Where Do Spare Parts For Older Complex Things Come From?

This question is one that most people don’t think about but has bothered me for while. I assume the same principles apply to older cars or appliances for example so I am including all of it in one question.

When things are manufactured it seems obvious that parts are available from the same source as the originally manufactured goods. However, whenever all goods similar to the original are discontinued, where do the spare parts come from?

I can think of a couple of ways that spare parts could be manufactured:

  1. A bunch of extras are made during manufacturing - that doesn’t seem right because suppliers would have no idea of how many to make and no idea of how many will be needed in the future and it costs a lot of money to store them for years or decades.

  2. The spare parts could be passed off to third party manufacturers. Where are those and how do they work? Do they make parts on demand?

If I order an alternator for a 1989 pickup which I have done recently, why would anyone have it, why do they have it, and where did it come from?

One source: There are companies devoted to the task of manufacturing and selling aftermarket parts for lots of different things. They typically can consult the history of similar products in the past to make reasonable guesses as to what percentage of 1989 Ford F-150 pickups will need a new alternator in their 19th year. This allows them to predict demand, estimate selling prices and generally construct a sensible business model.

Another factor is that not all machines will stop due to the same part breaking down. So a vehicle that stopped running due to a problem with its alternator still has a large number of working (albeit used) parts that can be salvaged for the repair of other similar vehicles.

Well, I have a 1966 Mustang, and so do a lot of people. Some of the parts are from Ford (“fomoco”, as it were) and some are reproductions. The more popular your “older complex thing” is, the easier stuff is to find because the more money there is in making it. It happens that most Fords at the time had most of the same parts, and that went on for quite some time - in other words, my Mustang can take a widget from a 65 Galaxy or a 70 Thunderbird or whatever. So that’s one end of the “spare part” thing - there’s a market for certain things.

You can make quite a bit of money selling olde timeyee cameras, for that matter - they’re not complicated, essentially two boxes with some felt and a dado. I’m going to run some up for Himself’s camera shop or maybe for Ebay. The fact is, there’s a community that wants to take plates, and they don’t want to (or think they can’t) build boxes.

Himself has a Ural motorcycle, which is a metric pain in the ass to find parts for. He had to get a wheel shipped to him from Russia. That’s because while the Ural people are very intense about their hobby, there’s a lot fewer of them than there are Mustang people. I believe there’s an equation where the crazy obsession of a group is inversely proportional to the number of objects of affection that are running around loose in the US. Somebody has probably written a paper.

Now, how do they keep things like ancient printing presses and such running? Custom parts, I’d imagine. I have heard that there is a major problem with the people who are still in iron lungs from polio, because you can’t get parts.

If you’re NASA looking for obsolete electronic parts to keep the space shuttle flying, you might look on eBay, at least according to this article from the New York Times.

There’s big business in brokering little tiny rare components, too. This place near me has zero inventory but makes a ton of money by knowing where to get that little tiny component you need for your 1920-style death ray (actually built in the 1920s).

I have a friend who, with his dad, bought a truckload of old school electronics components from a company that made said parts that went out of business. He stores them in his garage and every so often puts them on eBay (where his customers are usually maintenance workers) or pimps them out to brokers. The longer he lets them sit, the harder they are to find and the more he stands to make.

A lot of parts, such as our hypothetical 19 year old alternator, are easily rebuilt - there’s no shortage of businesses that can take your alternator, clean it up, replace the worn out internal bits and hand you the rebuilt widget tomorrow.

The nice part is that the ability to do this is generally interchangeable across all brands and ages of alternators - learn how to rebuild a Mopar alternator, and you know how to rebuild a Ford, assuming you have the right components on hand. And, you also possess the knowledge to rebuild starters and other electric motors.

After discontinuing a product, we will keep some spare parts, but not for years and certainly not for decades.

There’s a science to spare parts, and some predictions can be made based on known failure rates and repair trends. It also makes a difference if you manufacturer millions of a device a year, thousands or just hundreds. Obviously the more you manufacture, the better the information you have, and the more parts get stockpiled or are continued to be manufactured.

We’re not in the auto industry, but you would expect that a truck is going to last for 20 years, so someone will make money continuing to manufacture parts for a while, then someone will stockpile parts, and when they run out then you have to cannibalize or custom manufacture.

Mechanical parts and electrical motors can be custom manufactured, but it becomes difficult or impossible to do this with many electronics. From time to time, we have to discontinue or redesign products when parts are discontinued. In that case, after our spares are gone, then there isn’t anything which can be done.

My parents bought their house back in 1965. The previous owner had been a retired car dealer who had his lot on the property. Part of the property was a big storage building on the second floor of which he kept his parts department.

Move forward fifteen years and my father has decided he wants to clear out the second floor. He makes a few calls and finds some guys who volunteer to clear out everything for free. You can see what they were thinking. Sure, some of the junk was just junk. But they also hauled away several truckloads of early sixties Chevy parts that were not only never used but were still in their original boxes.

Being astute enough to see this ahead of time can make you very rich man. In our town we have this hideous junkyard next to the regional airport that the municipal authorities have been trying to relocate for years, and eventually had to bribe the owner to move by constructing band new building to replace his assemblage of rusting tin sheds. .

This “junkyard” is (quite literally) a gold mine. At the end of WWII and through the 50’s the owner looking to the future bought up many parts stocks for older planes, and often the planes themselves, that were being scrapped, mothballed etc. These cheap planes became the air transport backbone of many second and third world nations, and when they needed a critical part that was no longer being manufactured where did they have to turn? Right into this entrepreneur’s wallet.

He saw the future and it made him a multi millionaire.

I just learned last week that the USPS has been pulling all of its stamp vending machines because the manufacturer went out of business and there aren’t enough parts to maintain the ones in service. So sometimes, the complex machines just stop working and people stop using them.

Hear follows a cautionary tale :wink:

In 1999-2000ish the IT company I worked for purchased a pile of laptops for our engineers - Toshiba Satellites. After about 6 months, we had a few LCD screen failures, which were repaired. Then we had a few more, and the repairs took longer. Then someone broke a screen, and was told that it could not be repaired or replaced.

The issue was pursued by our bench engineer. He was told that Toshiba had built a certain number of laptops, with screens purchased from a third party. There was a design flaw, causing an inordinate number of screen failures. So Toshiba approached the third party manufacturer to order more replacement screens - and the third party would not supply them. They didn’t like producing then the first time round, and did not want to tool up to do it again. So Toshiba had to develop a repair strategy for the common fault (a board level repair replacing transistors) and purchased back all unsold stock for spare screens.

Eventually we could get dead screens fixed, but not if the screen was smashed.


Manufacturers can’t make all the parts ourselves, and so we are at the mercy of third-party manufacturers. As much as possible, you want to avoid single-source parts, where there is only one possible manufacturer, for reasons such as this.

However, this isn’t always possible, of course, and the best you can hope for is that you will be given enough notice to buy up existing stocks of parts to give you replacements for repairs, or enough parts to continue manufacturing while you go through the redesign process.

If you are desperate, and willing to pay, you can sometimes get a manufacturer to make a special production run of a discontinued part. I saw this happen when a customer was in dire need of some obsolete memory chips for a bunch of special-purpose computers that could not be replaced with COTS hardware.

There are many companies that specialize in recycling old hardware for scrap value and parts. There are also companies that buy parts from surplus and bankruptcy auctions.

The federal government has a bad habit of selling excess parts and equipment to reduce inventory costs, only to buy them again in a few years when the equipment breaks. The accountant says that the widgets have been sitting on the shelf in the supply warehouse for five years, costing us money, get rid of them. A year later, the widgets in the field are wearing out and need to be replaced.

I worked for a manufacture that supplied other companies components and obsolete product parts would be made. Large companies have policies in place to guarantee they will supply parts for a certain number of years. Sometimes the parts are available longer. Here is the way they handle parts in the order of usual practices.

  1. They use parts in as many models as practical, so even if the model is discontinued it uses the exact part the current models use.

  2. They try to make changes in components backwards compatible, so they work on old models and current ones.

  3. They make interchangeable parts for tooling that allows the tool to make the new parts most of the time and the old parts in short runs.

  4. They keep an old retired tool in storage and have short runs until the tool is unrepairable, or almost nobody wants a spare component it makes. A 16 cavity tool may be down to 1 cavity capable of molding the part.

  5. They scrounge their plant and suppliers plant for components in archives and displays for the component if they feel like doing you a favor, so you can fix the product.

  6. You’re super important and they hand tool a part for you or make a new tool to make the part.

My husband sometimes needs a specialty part for one of his machines and goes to his brother-in-law, who, if he’s able, will do a one-off in his machine shop for him. He wouldn’t do it for anybody else. My advice: be related to or suck up to somebody who owns a machine shop.