OVERVIEW
M16 fastener for the outer drive axle
Genuine VW/Audi 4B0-407-643-A passes through the wheel hub and bearing into the outer drive axle. Correct fastener selection maintains the clamped axle-to-hub connection required by the original assembly.
The A suffix identifies the M16 version. Confirm the thread and VIN split carefully when servicing older applications, because a visually similar M14 bolt is also used in this part family.
Technical details
- Complete factory number: 4B0-407-643-A.
- Factory specification: M16 × 1.5 × 72 drive axle shoulder bolt.
- Design: internal hex drive, flanged seating face and partially threaded shank.
- Quantity supplied: one individual drive axle shoulder bolt.
Thread diameter and pitch, effective bolt length and the seating arrangement must all agree with the axle and hub. A replacement axle or previously changed hub can alter the required hardware, so inspect the installed components as well as the vehicle identification.
Common reasons to replace
- The axle or wheel bearing repair requires a replacement retaining bolt.
- The internal hex drive is damaged and no longer accepts the tool securely.
- Threads, shoulder or seating face have suffered damage or substantial corrosion.
Inspect the axle's internal thread and the hub seating surfaces before fitting new hardware. A new bolt cannot correct damaged axle threads or an improperly seated wheel bearing.
Vehicle fitment
Observe the VIN cutoffs and the M16 thread requirement below. Match the original 4B0-407-643-A fastener before ordering.
| Vehicle | Model years | Engine | Configuration | Application restrictions |
|---|---|---|---|---|
| Audi A4 | 2001 | 1.8L turbo gasoline, AWM | B5 FWD / quattro | From VIN 8D-1-050001; original M16 outer axle bolt position. |
| Volkswagen Passat | 2001–2005 | 1.8L turbo / 2.8L V6 gasoline | B5 / B5.5 FWD sedan / wagon | From VIN 3B-1-050001; original M16 outer axle bolt position. |
| Volkswagen Passat | 2002–2004 | 4.0L W8 gasoline | 4MOTION sedan / wagon | Original M16 outer axle bolt arrangement; match full part number. |
| Audi A4 | 2005–2008 | 2.0L turbo gasoline | B7 sedan; FWD / quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi A4 / A4 Avant | 2005–2008 | 3.2L V6 gasoline | B7 sedan / Avant; quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi A4 Avant | 2005–2008 | 2.0L turbo gasoline | B7 wagon; quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi A4 Cabriolet | 2007–2009 | 2.0L turbo / 3.2L V6 gasoline | B7 convertible; 2.0L FWD / quattro, 3.2L quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi S4 | 2005–2008 | 4.2L V8 gasoline | B7 sedan / Avant; quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi S4 Cabriolet | 2007–2009 | 4.2L V8 gasoline | B7 convertible; quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi RS4 | 2007–2008 | 4.2L FSI V8 gasoline | B7 sedan; quattro | Original M16 outer axle/hub bolt only; match installed assembly. |
| Audi RS4 Cabriolet | 2008 | 4.2L FSI V8 gasoline | quattro; 6-speed manual | Rear axle-to-hub retaining bolt; M16 × 1.5 × 72. |
| Audi RS6 | 2003 | 4.2L twin-turbo V8 gasoline | C5 sedan; quattro | Front axle-to-hub retaining bolt; original M16 connection. |
Installation guidance
Follow the exact axle and wheel bearing service procedure for the vehicle. Observe the specified supported-vehicle condition, initial tightening, final torque and any angle stage; do not substitute a generic fastener torque.
Complete the axle installation checks and ensure that the wheel bearing has been loaded and secured as required before moving the vehicle. Replace other disturbed fasteners when the repair procedure requires it.
Ordering information
Supplied as one individual Genuine VW/Audi 4B0-407-643-A bolt. Verify the quantity and axle position needed for the repair.