
BMW M2, M3 or M4
Do I Need to Replace the Crank Hub
If you own a BMW M2 Competition, M3 F80, or M4 F82/F83, chances are you’ve heard the phrase “crank hub issue” mentioned in forums, videos or tuning groups. But what exactly is the crank hub, and why are so many people replacing it?
Let’s break it down in plain terms.
1. What Is the Crank Hub?
The crank hub is a crucial part of your engine — it connects the crankshaft (which powers your engine’s movement) to other vital parts like the timing system and harmonic balancer. Think of it as the engine’s central “pulley” that keeps everything moving in sync.
In BMW’s S55 engine, used in the M2 Competition, M3, and M4, this part was designed using a multi-piece hub without a locking key or pin — meaning it relies purely on tight tolerances and friction to stay in place.
2. Why Is This a Problem?
Under normal driving, the factory crank hub can function fine. But when the engine is pushed harder — either through tuning, spirited driving, or track days — that friction-only design can fail.
Here’s what can go wrong:
- The crank hub spins slightly out of sync with the crankshaft.
- This throws off the engine’s timing — meaning pistons and valves are no longer working in perfect rhythm.
- You may experience engine misfires, warning lights, or even complete engine failure in serious cases.
It’s a bit like your watch suddenly skipping seconds — not a big deal once, but disastrous if it keeps happening.
3. Who Should Be Concerned?
You should seriously consider replacing your crank hub if:
✅ You’ve remapped your engine or added performance upgrades
✅ You drive your M car on track days or enjoy spirited driving
✅ You want to prevent costly engine repairs down the line
✅ You’re planning a performance build or want peace of mind
Even if your car is stock, replacing the crank hub is a popular preventative upgrade — especially for owners who plan to hold onto the car long term.
4. What’s the Solution?
At Nevlock, we recommend upgrading to a one-piece crank hub solution — specifically designed to eliminate the slipping issue by using a single solid unit that locks into the crankshaft. Some designs even use pins or keys to physically prevent slippage.
Benefits of the One-Piece Crank Hub:
🔒 No more slipping — it stays locked in place under high stress
🧩 Engine stays in perfect timing, reducing wear and risk
🛡️ Protects against catastrophic failure
🛠️ Ideal for tuned or hard-driven cars
🏁 Track-proven reliability
5. Is It Easy to Replace?
It’s not a beginner job — replacing the crank hub involves removing the front of the engine, re-timing the chain system, and fitting the new hub with precision. For that reason, most people get it done by a professional workshop.
However, it’s a one-time job — fit it right, and you’ll never have to worry about it again.
6. Peace of Mind for Your M Car
Replacing your crank hub might not be the most exciting upgrade — but it’s one of the most important, especially if you’re tuning or tracking your BMW.
We stock high-quality one-piece crank hubs compatible with the S55 engine. These are the same products trusted by performance garages and track car builders.
Kits available with optional gaskets, bolts and tools — contact us if you need help choosing.