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-   -   How do you correctly navigate a 90* turn? (http://forums.pelicanparts.com/porsche-autocross-track-racing/928335-how-do-you-correctly-navigate-90-turn.html)

sugarwood 09-08-2016 04:20 PM

How do you correctly navigate a 90* turn?
 
When driving on remote back roads, I encounter a hard 90* turn, but not in an intersection. I never feel like I nail this downshift & turn. I need to slow down a lot, enough that 2nd gear is the correct gear to power out of the turn. Yet, let's say you're approaching this turn at 55 mph. It feels too fast to shift into 2nd gear. I feel like I shift into 2nd gear in the middle of the turn, which I know is wrong. What exactly is the correct procedure? Slow in a straight line until I am in 2nd gear territory, downshift, then take the turn? If I do this, I almost feel like I am slowing down too much. I feel like I can take the turn faster than the speed needed to be in 2nd gear. Or at least, the timing is off.

Cajundaddy 09-08-2016 05:31 PM

Depends on the corner, what leads into the corner, and what follows the corner. Lotsa different ways to do a 90.

One example of a typical street corner at a race track with a flat surface:

I expect the apex speed in a street car to be about 45. If I go through there at 47 I will end up in the dirt or my PSM will flash engagement reminding me I am driving foolishly. To make the most of a right 90 corner I will enter from as far left as possible to open up the radius a bit, brake in a straight line to about 50mph, turn in for a late apex and allow tires to set and scrub a little speed on my way to the apex. Once I have sighted my track out point I will add gas hoping to be full throttle at or shortly after crossing my late apex point as I unwind the wheel on my way down the straight.

For a 45 mph apex I would normally heel/toe downshift to 2nd gear in the braking zone so I will get the best launch out of the corner. If it were possible to carry third gear through apex above 4000 rpm I would use 3rd and avoid the downshift/upshift inputs. The tradeoff is max torque vs max driver focus.

This is a common 90 corner method at a race track. There are others. I don't recommend trying this and going "all-in" at your next canyon carving session on public roads.

sugarwood 09-08-2016 05:56 PM

Let's say heel/toe is not an option, and you can't brake and downshift at the same time. It seems like there is a "dead zone", where I'd have to slow down too much to get into 2nd, but taking the turn in 3rd is too high.

Cajundaddy 09-08-2016 06:42 PM

Quote:

Originally Posted by sugarwood (Post 9273739)
Let's say heel/toe is not an option, and you can't brake and downshift at the same time. It seems like there is a "dead zone", where I'd have to slow down too much to get into 2nd, but taking the turn in 3rd is too high.

With my students whose h/t is not ready I recommend brake > downshift > turn in > gas. That gets your entry speed down so 2nd gear won't be a 7k zinger. Release the clutch while still in a straight line to avoid upsetting the car. The solution to the "dead zone" of course is heel/toe. This smooths the transition to 2nd gear into one fluid motion. A very useful technique to make the most of corner entry.

winders 09-08-2016 07:49 PM

You are on the street. Of course there is going to be "dead zone". You can't drive on the street like you would on the track.

I know many racers that don't heel/toe and there is no dead zone for them on the track.

Cory M 09-09-2016 10:02 AM

Google "Scandinavian flick" :D

sugarwood 09-09-2016 05:19 PM

Chicane is not a 90 degree turn.
It's like a swerve, and certainly not reducing speed to 2nd gear.
I find them to be very different.

winders 09-09-2016 08:20 PM

Often a chicane is two 90 degree turns one after the other.....but like Charles said, whatever. You need to get a clue before you dismiss information from people that know a hell of a lot more than you do.

manbridge 74 09-09-2016 09:25 PM

True repentance is actually 180*.

Emo993 09-10-2016 03:33 AM

If your not sure of the 90. Always get braking done before turn in (with H&T down shift)....late apex...then full power. Best, Mark

RichardNew 09-10-2016 05:07 AM

If you really want to have fun try an early car with trailing throttle oversteer.

Go in really hot and lift off the gas. The rear will break loose. When the back end gets to the angle you want jump back on the gas and accelerate.

Trailing throttle oversteer is your friend. :)

Richard Newton

sugarwood 09-10-2016 06:29 AM

Quote:

Originally Posted by winders (Post 9275055)
Often a chicane is two 90 degree turns one after the other.....but like Charles said, whatever.
You need to get a clue before you dismiss information from people that know a hell of a lot more than you do.

First, there is no need to be a dick.
Perhaps I need to get a clue, or perhaps I have a different perspective and context than you.

The definition of chicane from Wikipedia says "One form of chicane is a short, shallow S-shaped turn".
Now, maybe there is no standardized definition of a chicane, and maybe some are 90 degrees, and that would explain the disconnect.

I have driven the "bus stop" at Watkins Glen, which I was told is a "chicane".
Look at the photo, do you see a 90 degree turn? I do not.
Navigating this chicane was nothing like the turn I originally described in this thread.
http://static.nascar.com/content/dam...tions/original

Here is a photo called "Le Mans Chicane".
Do you see a 90 degree turn?
https://upload.wikimedia.org/wikiped...rd_Chicane.jpg

Here is another photo titled "chicane", by the Institute of Transportation Engineers.
Do you see a 90 degree turn?
http://www.ite.org/images/calming/tcccp1.gif

sugarwood 09-10-2016 08:30 AM

Street racing forum? For crying out loud, I am talking about correctly taking a sharp turn where I am well within the speed limit in either gear.
What a sanctimonious prig. I am not doing anything even remotely resembling street racing, and frankly, do not appreciate your overtly disingenuous accusations.

mreid 09-10-2016 08:57 AM

Sideways

winders 09-10-2016 10:25 AM

The Monza chicane:

https://s-media-cache-ak0.pinimg.com...1dad80c13d.jpg

Emo993 09-10-2016 12:44 PM

Well, maybe Monza didn't like it either as a chicane.....it's being removed for 2017.....

sugarwood 09-10-2016 01:12 PM

Yea, we've already got that covered.

Quote:

Originally Posted by sugarwood (Post 9275283)
Now, maybe there is no standardized definition of a chicane, and maybe some are 90 degrees, and that would explain the disconnect.


winders 09-10-2016 01:30 PM

Quote:

Originally Posted by sugarwood (Post 9275632)
Yea, we've already got that covered.

Dude, you deserve no help......

Matt Monson 09-11-2016 07:27 AM

I suggest you take the turn 5 quarts low on oil.

Sicklyscott 09-11-2016 09:32 AM

Quote:

Originally Posted by matt monson (Post 9276177)
i suggest you take the turn 5 quarts low on oil.

:d


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