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Your motorcycle front fork has a thick metal disc with machined passages flowing between both flat sides, this is referred to as the piston or valve.
Stacked on one or both sides of this piston are the valving shims, and the check plates or shims to only allow the oil to flow through the piston and make the shims deflect in one direction, a complex collection of thin steel washers that flex when pushed by oil pressure. When the coilover compresses, oil flexes the compression shims open & pushes through the piston holes to the other side, creating friction & heat. If the damper is pushed harder, it flexes further, allowing more fluid through. After a bump, the coil spring pushes the bike back to ride height so oil is squeezed back through the piston & rebound shims to the other side, absorbing more energy.
Without these check washers or one way valves, the oil wouldn't be directed to flow through the piston, making the shims deflect and generating damping.
Your motorbike's internal valve shims come in a huge range of diameters & thicknesses, with the comp stack on one side & reb on the other, and are arranged in a very specific order to create the right damping characteristics. The piston and it's shim stacks are then attached to the end of the shock shaft using a locknut.
To make sure the suspension fluid can only flow through the correct holes, rubber o-rings and a teflon coated bush (or a soft PTFE band) seal around the outer diameter. We also sell complete shock pistons with the seals already installed.
It's all basic science but there are thousands of different variables that change the way it feels - our shim equivalence calculator can help - and that's why experienced tuners test and refine all that data on a suspension dyno. If you want to know more you can check out our suspension mods for your budget article to better understand how to approach tuning based on price vs performance, or watch Teknik's suspension guru Nick rebuild and revalve a shock.
Your motorcycle front fork has a thick metal disc with machined passages flowing between both flat sides, this is referred to as the piston or valve.
Stacked on one or both sides of this piston are the valving shims, and the check plates or shims to only allow the oil to flow through the piston and make the shims deflect in one direction, a complex collection of thin steel washers that flex when pushed by oil pressure. When the coilover compresses, oil flexes the compression shims open & pushes through the piston holes to the other side, creating friction & heat. If the damper is pushed harder, it flexes further, allowing more fluid through. After a bump, the coil spring pushes the bike back to ride height so oil is squeezed back through the piston & rebound shims to the other side, absorbing more energy.
Without these check washers or one way valves, the oil wouldn't be directed to flow through the piston, making the shims deflect and generating damping.
Your motorbike's internal valve shims come in a huge range of diameters & thicknesses, with the comp stack on one side & reb on the other, and are arranged in a very specific order to create the right damping characteristics. The piston and it's shim stacks are then attached to the end of the shock shaft using a locknut.
To make sure the suspension fluid can only flow through the correct holes, rubber o-rings and a teflon coated bush (or a soft PTFE band) seal around the outer diameter. We also sell complete shock pistons with the seals already installed.
It's all basic science but there are thousands of different variables that change the way it feels - our shim equivalence calculator can help - and that's why experienced tuners test and refine all that data on a suspension dyno. If you want to know more you can check out our suspension mods for your budget article to better understand how to approach tuning based on price vs performance, or watch Teknik's suspension guru Nick rebuild and revalve a shock.
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