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WalterBright 4 days ago

I've had an interesting experience taking apart my 72 Dodge and putting it back together again. It's clear that there was a great deal of thought put into its design. It's simple, easy to take apart, easy to fix, easy to put back together. The money is only put where it is needed. Frankly, it's first class engineering.

Contrast that with a Mercedes I used to have of similar vintage. It had expensive parts sabotaged by being bolted to inexpensive parts. It was difficult to assemble correctly. Money was spent in the wrong places. I had a long list of complaints about the erratic engineering in it.

For example, it had sodium-cooled valves, something one finds only on a race engine. They are used for cooling. The values slid into bronze valve guides. The bronze valve guides were pressed into aluminum heads. The trouble was, aluminum expands at twice the rate of bronze. So when the engine got a little hot, the valve guides would come loose, and you'd have to rebuild the cylinder head. The sodium-cooled feature was completely sabotaged by those valve guides. A proper design would have mechanical retention of the valve guides, and not rely on a press fit.

userbinator 4 days ago | parent | next [-]

"German (over)engineering" is a common term in the automotive community for that reason. As someone who has also looked at this in detail, the difference between domestic and import cars of that era was the former tended to value simple and "brute force" designs, while the latter focused on short-term optimisations and some amount of "showing off" the complexity thereof.

WalterBright 4 days ago | parent [-]

For another fun one, it had a mechanical fuel injection. The drive shaft to the injector had a fine-toothed spline on it, meaning you had 50 or so wrong ways to install it. Get it wrong and the engine just ran badly. The assembly had to be done blind. There must have been some trick to getting that injector on correctly, but I couldn't figure it out.

The correct way to engineer this is to have the male spline with an extra tooth and the female with a missing tooth - then it can only be assembled one way. A cost-free improvement, saving a lot of aggravation for the mechanic. (BTW, this is what Boeing does.)

WalterBright 4 days ago | parent | prev [-]

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