Why do auto parts stores not carry bolts needed for cars

[eljefino]

I keep a junk pile of old automotive bolts. I've also had to buy new ones. The OE dealer ones are top quality. The big box store ones aren't, they flash corrode within months. My junk drawer bolts also have whatever quality coating works, and are better for reuse than something generic. When applicable, OE bolts will have stuff like an unthreaded starting nub that helps align everything, or an integrated washer in the head.

The point about bolt head sizes also holds true. There are industry standards and the automakers don't follow them.

 

[Astro14]

I keep a junk pile of old automotive bolts. I've also had to buy new ones. The OE dealer ones are top quality. The big box store ones aren't, they flash corrode within months. My junk drawer bolts also have whatever quality coating works, and are better for reuse than something generic. When applicable, OE bolts will have stuff like an unthreaded starting nub that helps align everything, or an integrated washer in the head.

The point about bolt head sizes also holds true. There are industry standards and the automakers don't follow them.

Actually, they do follow them, but there is more than one industry standard.

I recommend these guys: www.bel-metric.com

With thanks to @Sam_Julier for the recommendation. They have both JIS and DIN standard head sizes (and yes, they’re different for the same thread size).

I have started ordering double the number needed from the dealer or from parts houses. E.G. I need to replace a pair of torx fasteners, so I buy 4, throw two in my storage. Do a suspension job that requires an M12/1.5x140mm flanged bolt - buy an extra.

They go in my “hardware store” - a set of organizers in which I have hundreds of fasteners. I typically have the bolt I need whenever I do a job.

 

[64bawagon]

I worked at an industrial supply house in the late70's to early 80's that specialized in fasteners. Even back then many automotive fasteners were "specials" in that they were designed and manufactured specifically for an auto makers use. When the OEM's use 500,000 of a bolt, screw, washer, etc they have a buying power to design whatever they feels is best for that application. Even if you could access them you couldnt buy enough of them to make it economical and you would never be able to recoup your investment. I have several bins of fasteners from repairs and vehicles that were scrapped. I never ever throw away a salvageable fastener