lower the car, the more spring or anti roll bar you need to add to compensate.
Second, MacPherson strut design places the damper very close to the wheel and tire. The more you lower the car the closer the spring perches get to the tire in a “coilover” scenario.
It is important to watch how much you lower your car as this can create all sorts of problems ranging from geometry, clearance, and shock travel problems.
Adjusting the Clicker Knobs
discuss how to adjust the knobs
discuss clicker setting vs force curve vs handling characteristic
discuss if understeer and if oversteer try x,y,z
Documenting Your setup and changes
As with any subject of complexity, you should incorporate some minimal form of documentation or you will get lost quickly and end up not utilizing the capabilities of your suspension. It can be something as simple as a pocket notebook, a note taking app on your phone, or something as complex as a custom formatted excel workbook. The important thing is to find something that works for you and is sustainable. These notebooks from Öhlins are a great way to document settings and changes you make from session to session.