Shifting smoothly in this car...
10-02-2009, 07:39 PM
#26
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That's because the 370z has a computer that can get the revs absolutely perfect. It is far easier to get it right by double-clutching, and if you're good at it it doesn't take any longer to do.
To single-clutch rev match perfectly you can't just keep your throttle in the same position, you have to move it to the exact right position and hold it there for the gear you are going into.
Can you do that? It's not the way you describe, the way you describe is indeed bad for the car, since you are just holding the throttle wherever it happened to already be. I wouldn't say it's terrible for the car though, go ahead if you want to, and maybe you are really so good that you can do it perfectly. But it seems a lazy way to avoid double-clutching to me.
To single-clutch rev match perfectly you can't just keep your throttle in the same position, you have to move it to the exact right position and hold it there for the gear you are going into.
Can you do that? It's not the way you describe, the way you describe is indeed bad for the car, since you are just holding the throttle wherever it happened to already be. I wouldn't say it's terrible for the car though, go ahead if you want to, and maybe you are really so good that you can do it perfectly. But it seems a lazy way to avoid double-clutching to me.
10-02-2009, 07:47 PM
#27
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Engaging/disengaging the clutch isn't what wears them out so much as slipping the plates, which is what you're likely doing. Double-clutching was invented for cars that didn't have synchros, so I'm not sure what you are talking about here.
Um, sure, you can shift into sixth at 45 MPH if you want to, I never said you couldn't, I said it didn't make sense. Why would you want to? If you have to do that to avoid jerkiness, then your shifting needs work.
Um, sure, you can shift into sixth at 45 MPH if you want to, I never said you couldn't, I said it didn't make sense. Why would you want to? If you have to do that to avoid jerkiness, then your shifting needs work.
What do you think happens when you push that pedal on the left down? Friction plates are pushed against steel plates to stop movement. That friction is what wears down the clutch. So yes every single time you push the clutch in while the car is running causes friction and wear.
"Double-clutching was invented for cars that didn't have synchros" So why are you doing it with a car that is constant mesh? You put the clutch in shift into nuetral so the rear end is disconnected then you put it back into gear....Also why do you think motorcycles don't have nuetral between each gear??? Constant mesh...
Still haven't answered my question. Why is my way hurting the car? Why does my car not "love" me?
10-02-2009, 07:52 PM
#28
Again you say it is bad for the car. Why? Lazy you say, but no one in the car ever feels the down shifts. Next double clutching is no different in finding the "perfect" rpm as you are hoping that you bliped for long enough in nuetral and that you didn't waste to much time in either gear. Also you are twice as likely to get the rear end squirly, my way you maybe have the car bog a bit because you didn't realize you were slightly accelerating. Try it on your next drive, I promise it will not ruin your car lol.
If double-clutching is causing your back end to come out when you don't want it to, then it isn't double-clutching that's the problem.
I can shift up and down all day without feeling any jerkiness, the only change is the sound of the engine. I can go through all the gears or skip them when appropriate. And I know I'm not damaging my clutch or tranny by doing so. What exactly do I need to improve by doing things your way?
You seem to be compensating for lack of skill and passing it off as the right way to do things.
10-02-2009, 07:55 PM
#29
What do you think happens when you push that pedal on the left down? Friction plates are pushed against steel plates to stop movement. That friction is what wears down the clutch. So yes every single time you push the clutch in while the car is running causes friction and wear.
10-02-2009, 08:02 PM
#30
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See you have absolutely no idea how a transmission works yet all you can say is that you are some perfect shifter. You have not once answered the question because you do not know. Never once did I say I have jerky shifts or that I can't double clutch, but I gave you reasons why I don't.
Your witchdoctor mechanic skills are the reason so many are missinformed. Yes the 370z uses computers, but that doesn't make the process wrong.
To the original poster try out all the methods do some research. Best thing you can ever do is know exactly what is going on when you put the car into each gear and how all the parts come together. The more knowledge you have to more of an understanding of why things aren't happening the way you want them to.
Your witchdoctor mechanic skills are the reason so many are missinformed. Yes the 370z uses computers, but that doesn't make the process wrong.
To the original poster try out all the methods do some research. Best thing you can ever do is know exactly what is going on when you put the car into each gear and how all the parts come together. The more knowledge you have to more of an understanding of why things aren't happening the way you want them to.
10-02-2009, 08:09 PM
#31
OK I'll bite.
How do the plates slip and cause friction when you push in the clutch to disengage the plates while they are rotating at the exact same speed? You could have talked about the throwout bearing, but you didn't. Please educate me on how clutches work.
How do the plates slip and cause friction when you push in the clutch to disengage the plates while they are rotating at the exact same speed? You could have talked about the throwout bearing, but you didn't. Please educate me on how clutches work.
10-02-2009, 08:13 PM
#33
Rotary Crawfish
Look folks it is not rocket surgery, drive the damn car and learn to not even be aware that you shifted any gears.
A perfect shift is a thing of beauty but in real life is few and far between!!
Of course I have never owned of my own desire an automatic trans car, since 1980 when I got a license every car has been a stick.
Keep practicing and one day you will get it all correct.
A perfect shift is a thing of beauty but in real life is few and far between!!
Of course I have never owned of my own desire an automatic trans car, since 1980 when I got a license every car has been a stick.
Keep practicing and one day you will get it all correct.
10-02-2009, 08:29 PM
#34
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He did a pretty good job for you.
You push that clutch in everything lets loose as you let go everything slides till it catches. No matter how quick you do it friction will happen. Now personally I have never had a problem with throwout bearings as the metal is designed for those stresses, but if you are then
maybe thats my proof.If you are trying to say that the clutch plate doesn't slow down...thats not true. Also you are ignoring the sitting in nuetral portion of the transmission.
Yes I know it's a motorcycle, but to give you an idea about neutral.
http://www.youtube.com/watch?v=UsnNgU8pKoc
This bike is in nuetral (I know because I had one) the second you put it into gear the clutch immediatly stops. With the clutch in. When you start rolling the clutch moves at engine speeds. (the reason I also know that sitting at stop lights with the clutch in is no worse then sitting in nuetral)
Go ahead and PM me cause we've already destroyed this poor thread and I just got out of work (only time I'm on here) and I'll by all means continue this debate as I'm always willing to learn.
10-02-2009, 09:03 PM
#35
I still don't see how plates that aren't touching one another are rubbing together and causing friction. No I've never had any trouble with throwout bearings, that's just the only part I can imagine that is under significant stress when pushing the clutch in (other than the dastardly clutch bracket).
Your links seem to confirm what I'm saying. What you are doing is rev matching by doing the work of the clutch alone. Double-clutching does the work of the clutch and synchros. You could argue that it's not necessary in a car with syncrhos, but when you're driving a car that you often have to drop three gears at a time in I think it's worthwhile.
Your links seem to confirm what I'm saying. What you are doing is rev matching by doing the work of the clutch alone. Double-clutching does the work of the clutch and synchros. You could argue that it's not necessary in a car with syncrhos, but when you're driving a car that you often have to drop three gears at a time in I think it's worthwhile.
10-03-2009, 12:46 PM
#36
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Why are you dropping three gears at a time? You must constantly be in the wrong gear? I'm more conscious of it because motorcycles you don't get the free shift from high to low, you have to hit every gear along the way. If you need the, no need to double clutch because it is a constant mesh transmission then ok use that haha.
As for the plates they do touch each time you let off of the clutch.
Found a great picture, see the external cone and drive dogs? Those are not splined (also called a freewheeling gear) it is moving from a gear on the input shaft moving the gear to the right of the "drive dogs" If you put the transmission into nuetral the input shaft (not shown) stops moving at engine speeds and now is just spinning from left over inertia.(Also sits on all freewheeling gears so it is not attached to the outputshaft which is why the clutch can be out and the car doesnt move when stopped) Before that freewheeling gear was moving exactly with the output shaft, now you just adjusted the speed of the input shaft which adjusted the speed of the gear to the right of the freewheeling gear therefore changing the speed of the freewheeling gear. Now you slide the groved syncrho over onto the drive dogs which are no longer alligned with the output shaft, Either A. you bounce it around till it slides in B. miss the gear entirely blame the car and say the transmission is horrible C. Do this
Yes it is a reverse gear, but same concept as that happens when you are at higher rpm and smash it into reverse and the gears don't go together.
If you move straight from gear to gear you are always leaving the input and ouput shafts in mesh. Hence constant mesh.
As for the plates they do touch each time you let off of the clutch.
Found a great picture, see the external cone and drive dogs? Those are not splined (also called a freewheeling gear) it is moving from a gear on the input shaft moving the gear to the right of the "drive dogs" If you put the transmission into nuetral the input shaft (not shown) stops moving at engine speeds and now is just spinning from left over inertia.(Also sits on all freewheeling gears so it is not attached to the outputshaft which is why the clutch can be out and the car doesnt move when stopped) Before that freewheeling gear was moving exactly with the output shaft, now you just adjusted the speed of the input shaft which adjusted the speed of the gear to the right of the freewheeling gear therefore changing the speed of the freewheeling gear. Now you slide the groved syncrho over onto the drive dogs which are no longer alligned with the output shaft, Either A. you bounce it around till it slides in B. miss the gear entirely blame the car and say the transmission is horrible C. Do this
Yes it is a reverse gear, but same concept as that happens when you are at higher rpm and smash it into reverse and the gears don't go together.If you move straight from gear to gear you are always leaving the input and ouput shafts in mesh. Hence constant mesh.
10-03-2009, 12:55 PM
#37
You can emulate swapping shoes to some degree by moving the seat forward (or back) to change the angle of your knees.
The same goes by switching frequently between an automatic car and the MT on the RX-8. You eventually quit thinking you're in a MT and only use your left foot when there is a clutch present.
10-03-2009, 12:59 PM
#38
You seem to have provided a nice explanation of why you should double-clutch large downshifts, like dropping two or three gears, which is what you often need to do in an RX-8 if you want to, say, pass another car while cruising. Seriously, you've never dropped from sixth to third in your RX-8?
Double-clutching allows you to sync those gears when doing large downshifts. You're using the above post to argue that pushing in the clutch to disengage it will wear down the plates (I'm far from convinced), but by doing so you seem to be also showing why double-clutching is a good idea for large downshifts, which is what you were arguing against in the first place. The problem you are talking about when dropping gears is exactly the problem that double clutching solves.
10-03-2009, 04:39 PM
#39
Registered
...no need to double clutch because it is a constant mesh transmission...
Nice diagram. Any chance the place you got that from has similar ones showing the rest of the action? One with the synchronizer partly slid over, with the synchromesh cones (and blocking ring) doing their job, then one fully engaged?
Ken
10-04-2009, 04:40 PM
#40
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- starting from stop: I have no problem getting the car going with just the clutch and no gas, and with traffic around here I had all the time in world to learn the friction point. However, for regular starts I must pre-rev (~2k) and let the clutch out slowly in order to be smooth and get moving quickly. I've never got the hang of just letting the clutch grab first then adding gas, because once the clutch starts to engage there is a "dead zone" in throttle response that is either all-or-none for me: I either don't add enough gas to keep the rpms up, or I'll over-rev, with no in-between point and all while trying to getting off the clutch smoothly without stalling. There are days I would spend practising not pre-revving, but those are the days where I end up arriving at work grumpy
The fix is pretty simple, and that's to apply a small amount of gas before the clutch bites. I'm not suggesting pre-revving which you obviously know about, this is slightly different. What I am suggesting is that after you've started releasing the clutch pedal but the tiniest fraction before you reach the biting point, then you start to add a small bit of power, and as you are progressively releasing the clutch pedal through the biting point out to it being fully engaged you progressively add more and more power.
It takes a bit of practice to get exactly right, but when you do the feeling of smoothness and power you get is amazing. The further out from the biting point you start adding power, and the more you add the easier it is (because the closer to pre-revving it is). The closer to the biting point you add the power and the less you add initially the more difficult it is but the smoother it feels.
10-07-2009, 06:20 AM
#41
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I've had my RX8 for about 6 months now, which is my first manual tans car. I've gotten spot on smooth with everything except 3rd to 2nd downshifts.
Seriously, engaging into 1st from a stop is the hardest part. For a long time I would either give too much gas and grind the clutch at about about 2.5-3k from a stop, which made the clutch grabbing point really obvious, or I wouldn't give enough and the rpms would dip really low and shake the car.
The biggest help I've found, to learn how to shift really smoothly, is to turn off any music in the car, and have the windows open. Hearing the engine really helps me shift perfectly. I'm starting to be able to do perfect shifts even with loud music playing!
Seriously, engaging into 1st from a stop is the hardest part. For a long time I would either give too much gas and grind the clutch at about about 2.5-3k from a stop, which made the clutch grabbing point really obvious, or I wouldn't give enough and the rpms would dip really low and shake the car.
The biggest help I've found, to learn how to shift really smoothly, is to turn off any music in the car, and have the windows open. Hearing the engine really helps me shift perfectly. I'm starting to be able to do perfect shifts even with loud music playing!
10-07-2009, 04:04 PM
#42
Look folks it is not rocket surgery, drive the damn car and learn to not even be aware that you shifted any gears.
A perfect shift is a thing of beauty but in real life is few and far between!!
Of course I have never owned of my own desire an automatic trans car, since 1980 when I got a license every car has been a stick.
Keep practicing and one day you will get it all correct.
A perfect shift is a thing of beauty but in real life is few and far between!!
Of course I have never owned of my own desire an automatic trans car, since 1980 when I got a license every car has been a stick.
Keep practicing and one day you will get it all correct.
10-07-2009, 04:07 PM
#43
I've had my RX8 for about 6 months now, which is my first manual tans car. I've gotten spot on smooth with everything except 3rd to 2nd downshifts.
Seriously, engaging into 1st from a stop is the hardest part. For a long time I would either give too much gas and grind the clutch at about about 2.5-3k from a stop, which made the clutch grabbing point really obvious, or I wouldn't give enough and the rpms would dip really low and shake the car.
The biggest help I've found, to learn how to shift really smoothly, is to turn off any music in the car, and have the windows open. Hearing the engine really helps me shift perfectly. I'm starting to be able to do perfect shifts even with loud music playing!
Seriously, engaging into 1st from a stop is the hardest part. For a long time I would either give too much gas and grind the clutch at about about 2.5-3k from a stop, which made the clutch grabbing point really obvious, or I wouldn't give enough and the rpms would dip really low and shake the car.
The biggest help I've found, to learn how to shift really smoothly, is to turn off any music in the car, and have the windows open. Hearing the engine really helps me shift perfectly. I'm starting to be able to do perfect shifts even with loud music playing!
10-07-2009, 05:38 PM
#44
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Are you joking? Do you drive an RX-8?
You seem to have provided a nice explanation of why you should double-clutch large downshifts, like dropping two or three gears, which is what you often need to do in an RX-8 if you want to, say, pass another car while cruising. Seriously, you've never dropped from sixth to third in your RX-8?
Double-clutching allows you to sync those gears when doing large downshifts. You're using the above post to argue that pushing in the clutch to disengage it will wear down the plates (I'm far from convinced), but by doing so you seem to be also showing why double-clutching is a good idea for large downshifts, which is what you were arguing against in the first place. The problem you are talking about when dropping gears is exactly the problem that double clutching solves.
You seem to have provided a nice explanation of why you should double-clutch large downshifts, like dropping two or three gears, which is what you often need to do in an RX-8 if you want to, say, pass another car while cruising. Seriously, you've never dropped from sixth to third in your RX-8?
Double-clutching allows you to sync those gears when doing large downshifts. You're using the above post to argue that pushing in the clutch to disengage it will wear down the plates (I'm far from convinced), but by doing so you seem to be also showing why double-clutching is a good idea for large downshifts, which is what you were arguing against in the first place. The problem you are talking about when dropping gears is exactly the problem that double clutching solves.
To be perfectly honest, I don't give a rip about the clutch, I engine brake, really I don't care they will outlast most of the parts on the car for daily wear, you just made the argument so I ran with it, but I kept trying to come back to the transmission. I also now know that all of that went over your head. I personally don't care if you double clutch and I'm sorry that the diagram didn't help you understand how a transmission works. Best thing I can tell you is to drive a motorcycle some time go from first to nuetral let the clutch out and then try to get into second gear. Its a nice audiable lesson that you may understand better because telling me that going from 6th to 3rd needs you to be in nuetral doesn't make any sense by what I told you. Nuetral is the problem.
I have a better idea. Get a buddy some time. Have the car completely turned off. Put the car in any gear you want with the clutch pushed to the floor and have the buddy push the car. Then put the car in nuetral and have the buddy again push the car. Please tell me which way your buddy thought was easier. (The easier is due to less parts moving) Less parts moving means less things are moving together. Has absolutly nothing to do with how many gears you decide to skip.
The thread is for smoother shifting. Double clutching is not a "smoother shifting" technique. If it works for you cool. By all means have at it.
10-07-2009, 05:45 PM
#45
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10-07-2009, 07:09 PM
#46
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The "no need to double clutch" concept is associated with synchromesh, not constant mesh. There are constant mesh transmissions without synchro. Constant mesh just means that the gears are always meshed, and shifting is done by the synchronizer ring engaging the drive dogs.
Nice diagram. Any chance the place you got that from has similar ones showing the rest of the action? One with the synchronizer partly slid over, with the synchromesh cones (and blocking ring) doing their job, then one fully engaged?
Ken
Nice diagram. Any chance the place you got that from has similar ones showing the rest of the action? One with the synchronizer partly slid over, with the synchromesh cones (and blocking ring) doing their job, then one fully engaged?
Ken
I always thought the dogs were on the synchro (earlier picture) making it no more different then any other constant mesh transmission (motorcycles is where you usually see that term) difference being the "synchro" is splined and generally the freewheeling is the gear. Shifting is done from a drum with pre made slots giving you the ratchet affect. (How car transmissions should be made)
I'll search and see if I can find any other pictures, I have GOBS of motorcycle tranny pictures and can have those all torn apart for you, but car ones are much harder to find.
07-14-2010, 09:06 PM
#48
ive always owned sports cars, well and one truck. I kinda enjoy throwing passengers around. Now i don't mean crappy shifting, i mean the gas companies like me lol. I don't slow down much to turn, and I love being in the gas and pinning people to the seat. Maybe im alone on this though. I just wait for the shift indicator beep.
07-17-2010, 01:08 AM
#50
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Quote from Wiki:
Manual transmission shifting
In a gearbox with neutral between each gear, a typical shift actually involves two gear changes, once into neutral, and again into the next gear. During any shift, disconnecting drive components via a clutch properly unloads the engine and transmission of undue pressure applied by the opposing components. Fully utilizing the clutch for each shift out of, and then into each gear is double clutching. Due to the absence of a neutral spacing, double clutching is ill-advised for sequential gear changes, as in a fully sequential gearbox such as a typical motorcycle.
Keeping the clutch pedal depressed while in neutral, as is performed during a typical shift, gives more economy of driver motion and effort compared to double clutching. Taken to extreme, sequential gearbox shifts and non-clutched shifts are also very quick and effortless. However, significant wear can take place on the separated clutch plates any time the engine and transmission have varying drive loads. In simple terms, wear occurs the more the clutch has to "slip" to match revolutions between the engine and transmission. Double clutching can minimize this clutch plate wear by encouraging matching of engine and transmission RPMs before the clutch plates are engaged.
Manual transmission shifting
In a gearbox with neutral between each gear, a typical shift actually involves two gear changes, once into neutral, and again into the next gear. During any shift, disconnecting drive components via a clutch properly unloads the engine and transmission of undue pressure applied by the opposing components. Fully utilizing the clutch for each shift out of, and then into each gear is double clutching. Due to the absence of a neutral spacing, double clutching is ill-advised for sequential gear changes, as in a fully sequential gearbox such as a typical motorcycle.
Keeping the clutch pedal depressed while in neutral, as is performed during a typical shift, gives more economy of driver motion and effort compared to double clutching. Taken to extreme, sequential gearbox shifts and non-clutched shifts are also very quick and effortless. However, significant wear can take place on the separated clutch plates any time the engine and transmission have varying drive loads. In simple terms, wear occurs the more the clutch has to "slip" to match revolutions between the engine and transmission. Double clutching can minimize this clutch plate wear by encouraging matching of engine and transmission RPMs before the clutch plates are engaged.
Yes I do check below. I do know that unless you drive like an asshat, downshifting to "pass a car" is a conscious pre thought out process. Plenty of time to downshift through the gears making my method still valid. Also many many many people shift without double clutching, I would be more than willing to wager a bet that MOST people do not double clutch. Your argument should have been for racing.
To be perfectly honest, I don't give a rip about the clutch, I engine brake, really I don't care they will outlast most of the parts on the car for daily wear, you just made the argument so I ran with it, but I kept trying to come back to the transmission. I also now know that all of that went over your head. I personally don't care if you double clutch and I'm sorry that the diagram didn't help you understand how a transmission works. Best thing I can tell you is to drive a motorcycle some time go from first to nuetral let the clutch out and then try to get into second gear. Its a nice audiable lesson that you may understand better because telling me that going from 6th to 3rd needs you to be in nuetral doesn't make any sense by what I told you. Nuetral is the problem.
I have a better idea. Get a buddy some time. Have the car completely turned off. Put the car in any gear you want with the clutch pushed to the floor and have the buddy push the car. Then put the car in nuetral and have the buddy again push the car. Please tell me which way your buddy thought was easier. (The easier is due to less parts moving) Less parts moving means less things are moving together. Has absolutly nothing to do with how many gears you decide to skip.
The thread is for smoother shifting. Double clutching is not a "smoother shifting" technique. If it works for you cool. By all means have at it.
To be perfectly honest, I don't give a rip about the clutch, I engine brake, really I don't care they will outlast most of the parts on the car for daily wear, you just made the argument so I ran with it, but I kept trying to come back to the transmission. I also now know that all of that went over your head. I personally don't care if you double clutch and I'm sorry that the diagram didn't help you understand how a transmission works. Best thing I can tell you is to drive a motorcycle some time go from first to nuetral let the clutch out and then try to get into second gear. Its a nice audiable lesson that you may understand better because telling me that going from 6th to 3rd needs you to be in nuetral doesn't make any sense by what I told you. Nuetral is the problem.
I have a better idea. Get a buddy some time. Have the car completely turned off. Put the car in any gear you want with the clutch pushed to the floor and have the buddy push the car. Then put the car in nuetral and have the buddy again push the car. Please tell me which way your buddy thought was easier. (The easier is due to less parts moving) Less parts moving means less things are moving together. Has absolutly nothing to do with how many gears you decide to skip.
The thread is for smoother shifting. Double clutching is not a "smoother shifting" technique. If it works for you cool. By all means have at it.
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