Cryo-Treated S54 Exhaust Hub with Tabs - E46 M3, MZ3, Z4M
Stronger and more durable exhaust hub to resist failures
The tabs on the exhaust cam hub drive the oil pump for the S54 VANOS unit. They act like pins that get inserted into a disc on the back of the VANOS unit. Unfortunately, the holes on the disc are too large which leads the tabs to vibrate inside the holes and eventually crack and break off. Broken exhaust hub tabs on the S54 will cause the VANOS to stop working and if one of the broken tabs ends up in the valvetrain, timing chain, or the oil pump chain, it could be game over for your engine.
This is a stock exhaust hub that has been cryogenically treated to remove residual stresses and improve wear resistance. It's much stronger than the original and will resist fatigue cracks far better.
To further reduce the chance of stress fractures on the tabs, the Dr. VANOS rebuilt VANOS unit has new holes drilled into the oil pump disc that are a tighter fit these tabs than the original holes.
This exhaust hub is sold on an exchange basis and a $50 core charge is included in the price. This core may be refunded to you upon the return of your good, original hub.
E46 (99-05) > M3
E36/7 / E36/8 Z3 (96-02) > Z3 M - S54
E85 / E86 Z4 (03-08) > Z4 M