Porsche & VW Part 021 109 015 M – What It Is and Which Vehicles Use It

If you are restoring an air-cooled Volkswagen or Porsche, you will eventually come across part numbers like 021 109 015 M. This number refers to a genuine OEM piston pin (also called a wrist pin) used in many classic air-cooled engines. Understanding what this part is, which vehicles use it, and how to verify you have the correct one can save you time and prevent engine assembly issues. This article covers everything you need to know about part 021 109 015 M, including its dimensions, compatible models, and practical buying advice.

What Is Part Number 021 109 015 M?

Part 021 109 015 M is a factory piston pin produced for air-cooled Volkswagen and Porsche engines. Piston pins connect the piston to the connecting rod and allow the piston to pivot as it moves up and down the cylinder. This specific pin is a press-fit design, meaning it is installed by pressing it into the connecting rod small end while the pin floats in the piston. The "M" suffix denotes a manufacturing revision; later versions (like 021 109 015 M) are interchangeable with earlier ones and may have slight dimensional or material improvements.

Key specifications of the 021 109 015 M piston pin:

Length: approximately 66 mm
Outer diameter: 22 mm
Wall thickness: about 4 mm
Material: case-hardened steel
Weight: around 80 grams

These dimensions are standard for many 1.2L, 1.3L, and 1.6L air-cooled engines produced by Volkswagen and Porsche from the 1950s through the 1970s.

Applications and Vehicle Compatibility

The 021 109 015 M piston pin was used across a wide range of Volkswagen and Porsche models that share the same basic engine architecture. It is important to confirm that your specific engine uses this pin, as later engines (like the 2.0L Type 4) use a different pin.

Volkswagen Models

Volkswagen Beetle (Type 1) – All 1200cc, 1300cc, and 1500cc engines built before 1975. Also used in the 1600cc dual-port engines up to the mid-1970s.
Volkswagen Bus (Type 2) – Early split-window and bay-window buses with 1.5L and 1.6L engines.
Volkswagen Ghia – Same powertrain as the Beetle, so the same piston pin applies.
Volkswagen Thing (Type 181) – Uses the 1.6L engine, compatible with this pin.
Volkswagen Type 3 – Fastback, Squareback, and Notchback with 1500cc and 1600cc engines (except the later fuel-injected versions that may have a different pin).

Porsche Models

Porsche 356 – Many engines in the 356 series, including the 1600 Super (616/15) and 1600 Normal (616/1), use the 021 109 015 M pin. However, some 356C and SC models with the 1720cc engine may require a slightly different pin; always verify with your engine code.
Porsche 912 – The 912 used a 1.6L flat-four derived from the VW Type 4 engine. That engine actually uses a different pin (22mm diameter but longer). The 021 109 015 M is not correct for the 912. So caution: despite the shared brand, the 912 engine is not the same as the 356/Beetle engine.
Porsche 914 – The 914/4 with the 1.7L or 1.8L VW-derived engine does not use this pin. The 914/6 has a flat-six, obviously different. So this part is typically not for the 914.

Important: Always check your engine code and original part numbers before ordering. A quick search of forums like TheSamba.com or Pelican Parts can confirm if your specific variant uses 021 109 015 M.

How to Identify the Correct Piston Pin

Piston pins can look very similar, especially after decades of aging and rust. Here’s how to confirm you have the right one:

Measure the diameter – Use a caliper to measure the outside diameter. It should be exactly 22.00 mm (0.866 inch). A tolerance of +/- 0.005 mm is acceptable. If you get 21.95 mm or 22.05 mm, it may be a different pin.
Measure the length – The overall length should be about 66 mm (2.60 inches). Some aftermarket pins are slightly longer or shorter; if it’s too long, it may hit the cylinder wall; too short and it may not fully engage the circlips.
Check the end finish – Original VW/Porsche pins have a chamfered edge and a smooth, ground surface. Aftermarket pins sometimes have a rougher finish or sharp edges.
Look for part number stamps – Most genuine pins are stamped with the part number (021 109 015 or 021 109 015 M) on the outer surface. If the number is missing or hard to read, rely on dimensions.
Visual inspection for wear – Any scoring, pitting, or discoloration means the pin should be replaced. This part is relatively inexpensive, so it’s better to buy new than to reuse a worn pin.

Buying Tips for Part 021 109 015 M

When shopping for this piston pin, you will find both genuine OEM and aftermarket options. Here’s what to consider:

OEM vs. Aftermarket – Genuine VW/Porsche parts (still available from dealers or specialist suppliers) are made to original specifications. Aftermarket pins from brands like Mahle, KS, or Glyco are also high-quality and often cost less. However, some low-cost generic pins may have incorrect dimensions or inferior metallurgy.
Set or individual – The 021 109 015 M is sold individually but usually you need four pins (one per piston). Some suppliers sell a set of four with part number AP-021109015M. Check that the set is complete.
Where to buy – Authorized VW/Porsche parts dealers, classic car parts specialists (like Pelican Parts, JBugs, or others), and local engine rebuild shops are reliable sources. Avoid unknown sellers on general marketplaces; counterfeits exist.
Price range – Expect to pay between $8 and $15 per pin for a quality aftermarket version, and $12 to $20 for genuine OEM. A full set of four should be under $80.
Also replace circlips – When you replace the piston pin, always install new circlips (retaining rings) that hold the pin in the piston. The circlip part number is often 021 105 317 or similar. A circlip failure can destroy an engine.

Final Recommendation

If your air-cooled VW or Porsche engine uses part 021 109 015 M, purchasing a set of four quality aftermarket pins from a reputable classic car parts supplier is the most practical route. They will meet OEM dimensions and material specifications at a lower cost than genuine VW parts. Just verify the pin length and diameter with your connecting rod and pistons before installation. For ultra-critical builds (e.g., high-performance or concours restoration), genuine OEM pins are still available and worth the extra cost for peace of mind. Always test fit the pin in the connecting rod – it should slide in with light hand pressure and not be loose.

By understanding exactly what 021 109 015 M is and following the identification tips above, you can avoid buying the wrong part and keep your classic engine running smoothly.