Driving forward with the clutch partly engaged is bad for the clutch. But does letting a car jerk forward, ie. by letting the clutch go up really fast, actually cause any damage to the car assuming that it doesn’t cut out?
Technical answers from people who know please, not people coming in having a guess like you see on many forums.
Hard engagement of the clutch, or sudden engagement, takes wear that would normally be absorbed by the clutch (a wearable item) and transfers the energy/wear to a bunch of other internal parts, including, but not limited to:
The entire drivetrain: Highlights include: all bearings, the engine internals (because hard engagement includes a period of engine lugging, which is bad for rods and terrible on valves).
So, by not engaging the clutch more slowly, the rest of the drivetrain is going to wear out in various ways/forms, and engine lugging – even momentarily – will reduce the life of the engine.
Think in terms of speeding up wear, rather than outright damage.
A great example: To save brake pads, go ahead and slam into a curb when coming to a stop when you get home.
It will certainly shorten the life of the anti-chatter springs, and put stress on all of the transmission and drivetrain parts. Will it “ruin” the car? Probably not, but it’s not going to extend it’s useful life…
You’re veering from one extreme (chronic clutch slippage) to the other (sidestepping the clutch pedal). The latter - by engaging a high-RPM engine with a zero-RPM driveline - brings into play the inertia of all of the rotating driveline parts, and can create stresses on parts well in excess of what the engine can cause at its own rated maximum load. In extreme cases, the loads will be so excessive that parts will break. In less extreme cases, wear will happen at an accelerated rate.
Somewhere in between is the happy medium. I’ve had good clutch longevity by developing a habit of launching with a mild acceleration rate with the engine at low RPM; this dumps the least amount of energy into the clutch via slippage (and according to my mental model, causes the least amount of per-launch wear on the clutch friction plate).
As with many things, neither extreme is desirable. Slow, drawn out engagement of the clutch wears its lining prematurely and can adversely affect the flywheel and pressure plate, creating hot spots in the metal which can cause shuddering. Sudden, instantaneous engagement of the clutch shocks other items, as mentioned by Philster and beowulff. Fortunately, it’s not an either/or choice. The thing to do is learn to engage the clutch smoothly and quickly.
Of course there’s a little more wear on things like universal joints and the entire drive line. But how much jerking can you do? It’s best to let the clutch out fairly fast and minimize the slippage. It’s more efficient fuel wise and wear wise. So ‘jerking’ would come into play mostly with the individual learning to drive a manual transmission.
PS. NO matter how good you think you are at shifting, the manual transmission vehicle will experience slightly more wear to certain components regardless of your ability.
I disagree w/ **Al Bundy
**
A good driver/shifter minimizes the am’t of slip at the clutch by using just the right am’t of power for a given situation (required engine load, road conditions, the need to accelerate to a certain tempo, speed, etc) with a precise and smooth action. Someone who shifts poorly – I’m considering all gears here – is going to be hard on the clutch, by forcing it to absorb more energy than necessary, and if you want to talk about rev matching… well, a poor shifter is tearing up synchros while a good shifter is reducing that wear to a minimum.
But your “P.S.” is odd. If you are good at shifting, you** minimize** the wear across all parts in the system. You can’t eliminate it. The whole system is wearing. Applying excess power wears everything more – just a matter of what that is based on just how you apply it, etc.