Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 05-24-2007, 04:51 PM   #1
Registered User
 
Join Date: Apr 2006
Location: Chicago
Posts: 1,518
Question about shifting

In my quest to become a better driver, I am about half way through Skip Barber’s “Going Faster – Mastering the Art of Race Driving”. I am currently reading the chapter about downshifting, and the book mentioned that in a race car you should put the clutch in, shift to neutral, let the clutch out, blip the throttle, put the clutch in, shift into gear, and let the clutch out when downshifting ( double clutching ).

It then goes on to discuss not shifting into neutral between shifts, and blipping the gas while the clutch is depressed between gears. It mentions that the blip is more effective if you shift into neutral and release the clutch rather then just depressing the clutch.

I am sure they are talking about race cars, but I would like to practice this during daily driving to be more adept when and if I ever get the chance to race. My question is with our cars is there any advantage to letting the clutch out in neutral when blipping the gas or is simply blipping the gas with the clutch depressed sufficient ?

From page 97 :

When the engine isn’t directly connected to the input shaft of the transmission, which would be the case if you let the clutch out, the blip isn’t as effective at speeding up the input shaft. There is some drag going on between the motor and the input shaft, and a blip, even with the clutch depressed, will speed up the shaft some. The blip is much more effective, however, if you positively connect the engine and input shaft by letting the clutch back out in neutral.

Hope this makes sense…

Thanks !

Nick

__________________
*
http://i146.photobucket.com/albums/r...s/DSC03717.jpg

1999 986 ( Black )
1998 MB C280 ( Black )
1999 BMW K1200RS ( Yellow )
2005 Audi A4 ( Red )
NickCats is offline   Reply With Quote
Old 05-24-2007, 04:55 PM   #2
Registered User
 
Join Date: Nov 2006
Location: Virginia
Posts: 846
That is a practice called "double de-clutching".

Race cars typically have "straight cut" gears. Passengers have "curved" gears, and synchonizers. The job of the syncrhos is to make double de-clutching obsolete.

Can you do it without harming your car? Yes, absolutely. It is also an integral skill in heal-toe downshifting. But, it is not necessary.

The goal of "blipping the gas" is to ensure that once you downshift into the lower gear, the engine will already be spinning at the correct rate. It makes for smoother downshifts.
__________________
1976 914 2.0
2000 Boxster 2.7 (sold)
1978 911 SC (sold)
1970 914 w/2056 (sold)
racer_d is offline   Reply With Quote
Old 05-24-2007, 04:58 PM   #3
Registered User
 
Join Date: Oct 2006
Location: MD
Posts: 447
Rev matching = essential.

Double declutching = waste of time with a synchro box. The synchros are faster than you are, and that's what they're in the trans for. Use 'em.
John V is offline   Reply With Quote
Old 05-24-2007, 05:28 PM   #4
Registered User
 
Join Date: Apr 2006
Location: Chicago
Posts: 585
When you go to shift you should hit the brake real hard before letting out the clutch.

(You and DJ are going to be on my heels at autocrosses soon enough so I need to edumicate you on the proper technique.)
Sammy is offline   Reply With Quote
Old 05-25-2007, 03:02 AM   #5
Registered User
 
Join Date: Oct 2006
Location: MD
Posts: 447
If you're autocrossing and shifting more than once, you're doing something wrong.
John V is offline   Reply With Quote
Old 05-25-2007, 03:56 AM   #6
Registered User
 
Join Date: Apr 2006
Location: Chicago
Posts: 585
Quote:
Originally Posted by John V
If you're autocrossing and shifting more than once, you're doing something wrong.
I usually agree with this statement but we have run some pretty small courses with tight 180's and garage boxes which unless you have a torque monster it is tough to get out of quickly. It seems to be a hit and miss depending on the course layout. The bigger groups like Chicago and Milwaukee always have a long course and I've never had to shift more than once.

Sammy is offline   Reply With Quote
Old 05-25-2007, 04:36 AM   #7
Registered User
 
Join Date: May 2006
Location: Rochester, NY
Posts: 172
I've encountered several autox courses where I wish I was skilled enough to give some thought into downshifting for the turn, so I don't agree with that statement at all.

I read that book, it was great :tup:

Also, this is probably a more personal experience, you know you've got things down when you find you can still heel-toe in stiletto's
__________________
http://farm1.static.flickr.com/211/4...7e5359a2_o.gif
Owned: 11 months
Miles: 78,000
Autocrosses: 22
Track Days: 1
http://www.crife.net
986 Girl is offline   Reply With Quote
Old 05-25-2007, 08:05 AM   #8
Registered User
 
Join Date: Sep 2004
Location: Atlanta
Posts: 1,820
there's also a single clutch technique that works with straight cut / non-synchro boxes, but it's tough to perfect. (BTW, no need to use the clutch when upshifting this type of transmission).

for the downshifts, first practice tapping the gas and pulling the car out of gear. you can give just enough gas to ease the load off the gears and the car will slide into neutral very easily.

once you're good at this, simultaneously blip the throttle a LOT and ease the car into neutral. it's a single blip that happens in two phases: as you just start the blip, you pull the car out of gear. once the car is in neutral, you continue the blip to match the revs. you're aiming to be in neutral with RPMs about 1200 higher than you were at in gear.

finally, when you're good at that, in one single motion, blip the throttle, ease the car into neutral, press the clutch, downshift, release the clutch and hit the gas. when you get good at it, you can seamlessly downshift a racing transmission with a single clutch press. this is a very good technique to learn even if you have a synchro box. it allows you to shift very quickly without burdening the synchros.
__________________
insite
'99 Boxster
3.4L Conversion

http://i156.photobucket.com/albums/t...1/KMTGPR-1.jpg
insite is offline   Reply With Quote
Old 05-25-2007, 08:26 AM   #9
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,709
I don't know if its the clunky 986 shifter or that 90% of my mileage is highway,
but I RARELY downshift anymore. Maybe one average downshift for each trip up to sixth gear...mmmm more like one downshift for two trips to 6th.

With my old Miata and the tight *snick snick* gear box I must have averaged one downshift for every upshift. Closest thing to a go kart for very little money. No need to drop $$$ on an Elise. Great fun matching revs in that car. I loved the way the car would shake a little when you revved it allot.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Perfectlap is offline   Reply With Quote
Old 05-25-2007, 10:13 AM   #10
Registered User
 
Join Date: Oct 2006
Location: MD
Posts: 447
Back when Nationals was at Forbes, there would frequently be one corner on the north course which required a downshift. Now that they moved to a smaller solo pad at HPT, somehow they eliminated the downshift corner. I did it anyway on the West course last year, and I'm still not sure it was a good idea.

The RX-8 had a great gearbox, though. The Boxster - not so much. I'm not comfortable at all downshifting that box to first.
John V is offline   Reply With Quote
Old 05-25-2007, 10:20 AM   #11
Registered User
 
Perfectlap's Avatar
 
Join Date: Nov 2004
Location: New Jersey
Posts: 8,709
when the first few positions are seperated by mere tenths, it's really not all an advantage to downshift in this car. Unless you are PERFECT it will probably cost you time. Probably wiser to experiment with a different line, braking sooner/later, etc.
I don't think I have ever downshifted to 1st in the Boxster, there was a guy in one autox club that would do it in his S2000 and I would just cringe every time I heard it.
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Perfectlap is offline   Reply With Quote
Old 05-27-2007, 05:56 AM   #12
Registered User
 
Join Date: Mar 2007
Location: Huntington, NY
Posts: 409
Speaking of Auto-X, I have not done one yet, but I was wondering do I need to let my insurance company know I am Auto-Xing? What's the deal with insurance and car events?

__________________
http://i25.tinypic.com/20aq3wn.jpg http://i26.tinypic.com/2zguetx.jpg http://i28.tinypic.com/2jdi1ok.jpg
2000 Boxster S: 18" Turbo wheels w/color crests, Litronics, Onboard Computer, Traction control, Cruise, Painted rollbar, Leather interior, Aluminum package, headlight washers, Porsche GT3 seats, windstop, Hi Fi six speaker amp package, DSP, CDR 220, Limited Slip, side airbags, BK Rollbar extender.
2000SoCalBoxsterS is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 09:16 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page