Discussion
This is a long standing debate between a friend and myself.
He is very fast and heavy to engage the clutch (almost stamping on the pedal) when driving, giving a very noticeable jolt when changing gear. He says it is to prolong clutch life, but isn't very nice as a passenger. His car has a hydraulic clutch, so no cable to stretch.
My car does have a cable, and I am much smoother, even when hooning, as I believe that being slower off the clutch will not show any noticeable amount more wear to the clutch.
Thoughts?
He is very fast and heavy to engage the clutch (almost stamping on the pedal) when driving, giving a very noticeable jolt when changing gear. He says it is to prolong clutch life, but isn't very nice as a passenger. His car has a hydraulic clutch, so no cable to stretch.
My car does have a cable, and I am much smoother, even when hooning, as I believe that being slower off the clutch will not show any noticeable amount more wear to the clutch.
Thoughts?
A jolt when changing gear is causing excessive wear to the clutch and god knows what else. Ideally you would use the clutch as an on/off switch when changing gear, but only if you rev match sufficiently to lift straight off the clutch without a jerk.
If you haven't matched perfectly then it's better to smooth out the jolt with the clutch pedal, it does cause some wear but nothing excessive unless you are totally hamfisted.
If you haven't matched perfectly then it's better to smooth out the jolt with the clutch pedal, it does cause some wear but nothing excessive unless you are totally hamfisted.
Dr Jekyll said:
A jolt when changing gear is causing excessive wear to the clutch and god knows what else. Ideally you would use the clutch as an on/off switch when changing gear, but only if you rev match sufficiently to lift straight off the clutch without a jerk.
If you haven't matched perfectly then it's better to smooth out the jolt with the clutch pedal, it does cause some wear but nothing excessive unless you are totally hamfisted.
That. Either technique is fine but the important thing is matching the revs going up and down.If you haven't matched perfectly then it's better to smooth out the jolt with the clutch pedal, it does cause some wear but nothing excessive unless you are totally hamfisted.
Sorry, I don't think I worded this right. I'm only talking about pressing the clutch in (engaging it) when about to change up. The jolt comes from accelerating to suddenly not accelerating.
I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Viperz888 said:
Sorry, I don't think I worded this right. I'm only talking about pressing the clutch in (engaging it) when about to change up. The jolt comes from accelerating to suddenly not accelerating.
I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Any difference in wear must be so small it doesn't matter...I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Viperz888 said:
Sorry, I don't think I worded this right. I'm only talking about pressing the clutch in (engaging it) when about to change up. The jolt comes from accelerating to suddenly not accelerating.
I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
The clutch technique is pretty much irrelevant in terms of clutch wear. What wears the clutch is the difference in speed between the engine and the gearbox, which is what the clutch will have to smooth out when the pedal is released. Doing it quickly and badly will knacker the engine and gearbox mounts if it's done often enough though. I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Viperz888 said:
Sorry, I don't think I worded this right. I'm only talking about pressing the clutch in (engaging it) when about to change up. The jolt comes from accelerating to suddenly not accelerating.
I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Isn't that dis-engaging the clutch?I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Your friend is right about the wear, no need to slooowly push down and intertia should keep things smooth, is your friend also lifting off before dis-engaging or just veery slow to actually change gear and re-engage?
scarble said:
Viperz888 said:
Sorry, I don't think I worded this right. I'm only talking about pressing the clutch in (engaging it) when about to change up. The jolt comes from accelerating to suddenly not accelerating.
I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Isn't that dis-engaging the clutch?I can see that this may reduce wear to the clutch in a very minor way (as releasing it slowly would cause some slip, and therefore wear), but are there any other disadvantages (other than discomfort.)
Your friend is right about the wear, no need to slooowly push down and intertia should keep things smooth, is your friend also lifting off before dis-engaging or just veery slow to actually change gear and re-engage?
My own personal opinion here. As with all thing mechanical, smooth is always better... And while your friend is considering clutch wear, he might wanna consider what punishment he's putting the hydrolic cylinders through as he stamps on and off the clutch pedal. They certainly would not appreciate it.
T0nup said:
My own personal opinion here. As with all thing mechanical, smooth is always better... And while your friend is considering clutch wear, he might wanna consider what punishment he's putting the hydrolic cylinders through as he stamps on and off the clutch pedal. They certainly would not appreciate it.
Hydraulic and just no.james_gt3rs said:
thiscocks said:
I don't know how he manages to create a jolt dis-engaging it unless something is knackered on the car?
It's because you are going from full throttle to none in an instant. Most people would lift off the gas, then press the clutch and change gear.It's possible to create a jolt when dis-engaging the clutch. It's particularly obvious when travelling in a slow queue of traffic in first gear, if you accelerate and then find you have to slow again. Whether you take your foot suddenly off the throttle, or suddenly dis-engage the clutch, you will get a jolt, because of the sudden transition from acceleration to deceleration.
If you engage the clutch fiercely with mis-matched revs you are sending a jolt (known as a transmission shunt) through the entire power train. The engine will be violently twisted in its mountings, the springs in the clutch plate will be compressed to their extreme, and all slack in any transmission components - gears, universal joints (propshaft or CV) will be suddenly reduced to zero. At the far end of the power train, the tyres will take a sudden torque input and in extreme cases, will lock up or lose grip and spin, depending on whether you're changing up or down. Using the clutch like a switch is something that's very very hard to achieve smoothly. Much better to accept a small amount of clutch slip, or take time to match revs with the right foot while slowly raising the clutch with the left.
When disengaging the clutch, once the throttle input has been reduced to little or none, it's practically impossible to wear the clutch. The transmission might experience a jolt, as it does with sudden engagement, but it's not under load, so far less damaging.
If you engage the clutch fiercely with mis-matched revs you are sending a jolt (known as a transmission shunt) through the entire power train. The engine will be violently twisted in its mountings, the springs in the clutch plate will be compressed to their extreme, and all slack in any transmission components - gears, universal joints (propshaft or CV) will be suddenly reduced to zero. At the far end of the power train, the tyres will take a sudden torque input and in extreme cases, will lock up or lose grip and spin, depending on whether you're changing up or down. Using the clutch like a switch is something that's very very hard to achieve smoothly. Much better to accept a small amount of clutch slip, or take time to match revs with the right foot while slowly raising the clutch with the left.
When disengaging the clutch, once the throttle input has been reduced to little or none, it's practically impossible to wear the clutch. The transmission might experience a jolt, as it does with sudden engagement, but it's not under load, so far less damaging.
Edited by Mr Grayson on Friday 15th March 23:05
Mr Grayson said:
It's possible to create a jolt when dis-engaging the clutch. It's particularly obvious when travelling in a slow queue of traffic in first gear, if you accelerate and then find you have to slow again. Whether you take your foot suddenly off the throttle, or suddenly dis-engage the clutch, you will get a jolt, because of the sudden transition from acceleration to deceleration.
If you engage the clutch fiercely with mis-matched revs you are sending a jolt (known as a transmission shunt) through the entire power train. The engine will be violently twisted in its mountings, the springs in the clutch plate will be compressed to their extreme, and all slack in any transmission components - gears, universal joints (propshaft or CV) will be suddenly reduced to zero. At the far end of the power train, the tyres will take a sudden torque input and in extreme cases, will lock up or lose grip and spin, depending on whether you're changing up or down. Using the clutch like a switch is something that's very very hard to achieve smoothly. Much better to accept a small amount of clutch slip, or take time to match revs with the right foot while slowly raising the clutch with the left.
When disengaging the clutch, once the throttle input has been reduced to little or none, it's practically impossible to wear the clutch. The transmission might experience a jolt, as it does with sudden engagement, but it's not under load, so far less damaging.
If you engage the clutch fiercely with mis-matched revs you are sending a jolt (known as a transmission shunt) through the entire power train. The engine will be violently twisted in its mountings, the springs in the clutch plate will be compressed to their extreme, and all slack in any transmission components - gears, universal joints (propshaft or CV) will be suddenly reduced to zero. At the far end of the power train, the tyres will take a sudden torque input and in extreme cases, will lock up or lose grip and spin, depending on whether you're changing up or down. Using the clutch like a switch is something that's very very hard to achieve smoothly. Much better to accept a small amount of clutch slip, or take time to match revs with the right foot while slowly raising the clutch with the left.
When disengaging the clutch, once the throttle input has been reduced to little or none, it's practically impossible to wear the clutch. The transmission might experience a jolt, as it does with sudden engagement, but it's not under load, so far less damaging.
You won't get a sudden jolt when disengaging in first, the sudden jolt is caused when lifting while the clutch is still engaged because the low ratio means the effect of engine braking is stronger. There is no jolt unless your car has stupidly high friction in the diff, propshaft, wheel bearings etc. and/or high rolling resistance due to square tyres or something. Generally inertia will keep it rolling fairly smoothly.
You may feel a bit of a lurch (not the same as a jolt!) if your dampers are f**ked and you were accelerating hard before disengaging because under acceleration the car is rotated backwards due to forces and stuff and I really need to get a life..
Edited by scarble on Friday 15th March 23:30
Ease off the throttle a little bit before dis-engaging the clutch and you should be able to press the pedal down fairly quickly without causing a "Jolt".
I find that changing gear smoothly is all about the throttle, if you can control that accurately then you can move the clutch or gearstick as quickly or slowly as you like.
I find that changing gear smoothly is all about the throttle, if you can control that accurately then you can move the clutch or gearstick as quickly or slowly as you like.
scarble said:
I'm pretty sure Op is confused and the lurch is down to re-engagement rather than dis-engagement.
I did some testing. So unless it's a fairly powerful car and also borked (e.g. brakes stuck)
No, definitely dis-engagement (pressing the clutch pedal in). Its not a particularly powerful car, but it is fairly floppy/soft, so it can maybe be felt more than in a stiffer car.I did some testing. So unless it's a fairly powerful car and also borked (e.g. brakes stuck)
It happens because the clutch in dis-engaged while still accelerating ie still on the throttle.
My question is: Is it better to do this, as I can see why it would prolong clutch life, as there is no slip (I can't see why there would be any stresses on the drivetrain) and a hydraulic clutch means no stretched wires.
Z.B said:
This. The problem has nothing to do with the clutch. It is crude use of the throttle!
Symbolica said:
Ease off the throttle a little bit before dis-engaging the clutch and you should be able to press the pedal down fairly quickly without causing a "Jolt".
I find that changing gear smoothly is all about the throttle, if you can control that accurately then you can move the clutch or gearstick as quickly or slowly as you like.
This is true, i'd never thought about it being due to the accelerator. Makes sense. I find that changing gear smoothly is all about the throttle, if you can control that accurately then you can move the clutch or gearstick as quickly or slowly as you like.
Edited by Viperz888 on Saturday 16th March 02:28
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