This doesnt sound right. First of all in a manual transmission car you HAVE to put the parking brake when you park the car. That’s what it is there for, and that’s what will stop the car from rolling. Putting it in gear is merely a safety measure and i have never seen my car roll even the slightest amount.So even if rolling the engine backwards could damage it(which i doubt since valve timing is mechanically related to the crankshaft position) it wont happen.
You seem to be under the impression that engines physically cannot rotate backwards. That’s incorrect.
If you are parked facing downhill in first gear and the car begins to roll downhill = forwards, the engine rotates in its normal direction, say clockwise.
If you are parked facing downhill in reverse gear and the car begins to roll downhill = forwards, the engine rotates in the opposite-to-normal direction, say counter-clockwise.
If you are parked facing uphill in reverse gear and the car begins to roll downhill = backwards, the engine rotates in its normal direction, say clockwise.
If you are parked facing uphill in first gear and the car begins to roll downhill = backwards, the engine rotates in the opposite-to-normal direction, say counter-clockwise.
As others have said, rotating the engine in the opposite-to-normal direction (counterclockwise in my example) can potentially damage parts inside the engine. So don’t set up a situation where a runaway would do that. That means leave the transmission set like situation 1 or 3 above, not like 2 or 4.
For round numbers, first and reverse provide the same resistance to the car rolling away. And on a steep hill with the right circumstances there’s more than enough oomph there to start the car rolling absent brakes.
Uh, no , they don’t. At least not always- I have three vehicles with manual transmissions. They are a Toyota Yaris, Ford Ranger, and Elantra GT. For the first two, reverse gear is much higher than first (I don’t like this. Who needs to go so fast backing up?) and the Elantra’s reverse is a good bit lower than first (This is better. The other two require slipping the clutch when backing).
To summarize the take-aways from what seems like the consensus in this thread:
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Use the clutch and gears for increasing speed, and the only the brakes for decreasing speed and stopping. Downshifting can be done only when you are at the right speed for that gear, but should not be used to slow the car (unless maintaining speed on a long downhill).
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When parking facing downhill, use first and the parking brake. When parking facing uphill, use reverse and the parking brake. Always park it in first or reverse with the parking brake on.
I checked-out some of those youtube videos on clutchless shifting, and while I understand the concept, I cannot bring myself to try it. I am currently lacking the nerve to try. :o
Add to the summary that the parking brake, esp if it is a hand brake, is your friend for starting forward on a hill. Used it often in my Wrangler.
I don’t think Rick (who I believe is an automotive mechanic) was responding to not using the parking brake, but rather what gear to leave it in uphill vs downhill. There’s a nice explanation by a poster named dyce in this thread on physicsfocums.com, with illustrations and everything as to how and why it should be parked uphill in reverse and downhill in 1st.
I would find it irritating and difficult to stay in the right gear on a 6-speed gearbox, which would be required for good fuel economy.
On the old 3-speed, it wasn’t much work to stay in the correct gear, and the auto-lost out on it’s poor operating efficiency.
What I like about a manual is that changing gears is so much smoother. I guess there must be expensive or CVT cars out there that don’t throw you around when they change gears (compared to a manual with an only-average driver), but I haven’t had the pleasure yet.
The only difficulty I had going from the bike to the car was getting used to using my foot instead of my hand. Maybe I could have ridden the wet clutch at 10mph on the bike, but they would have overheated if I’d tried that for very long.
(Slowing down using the gears is what you do when driving a 50yo truck in the mountains.)
The point of putting it in gear is in case the handbrake/emergency brake fails - for example, it is rare but not unheard of for the cable to snap. Then you want something else to provide resistance to prevent your car rolling away. Also, pulykamell’s link I have quoted below (which I appreciate wasn’t there when you made this post) explains that some engines rely on hydraulics for their timing, in this case the last part of your post could be incorrect.
Thanks - I hadn’t really thought about it this way, but I guess that’s sort of true. Because I have never experienced it, I didn’t think it was a possibility. For example, last night (after first reading this thread) I parked on my driveway, facing slightly uphill, applied the handbrake, put the car in first gear (engine off), and released the handbrake - the car simply rocked back very slightly and stayed there. I suppose all that means is my particular engine and transmission has enough resistance in it to prevent rolling back on a slight slope (which is all my driveway is). I have experienced the same thing in the past when parking (due to idiocy like forgetting to initially apply the handbrake, for example) but don’t recall the steepest slope I was on at the time. I see now that what you, Rick, and others are saying is given a sufficiently steep slope, this resistance could be overcome and the engine could turn backwards. Having had my ignorance fought, I will try to remember this advice in future and leave the car in reverse gear when facing uphill and first when facing downhill (with the handbrake on as well, of course, and the wheels pointing in the correct direction if I am on a kerb). Thank you both.
This I have done, mostly for fun but it came in handy once when the clutch was near to failing on a car I was driving. As such, for the few miles I had to drive before I could get it to a garage, I attempted clutchless changes all the time, and they usually worked just fine. The worst that can happen, if you don’t match the revs well enough, is a bit of grinding from the syncromesh when you attempt to engage the gear - if that happens, you’ll know it before you fully engage the gear (you won’t be able to engage it at all unless you really force it, so don’t do that) and you can simply move the gear lever quickly back to neutral and try again. I managed to get quite good at it in a fairly short space of time, so I only needed the clutch to move off from junctions (unless you are on a downhill stretch, I don’t know of a way to get a manual car to move off without the assistance of a clutch, without risking further mechanical damage - but I’d be pleased to hear otherwise).
Thanks for that, very helpful. Another small part of my vast ignorance has been fought.
Shifting without using the clutch is hard on the synchros.
Not sure what you mean by “have to.” There’s no legal requirement, and it’s certainly physically possible to park the car without touching the hand brake. You don’t even have to leave it in gear to be able to shut the engine off and pull the key.
I have a motorcycle for which a regular maintenance item is adjusting valve clearances. This procedure requires rotating the crankshaft to position the engine at top-dead-center, either with a wrench on the front pulley, or by manhandling the rear wheel with the gearbox in top gear. The service manual explicitly warns that the crankshaft should only be rotated in the normal direction; reverse rotation puts tension on the portion of timing chain that’s normally (relatively) slack, i.e. the portion that runs through the plastic tensioner/guide. With reversed chain travel and unusually high tension and very low speeds, it’s possible to snag and break the plastic tensioner/guide, necessitating expensive repair work.
The same may be true for any other engine with a timing chain. Moreover, variable valve timing systems common on cars these days (regardless of whether they are belt drive or chain drive) mean there could be all kinds of components in there that are not expecting reverse motion/loading.
Bottom line? setting up the engine to potentially spin backwards is risky policy.
Also, some cars roll the engine more easily than others. My driveway isn’t terribly steep, but if I park my warmed-up car on it without setting the handbrake, it will slowly roll the engine over and creep downhill.
I just bought a brand new Subaru WRX and I was surprised to find out that on an incline like a hill it has a feature that automatically keeps the brakes engaged till you begin accelerating in first gear, at first I thought it was sort of cheating because I’ve never had an issue on hills but the more I’ve driven it I really enjoy the feature its the first manual car I’ve owned that’s had this, is this a common feature now on new manuals?
Yes, “hill hold” is available on multiple models.
I rented a VW Jetta a couple of years ago with an automatic transmission that had this feature.
By have to i mean that that’s what you should use to prevent the car from rolling, and that’s what it is designed to do.
That’s why i would never rely on the engine to prevent the car from rolling.It was never meant to do that, and can easily roll .You should use the parking brake. I always do, and then leave the car in gear as an added safety measure(although pointing the wheels towards the curb seems safer) and that’s why i found it odd that you said the car will slowly roll downhill and rotate the engine.
As far as the engine being damaged by turning backwards, i stand corrected, i didnt really think it through.
I’ll confess that in my younger days I drove multiple manual transmission vehicles with either broken or not-particularly-efficacious parking brakes. Never had one roll away on me, even on hills. The reason you set the parking brake isn’t because the engine’s compression won’t reliably stop the car from rolling (it will), it’s because there’s a chance it might pop out of gear.
Hope this is not considered a hijack, but I’ve always wondered about this problem with snow driving with a manual.
Let’s say you are parallel parked in a snowy spot (i.e., cars directly in front and behind your car), and you need to rock the car out of the space (because you don’t have 100% traction due to the snow) … how does one do this, without feathering the clutch too much?
I’ve found that I really have to ride the clutch too much when doing this, because if I were to let the clutch out all the way, the amount of throttle I would have to give to avoid stalling would send me crashing into the car in front or behind me, should the wheels decide to catch traction suddenly. So I’m sure I’ve sent a few clutches to early graves in my day because of this.
Anyone have any tips for this?
If you need to creep forward or rock the car out of something or whatever, yeah, you’ve got to use the clutch. Not a big deal. You probably don’t want to make rocking out of the snow a daily occurrence, though. Usually what people are talking about when they tell you not to “ride the clutch” is not to rest your foot on the clutch pedal when you’re riding down the road. Using the clutch for necessary low-speed maneuvering is going to shorten the life of the clutch somewhat but it’s unavoidable.
Ok thanks, good to know that it’s unavoidable for very slow moving. I always wondered if I was just bad at that part of manual driving.
I’ve heard someone suggest waiting a little bit in between rock attempts to let the clutch cool off, in order to help mitigate the wear – does that make any sense?
This will depend on how much rocking you’re doing, and how well you manage the clutch and throttle. The heat dissipated in the clutch is a product of the slip RPM (when you’re not moving forward, this is just the engine RPM), the amount of torque you’re trying to transmit across the clutch, and the amount of time that it’s slipping. So if you’re good at keeping the engine RPM low while trying to rock the car free, then this will minimize how warm the clutch gets.
If you expect to encounter snow-clogged streets on a routine basis, snow tires may be a worthwhile investment; in the situation you describe, they will help minimize the amount of rocking required to free the car, which cuts down on the total clutch-slip time.
Bottom line though, the clutch is a wear item just as surely as brake pads are. We can adopt policies that result in less wear, but we can’t zero it out.
Letting the clutch cool down between attempts will reduce your chances of getting that horrible burning clutch smell, but I don’t know if it’ll actually reduce clutch wear versus just going for it.