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The snag with wheel chocks is that if you really do let the car roll up against them you can't get them out without doing a hill start every morning with a cold engine, and then you have to trust the handbrake alone while you get out and retrieve them.
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The snag with wheel chocks is that if you really do let the car roll up against them you can't get them out without doing a hill start ..........
Lever them out with a crowbar ~ cost about £7.
In any case, you'd only use them in case movement occurred, not to prevent further movement.
Edited by L'escargot on 10/10/2008 at 09:50
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Billy25 wrote>>so choose a gear opposite to the way the car is facing to the slope
Mapmaker responded>>Certainly not. Choose 1st gear.
(and then appended reasons.)
Thanks for that, Mapmaker. I'd never heard that, and had always done as Billy25 suggested. (OK, not always - but always since I stopped relying on my handbrake.)
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>>Thanks for that, Mapmaker. I'd never heard that, and had always done as Billy25 suggested<<
Yes! thanks for the explanation from me also!
I'd always been told (and followed) that if you were facing forwards down a steep slope, as well as h/brake, choose reverse, it was harder for the car to roll forward if the wheels want to naturally turn backwards, as it would have to overcome the friction of the tyre on the slope first, then turn the engine.
Billy
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Google for wheel chocks. Lots of choice price about £10 per pair.
A couple of house bricks or some 4 by 2 timber is cheaper though.
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A couple of house bricks or some 4 by 2 timber is cheaper though.
But not as elegant. I wouldn't want my drive littered with what looked like building site leftovers!
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You might want to be aware that fluid levels will be all over the place if the car is kept on a very steep drive. We used to park our old Ford Escort on the steep drive and one day noticed a wet passenger footwell. Further investigation found battery acid had leaked out over time, corroded the edge of the battery tray and then proceeded to rot the floor.
Also, the idea of engine and gearbox oil collecting in one end doesn't sound ideal either.
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But not as elegant.
Cut the timber into a shape that resembles a wheel chock then.
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Get a sleeping policeman! (I believe there is one due to leave the Met at the end of the year... :-)
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First is inevitably lower than reverse.
That's usually not the case.
>>Secondly, reverse gear works by bringing in an extra little gear; choose reverse and you are putting a lot of strain on that extra gear - it's not designed to be put under that sort of strain.
Again, the torque caused by the engine's compression is tiny when compared to the torque the engine actually produces when running, so, again, this isn't true.
If you have an engine with a timing chain, it is unadvisable to rotate it against the direction of rotation - Mercedes Benz workshop manuals specifically caution against it.
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>>>> First is inevitably lower than reverse.<<
Actually, maybe you are right! - i remember that scene in the film "Ice cold in Alex" when they hand-cranked the ambulance up the sand dune, in reverse and with the plugs out, as they said reverse was the lowest gear.
Soooo now i'm also confused! - what is the "best" way to park on a steep incline? (and to avoid argument you have nothing to use to chock the wheels!)
Billy
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The ratio of reverse gear is largely a matter of convenience for the gearbox designer - sometimes it's lower, sometimes higher than first.
If your car has a DMF, I would warn against leaving locked-in torque in the transmission. Likewise, as has been pointed out for chain drives, any timing drive with a sprung tensioner on the slack side of the belt or chain is not likely to respond positively to being loaded backwards. In an extreme case, the drive could jump a tooth on subsequent start up.
659.
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Likewise as has been pointed out for chain drives any timing drive with a sprung tensioner on the slack side of the belt or chain is not likely to respond positively to being loaded backwards. In an extreme case the drive could jump a tooth on subsequent start up.
Sorry, but that is a bit technical for the likes of me. What does it mean in practice - i.e. what should I do or not do?
Edited by tyro on 10/10/2008 at 16:31
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Don't leave your car parked in gear on a slope with the weight of the car taken by the drive system rather than the brakes when you have selected a gear of opposite direction to the one in which gravity is acting on the car. (Sounds like a VOSA directive, but I couldn't quickly think of a better way of putting it).
If gravity is pushing the engine of your car backwards, the tensioner which is normally on the slack side of the chain or belt is on the tight side. Constant gravitational force will push back a hydraulic tensioner to the point where the chain or belt will be very slack indeed. On a subsequent start up in the normal direction of rotation, there could be enough slack in the system for the drive to jump a tooth. This is one of the reasons I don't like hydraulic tensioners.
659.
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Thanks 659.
So, if I park facing uphill, I should put the car in reverse, not first. If facing downhill, put it in first, not reverse.
(I'm definitely a little slow on the uptake tonight.)
Oddly enough, that's the opposite of what I've been doing, though I have been using the handbrake as well.
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Reverse is often lower than first - but it does vary. Anyone really concerned ought to check their manual.
As a rule, you don't want to go terribly fast backwards and car makers often make reverse low for this reason (I think there are design reasons too where it is cheaper).
Other than the level in my garage and shed, I always engage a low gear in anything as I don't trust handbrakes! (Garage or shed, I don't use handbrake or gears - they are level and nothing at all means you can push it etc).
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- i remember that scene in the film "Ice cold in Alex" when they hand-cranked the ambulance up the sand dune in reverse and with the plugs out as they said reverse was the lowest gear. >>
Actually they cranked it up forwards - see this picture:
www.britishcinemagreats.com/title_films_page/...
I think when driving up sand dunes rear wheeel drive is better.
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Although i couldn't get that site to open Cliff, i assume the picture of them cranking Katy up forwards might be a "flip" of the original, (as used for car advertising)
It definately went up backwards :
Quote from wikipedia:
He panics, blunders into some quicksand, and buries his pack, though not before Anson and Murdoch see that it contains a radio set. They drag him to safety and, while he recovers, decide not to tell him of their knowledge. During the final leg of the journey, Katy must be hand-cranked in reverse up an escarpment, and van der Poel's strength is again crucial to achieving this.
and some "science" back it up! ;-)
www.open2.net/hollywoodscience/icecoldinalex2.html
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One of the common ways to implement reverse on a rwd gearbox a straight cut sliding mesh gear which is interposed between a small straight cut gear which is machined out of the solid layshaft, and another straight cut gear which is machined on the outer rim of the sliding outer collar of a synchro hub.
As the driving gear on the layshaft is quite small, and the gear formed on the outer collar of the synchro hub is larger than the other gears on the mainshaft, and the sliding straight cut gear is just an idler, then, reverse ends up being the lowest gear ratio in the gearbox.
Having said that, as an example to the contrary, the gear ratios on most Vauxhalls whether FWD or RWD do have a lower ratio in first (although the difference is small).
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I was rather surprised to find out (by accident) that reverse gear is both helically cut and fully synchronised on my Superb (Passat B5.5). Just the thing for impatient inhabitants of its country of mechanical origin, I think.
I've no idea what the ratio is, but my (proper) SAAB had quite a high reverse - also helically cut. You had to leave that car in reverse gear (just as well in view of the Girling disk handbrake) - it never rolled away.
659.
Edited by 659FBE on 10/10/2008 at 23:17
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