Table of contents
In this suspension upgrade guide, we'll explain how to unlock more handling performance from the BMW G29 Z4 Roadster.
The third-generation Z4 is based on the same architecture as Toyota's A90 Supra. This means it suffers from the same problems during fast driving: muted steering feel, mid-corner understeer, rear instability and excessive body roll.
However, all these issues can be solved with bolt-on aftermarket upgrades from Suspension Secrets. Not only will these Z4 suspension upgrades increase precision, control and feedback, they will maintain the car's excellent day-to-day usability.
G29 Z4 Suspension & Handling Overview
Unveiled in the summer of 2018, the G29 Z4 came in three flavours. The sDrive20i and sDrive30i packed a two-litre, turbocharged four-cylinder producing 197hp and 258hp respectively. The range-topping Z4 M40i was gifted a three-litre, turbocharged straight-six developing 387hp.
A midlife refresh in 2023 tweaked the Z4's appearance but the engine line-up went unchanged; a six-speed manual gearbox option was added to the M40i transmission list.
The G29 Z4 suspension is broadly the same as the A90 Supra's, however the BMW is equipped with a more conservative design of lower front control arms, severely limiting camber and caster angle. The front axle employs MacPherson struts while the rear axle is multi-link; adaptive dampers are equipped all-round.
Z4 Suspension Limitations
When driven hard on the road or track, the G29 chassis is found lacking in a number of ways.
Common criticisms of the G29 Z4 chassis:
- Lack of steering and chassis feedback
- Firm ride quality does not translate to sharp handling
- Significant rear instability during compressions and unloading
- Rear toe adjustment compromised by the addition of more negative camber
- Excessive body roll during fast cornering
The good news is these handling issues can be resolved with bolt-on Z4 suspension upgrades from Suspension Secrets.
Common Handling Problems (And How To Fix Them)
The G29 Z4 suspension upgrades detailed in this guide allow you to achieve the following…
G29 Z4 Suspension Fixes
1. Increase front camber and reduce understeer
2. Increase steering weight and feedback
3. Lower the centre of gravity and reduce body roll
4. Improve rear axle kinematics and increase traction and stability
5. Improve overall ride quality
With these changes implemented, we can confirm the G29 Z4 will offer a much more inspiring driving experience. It will turn into corners more eagerly and and also generate more grip mid-turn with less understeer. The following suspension upgrades will also reduce rear axle squirming under braking and throttle application, boosting driver confidence.
BMW G29 Z4 Suspension Geometry & Alignment Setup (Top Tip)
A full suspension geometry alignment is essential after installing new suspension parts. By correctly adjusting camber, toe, and caster (where available), alignment ensures you maximise grip, stability, and tyre life.
Benefits of a Z4 Geometry Setup
- Sharper steering response
- Increased cornering grip
- Improved rear traction
- Enhanced braking stability
A professional alignment is the single most cost-effective handling upgrade you can make.
Essential G29 Z4 Suspension Upgrades
This section covers essential BMW G42 M240i suspension upgrades that serve as a great first step to unlocking dramatically improved handling improvements. These upgrades form the basis of the Suspension Secrets Kinematics Kit and are the ideal starting point for both road and track-focused builds.
Adjustable Camber & Caster Plates
In standard form, the G29 Z4 does not offer enough front camber adjustment to achieve effective Fast Road or Track suspension geometry settings. This makes it difficult to significantly reduce the amount of understeer experienced at fast cornering speeds. The G29 Z4 adjustable camber plates from Suspension Secrets allow additional negative camber to be dialled into the front axle, significantly improving front-end grip and steering feel.
Why G29 Z4 Camber Plates Matter
- Reduce understeer
- Sharpen turn-in
- Increase steering feedback
- Improve tyre wear on track
Suspension Secrets camber plates also increase caster angle, providing dynamic camber gain as steering lock is applied. As well as further improving turn-in response, caster also enhances steering feel and weighting. An added bonus is that Suspension Secrets camber plates are fully compatible with aftermarket coilovers that use the OEM top mounts.
Solid Front Control Arm Bushes
One of the most significant weaknesses of the G29 chassis is the front bushes.
BMW fitted soft rubber, oil-filled bushes in the front lower control arms. Under braking and cornering loads, these bushes flex. That deflection changes suspension geometry dynamically, which is why the car can feel slightly vague under heavy braking or initial turn-in.
Replacing them with Suspension Secrets Solid Front Control Arm Bushes eliminates that unwanted movement.
Solid Bushes Improve
- Braking stability
- Steering precision
- Consistency under load
- Front end confidence
The steering feels more direct. The car holds its geometry instead of moving around on soft rubber. For fast road cars, this is one of the most worthwhile upgrades you can make.
Adjustable Rear Toe Arms
With front-end grip and response improved, it's time to turn attention to the Z4's rear axle.
During extensive road and track testing, we identified rear toe instability as the main cause of rear-end nervousness on corner exit. This is caused by the arm's factory-installed soft rubber bushes.
Suspension Secrets Adjustable Rear Toe Arms offer:
- Greater adjustment range than OEM arms
- Independent optimisation of camber and toe
- Solid mounting to eliminate flex/increase stability under load
- Improved straight-line traction.
Unlike the rubber‑bushed factory arms, our solid-mounted toe arms maintain consistent geometry during acceleration and high-speed cornering.
Suspension Package Explained
The G29 Z4 suspension upgrades described above are ideal for fast road cars that also take part in trackdays.
If you are looking to unlock even more handling performance from your BMW on circuit, you will need a comprehensive suspension upgrade package. Thankfully, Suspension Secrets manufactures the perfect kit...
Full Kinematics Kit
The G29 Z4 Suspension Secrets Full Kinematics Kit is the ultimate suspension upgrade for track driving. Equipped with this comprehensive and cost-effective package, your Z4 will boast fully adjustable suspension and solid bushes in place of the soft OEM rubber bushes that flex during hard driving.
G29 Z4 Kinematics Kit includes:
- Suspension Secrets Adjustable Rear Toe Arms
- Suspension Secrets Adjustable Camber Arms
- Suspension Secrets Adjustable Rear Traction Arms
- Suspension Secrets Solid Rear Control Arm Bushes
- Suspension Secrets Solid Front Offset Caster Bushes
All Suspension Secrets products have a Lifetime Warranty (including the bearings) and can be shipped internationally free of charge.
BMW G29 Z4 Suspension FAQs
Why does the G29 Z4 understeer when pushed hard?
BMW sets up the car with conservative camber and road-focused geometry from the factory. This limits front-end grip at higher cornering loads, leading to predictable but noticeable understeer at the limit.
What causes the vague steering and instability under braking?
Soft, oil-filled rubber bushes in the front control arms flex under load. This movement alters the suspension geometry dynamically, reducing steering precision and braking stability.
Why can the rear feel nervous on corner exit?
The factory rear toe arms use compliant rubber bushes, allowing toe changes under acceleration. This affects rear stability and traction when applying power hard.
What are the most effective first upgrades?
Adjustable camber plates, solid front control arm bushes and adjustable rear toe arms deliver the biggest improvements in grip, steering feel and stability.
Is a geometry alignment really necessary after fitting parts?
Absolutely. A professional suspension alignment ensures camber, toe and caster are correctly set, maximising grip, stability, tyre life and overall handling performance.
Developed and manufactured by Suspension Secrets, these G29 Z4 suspension upgrades unlock a new level of handling performance.