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      03-23-2016, 02:59 PM   #23
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Originally Posted by Uber V8 View Post
This. right. here... golden. I'm man enough to admit I never knew this. I taught myself how to drive a stick as a teenager and never thought to do anymore research until now. I feel like I missed out on on some good years of shiftin'
Oh wow, you certainly have missed out. Never too late to learn some new tricks though!
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      03-23-2016, 03:11 PM   #24
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Originally Posted by DSilk View Post
I agree with almost everything here. The one exception that I would raise is that it is incorrect to say that the coupe has no B pillar. It does (what do you think the shoulder harness portion of the seatbelts are attached to?). It just doesn't have rear windows that open. It isn't just the roof that makes the coupe stiffer than the convertible. It is also the B pillars behind the doors that help connect the 2 sides of the car together at the top.
Fair point. I guess the more precise way to phrase it would be that since the E92's front side windows are so much longer (because the rear side windows are so much shorter compared to the E90), unless you're 7 feet tall, the B-pillar on the E92 is well behind the driver's/front passenger's ears, and therefore the buffeting isn't nearly as bad as the E90 where the wide B-pillar is likely much closer to the driver's/front passengers ears.
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      03-23-2016, 03:22 PM   #25
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Quote:
Originally Posted by Uber V8 View Post
This. right. here... golden. I'm man enough to admit I never knew this. I taught myself how to drive a stick as a teenager and never thought to do anymore research until now. I feel like I missed out on on some good years of shiftin'
Well then just be grateful you're still alive and have an opportunity to check out what you've been missing! I forgot to mention that the other factor determining the size of the blip you'll need is how high up you are in the rev range in the current gear, since the RPM difference for a given speed between adjacent gears increases as you climb up the rev range.

So for example, let's say you're in 4th gear and want to downshift to 3rd, and you're currently doing 20 MPH. 20 MPH in 4th only has you doing about 1200 RPM, and therefore the required RPM increase for 3rd at that speed is pretty small, about +350 RPM in this car. As a result, you only need a tiny blip, in fact in that case I might not even blip at all. But now let's say you're in 4th gear planning to downshift to 3rd and currently doing 80 MPH. Now you're doing about 4850 RPM in 4th, and there's a bigger RPM increase to get to 3rd, about +1600 RPM in this car. That's over 4x the difference between 4th and 3rd at 30 MPH, so you of course need a correspondingly larger blip. The higher you are in the rev range when downshifting, the larger a blip you'll need to engage the lower gear smoothly.

And if you want to skip shift down, it's even more significant since you're going for an even lower gear where the difference at a given speed will be even greater -- so for example if I'm in 6th doing 60 on the highway and want to downshift to 3rd, even though I'm pretty low in the rev range in 6th (2700 RPM), the fact that I'm dropping 3 gears means I need a blip for a +2200 RPM change. In fact it's so significant that I'll double-clutch that one to spare my 3rd gear synchros. Double-clutching btw is when you shift to Neutral, let the clutch out, THEN blip the throttle (which revs up both the engine and gearbox since the clutch is engaged), then you shift into your desired lower gear. You'll find that the shifter goes into the gate much more smoothly this way when skip shifting down than by just doing a regular 6>3 shift. An alternative that I use if I'm only skipping over one gear, like 6>4, is a double blip. So in 6th, I'll clutch in, blip and move the shifter to 5th, KEEP the clutch in, then blip again and move the shifter to 4th. It's usually easier to get two consecutive smaller blips right than one big one, and passing the shifter through 5th even though I never engage 5th gear makes it easier on the synchros since 5th gear spun the gearbox up partway and then 4th finished the job.

The other thing you'll have to get a feel for is timing. Obviously after that quick blip of the throttle, the revs start falling again since you're not holding the throttle down (nor should you), so part of getting a smooth shift is knowing how quickly to re-engage the clutch. For example, after you get a feel for this, if you accidentally blip too much mid-shift and recognize that before even re-engaging the clutch, you can just hold the clutch in a little longer to wait for the revs to drop a bit more, thereby compensating for the overly aggressive blip. If you don't blip nearly enough though, you have to either blip again or just re-engage the clutch and deal with a bit of a buck since your revs were too low for your new gear.

Again, this all becomes instinct once you get on the road and start practicing, so don't overthink it. But I'm glad you were able to learn a new technique even after all these years!

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Last edited by jphughan; 03-23-2016 at 03:54 PM.
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      03-23-2016, 03:39 PM   #26
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All good tips. Only thing I would add is that I have a much easier time rev matching in "Power" mode with the sharpened throttle sensitivity than in regular mode. As such, I have my car set to startup in Power mode by default. The car feels so numb without it and downshifting requires a lot more throttle input.
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      03-23-2016, 03:42 PM   #27
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Quote:
Originally Posted by Iyzmi View Post
All good tips. Only thing I would add is that I have a much easier time rev matching in "Power" mode with the sharpened throttle sensitivity than in regular mode. As such, I have my car set to startup in Power mode by default. The car feels so numb without it and downshifting requires a lot more throttle input.
Very true, and this is especially helpful when you experiment with heel-toe. However, on track I found that the benefits of the more linear throttle behavior in Normal outweighed the simplified blipping, which actually isn't an issue at all out there because you're heel-toeing on track and you're also pushing the brake much farther than you normally would on the street, which makes it easier to get a solid blip. Sport never allowed me to manage mid-corner throttle as effectively, and when you stay high up in the rev range as one does on track, Normal doesn't create any numbness problem at all.
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      03-23-2016, 04:04 PM   #28
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Originally Posted by jphughan View Post
Very true, and this is especially helpful when you experiment with heel-toe. However, on track I found that the benefits of the more linear throttle behavior in Normal outweighed the simplified blipping, which actually isn't an issue at all out there because you're heel-toeing on track and you're also pushing the brake much farther than you normally would on the street, which makes it easier to get a solid blip. Sport never allowed me to manage mid-corner throttle as effectively, and when you stay high up in the rev range as one does on track, Normal doesn't create any numbness problem at all.
Heh, kind of ironic that normal works better for the track and sport works better for the street.
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      03-23-2016, 04:09 PM   #29
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Great thread guys. I have to say a learned a little bit by reading this.
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      03-23-2016, 04:13 PM   #30
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Originally Posted by modkrazy View Post
Performance-wise, it isn't a huge difference. You do get the carbon roof with the coupe, which lowers weight/center of gravity some. But supposedly the sedan is a tad more balanced front to back. Unlikely you can tell the difference.
Actually -

Coupe: Depending on source - BMWNA -51.2/48.8%, Car & Driver instrumented test - 50.8/49.2

Sedan: BMWNA - 52.2/47.8%

Convertible: BMWNA - 47.2/52.8 %
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      03-23-2016, 04:29 PM   #31
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Quote:
Originally Posted by jphughan View Post
Well then just be grateful you're still alive and have an opportunity to check out what you've been missing! I forgot to mention that the other factor determining the size of the blip you'll need is how high up you are in the rev range in the current gear, since the RPM difference for a given speed between adjacent gears increases as you climb up the rev range.

So for example, let's say you're in 4th gear and want to downshift to 3rd, and you're currently doing 20 MPH. 20 MPH in 4th only has you doing about 1200 RPM, and therefore the required RPM increase for 3rd at that speed is pretty small, about +350 RPM in this car. As a result, you only need a tiny blip, in fact in that case I might not even blip at all. But now let's say you're in 4th gear planning to downshift to 3rd and currently doing 80 MPH. Now you're doing about 4850 RPM in 4th, and there's a bigger RPM increase to get to 3rd, about +1600 RPM in this car. That's over 4x the difference between 4th and 3rd at 30 MPH, so you of course need a correspondingly larger blip. The higher you are in the rev range when downshifting, the larger a blip you'll need to engage the lower gear smoothly.

And if you want to skip shift down, it's even more significant since you're going for an even lower gear where the difference at a given speed will be even greater -- so for example if I'm in 6th doing 60 on the highway and want to downshift to 3rd, even though I'm pretty low in the rev range in 6th (2700 RPM), the fact that I'm dropping 3 gears means I need a blip for a +2200 RPM change. In fact it's so significant that I'll double-clutch that one to spare my 3rd gear synchros. Double-clutching btw is when you shift to Neutral, let the clutch out, THEN blip the throttle (which revs up both the engine and gearbox since the clutch is engaged), then you shift into your desired lower gear. You'll find that the shifter goes into the gate much more smoothly this way when skip shifting down than by just doing a regular 6>3 shift. An alternative that I use if I'm only skipping over one gear, like 6>4, is a double blip. So in 6th, I'll clutch in, blip and move the shifter to 5th, KEEP the clutch in, then blip again and move the shifter to 4th. It's usually easier to get two consecutive smaller blips right than one big one, and passing the shifter through 5th even though I never engage 5th gear makes it easier on the synchros since 5th gear spun the gearbox up partway and then 4th finished the job.

The other thing you'll have to get a feel for is timing. Obviously after that quick blip of the throttle, the revs start falling again since you're not holding the throttle down (nor should you), so part of getting a smooth shift is knowing how quickly to re-engage the clutch. For example, after you get a feel for this, if you accidentally blip too much mid-shift and recognize that before even re-engaging the clutch, you can just hold the clutch in a little longer to wait for the revs to drop a bit more, thereby compensating for the overly aggressive blip. If you don't blip nearly enough though, you have to either blip again or just re-engage the clutch and deal with a bit of a buck since your revs were too low for your new gear.

Again, this all becomes instinct once you get on the road and start practicing, so don't overthink it. But I'm glad you were able to learn a new technique even after all these years!
What's funny is as complicated as this may read, you actually explained it very well and it makes sense. Do you know if they teach this at HPDE? I still enjoy my DCT downshifts especially with my recent ACM exhaust mod, but I can imagine it's more rewarding with a 6MT.

Quote:
Originally Posted by GVFlyer View Post
Actually -

Coupe: Depending on source - BMWNA -51.2/48.8%, Car & Driver instrumented test - 50.8/49.2

Sedan: BMWNA - 52.2/47.8%

Convertible: BMWNA - 47.2/52.8 %
I love when people cite the sources, thanks for that. I do find it interesting that the E90 would be a tad more front heavy considering the additional rear doors and windows.
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      03-23-2016, 04:54 PM   #32
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Quote:
Originally Posted by Uber V8 View Post
What's funny is as complicated as this may read, you actually explained it very well and it makes sense. Do you know if they teach this at HPDE? I still enjoy my DCT downshifts especially with my recent ACM exhaust mod, but I can imagine it's more rewarding with a 6MT.
Part of my job involves explaining technical concepts to non-technical people who need to make decisions about technical things, plus I dabbled in mentoring, tutoring, and teaching courses in high school and college, and now I instruct at HPDEs, so I can usually find a way to explain even difficult concepts in clearly understandable ways. In the HPDEs I've attended, rev matching and heel toe were mentioned in class but never really focused on, although classroom discussions are to some extent guided by what students ask to learn about anyway. An instructor might suggest focusing on it as well based on your driving and/or agree to work on it with you if you say that you'd like to learn it, but honestly I'd recommend practicing off track, at the very least for rev matching. You have to learn that before you can heel-toe, and I learned rev matching by just going out onto unoccupied public roads and trying the various downshifts (5>4, 4>3, 3>2) in the middle of straightaways where there was no upcoming corner to deal with and therefore nothing else to focus on and no consequence of getting the blip even horribly wrong. Compare that setting to the track, where you're coming up to a corner fast, braking hard, and thinking about a bunch of other things, all of which can cause you to get crossed up mentally and mess up the shift, and on track messing up the shift can mean spinning your car (from locking up the rear wheels due to insufficient blip) or overrevving your engine (from panicking while approaching the corner and shifting too early). But once you get a feel for rev matching, heel-toe actually IS easier to learn on track because as I mentioned above, that's where you press the brake down far enough to make that easier. Once you've learned it there, it's still possible on the road though; you just have to rotate your foot more and lean into the throttle more than you would otherwise. I learned heel-toe on the track and just came into corners that required shifts a bit more slowly than I would have otherwise while picking it up, but I had it down in a day or so -- but that was after I had practiced rev matching in the manner I described above.
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      03-23-2016, 05:07 PM   #33
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Quote:
Originally Posted by jphughan View Post
Part of my job involves explaining technical concepts to non-technical people who need to make decisions about technical things, plus I dabbled in mentoring, tutoring, and teaching courses in high school and college, and now I instruct at HPDEs, so I can usually find a way to explain even difficult concepts in clearly understandable ways. In the HPDEs I've attended, rev matching and heel toe were mentioned in class but never really focused on, although classroom discussions are to some extent guided by what students ask to learn about anyway. An instructor might suggest focusing on it as well based on your driving and/or agree to work on it with you if you say that you'd like to learn it, but honestly I'd recommend practicing off track, at the very least for rev matching. You have to learn that before you can heel-toe, and I learned rev matching by just going out onto unoccupied public roads and trying the various downshifts (5>4, 4>3, 3>2) in the middle of straightaways where there was no upcoming corner to deal with and therefore nothing else to focus on and no consequence of getting the blip even horribly wrong. Compare that setting to the track, where you're coming up to a corner fast, braking hard, and thinking about a bunch of other things, all of which can cause you to get crossed up mentally and mess up the shift, and on track messing up the shift can mean spinning your car (from locking up the rear wheels due to insufficient blip) or overrevving your engine (from panicking while approaching the corner and shifting too early). But once you get a feel for rev matching, heel-toe actually IS easier to learn on track because as I mentioned above, that's where you press the brake down far enough to make that easier. Once you've learned it there, it's still possible on the road though; you just have to rotate your foot more and lean into the throttle more than you would otherwise. I learned heel-toe on the track and just came into corners that required shifts a bit more slowly than I would have otherwise while picking it up, but I had it down in a day or so -- but that was after I had practiced rev matching in the manner I described above.
Thank you for such sage advice. Looking at your car history, how does your GT4 compare to the E92 M3?
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      03-23-2016, 05:13 PM   #34
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Quote:
Originally Posted by jphughan View Post
Fair point. I guess the more precise way to phrase it would be that since the E92's front side windows are so much longer (because the rear side windows are so much shorter compared to the E90), unless you're 7 feet tall, the B-pillar on the E92 is well behind the driver's/front passenger's ears, and therefore the buffeting isn't nearly as bad as the E90 where the wide B-pillar is likely much closer to the driver's/front passengers ears.
This. One of the things I noticed when I was still in the hunt for my M.
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      03-23-2016, 07:17 PM   #35
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Originally Posted by Uber V8 View Post
Thank you for such sage advice. Looking at your car history, how does your GT4 compare to the E92 M3?
Decided to make the answer to this its own thread: http://www.m3post.com/forums/showthr...1#post19624331
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      03-26-2016, 10:38 AM   #36
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Quote:
Originally Posted by Iyzmi
All good tips. Only thing I would add is that I have a much easier time rev matching in "Power" mode with the sharpened throttle sensitivity than in regular mode. As such, I have my car set to startup in Power mode by default. The car feels so numb without it and downshifting requires a lot more throttle input.
How did you get the car to startup in Power mode by default?
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      03-26-2016, 12:06 PM   #37
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How did you get the car to startup in Power mode by default?
Setting in the "key menu". Go Option when you're in M settings.
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