Gearheads — what would happen if I...?
from cerebralhawks@lemmy.dbzer0.com to nostupidquestions@lemmy.ca on 23 Mar 21:09
https://lemmy.dbzer0.com/post/65875257
from cerebralhawks@lemmy.dbzer0.com to nostupidquestions@lemmy.ca on 23 Mar 21:09
https://lemmy.dbzer0.com/post/65875257
Always wanted to know this, always been afraid to Google it because I figured it would report me for self harm or something like that.
So, 1. What would happen if, while driving on the highway at highway speeds, you grab the gear shift knob and put it in park? Would it just lock up all the wheels or what?
And 2. What would happen if, also while driving on the highway, at highway speeds, you turn the car off (turn the key and remove it)?
I feel like both should be impossible while the car is in motion. But somehow I don’t think they are. And to a gearhead, these are probably really stupid questions. But as someone who barely understands how cars do what they do… I’m curious.
#nostupidquestions
threaded - newest
Transmission would make a lot of noise, grinding kind, as the park pawl attempted to engage. It could lock up the wheel if it successfully engaged. I know because I’ve done this accidentally on an old 1970’s car that had a shifter problem.
Nothing much - you’d lose power assist for the steering, and you’d have power assist for braking for 1 good stop. I’ve also done this.
So you’d basically break your transmission. Sounds like something that shouldn’t be allowed to happen.
Once upon a time, vehicle manufacturers assumed people have common sense and know how to properly operate a motor vehicle. Then as time went on, they’ve discovered just how many idiots there are out there, so newer vehicles tend to have lockouts and safety mechanisms to prevent such things.
Still, its best to assume that no vehicle has any such safety features to prevent you from making either one of these mistakes.
Maybe. Maybe not.
I didn’t that time, but I immediately put it back in gear. Probably took a few years off the parking pawl.
Shifter systems are designed to prevent this - this car had a shifter issue we were working on.
It’s a hard thing to do any more, the lock outs have gotten a lot better. Pretty much impossible with push-button shifters.
Every car I have driven, with the oldest being a ’77 manual, seemed to have something keeping the shifter from accidentally going into park for automatics or a gear too far down for a manual. I never tried to force it, but it seemed like they had functionality in llace to make it impossible or at least very difficult.
Note that you were replying to someone who said their car had a shifter problem
Not a gear head, but I had a friend in high school who was an idiot. While his girlfriend was driving on the main drag one day he stuck the car in reverse or park, not actually sure. We all braced for catastrophe, but nothing happened. The car basically was in neutral.
He also shut off the car while driving, but because it was in drive was unable to remove the keys. The driver had to shift to neutral, then she was able to restart it. Basically while it was off, there was no power steering, or power brakes.
ETA: this was in an 89 LeBaron.
I don’t know years, but one of my brothers once had a Chrysler LeBaron. I think it was a '93? White, convertible. One day, with me riding shotgun, he went to a boat ramp (ramp that leads into a lake) and floored it. Just before hitting the water, he pulls the e-brake and swings the wheel hard to one side. The back end whipped over the water and the car stopped, facing up the ramp. That started the fight, but it’s not why his friend broke his ankle. That was later. All in all it was a good night, even though it ended up with a trip to the ER. My brother’s still one of my favourite people in the world. And I do miss that car.
I, for one, would like to hear the tale of said ankle.
Honestly I don’t remember much, they were drinking (I was the designated driver) and the guy went to walk/run down a hill and rolled his ankle. I’m not 100% sure it broke, but he was hollering like a madman and I had some Tylenol on me for some reason and gave it to him, and I remember in the ER they asked what he had, and I recited the amount and ABV of what he drank, plus the dosage of acetaminophen down to the mg. My brother and his friend said I shouldn’t have mentioned the Tylenol so he could have gotten more morphine. I reminded them, this is why I’m the DD.
I take the bait and second the petition for the tale of the ankle. Come on you don’t mention an apparently irrelevant fact if you are not planning on sharing more about it
Replied to the previous comment ;)
Putting it in park at highway speeds depends mostly on how new the car is. Newer cars will put the transmission in neutral and probably yell at you with the dash. Older cars the parking lock isn’t strong enough to lock up the wheels at speed, so it’ll grind and clatter or just break. Ruining the parking lock.
Turning the car off on the highway just makes you coast to a stop. Depending on if its an automatic or manual transmission; you might loose power assist on the steering if the engine stops spinning. Pulling the key out normally activates the steering wheel lock. Which is a whole other problem if you are still moving… Some automatics prevent you from removing the key if the transmission isn’t in park though…
Makes sense. My car has an automatic transmission, I know that much. (Actually no, I have a CVT, and yes, I know it’s shit, but the car is paid off and it’s still going strong at 130k miles… dodged a bullet, it seems.) So I guess it would just sit in neutral until it’s stopped?
And yeah, makes sense about the key thing.
Ooh a CVT? Well that’s a different bag of worms I’m not directly familiar with, though I do know how they work and the nature of wear and tear of the parts they’re known for.
Honestly, I have no idea what would happen to a CVT if you put it in Park while driving, but I still bet nothing good…
You are probably thinking super old CVTs. Modern ones are great. Our Honda has 200k on it and CVT is fine. We did a fluid change around 100k and all was fine
From my understanding (this may not apply to all vehicles) is that Park works by engaging both a forward gear and reverse gear at the same time, effectively locking the transmission. So putting it in Park while driving is almost guaranteed to destroy the transmission. This is also why there’s a separate parking brake, highly recommended to use if parking on a hill.
When you turn the key off, then all but ancient cars will mechanically lock the steering wheel, as a theft prevention measure, meaning you will be completely unable to steer. And no I don’t mean the loss of power steering making it hard to steer, I mean physically mechanically locked, you will not be able to steer at all.
TL;DR - Regarding both questions, catastrophic damages and likely death 💀
You're right on the second, wrong on the first. Park is exactly the same as neutral, except there's a bit of metal that engages in the transmission to lock it in place. This is the "parking pawl". If the car is moving fast enough, that will simply break off. Slow enough, and it will lock the drive wheels. In a rear wheel drive car, that's not so bad, because you can still steer. Front wheel drive, the drive wheels lock up, and those are the wheels you use to steer, so good luck.
Interesting, I’ve done quite a bit of vehicle work in my life, but have never had the pleasure of tearing into an automatic transmission myself.
If my dad was still alive, I’d ask him what model vehicle in particular he supposedly learned that forward/reverse gear lock thing from.
I gather you have way more internal transmission knowledge than myself, but still I wouldn’t totally doubt that at least some transmissions built in the past might have worked a little differently regarding Park.
🤷
Oh sure, there were some super weird automatics back in the day, and I don't doubt that one or more behaved as you described, but those would be outliers.
My driving instructor included #2 in the lessons a decade (or 2) ago
You lost power steering and power breaks, so car was heavy but steerable. Goal was to put it back in neutral, start the car, and drive off
TLDR, keep calm and carry on.
Sounds like a good instructor. I’ve had my car shut down twice (different cars) while driving on high speed motorways and something like this would’ve been handy
My parents had an old car with a manual transmission, no power steering, no power brakes, and no steering wheel lock. My dad and I had a game where we would shut off the engine about 1/4 mile from home and coast all the way into the garage. Whoever could coast the furthest without speeding or needing to restart the engine would get bragging rights. If you did have to restart the engine, you got points for putting it in gear and clutch starting rather than using the key.
I wish I got along that well with my dad in a car! He tried teaching me how to drive in two different occasions and after ending up in arguments both times, we decided it was best I learned from a professional instructor and have him removed from the equation. We get along well otherwise, just not with a steering wheel involved.
don’t you have to hold break to do either of those things?