Manual car rolls when parked in gear, normal or not?

Suddenly while leaving the car, I noticed the car lunges forward in jerks, and stops again, before lunging forward again with a jerk.

BHPian Petrolhead_97 recently shared this with other enthusiasts.

I have a 2022 Suzuki 1.5L Petrol Ertiga with only 7.5k kms on it, almost 1 year 5 months old

Recently I had parked my car, in my apartment drive-through, which is a ramp leading to the basement, in first gear, and I tried to leave the car.

It has a moderate slope, (as most ramps do)

Suddenly while leaving the car, I noticed the car lunges forward in jerks, and stops again, before lunging forward again with a jerk, covering inches/ or a few cms continuously.

Is this normal?

I have been driving for years, and I had always thought that when parked in gear, it would be impossible for the car to move. So initially I got shocked to see this happen

Why does this occur? Is this normal or not?

Here’s what BHPian condor had to say on the matter:

If the car was parked facing the direction of slope, and engaged in 1st gear – then it will roll forward. Forward (slope) + Forward (gear) = Forward Movement.

I guess this is why people suggest to use the gear opposite of the slope direction in order to aid parking on slopes.

Here’s what BHPian sagarpadaki had to say on the matter:

If the slope is too steep then you will see that behavior because the gear is not able to resist the forward weight of the car. Did this happen even when you applied parking brake? Like condor said, put reverse gear when parking nose down and first gear when parking nose up.

Here’s what BHPian bladegradev8 had to say on the matter:

Interesting topic. Does anyone know how electronic parking brakes work? Is that a physical brake like the hand brake or does it electronically apply a gear too? How good is it at keeping the car stationary on a slope?

Here’s what BHPian SS-Traveller had to say on the matter:

Given a steep enough slope, it will still roll, turning the engine over in reverse. The concept of engaging gears so that the engine turns over in reverse, was due to engines self-starting once they start to turn over – especially diesels – and the car running away on its own power. Nowadays, with electronic control of fuelling, there is no way a modern engine will self-start even if turned over, since there is zero fuel supply.

The best options when parking on a very steep slope are 1. Turning the front wheels towards kerb (facing downslope) or away from kerb (facing upslope); 2. Handbrake & appropriate (low) gear for MT cars; and 3. Chocks (bricks, stones etc.) on at least 2 wheels – all applied together.

Here’s what BHPian svsantosh had to say on the matter:

So you are in MANUAL Car, and approaching a UP or DOWN Slope…

For UpWard Slope

1) Come to full stop on brakes (car engine on still)

2) When Vehicle is Running, and 1st Gear engaged (Clutch & Brake Fully Pressed, NO HAND BRAKE yet) turn key off

3) Release CLUTCH pedal first, car will not move because you are On Brake pedal press mode still (No hand brake yet)

4) Now release BRAKE pedal gradually – You will see car move backwards down the slope a few inches, the gear shaft has to rotate in sync with the dead crank and find its dead spot – can be a few inches movement, no hand brake yet. The Suspension spring opening up can cause creaks and moans – its OK!

5) Now the engine is holding the driven wheels with its compression vacuum – Now Engage Hand brake with good arm power.

Car will never move now.

Note – If car facing downward slope

All steps same except (2) Engage Reverse Gear

or AMT Cars similar story – Turn key off in WHILE in D or R mode

My wife’s minor accident and lessons

For Automatic

1) Into P (park mode) first (let the trans lock the wheels)

2) Yank the hand brake hard enough

If you dont engage hand brake properly and if you are in the direction of slope –> gear, the car will roll and piston move up and down. NOTE all the cylinders are not holding a dead car, its usually 50% fully closed and 50% open (depends on timing cycle). A turned off engine never has all 4 pistons or valves in same condition. Hence only few cylinders hold the car and it can try to rotate and move the car.

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