Get Out Of Jail Free - The Stall Start Recovery
The Stall Start technique is as old as four wheel drive itself and can used in a number of situations to regain control of a tricky situation.
Commonly taught at four wheel drive instructional courses as a means to safely descend steep hills, the stall start can also be employed to force a stalled vehicle from a water crossing.
Stall start recovery is most commonly used on steep hills that cannot be crested. Four wheel drives equipped with manual transmissions can be used to halt the car and then reverse back down a hill using a combination of low gearing and engine compression.
All vehicles are best controlled when they are being 'driven'. The ideal way to corner in a passenger car is to wash off speed before a corner and then apply acceleration through the corner while exiting. Coasting around in neutral or braking halfway into the turn is the perfect rollover recipe.
The same theory applies to tackling big hills in 4WD. The low gearing afforded by low range first or low range reverse gives far greater control than rolling down in neutral and applying the brakes.
In fact the clutch and brakes are your worst enemy coming down really steep hills. Stay away from them wherever possible. Occasional light pressure on the brake pedal can aid in controlling progress over obstacles but it's best to trust the engine and let the compression do the work.
Engaging the clutch sets the car in neutral and it will freewheel downhill and gain speed - the last thing you want.
How to Go About It
- When you determine that you won't be able to crest the hill - commit to a stall start recovery and deliberately stall the vehicle. Do this by allowing the engine revs to die and then apply the brake pedal. Do not engage the clutch. The engine will stall naturally.
- You will have come to a stop on the hill with the car in gear and your foot on the brake - perfectly in control.
- Test the holding ability of the brakes by easing the clutch in. Once you've determined the car is holding under brakes select low range reverse gear. Do this in one smooth motion from forward gear straight into reverse and immediately release the clutch pedal.
- Driveline torque may make it impossible to select reverse gear. If this happens do not use the clutch but hold the gear lever against the reverse 'gate' and give the key a quick flick. You are engaging the starter motor in an attempt to realign the drive-line and release any torque built up in the system. The key is only flicked long enough to rock the engine over - not long enough to start it. With lever pressure against reverse the transmission should slip into reverse gear.
- At this stage you are still stationary on the hill with your foot on the brake pedal and the car in reverse gear.
- Gently release the brake pedal being prepared to re-apply the brakes if necessary. The vehicle is being held by engine compression which is the same resistive force that will allow you to descend in a controlled manner. Petrol 4WD engines may start automatically, in the same way you 'push start' a car. Don't panic. Continue the descent as outlined below.
- Start the vehicle without engaging the clutch or the brake. Do this by turning the key just long enough to start the engine. The vehicle is now running and slowly descending the hill in low range reverse gear - under your control. Don't use the clutch. Use the brake smoothly and only as necessary. Don't use the accelerator. Do not cause the wheels to lock up and don't try and turn around to go down forwards. Simply reverse down the hill calmly. Concentrate on picking out the smoothest route.
Low range first or reverse gear in 4WD's is extremely snail-like. Many downhill descents even require the use of some throttle because progress can be so slow.
It's a good idea to get out and try your 4WD out in low range, first gear by going forwards down a few smaller slopes. You'll quickly understand just how tractable and controlled the low range side of your transfer case really is.
You can also try a key or stall start on flat ground to get a feel for the engine starting up and rolling off in gear. The stall start recovery can be accomplished in reverse or first gears.
As we pointed out in the intro the key start can also be implemented to propel a stalled vehicle from a water crossing. Turn the key in short, intermittent bursts so as not to burn out the starter motor and inch your way out of the creek.
Other 4WD recovery gear you may be interested in include the Hi-Lift Jack and the art of using a Snatch Strap.
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