How Coilover Ride Height Actually Works

Posted by Dežru Suspension Engineering on Nov 23rd 2025

How Coilover Ride Height Actually Works (and Why Dežru Doesn’t Use Adjustable Hub Brackets)

By Dežru Suspension Engineering

Why Ride Height Matters

Ride height is one of the most critical settings on any coilover system. It affects:

Center of gravity
Suspension geometry
Roll behavior
Bump/ droop travel
Ride comfort
Alignment and tire wear

But not all coilovers adjust ride height the same way — and the method dramatically affects how the suspension behaves.

At Dežru, we design our Subaru, Toyota GR Corolla, Euro, and exotic-platform coilovers using a fixed-length shock assembly with height adjustments made ONLY through the spring perch and helper spring.

This is the same approach used by high-end motorsport dampers, and it provides more consistent performance without compromising stroke or valving behavior.

Let’s break down how it works.

Two Types of Ride Height Adjustment Used in Coilovers

There are only two real ways coilovers adjust height:

1. Adjustable Hub Bracket (Threaded Lower Mount)

This is the method used on most aftermarket coilovers:

You thread the shock body up or down inside the lower mount
This physically changes the shock’s overall length
Ride height changes without affecting spring preload

But there’s a downside:
Changing shock length also changes bump travel, droop travel, and valving position in the stroke.
It can lead to:

Bottoming out
Harshness
Premature failure
Lost travel
Dead zones in damping

This is why high-end suspensions (Moton, Öhlins TTX, AST Motorsport, Reiger, EXE-TC, etc.) avoid this system.

2. Fixed-Length Shock (Dežru Method)

This is the method Dežru uses across Spec-S, Spec-R, and Spec-RS:

The shock body + shaft length is fixed and optimized
The lower mount/hub bracket is also fixed
Ride height changes are made only with the spring perch + helper spring

This keeps bump/droop travel exactly where the valving is engineered to work best.

Why we use this design:

✔ More consistent damping behavior
✔ Full suspension stroke preserved
✔ Lower internal temperatures
✔ Better control over mid-stroke support
✔ Correct geometry for daily, track, and rally use

No matter how much height adjustment you dial in, the shock internals always operate in their ideal range.

So How Does Ride Height Adjust on a Fixed-Length Coilover?

With no adjustable hub bracket, the adjustment happens here:

1. Spring Perch (the lower spring seat)

– Threading the spring perch up = raises the car
– Threading the spring perch down = lowers the car

This changes spring position relative to the chassis, which changes ride height.

2. Helper Spring (on all Dežru fixed-length models)

The helper spring ensures:

Zero preload at full droop
Full contact between spring + perch
Smooth transition into loaded travel

The helper spring collapses at static ride height, so it does not affect stiffness — it affects only ride height and droop control.

Important: Preload ≠ Ride Height

This is the biggest misconception in suspension setup.

On Dežru fixed-length assemblies:

✔ Changing preload does NOT significantly change ride height

Preload affects:

Initial movement
Ride harshness
How quickly the car settles

But ride height is determined by:

Perch position
Spring free length
Motion ratio of the suspension arm
Vehicle weight distribution

This is why Dežru ships every kit with:

Starting perch positions
Recommended preload settings
Helper spring install positions

How to Set Ride Height Correctly (Dežru Method)

Here’s the proper method for fixed-length suspensions:

1. Set each perch to the recommended baseline

This gets the vehicle close to our engineered height.

2. Install the coilovers and put the car on the ground

Bounce the suspension or roll the vehicle to settle it.

3. Measure ride height at the pinch weld OR wheel arch

Do not use perch measurements side-to-side.

WHY?

Because vehicle weight distribution is not symmetrical.

Even at factory height:

Engine is offset
Driver weight sits on the left
Fuel tank is off-center
Battery, exhaust, and drivetrain components bias the car

Measuring at the body ensures true height.

4. Adjust the spring perch

Raise perch = higher ride height
Lower perch = lower ride height

5. Match the look + function you want

Daily driving, track, rally, or off-road each benefit from different height ranges.

6. Get an alignment after height changes

Critical for handling and tire wear.

Why Dežru Chooses the Fixed-Length Design

Performance-first reasons:

1. Prevents loss of suspension stroke
Threading a shock into a lower mount reduces bump travel — not acceptable for performance.

2. Keeps valving in the correct operating window
Our pistons, bleed circuits, and shim stacks are tuned to specific shaft positions.

3. Improves reliability and heat control
No need to run excessively short bodies or bottom out against internal components.

4. Motorsports-proven architecture
Rally and endurance dampers nearly always use fixed-length construction.

Who Benefits Most From This Design?

Owners who want:

predictable handling
better traction
improved mid-corner grip
proper droop travel
consistent behavior over bumps
reduced shock heat
OEM+ comfort with performance capability
track neutrality and stability

This matches Subaru WRX/STI, GR Corolla, BMW, Audi, and Porsche applications where geometry and stroke are critical.

Summary

Dežru Ride Height Adjustment = ONLY the Spring Perch + Helper Spring

No adjustable hub bracket.
No changing shock length.
No sacrificing travel.
No valving inconsistencies.

This gives you:

✔ True performance geometry
✔ Maximum usable travel
✔ Better heat control
✔ More predictable damping
✔ Simplified, reliable setup
✔ Motorsport-grade consistency

This approach is used at the highest levels of suspension engineering — and it’s the foundation of every Dežru kit.