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|Initial D World - Discussion Board / Forums > Technical Discussion > Car Jerking|
|Posted by: strategist102 Oct 16 2013, 10:01 PM|
I'm relatively new to driving stick shift, and I had a couple of questions about clutch control.
My usual procedure when moving off from 1st is to release the clutch to the biting point, let it slip for about 2 seconds, and then fully release the clutch. I try to make sure my rpms are high so the car won't stall.
However, I've noticed that if I hold the clutch at the biting point for a bit longer and I release the clutch the car starts to jerk a bit.
I've also noticed that sometimes my upshifts will produce a jerk in the car. My procedure for this is: clutch in, shift, clutch out but when I release the clutch it's done as smoothly and controlled as possible.
So, in summary:
Why does the car jerk when I hold the clutch at the biting point for a relatively longer time?
Why is it that more throttle allows you to release the clutch faster?
And, how can I reduce the jerkiness of the car when I'm upshifting?
|Posted by: TranceKitsune Oct 16 2013, 11:07 PM|
|When upshifting you may want to balance your release of the clutch with your throttle pedal. You want to slowly press in the accelerator while your foot eases off the clutch between shifts. At least that's what I would do to get a good shift and make it silky smooth in my car. More throttle allows you to release the clutch faster because you are putting air/fuel into the engine when pushing the throttle down. That is what is essential to the engine "breathing" so when you stall, its because the engine is not getting its air/fuel mixture. When it lunges forward between a shift without any throttle applied it is because there was a quick drop in the air/fuel within the engine (since you did not press down the accelerator pedal). RPM change between gears can be a factor as well I believe..|
|Posted by: sideways Oct 17 2013, 12:56 AM|
Pretty broad question that can have a few answers for a lot of different reasons. Might be that the extra rpms + extra slipping is juuuust starting to over heat the clutch causing wonky engagement manners, or it might not be.
A few reasons- More rpms/throttle means you have more force in the flywheel- More force in the flywheel means you have more force to move the car.
Biggest thing? Just practice. Every car is different- Youll simply have to experiment with the timing of the shifts, the closer you time the engines rpms to where they "should" be in the next gear when engaging the clutch, the smoother the shifting will be. You can of course fudge this a bit by engaging the clutch in a smoother fashion, but that should be the goal. Within no time as you start to work out the timing youll be able to turn it into muscle memory.
|Posted by: Nomake Wan Oct 17 2013, 05:44 AM|
| Practice, practice, practice. Coming up to a red light or a stop sign? Use that to practice downshifting. You have to slow down anyway, right?
But yeah, it's all about practice.
|Posted by: Kiroshino Oct 17 2013, 07:03 AM|
Pretty much what caused (and still causes) the jerkiness when I shift poorly. Look up rev matching.
Like everyone has said already, it most likely comes down to practice.
|Posted by: Spaz Oct 17 2013, 10:32 AM|
| From a stop, is it more a jerking or a shuddering? If it's the latter, it may be the disc in basically an "indecisive" position where it's grabbing and letting go. This is most common with puck style racing clutches but it can happen with street clutches as well.
Regardless, the cause is that the engagement is not smooth. The only time you should be pausing the travel of the clutch pedal is in a full-on launch of the car.
|Posted by: THE_HONDA_CG2 Oct 17 2013, 11:13 AM|
| I go with everything that everyone else is saying in the thread. Bottom line you need to practice. I can't drive a stick shift proficiently yet, but I have gotten to move Fragger's DelSol out of first before a couple of times. I notice that I jerk all the time and it spooks me since it always feels like I'm doing something wrong. If you hesitate while trying to control the throttle, you will stall. If you're not stalling all the time like me, then you should be on the right track!
Driving a stick shift is all about feeling the car and getting timing down. Once you master those then it you should commit it to the little notebook in your brain. From there it should be smooth sailing! Good luck!
|Posted by: strategist102 Oct 17 2013, 08:05 PM|
| Hi (again)
Thanks for the responses! I definitely appreciate them.
From what I've seen the main consensus is to practice. And yes I definitely agree with that nugget of truth. And although I am working on getting more practice w/ my Teggy I'd like to know how a manual transmission functions, more specifically the clutch and how it engages power from the engine to the wheels.
While learning stick I usually use my instincts and body to feel how the car handles. And for a while that's generally lead me in a decent direction but what I'd really like is for me to expand on my knowledge of clutch control. That way I'd be reassured that my instincts are right and it's another way for me to practice.
Ramble aside. I'd like to clarify one of my questions regarding jerkiness.
So, my procedure when I experience this jerkiness is as follows.
1. Shift from N to 1st.
2. Release Clutch Pedal to biting point. I don't pop the clutch while doing so and the motion is smooth.
3. Simultaneously w/ Step 2 once I reach the biting point, I add some throttle. The car starts to move forward.
Now, normally what I'd do after Step 3 is that I'd smoothly release the clutch pedal all the way upwards.
However, when I noticed the jerking I think I left the clutch at the biting point for a bit longer than I usually do and the result is that the car jerks forward a bit.
My question is why is this so?
|Posted by: Nomake Wan Oct 17 2013, 08:45 PM|
For the sake of your clutch's life, you should not apply power until it's fully engaged. However, as a beginner you probably won't be able to get your 'start from a stop' shift smooth that way, so some amount of slipping is going to happen. While that's fine since you're learning, you should not think that this is the correct way of doing things. Being perfectly smooth with the shifting either means you're a god (in which case you may not even need to clutch if you're that good) or you're slipping the clutch and should stop that.
You want the transmission to be fully engaged before adding torque (power) to it. If you're slipping the clutch a lot with power applied then suddenly release it, you're forcing the clutch to suddenly compensate for the friction difference and the result is what you experienced.
Sounds like a typical beginner move, which is fine, you are. Try to force yourself to learn how to have the clutch fully engaged before applying power. You'll probably want to practice doing this while rolling (3-2, 2-3, 4-3, etc etc) since it's a lot easier. Once you've got rolling shifts down, then you can work on improving your 0-1 shift.
Just understand that while it might seem like I'm being harsh or name-calling, I'm really not--you really are new, so don't feel frustrated. You lack experience, experience which you seem more than eager to gain. It takes time, but eventually you won't even have to think about it. Your body will just do all the work by itself.
|Posted by: Tuskano Oct 17 2013, 09:34 PM|
| ^ This ^
I was like that too. I am still new and I have had my moments when driving. Pretty soon you will be barely thinking when you shift and your motions will all be down. Just practice daily and you'll be good to go.
|Posted by: strategist102 Oct 18 2013, 01:23 AM|
Thanks for the explanation but I think I'm a bit confused about what you typed.
Your advice is to not add power until the clutch is engaged. However, if I were to fully engage the clutch from N to 1st, I'd need to release the clutch excessively slow in order to not stall the car. In addition to that one of the reasons why I would add gas once I reach the biting point is that the RPMs drop to a point close to an engine stall and in order to prevent the stall I'd have to add some gas.
Perhaps what you're talking about is what I should do when I upshift.
Also, I think I wasn't precise with my description of when I jerk the car. The throttle that I apply is constant, no more than 1500 RPM. And as a friendly reminder, I don't drop the clutch when I release it from the biting point towards fully engaged.
Again thanks for your input, but I'd really like some clarification about your advice.
|Posted by: Nomake Wan Oct 18 2013, 06:34 AM|
Sure. The way you wrote it, it seemed to imply that you were adding quite a bit of power without a fully-engaged clutch. And to be fair, I'm not sure how much torque your vehicle actually has but 1500 RPMs could be on the high side for how fast you're slipping the clutch.
The point here is that you want to slip the clutch as little as possible. The only way to accomplish this is by knowing clutch feel (experience) and knowing what you can get away with rev-wise from a dead stop (experience, knowledge). Some cars have quite a bit of torque and can actually go into first really easily. Some cars have incredibly short first gears that require a quick 1-2 from a dead stop. Some have really long first gears and need a little bit more care.
So what I said is correct--you do not want to add power until the clutch is fully engaged. From a dead stop you're not going to be able to 100% accomplish this, but you want to reduce the amount of time you slip the clutch to a bare minimum. If you apply too much power before the clutch is fully engaged, then you end up with the situation I described where the clutch slips, slips, slips then bites as it finally overcomes the friction difference and all of a sudden you have a surge of torque through the transmission.
Does this make sense?
|Posted by: strategist102 Oct 18 2013, 11:45 AM|
| Ok cool. Thanks for clarifying your advice.
And Kudos to everyone for their input. It's much appreciated!
|Posted by: APaul1 Oct 23 2013, 06:31 PM|
|sorry I'm not being helpful but anyone thought about https://www.youtube.com/watch?v=qv9VKKXwVxU from the thread title alone?|
|Posted by: Nomake Wan Oct 23 2013, 09:09 PM|
|Posted by: khat17 Nov 25 2013, 10:06 PM|
| I thought about this.
Things I'd suggest would be to practice somewhere flat. Start off by just easing off the clutch while in first. You should be able to roll off with good control of the clutch. Use this to get to know your car and how it feels overall.
Once you've done this a bit you can probably start playing around with shifting without the clutch. While it can be done with just about every manual transmission it's best to learn your vehicle before trying this.
|Posted by: RickkyyP Nov 27 2013, 01:59 PM|
| As has been said a million times practice practice practice. When your drive every day in a manual car then you'll soon be smooth as anything.
99% of people in the UK (and in Europe as well I think) learn to drive with a stick shift so every time they're in car they are gaining practice.
Once you've got smooth acceleration than you can start learning how to rev match (blip) the throttle as you go down through the gears so as not to upset the car.
|Posted by: Wanderer Nov 27 2013, 02:09 PM|
| Practice, as afore mentioned and remember not to hesitate with the throttle.
[ Post made via Mobile Device ]
|Posted by: ChennyZ Jan 28 2014, 07:56 AM|
| practice! sometimes when im on a small incline, i play with the throttle/clutch to keep the car rolling.
clutch in so you can roll backwards a little (no brakes are used!)
then try to feather up the incline. back and forth.
make sure there's no car behind you unless you trust your foot skills. i have scared someone once when i was rolling backwards on a hill. i looked in my rear-view mirror and his face was priceless hahah.
|Posted by: Spaz Jan 28 2014, 09:30 AM|
|Yeah, because that's great on your clutch. It's not the single most expensive wear part in the car or anything.|
|Posted by: ChennyZ Jan 30 2014, 11:47 AM|
|that's when you fix it|
|Posted by: strategist102 Jun 6 2014, 04:54 PM|
| Have any of you guys "felt the clutch" while releasing the clutch pedal through your feet?
I mean I can tell when the flywheel is slipping on the clutch plate through the vibrations transmitted throughout the car but what I'm wondering is if anyone has ever felt the flywheel and clutch plate physically connect through their feet alone.
|Posted by: Nomake Wan Jun 6 2014, 08:23 PM|
Why does that matter? You shouldn't be leaving your foot on the pedal that long anyway.
|Posted by: strategist102 Jun 6 2014, 09:22 PM|
| Just cause....
I wanna know if it's possible to feel the clutch plate and flywheel connect through your feet. Just for feedback purposes.
|Posted by: Nomake Wan Jun 7 2014, 12:04 AM|
|See above. You shouldn't be leaving your foot on the pedal that long. If you have your foot on the pedal so long that you can feel the engagement, you're slipping. Don't do that.|
|Posted by: MetalMan777 Jun 7 2014, 03:50 AM|
|Clutch pedals aren't really designed to let you feel anything through them. I suppose if you have a cable actuated clutch you might, but no way with a hydraulic pedal.|
|Posted by: Spaz Jun 7 2014, 10:37 AM|
| You may be able to depending on the clutch... My Exedy Twin vibrates audibly on engagement and can be felt, though that may be through the chassis into the pedal assembly.
Aggressively launching the car can also create clutch vibrations that can be felt, again though likely through the chassis. A stiffer chassis will definitely transmit these more than something commuter-y, but at the same time so can worn components, such as motor mounts, where you're feeling the motor move, not the clutch.