The Methusalean Clutch

One of the many admirable – appealing – things about manual transmissions is that they usually last longer than automatic transmissions, which they do because they’re just a box of gears in metal box filled with oil. They’re basically pretty simple. Automatics have pressurized hydraulic controls and electronics that add failure points that manuals – being mechanical things – lack.

But there is one thing about manuals that everyone who owns a vehicle so equipped will eventually have to deal with if they own it long enough. That thing being the clutch.

The clutch is the thing that physically connects the spinning crankshaft – via the spinning flywheel – to the transmission, which in turn turns the wheels that cause the car to move. Because it is a physical connection, that connection has to be disconnected during gear changes and whenever the vehicle isn’t moving – unless you put the transmission in neutral – because the engine is not strong enough to turn the Earth. The resistance will stall the engine. And changing gears without momentarily interrupting the connection is hard on the transmission (if not timed exactly right).

That’s why it is necessary to push in the clutch pedal when the vehicle is not moving and the transmission is not in neutral – in order to allow the engine to keep on running. Pushing the clutch pedal in disengages the clutch – which is a disc with little friction pads on it that are made of a material similar to brake pads.

When you let the clutch pedal out, the clutch reconnects the engine to the transmission – and the vehicle moves. Shazam!

Of course, this entails wear – just like your car’s brakes wear over time from slowing down the car. Eventually, you will have to replace the brake pads – and the same goes for the clutch. But you can extend the life of the clutch, just as you can extend the life of brake pads. There are people who manage to drive 200,000 miles or more before they have to replace the clutch.  These are drivers who are masters of the art of clutch preservation.

Here are some of the things they do – and don’t do.

Avoid riding the clutch – 

This one’s obvious. Try to avoid partially depressing and holding the clutch pedal partially in as you’re trying to get the car going. People learning how to drive a manual-equipped cars typically do this to avoid stalling the engine. The sooner you learn how to engage the clutch smoothly and quickly, the better it will be for the long-term survival of your clutch.

Releasing the clutch too quickly will shorten clutch (and throwout bearing) life – and cause coffee spillage. On the other hand, trying to avoid spilling any coffee by taking too long to release the clutch as you get going will accelerate wear of the friction material that exerts the clamping force because you’re literally burning up the clutch’s friction material; you will smell it if you do this.

There is a fine art to easing out the clutch without riding the clutch. Once mastered, you’ll be a smoother driver and your vehicle’s clutch ought to last longer.

Avoid coming to a complete stop – 

The majority of clutch wear occurs getting the car going from a dead stop. That and in between gear changes.

This makes sense when you think about it. The clutch has to “grab” the flywheel and establish that physical connection between the engine and the transmission in order to get the vehicle moving. This disconnect/re-connect also happens during each upshift and downshift.

The typical vehicle weighs around two tons. That’s a lot of weight to get moving. Driving off smoothly necessarily entails some slippage. You can’t eliminate it. But if you reduce the number of times you have to start from a complete stop, you can greatly reduce wear because the clutch wears less when the car is already rolling a little bit when you let out the clutch.

Good drivers look ahead and drive accordingly.  If the light up ahead is red, why rush up to it? Let inertia carry you forward and – ideally – still be moving when the light turns green. Even if the car is just barely moving, you’ll impart less wear on the clutch when you let it out because the vehicle is already in motion.

Try not to shift as much, when you don’t need to –

Each time you engage/disengage the clutch, as during the process of shifting up or down, there is wear as the clutch surface grabs the flywheel when you release the clutch pedal. This can be reduced by shifting less often, as by going from third to fifth (skipping fourth) when you’re up to speed enough to do that without bogging the engine. “High performance” downshifts and upshifts are fun – but they’ll also shorten the clutch’s life.

Speed is indeed a question of money – how long do you want to go?

Don’t keep your foot in it –

When the car is stopped, try not to hold the clutch pedal down as this exerts continuous pressure on the “spring” portion of the pressure plate, which is part of the clutch system. The pressure plate is what physically disengages the clutch when you push down on the clutch pedal.

Instead, shift the transmission into neutral and then let the clutch out until it’s time to get moving. This eases the pressure on the pressure plate  – which isn’t the clutch, but if you need a new one, you’ll have to do pretty much the same work to get to it in order to replace it (because the transmission has to come out to get at it).

One last thing – which also isn’t the clutch, per se. Modern vehicles – those made since the ’80s, roughly – have hydraulically assisted clutch pedals rather than just pedals, linkage rods and springs. There is a thing called the slave cylinder, which works like the master cylinder in a brake system – and just like a brake system’s master cylinder, if the fluid is never changed, the master cylinder will fail sooner. When it does, the car will become undrivable because the clutch pedal will go to the floor and you will have a time keeping the car from stalling out when it’s not moving – without abusing the transmission.

Changing out the system’s fluid – bleeding it, as you would a brake system – is the preventative.

Check the fluid reservoir at least as often as you check the fluid in the brake system’s master cylinder. They use the same fluid and it should look clear. It will turn progressively darker over time.

Don’t let it turn black.

Regular fluid changes – at least once every three or four years – are particularly worth doing if your vehicle is one that has the clutch slave cylinder mounted inside the transmission – because if it fails, the transmission will have to come out to replace it.

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