What is 'clutch coasting'?

What is 'clutch coasting'?

It is perhaps important to understand the clutch before describing clutch coasting and the effect on driving as well as the result in a driving test.

 

The Clutch
The clutch pedal is the left pedal and operated by your left foot, not surprisingly.  The clutch itself is situated between the engine and gearbox.  It’s a connection which the driver has complete control over and requires extensive practice in its use.

Simply described, the clutch is made of two plates.  A clutch plate is connected to the flywheel of the engine and rotates at the same speed of the engine.  The other is a pressure plate and is connected to the gearbox and only rotates when it’s held against the clutch plate by very strong springs.  Each time you push the clutch pedal in, you force these plates apart, breaking the drive connection.  When in neutral, no gear is selected and even though both clutch & pressure plates are touching, the car wheels will not turn unless the car is already in motion.

Good clutch control, engaging both plates fully and smoothly, comes with practice, and is essential when moving off or changing gear.  As you become more proficient, you will be able to judge exactly the gear you need for the speed you intend to travel.

Clutch Coasting

Coasting in general occurs while the vehicle is moving; it’s not being driven by the engine.  This occurs either when the clutch pedal is held down or the gear lever is in the neutral position while the car is in motion.  Each time you change gear you coast a little, this is unavoidable, but naturally should be kept to a minimum.

Otherwise, any form of coasting is wrong because:

• Control of the vehicle is severely reduced – effectively just the steering wheel and brakes.
• Should something unexpected happen – it could be difficult to select the correct gear.
• Downhill, the car will gather speed requiring more braking where engine braking would capably assist.
• Steering response will be affected on corners and bends.

Coasting most frequently occurs when keeping the clutch depressed while turning at intersections, dressing the pedal too soon before coming to a stop at a stop sign or traffic lights, or keeping the pedal depressed too long after a gear change.

To maintain good clutch control, the engine and road speeds must be properly coordinated when changing gears.  It’s important not to slip or ride the clutch, nor to coast with the clutch fully disengaged.

Some would argue that it’s cheaper to wear out your brake pads rather than wear out a clutch due to engine braking. Still, the cost of getting into accidents (to property, life, and limb) is definitely greater than whatever marginal savings in fuel costs and brake pads you will get from coasting.

Q-Safe Driving Test – Clutch  Control (Clutch coasting errors are underlined).

Performance Outcome – The applicant should be capable of controlling the cutch in a manner that produces a smooth take up of power to the driving wheels and assists in the changing of gears.

 NCDE (Non-critical driving error) -  This is an error which does not by itself compromise the safety of other road users or the safe operation of the vehicle, but if you accumulate nine or more errors, you will get an unsuccessful result.

1. Excessively and continuously rides the clutch (includes during the low speed manoeuvres).
2. Rests foot on the clutch (when not being operated) for more than 15-seconds (except motorbikes).
3. Releases the clutch too quickly.
4. Coasts with clutch depressed prior to or during a turn.
5. Coasts with the clutch depressed for a duration of between 3 and 5 seconds.
6. Fails to use the clutch in an appropriate manner to maintain control at low speeds (for example during heavy slow moving traffic and reversing manoeuvre).
7. Operates the clutch incorrectly.

NOTE:  For low speed tight cornering on the reverse park manoeuvre, the driver may need to feather the clutch to maintain good control.  For low speed driving with less manoeuvring, such as slow moving traffic or straight reverse, it may be more appropriate to fully release the clutch.

SRDE (Specific repeated driving error) This error is recorded if you repeat the same error a specific amount of times (usually 6 or more times).  By demonstrating a lack of skill or ability, it indicates you are not ready to drive safely on your own, an unsuccessful result – more practice needed.

1. Repeated clutch coasting (6 or more times)
2. Repeated stalling (6 or more times)

CDE (Critical Driving Error) Safety or other road users is compromised or indicates an inappropriate level of skill or ability.  Unsuccessful result.

1. Operates clutch in a manner which compromises the safe operation of the vehicle.

NOTE:  This includes cutch coasting for more than 5 seconds or coasts with the clutch depressed prior to or during a turn where safety is compromised.

Good clutch control, as previously mentioned, comes with practice, and is essential when moving off or changing gear.  As you become more proficient, you will be able to judge exactly the gear you need for the speed you intend to travel.