Parts for your 2018 Holden Commodore-Bump stops

2018 Holden Commodore bump-stops — what they do and when to replace them

Technical sources confirm the 2018 Holden Commodore (ZB, based on Opel Insignia B) is equipped with bump-stops. GM Global Service Information refers to a “strut jounce bumper” in the front MacPherson strut assembly and a “rear shock absorber jounce bumper.” GM/ACDelco and Monroe parts catalogues list protection kits (dust boot with jounce bumper) specifically for this model, across FWD and AWD variants. So, bump-stops are absolutely relevant on the 2018 Holden Commodore.

The bump-stop (aka jounce bumper) is the quiet achiever of the Commodore’s suspension. It’s a dense, microcellular polyurethane foam piece that acts like a secondary spring at the end of suspension travel. When the road gets lumpy, the car’s strut or shock compresses the bump-stop progressively, protecting the damper and body from hard metal-to-metal contact. On the ZB Commodore’s MacPherson-strut front and multi-link rear setups, the bump-stops are tuned to curb harsh bottoming, keep the tyres planted, and preserve steering precision under heavy loads, towing, or big hits on rough Kiwi and Aussie roads.

Because they live inside the wheel well and often inside the strut boot, they can quietly degrade with age, oil exposure, UV, or repeated bottoming. Cracked or crumbling bump-stops reduce travel control and can make the car feel crashy. As part of routine servicing, it’s smart to have them inspected whenever shocks/struts are checked—typically every 40,000–60,000 kilometres, or any time the damper is removed.

Replacement is straightforward when pairing new shock absorbers or struts—best practice is to renew the bump-stops and dust boots together, in axle pairs, using the correct parts for your specific trim (including FlexRide/Adaptive variants and VXR). Keeping the boots intact matters, because they shield the bump-stop and damper rod from grit that accelerates wear. After any front strut work, a wheel alignment is recommended to keep tyre wear tidy and steering feel on point.

Common signs they’re due:

• Thuds or a harsh “bottoming” feel on big bumps or speed humps
• Visible cracking, collapse, or crumbling foam when the boot is pulled back
• Oil-soaked bump-stops from a leaking damper

If lowering the vehicle, don’t trim bump-stops unless the spring or damper manufacturer specifically instructs it—using purpose-made, shorter progressive stops is the safer play. For towing or frequent heavy loads, ensuring healthy bump-stops helps maintain stability and stops the car from smashing into full bump travel. Quality OE-equivalent kits from GM/ACDelco or reputable aftermarket suppliers will keep the Commodore riding right for years.

Do all 2018 Holden Commodores have bump-stops?
Yes. All body styles and trims—Liftback, Sportwagon, Tourer, FWD, AWD, and VXR—use jounce bumpers at the front and rear. They’re integral to the strut/shock assemblies and are considered a normal wear component.

How often should bump-stops be replaced?
There’s no strict interval, but they should be inspected every 40,000–60,000 km and replaced if cracked, crumbling, oil-soaked, or when fitting new shocks/struts. Age, rough roads, and lowered springs can increase wear.

Can bump-stops be upgraded or trimmed for lowered setups?
Use the correctly matched sport or short bump-stops supplied with your springs or dampers. Avoid cutting them unless the manufacturer says so—maintaining proper progressive engagement and remaining travel is crucial for ride and handling.