Clutch Question
Discussion
Hi, i'm currently learning to drive and have a quick question on using the clutch and hoping you could help.
Say I have the clutch raised to just above the biting point then the car will crawl say around 2mph, now if I lift it a bit more it will say go upto 10mph.Now if I was to dip the clutch back to the original position ie just above biting would this physically slow the car down to a crawl or will it just take the momentum away allowing the car to eventually slow itself down?
I hope i've explained this clearly and cheers for anyy advice.
Say I have the clutch raised to just above the biting point then the car will crawl say around 2mph, now if I lift it a bit more it will say go upto 10mph.Now if I was to dip the clutch back to the original position ie just above biting would this physically slow the car down to a crawl or will it just take the momentum away allowing the car to eventually slow itself down?
I hope i've explained this clearly and cheers for anyy advice.
Depends how much you let it slip. This is complicated by the fact that the amount of slip for a given clutch pedal position will change depending on how fast the car is moving and throttle setting. There isn't a single "biting point" so much as a varying degree of friction. If in doubt, look up how a clutch works, I found it helped when I was learning. Other than that, just experiment with how it feels - it's the only way really.
But as said above, don't slip the clutch more than necessary. Play around with it for a bit to learn how it interacts with the throttle, but in normal driving, apart from pulling away, you'll generally want it fully engaged, or fully disengaged, not held somewhere in the middle.
But as said above, don't slip the clutch more than necessary. Play around with it for a bit to learn how it interacts with the throttle, but in normal driving, apart from pulling away, you'll generally want it fully engaged, or fully disengaged, not held somewhere in the middle.
Thanks i'm just wondering if by dipping it physically slows the car down or merely takes the power away.
Say for example i'm in a line traffic and i'll edge up to the car in front, sometimes merely dipping the clutch isn't enough because the momentum will still carry me albeit slowly into the car in front.But the way she explains it it's like she thinks that by dipping the clutch it will perform some braking on the car.
Say for example i'm in a line traffic and i'll edge up to the car in front, sometimes merely dipping the clutch isn't enough because the momentum will still carry me albeit slowly into the car in front.But the way she explains it it's like she thinks that by dipping the clutch it will perform some braking on the car.
DanGPR said:
It doesn't slow you down, it just lowers the friction acting on the clutch, thus decreasing power transmitted to the wheels.
When you dip the clutch the car will slow down very gradually from the general friction caused by the wheel bearings and transmission.
Just to confuse you, if you were facing downhill then the car might even pick up momentum and go faster!
Opara said:
Thanks i'm just wondering if by dipping it physically slows the car down or merely takes the power away.
Say for example i'm in a line traffic and i'll edge up to the car in front, sometimes merely dipping the clutch isn't enough because the momentum will still carry me albeit slowly into the car in front.But the way she explains it it's like she thinks that by dipping the clutch it will perform some braking on the car.
You are spot on. The clutch connects the engine to the box. When the clutch is all the way down the engine and transmission are disconnected. This is not what is happening in neutral though. Like others have said though it is best not to slip or ride the clutch. Say for example i'm in a line traffic and i'll edge up to the car in front, sometimes merely dipping the clutch isn't enough because the momentum will still carry me albeit slowly into the car in front.But the way she explains it it's like she thinks that by dipping the clutch it will perform some braking on the car.
Back to first principles. The clutch is (grossly simplified) two discs. One attached to the gearbox, one attached to the engine (which is also the flywheel for the engine). One of the discs has a high friction surface (like a brake pad) which grips onto the other disc. Normally, a big spring forces the two hard together, which makes the full force of the engine go to the gearbox.
If you press the pedal to the floor the two plates are forced apart so that no power goes from the engine to the gearbox.
When you press the pedal a little the two are forced apart a bit, allowing the friction surface to slide across the other disc. It still grips a little, but not so much that the engine is fully connected to the gearbox. That's "slipping the clutch".
So if you push the pedal all the way back down again the engine isn't connected to the wheels at all, so it's just coasting along. If you're on the flat the car will gently slow to a halt.
If you press the pedal to the floor the two plates are forced apart so that no power goes from the engine to the gearbox.
When you press the pedal a little the two are forced apart a bit, allowing the friction surface to slide across the other disc. It still grips a little, but not so much that the engine is fully connected to the gearbox. That's "slipping the clutch".
So if you push the pedal all the way back down again the engine isn't connected to the wheels at all, so it's just coasting along. If you're on the flat the car will gently slow to a halt.
Opara said:
Cheers I think i've got this now, my instructor was confusing me.
So if you were driving say 10mph, whether you dip the clutch to biting or all the way down it will still take the same time and distance to come to a stop?
On the flat - no, it'll go a bit further if you're slipping the clutch (i.e. if it's biting a bit) because you'll be getting some power transmitted to the wheels.So if you were driving say 10mph, whether you dip the clutch to biting or all the way down it will still take the same time and distance to come to a stop?
The clutch isn't a way of slowing down. Either brake, or just back off the throttle to slow the car. Then put the clutch fully in just as the engine starts to judder, to prevent it stalling.
If you're just inching forwards in traffic, you might just slip it a bit and never let it fully engage. In this case, you will let the pedal out, say half way, just get moving, then push the pedal back in again. Maybe that's what the instructor is referring to?
Opara said:
Cheers I think i've got this now, my instructor was confusing me.
So if you were driving say 10mph, whether you dip the clutch to biting or all the way down it will still take the same time and distance to come to a stop?
Ish, you will still slow down at a similar rate but you do partially have the car in drive if the clutch is still biting, however partially that might be. this would mean that you would come right down on your speed but then continue to crawl along at 2mph or so like you suggested before.So if you were driving say 10mph, whether you dip the clutch to biting or all the way down it will still take the same time and distance to come to a stop?
You could overcome this and apply the brakes in which case its going to pretty much come to a stop at same rate and in same distance but...... if the clutch is engaged too much i.e. not quite dipped enough, you will run the risk of stalling if you try and come to a complete stop as the friction disks are still partially 'slipping' on one another. If the friction is too great. this in turn causes a load on the engine and if its too great then the engine will stall.
Opara said:
Cheers I think i've got this now, my instructor was confusing me.
So if you were driving say 10mph, whether you dip the clutch to biting or all the way down it will still take the same time and distance to come to a stop?
Probably not. If the clutch is at the biting point, it is actually transmitting drive to the wheels (the biting point is literally the point at which the two discs start to bite together, a bit like the two sides of velcro) so if the clutch was at biting point at 10mph in 2nd gear the engine would be transmitting power to the wheels. So if you were driving say 10mph, whether you dip the clutch to biting or all the way down it will still take the same time and distance to come to a stop?
That would probably make the engine run a bit slower, so the ECU will start putting extra fuel in to make the engine run at its normal idling speed. That may actually make the car accelerate a bit to get the road speed and the engine speed within the clutch slip tolerance.
Generally speaking you should only ever be slipping the clutch at idle. But when you're learning it's difficult to time the gearshifts just right to allow a nice smooth change. Concentrate on not hitting stuff for now, and then practice the fun things later.
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