Your goal for heel & toe downshifting |
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
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Topic: Your goal for heel & toe downshifting Posted: 02 August 2011 at 9:57am |
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For those of you with manual transmissions, you may have heard of "heel & toe" downshifting to match engine revs with the trans for proper shifting when slowing down for a corner. Simply put, when braking and downshifting from 3rd to 2nd gear for a corner, you may be in 3000rpm in 3rd when you make the shift, but to be at the same speed in 2nd gear, your engine may want to be at 4200rpm. So you need to "blip" the throttle to bring the revs up around 4500rpm before releasing the clutch. This makes for a smooth transition into 2nd gear. (google this topic for proper instructions if you've never heard of this) Here is a video of a true master at work on the racetrack. Under heavy braking he pivots his right foot to blip the throttle for each downshift. It's amazing to watch. http://www.youtube.com/watch?v=73MvmT5C-ik (edit: ok...he does have a lightweight flywheel and clutch to increase throttle response) |
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Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 02 August 2011 at 10:09am | |
An auxiliary accelerator button on the shifter would be perfect for this. Colby, let's figure out how to rig one up! An electric solenoid activating the TB throttle lever (or the gas pedal/throttle cable I suppose) wired to a small spring loaded button mounted on the front of the shifter knob where a finger could press it while braking and double-clutching... How difficult could it be? Of course, you'd want to make triple sure it couldn't get stuck in the ON (full throttle) position!
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 02 August 2011 at 6:19pm | |
Colby and Gary might actually try something like your suggestion, Patrick. Here's more fancy footwork, rally car style. Extremely impressive "dancing" done by Walter Röhrl. http://www.youtube.com/watch?v=DbU4GZkt7ig
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karnak
Senior Member Joined: 28 August 2009 Location: Canada Status: Offline Points: 349 |
Post Options Quote Reply Posted: 02 August 2011 at 6:21pm | |
Can we use clothes line? please.... i wanna use clothes line
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 02 August 2011 at 7:16pm | |
Check with dad to see if he has any of that "rideguide" steering stuff for the old boat.
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Colby
Admin Group Joined: 30 March 2009 Location: Abbotsford/Sask Status: Offline Points: 665 |
Post Options Quote Reply Posted: 02 August 2011 at 11:29pm | |
Nah, for the amount of work involved you could just learn how to do it properly and then be able to use the technique in any car. |
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88 Formula 5 speed
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Capt Fiero
Admin Group Founding Member Joined: 12 February 2007 Location: Canada Status: Offline Points: 4039 |
Post Options Quote Reply Posted: 03 August 2011 at 6:50am | |
Just side note, I do 1/2 of that trick in my normal driving. I commute in stop and go traffic for almost 2hrs each day. I rarely even step on the clutch pedal anymore to shift. When I am down shifting, tap the throttle to rev match and shift, when I am up shifting, just ease off the gas enough to unload the transmission without slowing the car down slip it out of gear and wait for the rpms to drop to where you need it for the next gear and slip it in. Now as to getting a "rev" button, you guys are thinking way to much. You don't need to touch the throttle plate or throttle body to get it to rev. All the throttle body does is increase airflow. Just install a small air solenoid in the pcv line with a single wire. Hit the button solenoid opens up and engine rpms jump. However learning to do it the right way would be better. |
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Capt Fiero
88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 03 August 2011 at 8:32am | |
It is. ...and it's fun!
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Patrick
Newbie Joined: 19 April 2008 Location: Vancouver Status: Offline Points: 5 |
Post Options Quote Reply Posted: 03 August 2011 at 5:30pm | |
No offence Dave, but I don't believe you've thought this through enough. There's no chance that opening the PCV line momentarily is going to rev an engine anywhere near as quickly or as high as banging the throttle plate wide open. IMO, a slight little "blip" in the RPM wouldn't be of much help when wanting to ram back down into 1st gear in a real tight, slow corner while racing on the track.
What's the "right way"? I think constantly relying on rev limiters on the track is being lazy. (Learn the "right way" to respect engine redlines.) Same with ABS brakes. (Learn the "right way" to brake without locking up the wheels.) Hell, even using soft-compound race tires gives a helluva unfair advantage. (Learn the "right way" to corner without spinning out.) What about turbo/super chargers? (Learn the "right way" to improve engine aspiration.) Should everyone be restricted from using "technology" on the track. Hell no, it's part of the game. From my perspective, why dick around with the fancy footwork trying to "heel" the brake while "toeing" the gas pedal? If there's a electo-mechanical way of accomplishing the same thing (and probably doing it much more efficiently, dare I say "better"), why not? I'm going to have to do this now just to show you guys. (...although my projects advance with glacial speed, so don't hold your breath waiting.)
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beken
Admin Group Joined: 12 February 2007 Location: Canada Status: Offline Points: 1462 |
Post Options Quote Reply Posted: 31 August 2011 at 5:37pm | |
It's not that easy to do with a Fiero. The pedal placement is not exactly
optimal. Great fun in the MINI though However, the Infiniti G37S, and Nissan 370Z automatic transmissions automatically blip the throttle when you downshift manually so they essentially have their ECM do it. |
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Beken (aka Ken) - bekentech@westcoastfieros.com Original and still the owner of an 85SE 2M6 4spd |
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 31 August 2011 at 11:09pm | |
What's the problem with the pedal alignment in a Fiero? Gas pedal too low when at full brake pressure? Don't tell him, but I'll try out Brian's car on Sunday.
May as well leave it in "D" for cars like that. The computer that controls the transmission in "sporty" cars is getting pretty darn good that there is almost no point in trying to shift yourself. My wife's car (from 2003) has a very smart auto trans that will hold a gear in a corner (so no upshifting on you mid-turn), and will downshift when you brake so if you are at highway speeds and have to slow down for something and then get on the gas again, it's in the right gear. You avoid the dreaded pause you get in a regular car as it shifts from a high gear to a low gear to accelerate rapidly. They will also adapt to how you drive and shift accordingly. Drive briskly and it will shift accordingly. Drive like you are jogging to Safeway and it will be sedate. I was impressed with it. Cheers, Allan |
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Bassman
Senior Post God Sir Brian Joined: 12 February 2007 Location: Canada Status: Offline Points: 2501 |
Post Options Quote Reply Posted: 01 September 2011 at 7:16am | |
Ya whatever Allan...go ahead, beat the crap out of my car...lol
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Brian (Bassman)
86 GT Fastback 3.2L 2013 Mazda3 Sport GS SkyActive [IMG]http://i170.photobucket.com/albums/u243/Bassman68/BassmanSignature.png"> |
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 01 September 2011 at 10:39am | |
...but it would be kind to your car to rev match when downshifting. If anything, it would be unkind to my foot if I had to distort it in order to blip the throttle. So I think you owe me beer for putting the concerns of your car ahead of my foot. |
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Bassman
Senior Post God Sir Brian Joined: 12 February 2007 Location: Canada Status: Offline Points: 2501 |
Post Options Quote Reply Posted: 01 September 2011 at 1:09pm | |
Really...man your pushing it now, already asking for the beer I will take from you?...Really???...lol
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Brian (Bassman)
86 GT Fastback 3.2L 2013 Mazda3 Sport GS SkyActive [IMG]http://i170.photobucket.com/albums/u243/Bassman68/BassmanSignature.png"> |
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 01 September 2011 at 1:25pm | |
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AllanJ
Senior Member Joined: 28 July 2010 Status: Offline Points: 254 |
Post Options Quote Reply Posted: 03 September 2011 at 11:05pm | |
Very quickly checked out heel & toe on Brian's Fiero tonight. Pedal height is fine, but the distance between the brake and gas is more than I'm used to for the method I use (left side/right side of foot). I'd either need to change the way I do H&T or get an aftermarket gas pedal that is a bit wider.
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