Question for you all,

If I just sit there with the car in neutral and blip the throttle it revs in a nice lazy fashion, but if I press the clutch and do the same the throttle response is much sharper, the engine revs much faster and the car wobbles as a result.

Why is this? Is there a sensor on the clutch to adjust the throttle response? What is the benefit of having a sharper throttle response with the clutch depressed?

Thanks,

Chris.

the engine is not having to rotate the gearbox when the clutch is depressed , so its doing less work , hence faster pick-up ........ perhaps

It's a big difference though. Without the clutch pressed the engine feels almost lazy. Press it in and VROOM from just a blip. It behaves totally differently. Try it! You'll see what I mean....it's wierd.

i have noticed this as well i guessed it was just the gear box slowing the engine.

there's a secret switch in the gearbox that tells the engine when your in neutral or not so it revs quicker and more freely when in neutral, it should accelerate quicker too so go try it and report back.

It's not whether it's in gear or not....it's whether the clutch is pressed. The gears are in neutral all the time when I'm testing this. It revs quicker when the clutch is down than when it's up....a lot quicker.

It's not whether it's in gear or not....it's whether the clutch is pressed. The gears are in neutral all the time when I'm testing this. It revs quicker when the clutch is down than when it's up....a lot quicker.

your wasting good fuel which coud be used to actually move the vehicle :P

the engine is not having to rotate the gearbox when the clutch is depressed , so its doing less work , hence faster pick-up ........ perhaps

:iagree:

it's all about reciprocating inertia!

that's why people spent out vast sums on flywheel/crank/rod lightening

:iagree:

it's all about reciprocating inertia!

that's why people spent out vast sums on flywheel/crank/rod lightening

Interesting. So how much of the gearbox internals actually rotate when the clutch and flywheel have contact in neutral? The idle speed never even dips when you lift off the clutch when in neutral so I can't see it being that much more than the input shaft.

Ithink that quite a few cars today have a switch on the clutch pedal - so this could be modifying the engine's response to an increasing throttle pedal position. There will always be a bit of drag, or load on the engine from the transmission - if only from the release bearing. Also remember that the oil will be getting churned around by any rotating gear wheels, that will be seen as a load. As far as I know, dipping the clutch does not 100% disconnect the driven surface from the friction plate - it just removes as much "load" as is necessary to stop the drive or to change gear.

i was taking the **** with my post :confused:

it may rev easier because as others have said there is less drag on the engine, simple as that.

Interesting. So how much of the gearbox internals actually rotate when the clutch and flywheel have contact in neutral? The idle speed never even dips when you lift off the clutch when in neutral so I can't see it being that much more than the input shaft.

no, both shafts will be rotating, and all of the gears (except reverse) are allways engaged with each other, so these will all be spinning at different speeds too

:iagree:

it's all about reciprocating inertia!

that's why people spent out vast sums on flywheel/crank/rod lightening

true, but isn't the flywheel directly connected to the engine and all those other parts in the engine - pressing the clutch pedal wouldn't alter the effect their mass has on how quickly engine revs :confused:

yeah, he's just saying about lowering the unsprung type weight to make the engine rev mroe freely

Clutch up, engine has to spin the clutch plate and associated spring, backing plate, housings etc. These are all rotating mass at a distance away from the centre of the shaft and thus provide inertia that resists the engine turning. Also, clutch up in neutral, the input shaft and all the gears are being turned also. (not the output shaft, if that were turning, the car would be driving forward).

Clutch down you have just the engine and flywheel.

There is a sensor on the clutch, as cruise switches off when you dip the clutch, but IMO the difference is in the rotational inertia.

Chris