Öhlins Knowledge Centre - Rear Suspension

Öhlins
Knowledge Centre

Motorcycle & Scooter Shock Absorbers

When you fit Öhlins suspension you fit over 40 years of World Championship-winning experience and know-how. Learn about the types of Öhlins shock absorbers the springs, damping and shock length and how to adjust and maintain them.

Öhlins Shock Absorber Types

Most Öhlins rear suspension units are high pressure Monotube type shock absorbers. With this design the damping fluid is kept under pressure from a gas separated by a piston.

Some shock absorbers are “emulsion” type, oil and gas mixed inside the shock absorber.

In some models everything is fitted inside the main shock absorber.

Or fixed directly on top of the shock absorber.

The piston is sometimes fitted in an external reservoir, connected by a hose.

The fluid is pressurised by nitrogen, which prevents cavitation and enables smoother performance. An external reservoir also enhances fluid cooling, increasing service life for the fluid and components.

Öhlins shock absorbers with external rebound damping adjustment also have an integrated temperature compensation. As the temperature increases and the fluid flows more easily, the flow is regulated proportionally to give constant performance regardless of temperature.

Öhlins Shock Absorber Springs

All Öhlins motorcycle & scooter shock absorbers have adjustable preload of the spring action. Adjusting the spring preload moves the spring seat,
decreasing or increasing the initial spring force, which will also slightly lower or raise the motorcycle rear ride height.
Spring preload is a fundamental setting for the suspension function, because if incorrectly set, all other adjustments can be compromised.

SPRING SET-UP

Damping STX Type Shocks

Öhlins suspension with higher specification provides individual adjustment of both compression and rebound damping. This adjustment enables users to adapt the performance of the shock to riding style and environment.

This is achieved when fluid is forced through needle valves at a low rate of flow and through a number of orifices in the piston at a high rate of flow. The flow through these orifices is regulated by shims (thin steel washers) that, at high pressure, are deflected to open for the fluid. On most models the needle valve can be adjusted from the outside.

By altering the size of the shim-stack (i.e. number, thickness, diameter) the characteristics of the damping action can be changed. However, this should only be done by an authorised Öhlins technician.

Compression Damping (STX)

When movement of the motorcycle causes compression of the shock absorber, the fluid flows through the needle valve (combined compression and rebound valve) in the piston rod. If the velocity of the compression movement is high, like in the case of rapid compression, this will not be sufficient and so the shims under the piston will open to allow for a greater rate of flow. The fluid that is displaced by the volume of the piston rod is forced into the external reservoir via a separate compression valve. The separating piston is displaced, thus increasing the gas pressure.

Rebound Damping (STX)

When the spring forces the shock absorber to return (extend) again, the fluid flows back through the needle valve. The fluid flowing into the chamber is forced by the pressure of the gas back into the shock absorber via a separate non-return valve. If the piston velocity is high, the shims on top of the piston will also open to allow the fluid to flow through.

Compression Damping (TTX)

On the TTX type shocks (Twin Tube) instead forcing the damping fluid through a number of orifices in the piston, the flow is directed through a second, outer tube before passing through the regulating compression damping adjusters and onwards to the upper (negative pressure) side of the piston.

Rebound Damping (TTX)

Upon rebound, the fluid reverses flow, through the rebound adjuster and back down the secondary, outer tube to return the lower side of the piston. This system further reduces the risk of cavitation and provides very precise damping control at all stroke speeds.

Öhlins Compression Damping Adjustment

If the bike feels soft, unstable, is using too much wheel travel and you have the perfect spring for you, close the compression adjuster two [2] clicks. This will increase control of the wheel during acceleration. It will also help ride height and falling through the stroke too quickly.

If the bike feels high, has bad grip at throttle opening and feels rough over small or medium bumps during acceleration, open the compression adjuster two [2] clicks. Test run and make necessary corrections. When you have sufficient feel of the motorcycle you can make further fine adjustments.

When you feel you have achieved an improvement, go back to where you started and check once more. Note other relevant factors such as tyres, temperature etc. Test run to make sure whether further fine adjustments should be made.

Compression damping controls the energy absorption when the shock absorber is being compressed, therefore, controls how easy the shock absorber compresses when the rear wheel is being loaded or hits a bump.

Adjuster type 1

Adjust by turning the knob on top of the reservoir. Turn clockwise to increase damping, turn counter clockwise to decrease.

Adjuster type 2

Adjust by turning the knob on top of the reservoir. Turn clockwise to increase damping, turn counter clockwise to decrease.

Adjuster type 3

Adjust on top of the reservoir. Turn the slotted screw clockwise to increase damping, turn counter clockwise to decrease.

Adjuster type 4

Adjust on top of the reservoir. High speed: Turn the hexagon screw. Low speed: Turn the slotted centre screw. Turn clockwise to increase damping, turn counter clockwise to decrease.

Resetting the adjuster

1. Turn the adjuster clockwise to fully closed position (position zero [0]).

2. Turn counter clockwise to open, and count the clicks until you reach the recommended number of clicks. Check the recommended set-up data in the mounting instructions provided with the shock absorber.

Öhlins Rebound Damping Adjustment

If you have got a good feeling for the bike with spring, preload and ride height but the bike runs low and packs down under acceleration bumps, with lost line and/or lost comfort and traction, open the rebound adjuster two [2] clicks.

open the rebound adjuster two [2] clicks.

If the bike is nervous and moving a lot or has a high feeling entering corners, close the rebound adjuster two [2] clicks. Fine tune one [1] click at the time. Test run and make the necessary adjustments. For original rebound setting see the mounting instructions for your shock absorber.

Rebound damping controls the energy absorption when the shock absorber is being extended and controls how fast the shock absorber returns to its normal position after being compressed.

Rebound damping adjuster

Turn the wheel on the piston shaft above the end eye/bracket. Turn clockwise to increase damping, turn counter clockwise to decrease it.

Resetting the adjuster

Turn the adjuster clockwise to fully closed position (position zero [0]). Then, turn counter clockwise to open, and count the clicks until you reach the recommended number of clicks. Check the recommended set-up data in the mounting instructions provided with the shock absorber.

Öhlins Spring Preload Adjustment

#1 Mechanical Adjuster

Use a C-spanner. Loosen the lock nut (1A). Move the lower spring platform (1B) to the desired position. Turn clockwise to increase the preload, turn counter clockwise to decrease it.

#2 Hydraulic Adjuster

Turn the Hydraulic Adjuster knob to set the spring preload. Turn clockwise to increase the preload and turn counter clockwise to decrease.

#3 Integrated Hydraulic Adjuster

Turn the hexagon screw on the hydraulic adjuster to set the spring preload. Turn clockwise to increase, turn counter clockwise to decrease.

#4 Mechanical 3-Step Adjuster

Use two C-spanners. Turn the adjustment rings. There are three [3] adjustment positions (A, B and C).

#5 Mechanical Adjuster

Unlock the nylon screw on the spring adjuster with a screwdriver (5A). Use tool 03199-01 and turn the spring adjuster clockwise to increase the preload (5B), turn counter clockwise to decrease it.

Rear Shock Length Adjustment

By adjusting the length of the shock absorber, both the steering geometry and the chain force can be changed.

Shorter

A shorter shock absorber will result in a lower motorcycle. The fork angle and the trail values will increase and normally the chain force will be reduced, resulting in reduced anti-squat. Changing the length of the shock absorber will also slightly change of centre of gravity.

Longer

A longer shock absorber will result in a higher motorcycle. The fork angle and trail will decrease and normally the chain force will increase with more anti-squat as a result. A slight change of centre of gravity is another result of changing the length of the shock absorber.

Length Adjustment

It is advisable to remove the shock absorber from the vehicle before adjusting the length. Using two wrenches, hold the upper nut with one hand and loosen the lock nut with the other (lower nut). Turn the end eye/bracket to the desired length and retighten the lock nut (Tightening torque: 40 Nm). One [1] turn is 1mm of shock absorber length. Ensure to measure the ride height before and after adjusting the length.

1. Put the motorcycle on a workstand so that both wheels are off the ground and the suspension is unloaded.
2. Mark, e.g. with a piece of tape, a point immediately above the rear wheel axle.
3. Measure the distance from the marked point to a fixed point, e.g. the wheel axle (R1).
4. Measure the distance from the bottom of the upper triple clamp to a fixed point, e.g. the front wheel axle (F1).
5. Put the motorcycle on the ground so that the front and the rear suspensions are slightly compressed. Repeat the measuring procedures (R2 and F2).
6. Sit on the motorcycle in normal riding position, properly outfitted in your riding gear. Repeat the measuring procedure (R3 and F3).

Guideline Measurements

If no other recommendations are given in the Mounting Instructions follow the recommended measures below:

Free sag (r1-r2), (f1-f2)

Rear 5-15 mm Front 20-30 mm

Ride height (r1-r3), (f1-f3)

Rear 25-35 mm Front 30-40 mm

Adjustment and Set-up Recommended Adjustment Range

Rebound and compression damping: ±5 clicks from original (basic) setting.

When you set-up your bike you need to do it together with the front fork and on all types of tracks/roads that you want to optimise, there are no set-ups that will be 100% perfect on all tracks/roads, you will need to compromise.

During this process, always prioritise: Safe feeling, stability and comfort. This will enable you to ride safer and use less energy.

Rear Suspension Care

A suspension unit service should be carried out by an Authorised Öhlins Service Centre every 30,000 km or 3 years (which comes first). Taking your Öhlins suspension to a non-Authorised Öhlins Service Centre could result in damage or the use of counterfeit, poor quality parts.

Ensuring the use of correct tyre pressures, the correct spring to suit your weight or riding style, preventive maintenance and regular inspection will help maintain reliable function of your suspension. If there is any need for additional service, contact an authorised Öhlins Service Centre.

Cleaning

Clean the shock absorber externally with a soft detergent and then use compressed air to remove any residues. Ensure that all dirt is removed. Lift the bump rubber and clean the area below. Keep the shock absorber clean and spray it with oil (WD40, CRC 5-56 or equivalent) after washing. Wipe off excessive oil with a cloth. Take care not to spray water directly into the adjuster knobs and/or the ball joints.

Inspection

1. Check ball joints for possible excessive play or stiction.

2. Check the piston shaft for leakage and damage.

3. Check the shock absorber body for external damage.

4. Check the reservoir for external damage that can restrict the floating piston from moving freely.

5. Check for excessive wear of rubber components.

6. Check the attachment points of the shock absorber to the vehicle.

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