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Old 03-03-2004, 05:19 AM   #1
volkl23
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Default Lurching foward when foot off gas (fast shifts)

Whenever I drive spiritedly (read: shifting around 6200rpms) and shift, I always see my passengers lurch foward whenever I gas off/clutch in in preparation for my next upshift. I really don't feel it since I'm driving, but is quite apparent in the jerking motion of my passengers. I'd say this only happens during my 1-2 and maybe a little in 3rd.

I would like to think that I shift smoothly- the clutch in, shift, clutch-out are quite fluid and jerk-free. It's just whenever I let off the gas for the next upshift that happens.
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Old 03-03-2004, 06:36 AM   #2
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It's normal, the only way to make it better is to ease off on your shifting. 4 wheels of power is good, but during the upshift, they become 4 wheels of engine braking for a split second causing the movement.
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Old 03-03-2004, 09:10 AM   #3
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"clutch in" a little sooner, as compared to your right foot getting off of the gas...
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Old 03-03-2004, 01:14 PM   #4
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Thanks guys! I'll give that a try
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Old 03-03-2004, 01:22 PM   #5
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the old back and forth satanic teletubby dance...
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Old 03-03-2004, 01:43 PM   #6
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Just a theory here... I don't think there needs to be any deceleration (in the form of engine braking) at all on in order for the passenger's head to jerk forward. Under acceleration, you muscles are resisting the accelerative forces and keeping your head off the headrest. If acceleration is suddenly reduced or cut (if only by depressing the clutch pedal), there will be a delay between when the passenger is still resisting forces and when he relaxes. This would be your head jerk. The reason the driver is less prone to the head jerk is that he is the one controlling the acceleration/deceleration and therefore unconsciously anticipates the changes in forces and adjusts accordingly.

I don't know if I'm making any sense, but like I said, it's just a theory.
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Old 03-03-2004, 01:47 PM   #7
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Your passengers' heads will bob when shifting in ANY manual transmission car. As a driver, you anticipate the deceleration as you lift off the gas and tense your neck muscles to prevent your head from moving. Your passengers do not do this, so the deceleration that occurs as you transition from gas to no gas will cause their heads to move forward. Likewise, the transition from no gas to gas as you complete the shift will cause their heads to move back.

Even when shifting normally, I have noticed that my passengers heads will bob, especially on the 1 -> 2 shift. I have also noticed, however, that most of my passengers aren't aware that their heads are moving or are not bothered by it.
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Old 03-03-2004, 01:47 PM   #8
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Have you ever driven a motorcycle with a passenger on the back? Vroom, helmet clunk, vroom, helmet clunk, vroom, helmet clunk
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Old 03-03-2004, 01:55 PM   #9
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Quote:
Originally posted by Overdue
If acceleration is suddenly reduced or cut
There's your problem right there. Just don't stop accelerating.
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Old 03-03-2004, 02:00 PM   #10
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i have this same problem, my friend always rags on me about how rough my car is. i told him what do you expect. a luxury ride? this is a sport car. something you don't know nothing about. hehhehe.
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Old 03-03-2004, 05:08 PM   #11
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No other manual car I've ever owned dived and lurched so much on high RPM shifts (and, yes, this isn't my first AWD turbo car). It almost feels like there's too much exhaust back-pressure when shifted at high RPM. The suspension is a little on the soft side, but the car's not digging the rear very hard on acceleration, so it shouldn't be only weight transfer. hmmm

It shifts very smoothly at low and mid RPM and mid-level boost, but it definitely lurches pretty hard on full boost/high RPM shifts.

Anyone have a reduction in the lurchiness when using a freer-flowing exhaust?
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Old 03-03-2004, 05:19 PM   #12
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Quote:
Originally posted by Slowpoke
Your passengers' heads will bob when shifting in ANY manual transmission car. As a driver, you anticipate the deceleration as you lift off the gas and tense your neck muscles to prevent your head from moving. Your passengers do not do this, so the deceleration that occurs as you transition from gas to no gas will cause their heads to move forward. Likewise, the transition from no gas to gas as you complete the shift will cause their heads to move back.

Even when shifting normally, I have noticed that my passengers heads will bob, especially on the 1 -> 2 shift. I have also noticed, however, that most of my passengers aren't aware that their heads are moving or are not bothered by it.

for some reason i dont have this problem. one person even told me that if she were blind and deaf she'd think she was riding in an auto
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Old 03-03-2004, 05:40 PM   #13
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Quote:
Originally posted by Stanley
Have you ever driven a motorcycle with a passenger on the back? Vroom, helmet clunk, vroom, helmet clunk, vroom, helmet clunk

Good point!
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Old 03-03-2004, 06:19 PM   #14
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I have a question, I just got my WRX, I am not used to the shifting as right now so I rev it to about 2.5 then take my foot off the clutch. Wanted to know at about what RPM you guys start taking your foot of the clutch.

Thanks!
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Old 03-03-2004, 06:24 PM   #15
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yeah
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Old 03-03-2004, 06:33 PM   #16
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Quote:
Originally posted by Stanley
Have you ever driven a motorcycle with a passenger on the back? Vroom, helmet clunk, vroom, helmet clunk, vroom, helmet clunk

ROFL!


Yeah, that's why I made her get her own damn bike.
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Old 03-03-2004, 06:44 PM   #17
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Quote:
Originally posted by jonik
I have a question, I just got my WRX, I am not used to the shifting as right now so I rev it to about 2.5 then take my foot off the clutch. Wanted to know at about what RPM you guys start taking your foot of the clutch.

Thanks!
all depends on my mood and the flow of traffic.
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Old 03-03-2004, 06:56 PM   #18
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Quote:
Originally posted by lettucemanatee
all depends on my mood and the flow of traffic.
Don't really understand, can you elaborate?
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Old 03-03-2004, 07:29 PM   #19
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Quote:
Originally posted by jonik
Don't really understand, can you elaborate?
like sometimes i'll be in the mood just to hear the engine scream, sometimes i like driving normally, sometimes i just like cruising. it all depends on what kind of day i've had, how early/late it is, and what kind of music i'm currently listening too. you have music moods dont you? i know i do, i also have driving moods. might sound immature, but nothing calms me more than driving like a jerk for about 5 mins then cruising around till my steam has cooled if i'm pissed about something.

about the traffic thing, if its constant slow moving traffic, i usually shift at around 2 because i really have no need for the acceleration that the torque at higher rpms would bring me. sometimes i can just go along at idle in 2nd gear. if it's stop and go traffic i'll let it go to around 4 just for the sole comfort of not having to upshift then downshift over and over again.



edit: just noticed you said 'take your foot off the clutch.' are you launching, rather starting from a standstill, at 2.5k rpm? if this is the case usually b/w 1k and 1.5k rpm's here during normal driving. very slow moving traffic i just slip the clutch out w/o giving it any gas and idle in gear as my motion. i learned how to drive stick on my wrx and when i started i was in b/w 2k and 2.5k from starting motion from a stop. it just takes practice and getting accustomed to the the timing of releasing the clutch and depressing the gas. i was teaching someone how to drive a MT on my car last week and told them to keep the rpms b/w 2k and 2.5k to start off with from a stop until they were comfortable with the timing. then they could work on lowering the launch rpms. no need in continuing to slip the clutch at a higher rpm if you can do it at a lower one.

Last edited by lettucemanatee; 03-03-2004 at 07:34 PM.
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Old 03-03-2004, 07:35 PM   #20
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Quote:
i usually shift at around 2 because i really have no need for the acceleration that the torque at higher rpms would bring me.
I don't know if your talking about starting up but that is what im talking about, what I meant is what RPM do you start to release your clutch when your in netural and you put it to 1st gear.
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Old 03-03-2004, 07:47 PM   #21
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Quote:
Originally posted by jonik
I don't know if your talking about starting up but that is what im talking about, what I meant is what RPM do you start to release your clutch when your in netural and you put it to 1st gear.
i thought you were talking about like if you were already in gear, in motion and going for an upshift. like what rpm would you go from 1-2 or 2-3, etc...

i edited post to explain what i do from a stop.
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Old 03-03-2004, 08:54 PM   #22
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Quote:
Originally posted by lettucemanatee
i thought you were talking about like if you were already in gear, in motion and going for an upshift. like what rpm would you go from 1-2 or 2-3, etc...

i edited post to explain what i do from a stop.
Thanks.
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Old 03-04-2004, 08:37 AM   #23
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Quote:
Originally posted by lettucemanatee
for some reason i dont have this problem. one person even told me that if she were blind and deaf she'd think she was riding in an auto
I get that too. It's not so much the RPM at the point when you shift as it is how quickly you let off the throttle and then get back on. It's a subtle technique that makes a big difference in your passengers' comfort. To be honest, it's something I never gave much thought to when learning to drive manual. But the more people I ride with who could use some practice , the more I analyze what causes the jerkiness and what can be done to prevent it.
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Old 03-04-2004, 08:53 AM   #24
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For a good technique on shifting, check out Mike's website at www.spdusa.com Not only is it a great website for driving techniques, but he gives a very thorough explanation of the wrx and it's tuning possibilities. He's all for long-term car life as opposed to simply making your car go fast. I've tried his shifting technique and found that it works: simply take your foot slowyly off the gas pedal right before you shift, wait a second (you'll feel the engine start to slow the car down slightly) then quickly push in the clutch, shift gears smoothly = no slamming the shifter into gear, and let the clutch back out. See his website for more details. Hope this helps.
-www.spdusa.com
-click on "other information"
-click on "driving tips"
-click on "shifting tips"
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Old 03-04-2004, 09:06 AM   #25
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Let's get back on the original topic, shall we? There are plenty of threads about launching and newbie shifting, and whatnot.

Quote:
Originally posted by lettucemanatee
for some reason i dont have this problem. one person even told me that if she were blind and deaf she'd think she was riding in an auto
What I said in my original reply applies here. "I have also noticed, however, that most of my passengers aren't aware that their heads are moving or are not bothered by it." What I have found is that unless the passenger's head is being jerked around by your shifting, head movement has no effect on perceived smoothness of your shifts.

Next time you drive with someone in the passenger seat, look at him/her out of the corner of your eye when you shift. You will see your passengers head move forward, even if it's a slight bit, every time you let off the gas to shift.
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