In Which Black Aeronaut Teaches You About Cars

[Black Aeronaut]

There are some things that are automatic to do with one that will really screw with the other.

I nearly blew up when I saw one fellow (after discussion of parked cars not staying put) who (rather loudly) insisted that the only proper way to park any car was with the transmission in gear and the parking brake locked.

For a manual shift, this may well be correct.

Doing this on an automatic transmission is a good way to kill your transmission, and I had to say so.

Nooot quite true.  The nature of the torque converter prevents this from being an issue.  The real issue is that should the parking brake fail, then there is nothing preventing the vehicle from moving.  Which is why automatics have the "Park" feature in the first place.

Really, what will ACTUALLY destroy an automatic is relying on "Park" without the parking brake engaged.

Most vehicle manufacturers and auto mechanics do not recommend using the transmission's parking pawl as the sole means of securing a parked vehicle, instead recommending it should only be engaged after first applying the vehicle's parking brake. Constant use of only the parking pawl, especially when parking on a steep incline, means that driveline components, and transmission internals, are kept constantly under stress, and can cause wear and eventual failure of the parking pawl or transmission linkage. The pawl might also fail or break if the vehicle is pushed with sufficient force, if the parking brake is not firmly engaged. Replacement can be an expensive operation since it not only requires removing the transmission from the vehicle, but it's usually the first component to be installed in the gearbox case during a complete rebuild.

Article with citations and a helpful picture here: https://en.wikipedia.org/wiki/Parking_pawl

Yeah, I recognize that automatics are "always park it in Park, never Neutral or Gear, use the parking brake only if you're on some sort of incline", manuals are "in gear or neutral, parking brake always always always".

My dad who would have been over 90 now, was "always park in gear, especially on an incline, the parking brakes are not strong enough to hold a car in place on their own".

Actually, it's the exact opposite, though your dad can be excused for not being right because gear ratios back then are not the gear ratios used now.

Thing is, cars were HEAVY back then, and then engines didn't have nearly as much power or torque as they do now.  So 1st gear usually had to be something absurdly low, like 3.9:1, whereas modern light-vehicle transmissions now use a ratio like 2.5:1 for 1st gear.

I've seen my light pick-up actually begin rolling backwards on an incline while it was parked in 1st gear - the parking brake at the time was broken and I'd been working on getting it fixed.

Really, if your parking brake isn't strong enough to keep the vehicle in-place on an incline on its own, then your parking brake has failed and you need to get it looked at - like yesterday even.