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What Is Part Supersession?

Photo of VW Golf with all parts removed and laid out around body of car.

Supersession (not the show) is the totally boring thing that keeps poorly designed cars on the road. Be it Ford's stupid door lock issue or, Ford's horrific gearbox issues or even Ford's seatbelt recall for the brand new Ranger. In all of these cases, supersession played a big roll in making these consistent problems (kind of) go away.

So, what is part supersession?

All in all it's pretty simple to understand. A brand new part for a brand new car can only be engineered so much. On top of that, while enginerds can statistically model a large portion of a vehicles lifespan, they can't show what is going to happen in every climate, every driving scenario and after 10 or 20 years on the road.

The problem here is that, if one of the parts on these brand new cars has an unrealised problem and they continued to sell the exact same part that had issues in the first place, it could cause massive issues with driveability and safety, brand loyalty or (worst of all) start an expensive recall.

To combat this, a lot of parts that are already in production might get little updates to change materials or design.

Now, most part numbers are something completely meaningless to you and I however, quite often manufacturers end part codes with 2 letters (i.e. 111-234-66-AA or 111-234-66-AB). These 2 little letters at the end of the part number tend to indicate every time a redesign has been put into production.

Why does supersession matter then?

Well, while we've got plenty of things to complain about when it comes to enginerds, each time a part is superseded a slight improvement is put into production. For example, Ford's ongoing door lock problems may be improved slightly by making the plastic internals less likely to break or by changing the material to be literally anything other than plastic.

All in all, this is a really good thing. And to those in the know it's almost a living timeline of how poorly a part was designed in the first place (especially if a part number ends in "MB").

Why should you care about supersession then?

Well, unless you're a mechanic (if you are, check out how to be a Kashy mechanic here), an engineer or one of the ruinous bean counters that stifle great mechanical advancement, there isn't any reason for you to care.

Mechanics (of course) care because it means that long-running issues may be solved by an updated part. Engineers care because it's their job and the bean counters care because it all costs money.

However, this blog post is a silly bit of fun to write and a good way to increase our SEO (that mysterious internet term that makes or breaks a business). At the very least it will give you something to bore your friends with at the next dinner party.


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