# Are automobiles manufactured on Monday and Friday more likely to be defective? **URL:** \ **Category:** Factual Questions\ **Created:** [November 14, 2002, 6:00am UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683 "2002-11-14T06:00:32Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [November 14, 2002, 6:00am UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/1 "2002-11-14T06:00:32Z")
Does anyone know of any research into the assertion that cars manufactured on Mondays and Fridays are more often defective? The claim is that this is because the workers are more likely to be drunk or otherwise messed up by the past weekend or the upcoming weekend. I thought that I read once that this has been checked out and found to be an urban legend. I’ve just checked Google, Cecil’s archives, and the SDMB archives though, and I can’t seem to find anything relevant. ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [November 14, 2002, 1:07pm UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/2 "2002-11-14T13:07:38Z")
Oh, I also checked snopes and didn’t find anything there either. ---
**Author:** ![muttrox](https://avatars.discourse-cdn.com/v4/letter/m/a8b319/32.png) [@muttrox](https://boards.straightdope.com/u/muttrox)\ **Post date:** [November 14, 2002, 1:24pm UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/3 "2002-11-14T13:24:04Z")
I’ve never even heard of this. Sounds kind of stupid to me offhand. Aren’t those plants highly roboticized anyhow? Who exactly is claiming this. The burden of proof is on them to demonstrate it, not for you to refute it. ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [November 14, 2002, 1:53pm UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/4 "2002-11-14T13:53:27Z")
Well, some of these things refute it: [ul] [li]What day was a car built? Final assembly takes bodies and doors and hoods and seats and dashboards and engines and transmissions and, well, _everything in the car_ and sticks them together.[/li][li]Assemby is primarily human work, so you _could_ have human problems. Sure we’re talking unskilled labor, but the assembly process is as error-proofed as we can make them – even engineers could do most of the jobs :).[/li][li] The manufacturing schedules of all of the thousands of bits and pieces make it statistically impossible that a car assembled on a Monday would coincidentally contain a majority of parts also assembled on Monday.[/li][li]Most vehicle problems aren’t attributed to assembly problems, but to manufacturing defects. This means an alternator is bad, so someone at Visteon screwed up. Okay, it means we screwed up for not catching it and making Visteon certify all parts, but you see the point.[/li][li]Many production plants are in seven-day production – there’s not really a designated drinking/hangover day![/li][/ul] ---
**Author:** ![Joe\_Cool](https://avatars.discourse-cdn.com/v4/letter/j/ecb155/32.png) [@Joe\_Cool](https://boards.straightdope.com/u/Joe_Cool)\ **Post date:** [November 14, 2002, 3:16pm UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/5 "2002-11-14T15:16:56Z")
Yeah, I hear 40% of all defects are in cars built on Monday or Friday!! 😃 ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [November 14, 2002, 3:42pm UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/6 "2002-11-14T15:42:33Z")
The idea has been around for a long time. It was popularized in some book in 60’s or 70’s, I think either Ralph Nader’s “Unsafe at Any Speed” or Arthur Hailey’s bestseller, “Wheels”. Note that the latter is fiction. You may be of the opinion that the former is also, but the latter is labelled as such. ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [November 14, 2002, 4:19pm UTC](https://boards.straightdope.com/t/are-automobiles-manufactured-on-monday-and-friday-more-likely-to-be-defective/136683/7 "2002-11-14T16:19:07Z")
Thanks for the help. The problem is that I’m arguing against someone who I suspect is an idiot, and it would be useful if there were somewhere a complete, definite rebuttal of this idea in one place. I know that this guy has the burden of proof, but I suspect that he will just say, “You didn’t disprove me, so I’m right. Nyaah, nyaah, nyaah!”.