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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?

dlu
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William
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    Related question: is there any mechanical proof to the claim that reverse is the "strongest" gear? – William Nov 22 '16 at 04:02
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    that sounds like a new question. But it would mostly depend on the brand and model of gearbox. – Criggie Nov 22 '16 at 10:05
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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 Nov 22 '16 at 12:26
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    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 Nov 22 '16 at 12:29
  • Related... and closed as opinion based: http://mechanics.stackexchange.com/q/11264/12030 – JPhi1618 Nov 22 '16 at 18:57
  • If you don't leave it in gear and the car rolls it will likely damage the whole car… For whatever it is worth for many years (all of the original 900 at least) SAAB locked the transmission in reverse as an alternative to the steering wheel lock. – dlu Nov 23 '16 at 02:13
  • @RemcoGerlich, how would being in gear when the car was pushed cause damage? I can see it making it a bit more difficult to move the car, but I'm wondering what damage would be done. – dlu Nov 23 '16 at 02:14
  • @dlu: if the other cars have to use more force, the chance of scratches, bumps etc goes up. – RemcoGerlich Nov 23 '16 at 07:53
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    @makinbacon damaging my drivetrain when the vehicle starts rolling on a hill is my slightest worry. Should my parked vehicle start rolling on hill I have way bigger issues than my drivetrain: Think "other people crushed by my car" – Martin Nov 23 '16 at 10:11

11 Answers11

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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 requires 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.

Dmitry Grigoryev
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dlu
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    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 Nov 22 '16 at 05:48
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    @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 Nov 22 '16 at 12:21
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    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 Nov 22 '16 at 17:00
  • Pedantic is good :-) – dlu Nov 23 '16 at 00:04
  • On the other side of the coin, is second gear better than first to use for push starting since it has a lot lower ratio than first? – method Nov 23 '16 at 03:19
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    @method: yes, and higher gears would be better if it wasn't for the fact that you'd have to be lightning fast on the clutch, 2nd gear is usually a decent sweet spot. – whatsisname Nov 23 '16 at 04:10
  • Can you please elaborate, how would a higher gear work if you weren't limited by your speed on the clutch – method Nov 23 '16 at 04:12
  • It's not so much the clutch as the balance of road speed to engine speed and the possibility of getting the car moving fast enough to spin the engine fast enough to start. First would spin the engine faster but it would be harder to push manually. Higher gears are easier to push but result in slower engine speeds. Second is a good balance. – dlu Nov 23 '16 at 04:22
  • I use either first or reverse, depending on the presumed direction I need to move the vehicle when I start. Personally I do not see a big difference on them. Most important is that the gear is either the first or reverse – Martin Nov 23 '16 at 10:06
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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.

fIwJlxSzApHEZIl
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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 Nov 22 '16 at 05:35
  • 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 Nov 22 '16 at 06:11
  • Answer can be simplified by removing mention of the angle of the wheels, as that is not material to the question. – Mathieu K. Nov 22 '16 at 07:43
  • I do the same except I've been told not to put a gear in at all on flat ground. But I guess on flat its a matter of taste. – Sumyrda - remember Monica Nov 22 '16 at 10:05
  • @Sumyrda Not in Kansas ;-).. phhhhh..... – Peter - Reinstate Monica Nov 22 '16 at 13:52
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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 - Reinstate Monica Nov 22 '16 at 13:54
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    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 Nov 22 '16 at 14:25
  • The motor turns in one direction, the transmission is what converts the torque to forward or backward drive, I don't think that the Gear is going to make a difference because of this. – Malachi Nov 22 '16 at 15:27
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    This answer is badly wrong. There is no such thing as the transmission "fighting against gravity". Rather, the way you're doing it, if the vehicle does manage to move despite friction in the transmission and engine, it will turn the engine backwards, which has the possibility to damage the engine. – R.. GitHub STOP HELPING ICE Nov 22 '16 at 16:50
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    @R.. Really turning and engine backwards can damage it? How? – paparazzo Nov 22 '16 at 16:59
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    @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.. GitHub STOP HELPING ICE Nov 22 '16 at 17:05
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    I believe the danger in some engines (ask me how I know...) is that if you turn it backwards, the cam chain/belt may skip one or more teeth, as I'm guessing the tensioners are designed for one predominant direction of rotation and not the other. Your valve timing will then be off, possibly causing interference with the pistons if you try turning the engine over. – Lyle Nov 22 '16 at 21:28
  • If you have a reverse gear synchronizer, the transmission may allow reverse motion without engaging the gears, so it will do nothing to slow movement. Therefore you should select a gear matching the direction the vehicle would roll, not "against gravity". – Ben Voigt Nov 22 '16 at 22:09
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    It seems very unlikely that engine damage due to the wrong gear would be a problem in the real world – for the damage to happen, first the parking brake would need to fail, then the engine compression would need to be inadequate to hold the car, then the car would have to survive whatever caused it to stop as it ran down the hill with the engine spinning backwards. Possible? Sure, but it seems that the damage from the collision at the bottom would almost certainly be a bigger problem than the engine running backwards for a few seconds – but still there's no harm in using the right gear… – dlu Nov 22 '16 at 23:41
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    I do the exact opposite: I turn the wheels so that, in case the vehicle accidentally moves, it moves against the curb/hillside/obstacle. That way it won't roll down the slope/hill. – Martin Nov 23 '16 at 10:09
  • Seriously: I think your answer leads other to dangerous actions. – Martin Nov 23 '16 at 10:14
  • @dlu It might not even need a full revolution of the engine in reverse direction to cause damage. The car rolling a few cm before stopping at the curb may be enough. – JimmyB Nov 29 '16 at 15:04
  • @JimmyB can you say more about the way the damage could happen or do you know of engines that are susceptible to damage from being driven backwards? – dlu Nov 29 '16 at 19:16
  • @dlu Lyle above has an important point about the belt tensioners. – JimmyB Nov 30 '16 at 16:18
  • So, I'm puzzled by this. I get that an engine could be designed so that it can't / shouldn't be run backwards, but moving it backwards a bit seems like something that you could almost count on happening at some time in the life of an engine in a car with a manual transmission. Besides the example we're talking about here it seems that getting hit/pushed while parked in gear, stalling on a hill, and I'm sure other circumstances could result in the engine moving backwards for a bit, maybe even a few revolutions – it seems odd to me that there wouldn't be more problems if this is true. – dlu Dec 02 '16 at 06:00
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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.

dlu
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kyle_engineer
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    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 Nov 22 '16 at 18:17
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    @Leliel exactly. Not only do you have catastrophic failure of 2 or more systems, but now you have a 2 ton snowball as well. – kyle_engineer Nov 22 '16 at 18:54
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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.

Greg H
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None.

That's what your parking brake is for.

Explanation

It's called a parking brake for a reason. If parking on a steep incline, turn your wheels so that your car will roll against the curb if the brake fails. Better yet, as the last step when parking, let the car roll (gently!) against the curb already.

If you use a gear to keep your car from rolling, that puts a strain on the engine and the entire drive train for which it wasn't designed. Specifically, a mechanic at my local garage described it as "hanging on the cam belt", which would lead to greater wear on it.

SQB
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    I have always been under the impression this is illegal in most states in the USA. (finding the actual law is a little harder but ex: https://www.dmv.ca.gov/portal/dmv/detail/pubs/hdbk/parking) – Austin French Nov 22 '16 at 23:28
  • @AustinFrench That what is illegal? The link provided states exactly what this answer discusses. – Dave Newton Nov 23 '16 at 03:54
  • Perhaps use a wheel block / wheel chock for long term (weeks+) parking on an incline. – SQB Nov 23 '16 at 09:06
  • I am not convinced: When you start to move your vehicle, parked on a slope, the strain on the drivetrain should be heavier. And surely your drivetrain is designed to cope with that – Martin Nov 23 '16 at 10:03
  • @Myself: the drivetrain surely is designed to cope with that. The cam belt? Not so much. Though I'm surprised that this would actually be what the load would rest on – the cams should always run light enough to avert any load on the belt, shouldn't they? – leftaroundabout Nov 23 '16 at 10:28
  • @leftaroundabout I suppose there is no additional strain on the timing belt.. – Martin Nov 23 '16 at 10:33
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    @DaveNewton the link states: "Always set your parking brake and leave the vehicle in gear or in the "park" position." – Austin French Nov 23 '16 at 15:18
  • @AustinFrench I don't think SQB is saying to keep it in neutral, just not in gear. Could be wrong, though. – Dave Newton Nov 23 '16 at 17:47
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    @DaveNewton when a manual is not it gear, it is in neutral... Also, I did not downvote or anything. I think the question is subjective regardless of the law (as the law is rarely enforced unless there is an accident) but it is worth noting I believe. – Austin French Nov 23 '16 at 19:34
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    @AustinFrench Sorry, I was thinking auto trans with a separate park mechanism :/ Derp. – Dave Newton Nov 23 '16 at 20:15
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You certainly want either neutral, 1st or reverse (depending on circumstances, see other answers). One aspect that I see influencing this is a gearbox lock - some cars have an anti-theft feature that can lock the gearbox, preventing the thief from shifting. On such cars, reverse is preferred, as it makes it much harder to drive the car away.

Matej Lieskovsky
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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.

Old_Fossil
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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 Nov 22 '16 at 10:16
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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 Nov 22 '16 at 14:50
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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 Nov 22 '16 at 17:28
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ok a real answer first that doesn't rely on special conditions

if you are pointing uphill put it in reverse. this is to prevent any damage from rolling because you have a house in San Francisco. you should also steer the front wheels to the left (right if you're british) so the back of the front tires are effectively chalked by the curb.

if you are pointing down hill then it should be first. you should also steer the front wheels to the right (left if you're british) so the front of the front tires are effectively chalked by the curb.

now for some conditionals

1st gear, low range 4wd, diffs locked, under drive engaged, and axles set to low gear. yes this does give you 3 shifters and 2 buttons. more is better right?

enter image description here

Cc Dd
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  • If the car is pointing uphill, it seems like gravity would want to pull it backwards, down the slope, so putting the car in reverse gear would seem to make gravity's job easier than if you were to put it in first gear. If the car is pointing downhill, gravity wants to pull it forward, down the slope, so first gear would seem to make that easier than reverse would. Or are you using "pointing uphill" and "pointing downhill" different from how I understand them? What you state feels backwards (not pun intended). – user Nov 29 '16 at 15:39
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    @MichaelKjörling The reason to use forward gear for pointing downhill and rev for uphill is so if the car does roll you will not spin the engine backwards. But whichever one of those gears are lower will be the gear that will hold the best regardless of direction. engine compression is engine compression regardless of which way it is spinning. – Cc Dd Nov 30 '16 at 03:20
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To add an answer with sources, I own a Hyundai i20. Page 5/4 (191 of pdf) of the owner's manual states:

Before leaving the driver's seat, always make sure the shift lever is engaged in 1st gear for manual transaxle or P (Park) for automatic transaxle, set the parking brake fully and shut the engine off. Unexpected and sudden vehicle movement may occur if these precautions are not taken.

Page 5/8 (195 of pdf) states:

Before leaving the driver's seat, always set the parking brake fully and shut the engine off. Then make sure the transaxle is shifted into 1st gear when the vehicle is parked on a level or uphill grade, and shifted into R (Reverse) on a downhill grade. Unexpected and sudden vehicle movement can occur if these precautions are not followed in the order identified.

I'd rather take my advice from the manufacturer of the vehicle!

Dezza
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  • Even when the manufacturer appears to contradict themselves between the two snippets? Also, the manufacturer is interested in covering their own rear; if they state to do something, and it can be shown that the driver didn't, then if because of the driver's actions there is an accident, the manufacturer can't really be held to blame, can they? If they had said nothing in the manual, someone would almost certainly argue (perhaps in a court of law) "well, you didn't say I couldn't do it that way!" and the court would have to agree because that was indeed the case. CYA is a real thing. – user Nov 29 '16 at 15:44
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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.

paparazzo
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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.

alephzero
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    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 Nov 22 '16 at 18:06
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    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 Nov 22 '16 at 18:36
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    Relying on the parking brake alone merely to guard against a rare occurrence probably already accounted for by an interlock switch is not a good idea. – Lyle Nov 22 '16 at 21:42
  • Furthermore... would that really happen to anyone? Well, to someone who usually only drives automatic, perhaps. When I drive automatic, I tend to find myself first feeling around for the clutch pedal, before I recall there isn't one and I can just turn the key. – leftaroundabout Nov 23 '16 at 10:34
  • older cars in europe - certainly anything from 2001 onwards - are likely to allow you to start the car in gear. More modern cars in europe require the clutch to be depressed (manual) or the brake to be depressed (automatic/electronic clutch) before you can start the car. – Mauro Jan 08 '18 at 15:13