Replatform Your Auto Parts Store Without Losing Fitment Data

A 40,000-SKU auto parts store can launch on a new platform with every product in place and still lose its best organic traffic inside a month. The products moved. The URLs did not, and the fitment table that told shoppers a rotor fits a 2019 F-150 with the 3.5L EcoBoost got flattened into a text field that just says “2015-2020 F-150.” Google keeps sending visitors to old URLs that now return a 404, and the shoppers who do reach a product page can no longer trust the fit check.

You have already picked the platform. If you are still deciding, start with our breakdown of the best ecommerce platform for auto parts. This post covers what happens after that decision. Capture a baseline first, then do the two jobs that decide whether the new store keeps its rankings and sells the right part to the right truck: the redirect map and the fitment mapping.

What do you need to inventory before an auto parts migration starts?

You need a list of every URL that earns traffic or backlinks, plus a count of fitment records for every SKU. Those two numbers are your baseline, and without them you have no way to prove the migration worked.

Pull at least 12 months of landing page data so seasonal pages show up. A winter battery page or a spring lift kit page can look dead in an August export. Most teams remember product pages and forget the pages that actually rank for vehicle searches.

• Every indexable URL with its organic clicks and backlinks. Export from Google Search Console, then add a full site crawl so you catch pages that earn links but little search traffic.
• Vehicle landing pages. Pages like a “2018 Jeep Wrangler JL lift kits” category often outrank individual products. Many stores generate these with a fitment app, and they disappear the day that app is uninstalled.
• Fitment application counts per SKU. A single brake pad set can carry hundreds of application records once you count every model year and engine. Write the count down for each SKU now, while the old system is still running.

How do you map redirects for a catalog with tens of thousands of URLs?

Map old URLs to new URLs with a stable key like SKU or manufacturer part number, never by matching product titles. Every old URL should land on its closest real equivalent, because Google’s own site move guidance warns against sending many old URLs to one unrelated page such as the home page.

The mechanics are a join, not a guessing game. Export old URLs with their SKU and new URLs with their SKU, then match the two in a database or spreadsheet. Categories map by category path. Vehicle landing pages map to the new store’s version of the same vehicle page. Discontinued parts go to the superseding part number when one exists, and to the matching category when it does not. Google recommends keeping redirects in place for at least one year. For an auto parts store, where old part number links live on in forum threads and install videos, keep them permanently. Our guide to 301 redirects during a site migration covers the redirect basics in more depth.

Check your new platform’s redirect rules before you build the map

Each platform handles redirects differently, and the differences matter at catalog scale.

Shopify puts product URLs under /products/ and category URLs under /collections/, so almost every URL from a store on another platform will change. Standard Shopify plans allow a maximum of 100,000 URL redirects, while Shopify Plus allows 20,000,000. Shopify also skips a redirect when the old URL still loads a valid page, so a leftover page can quietly block one.

Run the math on a real catalog. Take 40,000 SKUs and 6,000 category URLs. Add 60,000 indexed vehicle landing pages and you are at 106,000 redirects before you count a single blog post. That is over the standard cap. You either move to Plus or prune old URLs that have zero clicks and zero backlinks, and let those return a 404 on purpose.

BigCommerce creates 301 redirects on its own when a storefront URL changes after launch, and it offers a Redirects API for managing redirects in bulk. That automatic behavior helps after go-live. It does not build your migration map, so you still load the old-to-new redirects yourself.

How do you move ACES fitment data to a new platform without losing detail?

Keep fitment in a structured format where each qualifier is its own field, and treat the ecommerce platform as the place fitment is displayed, not the place it is stored. Most ecommerce platforms do not read ACES files natively, so fitment usually lives in a dedicated fitment app or in an external database, such as a PIM, that feeds the storefront.

ACES is the Auto Care Association’s standard for fitment data, and PIES is its standard for product information. Both were updated in April 2026 to ACES 5.0 and PIES 8.0, along with a new version of the Vehicle Configuration Database, VCdb 2.0. A migration is a good moment to confirm which version your suppliers send. If your old store held fitment inside a plugin’s own database, ask that vendor for a full ACES export before you cancel the subscription. Some vendors only export a flattened CSV, and you want the full file.

The detail matters more each year. The average light-duty vehicle on U.S. roads is now a record 12.9 years old, according to the Auto Care Association, so a growing share of your buyers drive older vehicles where engine and submodel differences decide whether a part fits.

These are the three failures that show up most in fitment migrations:

• Qualifier loss. Qualifiers like engine or submodel get collapsed into a notes field or dropped. The fit check then says yes for vehicles the part does not fit, and returns climb.
• Range flattening. “2015-2020” gets stored as a text string instead of six separate years, so a shopper who selects 2017 gets no match and leaves.
• Fitment stored as variants. Shopify raised its limit to 2,048 variants per product in October 2025, which tempts teams to load each vehicle as a variant. Variants are built for options a shopper buys, like finish or size. Mixing them with vehicle compatibility tangles your inventory with your fitment and breaks the next time an application list grows.

Verification is simple to describe and tedious to do. Compare the application count per SKU between the old export and the new system, and treat any SKU whose count dropped as a defect until someone explains it. Then test your top 200 SKUs by revenue on staging with real vehicles, including two engines on the same model year. If you want more on how fitment accuracy connects to returns, read our post on fitment data and auto parts conversions.

How long does an auto parts replatform take, and when should you launch?

For a catalog between 10,000 and 100,000 SKUs with ACES fitment, plan on about four to six months from baseline audit to launch. Launch in your slowest month, and expect some ranking movement for a few weeks afterward.

Google says rankings can fluctuate during a site move and that a medium-sized site can take a few weeks for most pages to move, with larger sites taking longer. That is normal. Losses that last past 90 days almost always trace back to missing redirects or vehicle pages that stopped rendering. Pick the launch window from your own analytics, not from a calendar guess. A store heavy in off-road and towing parts peaks at different times than one that sells batteries and wiper blades.

What this looks like when Blayzer runs the migration

Our ecommerce migration process runs in a fixed sequence, with some phases overlapping:

1. Baseline audit: A URL inventory with traffic and backlinks, plus fitment counts per SKU.
2. Fitment data model and mapping: Decide where fitment lives on the new stack, then map ACES fields and qualifiers into it.
3. Build and catalog import: The storefront build and ERP connections run in parallel with the data work.
4. Redirect map and staging QA: Every redirect gets tested, and fitment counts are reconciled before the revenue-SKU spot checks.
5. Launch and post-launch monitoring. Close review of 404s and Search Console until rankings settle.

Who owns what:

• You own fitment accuracy. Your source records and supplier ACES feeds are the truth the migration copies, so errors there carry over.
• You own access and sign-off. That means ERP credentials for the integration and final approval on the revenue-SKU spot checks.
• Blayzer owns the data work. The mapping scripts and the redirect map, including reconciliation of fitment counts before launch.
• We own the build and launch. The platform build and launch-day validation, followed by post-launch monitoring.

If you are moving to BigCommerce, see our BigCommerce partnership for how that build is supported.

Frequently asked questions

Will I lose SEO rankings when I change ecommerce platforms?

Expect some movement, not a collapse, if every old URL redirects to its closest match. Google says rankings can fluctuate during a move and that medium sites often take a few weeks to settle. Losses that last usually trace back to missing redirects or to vehicle pages that no longer render on the new store.

How long should I keep 301 redirects after a migration?

Google recommends keeping redirects for at least one year and says that, for users, keeping them indefinitely is worth considering. For an auto parts store, keep them permanently. Old part number links live on in forum threads and YouTube descriptions, and they keep sending buyers for years after launch.

Can I migrate ACES fitment data to Shopify?

Yes, but not into Shopify’s core product fields alone. Shopify does not read ACES files natively, so fitment usually lives in a third-party fitment app or an external database that feeds the storefront. Before you choose an app, confirm it imports ACES with qualifiers intact and can export your data if you leave. Before you choose an app, confirm it imports ACES with qualifiers intact and supports the ACES version your suppliers send, since some apps have not yet added support for ACES 5.0. Also make sure it can export your data if you leave.

Should I redirect discontinued auto parts to the home page?

No. Google specifically warns against sending many old URLs to one unrelated page like the home page. Send a discontinued part to its superseding part number if one exists, or to the category for that part type and vehicle. If neither fits and the page has no traffic or links, let it return a 404.

What is the difference between ACES and PIES?

ACES is the Auto Care Association standard for fitment: which vehicles a part fits, including qualifiers like engine or submodel. PIES covers product information, such as descriptions and packaging details. The current versions, ACES 5.0 and PIES 8.0, were released in April 2026, so check which version your suppliers send.

How do I check fitment data after a migration?

Compare application record counts per SKU between the old export and the new system, and treat any drop as a defect until someone explains it. Then test your top revenue SKUs on staging with real vehicles, including different engines on the same model year, and confirm the fit check gives the same answer as before.

Before you set a launch date

Pull the two baseline numbers this week: every URL that earns traffic, and the fitment record count for every SKU. If your team cannot produce both from the current store, that gap is where your migration plan starts, and it is far cheaper to find it now than after launch when the 404s are already costing you vehicle-search traffic. Talk to us about mapping your fitment data and redirects before your build contract locks in a launch date.