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up vote 8 down vote favorite

I've been told that reverse is the "strongest" gear, so in a manual transmission vehicle you should park your vehicle and leave it in reverse in the event of a parking brake failure. Others have said first or second gear are fine as well.

Is there a "best gear" to leave your manual vehicle in when parking it?

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2  
Related question: is there any mechanical proof to the claim that reverse is the "strongest" gear? – William 14 hours ago
1  
that sounds like a new question. But it would mostly depend on the brand and model of gearbox. – Criggie 8 hours ago
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I've always been taught to leave it in free. And now that I have kids who like to sit behind the wheel (and who knows, get a key and turn it some day) I'm quite happy with that. – RemcoGerlich 6 hours ago
1  
Also in Paris and other large cities, it's very common to push other cars a bit to make a tiny parking space a bit bigger. Leaving it in a gear means damage to your vehicle. – RemcoGerlich 6 hours ago
up vote 13 down vote

When I'm on a hill with the front of my car facing up the hill I park the car in first and turn the wheels away from the curb so the transmission is fighting against gravity.

When I'm on a hill with the front of my car facing down the hill I park the car in reverse and turn the wheels into the curb so again the transmission is fighting against gravity.

When I'm on flat ground I park in first as reverse is too finicky to deal with that frequently :)

Happy to be wrong here. Just what I've always done - opposed the forces of gravity with the opposite transmission gear.

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I'm the same, only I've always been told you angle the wheels that way so that if the car rolls they 'wedge' themselves into the curb and (hopefully) stop the car from moving further. – MeltingDog 13 hours ago
    
I always "lean" the car against the curb on a hill, the way described by @anon. I find it actually pretty cool, I slip into neutral and feel the car settle itself down, then I rip the handbrake and put it in Park. – tlhIngan 12 hours ago
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I think you are right, but actually, is there a mechanical reason that pushing a car is harder "against" the gear? It could easily be the same in both directions. – Peter A. Schneider 4 hours ago
3  
Can you provide some sort of source for the fact that the transmission "fights against" moving in the wrong direction? The transmission doesn't have a ratchet in it, does it? – Tanner Swett 4 hours ago
1  
@Paparazzi: My understanding is that it has something to do with the valve timing and clearance, and that the pistons might hit the valves when it's turned in reverse. This sounds unlikely to me, but everything I've ever read about turning the crankshaft by hand when working on the engine has included warnings to turn it only in the forward direction. I suppose it's possible that it has something to do with the oil pump mechanisms instead. – R.. 1 hour ago
up vote 9 down vote

The lower the gear, the better the job the engine compression will do at holding the car if the brake fails, that's because a lower gear makes the engine spin faster and require it to do more work for the car to move. So 1st is better than 2nd, between reverse and 1st it's not so obvious – but from the examples people are finding it looks like 1st is a bit better.

Bottom line, 1st or reverse, leaning towards 1st.

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1  
I checked three different cars from three different countries and all had a higher gear ratio in first than reverse, of course this could be a case of selection bias – method 12 hours ago
2  
@method That doesn't sound like selection bias, just a small sample. Selection bias is where something specific about the way you selected the sample gives biased results. For example, if you work in a hospital, you might believe that most people are sick but that would just be because sick people go to hospital more, so your sample includes more sick people than the population as a whole. Unless you think something about the way you chose the cars might have caused you to select cars with the gear ratios you describe, it's not selection bias. – David Richerby 6 hours ago
1  
Pedantically, the transmission won't be holding the car in place, the compression of the engine will be doing that - multiplied by the gear that the transmission is in. – KevinDTimm 1 hour ago
up vote 2 down vote

So, looking at a couple common manual transmission gear ratio charts, first gear would be best. Why? It has the highest ratio. Although it is (in the charts I found) very close to reverse.

Here's a chart for Honda Civics (up to '91 I think)

Here's a PDF from Toyota's press room with their Corolla specs.

Highest ratio = greatest amount of torque applied to the wheels from the crank. Conversely, more torque needs to be applied to the wheels to force the crank to rotate. Also, from my understanding, the forward or reverse gears make no difference except that (I imagine) your motor REALLY won't like being rotated backward. So in that regard maybe it would be better to choose the gear that suits your hill directionality... but at the same time, if you brake and trans fail to hold your car on a hill, chances are things could go VERY wrong very quickly.

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1  
If both the brake and transmission fail to hold the car, things aren't going to go wrong quickly. They're already well and truly wrong, and may get much worse fast. – Leliel 24 mins ago
up vote 1 down vote

I have an alternate suggestion for using reverse with a stick shift to park. Perhaps merely to facilitate backing out of the parking space. In first gear you increase your odds of ramming into the curb if momentarily distracted.

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That only works if you park nose-in - if you reverse park (and you should, it's much safer), the opposite would apply... – Nick C 8 hours ago
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And in reverse you increase your odds of ramming into traffic if momentarily distracted. I think the better advice would be to not drive distracted. – Joey 3 hours ago
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when I drove a Manual Transmission I always put it into the Gear I wanted it in even if it was already in gear after I had started the car, so that I knew what gear I was in. never start a car and hit the gas. – Malachi 1 hour ago
up vote 1 down vote

First gear when pointing down hill, reverse when pointing up. If your car ends up rolling, the engine will turn in the correct direction. If you park in reverse pointed downhill and your car rolls the engine will turn backward, and vice versa. This can cause various problem with the engine including skipping a tooth or binding on the timing chain/belt and is almost universally cautioned against when working on engines.

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up vote 0 down vote

The lowest gear to go up the hill. Lowest for mechanical advantage (you are using compression in the engine as the force). Up the hill as that is the direction of force the transmission is designed for. So first if pointing up the hill. Reverse if pointing down the hill. Level ground reverse as reverse gets less wear and tear in normal use and it is also typically a lower gear than first.

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up vote -1 down vote

Habitually leaving a manual transmission car in gear is a bad idea. One day you will jump in the car, turn the ignition, and discover that the starter motor is more powerful than the handbrake (you will start moving before the engine even fires!), but the object you just hit was stronger than the car.

Automatic transmissions may have a lock that prevents you starting the car when the transmission is engaged, but (at least in the UK and Europe) manual transmissions do not.

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1  
Most manual cars in the U.S. have an interlock switch on the clutch that prevents that from happening, just like an automatic does on the gear selector. However, that switch can be disabled, sometimes as a user-option like my Jeep. (crawl under the dash, unplug the wire from the switch, and put it on a jumper instead, which is factory-mounted to the firewall) Without that interlock, you're correct about the starter being able to move the car. – AaronD 35 mins ago
    
Also, all manual transmission car I ever drove require to disengage the engine by pressing the clutch to start, simply "turning the key" or pressing a button is not enough. So you don't jump into an object. – Francesco 4 mins ago

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