Genuine Mazda Front Lower Ball Joint & Rear Lateral Arm Locking Nut
Replacement Genuine Mazda suspension locking nut for all Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models.
This large flange nut is used at several safety-critical suspension connections. It secures the front lower wishbone ball joint to the front hub carrier and is also used where the rear lateral suspension arms connect to the rear knuckle.
The locking feature helps resist loosening caused by suspension movement and road vibration, while the integrated flange provides the correct seating area against the adjoining component.
Six nuts are used across the confirmed positions on each vehicle. This comprises two front lower ball-joint applications and four rear lateral-arm applications. This listing supplies one Genuine Mazda nut.
Important application note: This is the larger of the suspension nuts used around the NC knuckle assemblies. Several similar-looking Mazda nuts are fitted elsewhere and should not be assumed to be interchangeable.
- Part type: Suspension flange locking nut
- Common names: Ball-joint nut / lateral-arm nut / suspension lock nut
- Installation area: Front and rear suspension
- Front position: Lower wishbone ball joint to front hub carrier
- Rear position: Rear lateral suspension arms to rear knuckle
- Side application: Left and right
- Quantity fitted at front: 2 per vehicle
- Quantity fitted at rear: 4 per vehicle
- Total confirmed quantity per vehicle: 6
- Quantity supplied: 1 nut
- Ball joint included: No
- Suspension arms included: No
- Associated bolts or studs included: No
- Brand: Genuine Mazda
- Part No.: 9YB04-1404
- Mazda catalogue format: 9YB0-41-404
- MX-5 fitment: Mk3, Mk3.5 and Mk3.75 NC models
Typical reasons for replacement:
- Original locking nut removed during suspension repairs
- Locking feature weakened through previous use
- Threads damaged, corroded or cross-threaded
- Flange or seating face distorted
- Hexagon rounded during removal
- Original nut seized onto the ball-joint stud or suspension bolt
- Lower wishbone or rear lateral arm being replaced
- Incorrect general-purpose nut previously installed
Quantity advice: One nut is required at each individual connection. Six are used across all confirmed front and rear positions, but this listing supplies one nut per order quantity.
Fitment advice: Confirm the suspension position before ordering. This is the larger nut used at the front lower ball joint and rear lateral-arm-to-knuckle connections. It is not the smaller nut used at other NC steering and suspension joints.
Replacement advice: Locking suspension nuts should be renewed after removal where required by the Mazda workshop procedure. Do not replace this component with a standard non-locking nut.
Thread inspection: Inspect the corresponding ball-joint stud, suspension bolt or arm fixing before installation. A new nut will not repair damaged, stretched or cross-threaded male threads.
Seating inspection: Ensure the nut flange and mating surface are clean, flat and free from heavy corrosion or burrs. The nut must seat squarely against the adjoining component.
Tightening advice: Tighten the nut using the Mazda procedure and torque specification applicable to its exact installation position. The required specification may differ between the front ball-joint and rear lateral-arm connections.
Alignment advice: A four-wheel alignment check is recommended after replacing suspension arms, ball joints or other components that can affect suspension geometry.
Other items to inspect: Check the associated ball-joint dust boot, suspension-arm bushes, rear knuckle bushes, mounting bolts and equivalent hardware on the opposite side.
Useful tools / consumables: Correct-size socket or ring spanner, breaker bar, calibrated torque wrench, ball-joint separator where required, penetrating fluid and suitable vehicle lifting and supporting equipment.
Difficulty guide: DIY Difficulty: Moderate. Access and removal difficulty depend on the installation position and the condition of the original suspension hardware.
Why Genuine Mazda? Genuine Mazda suspension hardware matches the original thread, flange dimensions and locking specification. Correct fasteners are particularly important at load-bearing ball-joint and suspension-arm connections.
What’s in the box: One Genuine Mazda front lower ball-joint and rear lateral-arm locking nut, part number 9YB04-1404.
Installation notes: Raise and support the vehicle safely before dismantling the suspension. Clean and inspect the corresponding threads, then start the new nut by hand to prevent cross-threading. Confirm that the ball-joint taper or suspension-arm connection is fully seated before tightening. Apply the Mazda tightening procedure for the exact installation position and check all disturbed suspension components before road use.
| Make | Model | Sub Variant | Chassis / Code | Years | Power (PS) | Engine Codes | Fuel | Transmission | Notes |
|---|---|---|---|---|---|---|---|---|---|
| Mazda | MX-5 | Mk3 NC1 – 1.8 / 2.0 / 2.0 Sport | NC / NCEC | 2005–2009 | 126–160 | L8-VE / LF-VE | Petrol | Manual / Automatic | Used at both front lower wishbone ball joints and the rear lateral-arm-to-knuckle connections; six confirmed applications per vehicle; sold individually |
| Mazda | MX-5 | Mk3.5 / Mk3.75 NC2/NC3 – 1.8 / 2.0 / 2.0 Sport | NC / NCEC | 2009–2015 | 126–160 | L8-VE / LF-VE | Petrol | Manual / Automatic | Used at both front lower wishbone ball joints and the rear lateral-arm-to-knuckle connections; six confirmed applications per vehicle; sold individually |
| Vehicle Manufacturer | OEM Reference Number |
|---|---|
| Mazda | 9YB04-1404 |