Progressive Suspension Shock Part Number: How to Find the Right One

Finding the correct progressive suspension shock part number is essential for replacing or upgrading your motorcycle’s rear suspension. Whether you ride a Harley, cruiser, touring bike, or off-road machine, using the right part ensures proper fit, performance, and safety. This guide explains how to identify your current shock, decode progressive suspension part numbers, and find a compatible replacement without guesswork.

Why the Part Number Matters

Progressive Suspension manufactures a wide range of shocks for different makes, models, and riding styles. The part number encodes critical details like spring rate, ride height, reservoir type, and damping adjustability. Installing the wrong shock can lead to poor handling, bottoming out, or excessive stiffness. By matching the exact part number, you preserve the intended suspension characteristics.

Where to Find Your Current Part Number

Before searching for a replacement, locate the part number on your existing shock. It’s typically stamped or printed on the shock body, often near the lower mount or on the reservoir. Look for a code starting with a letter or number sequence, such as 412-1234 or 444-xxxx. On older shocks, the number may be faded; a flashlight and a clean rag can help.

If you cannot read the number, check your motorcycle’s service manual, or look for any aftermarket documentation from a previous owner. Another option is to measure the shock’s eye-to-eye length, spring diameter, and stroke, then match those specs to a replacement part number.

Decoding Progressive Suspension Part Numbers

Progressive uses a consistent numbering system. The first three digits often identify the shock family. For example:

• 412: Standard emulsion shocks for cruisers
• 444: Premium piggyback reservoir shocks
• 877: Higher-end adjustable shocks for touring and performance

The following digits specify length, spring rate, and valving. For instance, 412-1240 might indicate a 12-inch shock with a medium spring rate. However, exact tables vary by model year and application. It’s best to verify using an official cross-reference guide from Progressive Suspension or your dealer.

How to Find a Replacement Part Number

If you have the original part number, enter it into Progressive Suspension’s website or a trusted dealer’s search engine. You can often get a supersession number if the original has been discontinued. Many online retailers also list fitment charts by make and model.

Using the Motorcycle’s Make and Model

If you don’t have the original number, start with your bike’s year, make, and model. Progressive provides application-specific listings. For example, a 2018 Harley-Davidson Street Glide commonly uses a 444 series shock. You can narrow down the part number by selecting your bike from the manufacturer’s catalog or using an online parts finder.

Cross-Referencing by Dimensions

Measure the existing shock’s center-to-center length (with no load), spring diameter (inner and outer), and stroke. Then compare these numbers against the specifications listed for each progressive part number. This is especially useful for custom builds where the bike’s model isn’t in standard charts.

Common Progressive Suspension Shock Part Numbers

Here are a few typical part numbers to illustrate the format:

• 412-1210: Emulsion shock, 12.5-inch length, medium spring, for many Harleys
• 444-2220: Piggyback reservoir shock with adjustable rebound, 13-inch length
• 877-1230: Premium series with compression and rebound adjustability, 13.5-inch Always confirm with the official catalog because minor variations exist for different model years.

What to Do if the Part Number Is Obsolete

Progressive periodically updates its lineup. If your part number is no longer listed, contact Progressive customer support or an authorized dealer. They can suggest a modern equivalent with the same mounting dimensions and spring rate. Avoid using generic shocks without verifying fit; they may lack proper damping for your bike’s weight.

Tips for Ordering the Correct Shock

• Verify mounting hardware: Shocks come with different eyelet sizes (e.g., 10mm, 12mm) and bushing lengths. Match your original.
• Spring rate: Your bike’s weight and your riding style determine the proper spring. Most Progressive shocks are preconfigured, but some allow spring changes.
• Reservoir space: Ensure the shock reservoir clears your bike’s fender, saddlebags, or exhaust. Measure clearance before buying.
• Return policy: Buy from a seller that accepts returns if the part doesn’t fit. Test fitment before final assembly.

Final Recommendation

Start by locating the part number on your existing progressive suspension shock. If it’s legible, use that to find a direct replacement or supersession. If not, use your bike’s make and model along with dimension measurements to identify the correct part number from Progressive’s catalog. Always cross-reference with an official source or a knowledgeable dealer. By taking these steps, you can confidently purchase the right shock and restore or upgrade your motorcycle’s ride quality.