What Part(s) Of A Car Still Make No Sense?


I once heard an automatic transmission referred to as “The Black Box of the Devil Himself.” How the myriad pumps, bands, fans, valves, accumulators, gears, clutches, and even computers work in harmony to provide smooth and durable power delivery for decades remains a mystery to the uninitiated. I certainly haven’t disassembled a gearbox, nor do I have the time and knowledge base to do so.

It’s likely that many of us in the car hobby do not know how an automatic transmission actually works. Watching YouTube videos as a hobbyist doesn’t really count, and I reckon very few people have torn down the Devil’s Black Box (as it were) to see the insides firsthand. Those who have are potentially rewarded with a skilled trade that could pay quite well. But that’s only one example, so what other parts still don’t make any sense to us?

Yaw’ll Help Me With This

Yaw Sensor Accelerometer Cutaway view

Meet the yaw sensor. This little gyroscopic doo-dad is at the heart of many an active handling system, and its been commonplace in vehicles for well over a decade. Heck, even my 2011 Ford Ranger has one, and it barely has anything else. I give this part a lot of credit for making travel on low friction surfaces a whole lot easier, and it all starts with gyroscope in the sensor.

One day I’d like to dissect one of these sensors. I’d love to see how changes in yaw are translated into a change in values that a computer processes, eventually leading to a change in power or brake application at any of the four wheels on a vehicle. It’d probably be quick, easy, and clean, not unlike taking apart a throttle position sensor. It would be much easier than finding the space to do that with an automatic transmission!

So the question goes back to you and everyone else in the Hagerty Community: What parts of a car still make no sense?


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    I disassembled an automatic transmission from a junk Nissan D21 once, just for the fun of it. I still have some of the pieces as a display in my office at work. Even more amazing than the automatic transmission itself are the folks that designed and built those things back in the 1930s-1940s before computers.

    Gauge clusters make no sense to me. I’ve given up on more than one 1980-1986 Ford truck cluster after narrowing it down to that strange copper/plastic/sheeting stuff. So now two of my trucks have an aftermarket temp gauge and the fuel level is anyone’s guess since I never remember to write down the mileage at fill up.

    By your phrasing “Make no sense”, you’re really meaning “inscrutable”, “enigmatic” or “unexplainable”.

    I took it as “unnecessary” or “pointless”.
    By that definition, I’d nominate most of the modern safety babysitters, such as lane-drift warnings, sensors for announcing a car beside you, and the myriad other detectors replacing actual human attention and awareness.

    I think the question here was poorly chosen as below is what makes no sense.

    What I always questioned is the dimming rear view mirrors in your truck or SUV with factory tinted rear windows?

    Do you really need it?

    How about the rear view mirror in the Lotus Elise. It has no rear window. It was cheaper to put it in vs DOT waiver.

    Now if you mean what on a car is a mystery to you. Well nothing. It is a mechanical vehicle that functions and nothing is really a mystery if you have worked on cars.

    I agree the babysitting options make me wonder. They actually reduce the driving skills. Most have many false signals and you just can replace the responsibility of a driver.

    What makes no sense is we spent 125 years refining the ICE engine yet the Government wants to force mfgs to perfect EV models in 20 years? Just not going to happen.

    You didn’t have to bring EVs and the government into this conversation. Not one bit. The article/prompt above had nothing to do with either of those.

    We get it, you’re smarter than everyone here, including the authors. We are all so proud of you.

    Some folk can’t help but to inject their political peeves anywhere they can.
    It’s a shame — they ruin otherwise good messaging.

    Shoot, Sajeev, tearing an automatic transmission apart is easy – child’s play, really. Now, re-assembling one into working order, THAT will put most folks into a padded room…

    But what makes no sense to me is that manufacturers keep trying to “improve” things that really didn’t need improvement. They claim it’s to make things “easier” and/or “safer”. In fact, their efforts often make things harder and potentially more dangerous. At the risk of re-opening a well-worn can of worms, I submit: doing away with tactile knobs and switches and replacing them with touch screens. Makes no sense to me. Pitching analog gauges and making things electronic and digital are close behind that, IMHO.

    In my early mechanicing days, I worked for a landscaping outfit with lot sweepers. We used to go down to the local boneyard and pick up core TH400s and C6s for $25 a piece. We would disassemble them until we found the burnt clutch pack or other offending failed component, rob the component out of one of the other cores, put the thing back together, and throw them on the shelf for bench stock. Some failed right out of the box, some we would get 6 months to a year out of. Might not have been the most efficient operation, but it was still a helluva lot cheaper than a professional rebuild

    As far as the subject goes, 2000s era BMWs have this valve in the valve cover that essentially performs the function of a PCV valve. When they fail, you get full manifold vacuum applied to the crankcase, with all kinds of adverse symptoms such as lean burn codes, oil in the intake, whistling through the crank seals due to the vacuum, etc. These wonderful little gadgets are part of the valve cover, and the proper BMW-approved repair is a new valve cover. Fortunately the aftermarket does offer just the valve, and if you are skilled enough to cut the old one out without damaging the valve cover and without putting a bunch of plastic shavings in the engine… it’s a 30 dollar repair

    You’re right – that makes no sense. Unless you are the manufacturer/supplier of valve covers for 2000s era BMWs, then it makes perfect sense! 😜

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