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Thread: Downhill descents with AUTO's

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    Hardcore belzi82's Avatar
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    Downhill descents with AUTO's

    Downhill Descents
    Driving through the brakes with an auto

    There is another very effective method for taking auto fourbies down steep hills (slippery or rock hopping), often referred to as "driving through the brakes".

    Here's the gist of it, see if you can get the hang of it after a bit of practice.

    Basically you select low first and apply modest, steady pressure to the brake with your LEFT foot. Enough to hold the car with the handbrake off, then gently apply power and the car will move slowly in a very controlled way, in fact dead slow if you want. If you lift off the gas and it gently stops then you have about the right brake pressure. On muddy slopes you will need to keep on enough power to keep all the wheels turning slowly and steadily whilst keeping absolutely constant pressure on the brakes.

    A few of things happen when you use this technique,
    1. you tend to fool the open diffs into seeing very similar torque across the axle so you get a very even drive across axles, particularly true on the front axle where your brakes become the dominant load on the axles, not the tyre grip (or lack of it)
    2. you get all four wheels receiving very close to the same drive torque and nice and slow. You can suddenly feel the car biting on all four wheels insead of slipping and sliding as it will do if you attempt to roll down the hill on brakes alone.
    3. your torque converter is slipping heaps (you are forcing it to) but your engine rpm will be somewhere around 1000-1500 (not at idle) and that usually means the torque converter will be trying hard to connect engine & tranny .. this is one you would have to ask an expert about, but I have heard claims that this is one of the reasons this technique works so well.

    You can crawl down slopes and rock ledges where you are on three wheels momentarily but despite a little bit of slip the car quickly regains composure as you still have all four wheels (restrained by the brakes) being driven nice and steadily. The same piece of track tackled on brakes alone would have been pretty dicey.

    This technique very valuable whenever you want to crawl an auto fourbie through a hard bit and you can easily go as slow as a manual in Low first.

    My guess is that your ATF fluid heats up a bit doing this but you are only doing it a couple of minutes here and there, plus your front discs may makes some weird squealing and rattling noises as the calipers move about under the combined forces of braking and drive. Nothing too alarming though as they are still working

    Some 4WD training instructors teach this technique.

    Go out and practice it and soon you will be using it often in the hard stuff. When you are good at it, you just apply a bit of brakes with the left foot whilst maintaining or slightly increasing the power anytime you look like losing momentum UPHILL because it helps even out the cross axle torque (poor man's LSD).

    BTW, don't forget the key factor of tyre pressures. Let them down to 25psi to start with and that alone will make a big difference.
    A woodland in full color is awesome as a forest fire, in magnitude at least, but a single tree is like a dancing tongue of flame to warm the heart.

  2. The Following 8 Users Say Thank You to belzi82 For This Useful Post:

    bad055 (6th November 2012), big_fletch (18th September 2011), Finly Owner (18th September 2011), FNQGU (15th May 2014), Nixon (24th September 2013), Seanz (2nd January 2014), Woof (18th September 2011), Yendor (18th September 2011)

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    I don't have an auto but if I wish to pull of some speed on a descent I softly apply some hand break, as with Patrols this is on the drive shaft so it works much the same as engine braking & a whole lot less chance of locking up a wheel.

    Im tipping the same method would also work well with an auto.

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    Quote Originally Posted by patch697 View Post
    I don't have an auto but if I wish to pull of some speed on a descent I softly apply some hand break, as with Patrols this is on the drive shaft so it works much the same as engine braking & a whole lot less chance of locking up a wheel.

    Im tipping the same method would also work well with an auto.
    This is the method I currently use with my auto and I find it works well.

    I am keen to give the "driving through the brakes" a go if it is a better way of doing it.

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    Hardcore belzi82's Avatar
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    Quote Originally Posted by Yendor View Post
    This is the method I currently use with my auto and I find it works well.

    I am keen to give the "driving through the brakes" a go if it is a better way of doing it.
    I use both ways - depending on the descent!
    A woodland in full color is awesome as a forest fire, in magnitude at least, but a single tree is like a dancing tongue of flame to warm the heart.

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    Banned Bigrig's Avatar
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    Quote Originally Posted by belzi82 View Post
    I use both ways - depending on the descent!
    I rarely user the handbrake as it doesn't prevent the rear diff from opening up, but 'brake feathering' is a definite friend of mine - showed Ray through how to do this up at Landcruiser last time - learn how to do it properly, and not only can you turn a downhill section into a doddle, but you will definitely be able to climb uphill shelfs etc easier also ...

    That said, got the reduction gears now, so virtually don't touch the brakes downhill, but still use it often going uphill (do it right, and you'll go nigh on as far as someone with a rear locker!).

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    Smart like tractor Ben-e-boy's Avatar
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    Quote Originally Posted by Bigrig View Post
    I rarely user the handbrake as it doesn't prevent the rear diff from opening up, but 'brake feathering' is a definite friend of mine - showed Ray through how to do this up at Landcruiser last time - learn how to do it properly, and not only can you turn a downhill section into a doddle, but you will definitely be able to climb uphill shelfs etc easier also ...

    That said, got the reduction gears now, so virtually don't touch the brakes downhill, but still use it often going uphill (do it right, and you'll go nigh on as far as someone with a rear locker!).
    the last beerburrum trip in the wet proved that at the 3 step ups didnt it
    I recall that one clearly
    96 GQ coil/Cab
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    Banned Bigrig's Avatar
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    Quote Originally Posted by Ben-e-boy View Post
    the last beerburrum trip in the wet proved that at the 3 step ups didnt it
    I recall that one clearly
    Yessum boss ... did indeed!!!

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    Patrol God Dhuck's Avatar
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    What are brakes?
    In the words of a Dhuck "QUACK".

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    Smart like tractor Ben-e-boy's Avatar
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    Quote Originally Posted by Dhuck View Post
    What are brakes?
    Its those trees that arnt big enough to damage you vehicle but are big enough to slow you down.... or an import if your in the city. the beauty of imports is that they can be used as a wheel chock or a ramp
    96 GQ coil/Cab
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    Quote Originally Posted by Ben-e-boy View Post
    Its those trees that arnt big enough to damage you vehicle but are big enough to slow you down.... or an import if your in the city. the beauty of imports is that they can be used as a wheel chock or a ramp
    Love the way you think...............hahhahahahahahaha

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