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  #31  
Old 06-08-2011, 04:54 PM
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Default Re: How To Brake?

Thanks for the feedback! I am with you on long sweepers and threshold braking.

In my experience, T12 at Mid Ohio is indeed tricky if you hold the brake as you approach the apex. As you describe, the track flatens and falls away but has positive camber on the approach. Keeping the front end loaded with the track falling away equals

http://www.youtube.com/watch?v=pLXIyiCfTmo

For me it's best taken with straight line braking, off early, settle, touch of throttle and all is good.

Quote:
Originally Posted by NickW View Post
how large you need the traction circle to be at whichever end you need it at most.
Can you elborate?

I can't imagine the braking in a kart can compare to a GT car at Mid Ohio but what do you do in Keyhole and Carousel?

I find my chassis has the best balance if I apply LIGHT brake at initial turn in and hold the same pressure half way to 2/3 through the corner.....basically braking and turning together but very gently and with steady arc'd steering. The tough part is in not applying too much initial brake and trusting that I can maintain constant pressure and the car will arc smoothly.
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  #32  
Old 06-08-2011, 06:43 PM
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Default Re: How To Brake?

Quote:
Originally Posted by bman View Post
Can you elborate?

I can't imagine the braking in a kart can compare to a GT car at Mid Ohio but what do you do in Keyhole and Carousel?

I find my chassis has the best balance if I apply LIGHT brake at initial turn in and hold the same pressure half way to 2/3 through the corner.....basically braking and turning together but very gently and with steady arc'd steering. The tough part is in not applying too much initial brake and trusting that I can maintain constant pressure and the car will arc smoothly.
At the Keyhole we go to threshold brake immediately (braking in a straight line after the chicane), then turn in after braking is complete, apexing twice around the turn, riding the concrete patch for the most traction. Throttle application is immediate because the chassis is settled (unlike a car), increasing the throttle as long as the front end stays planted in the right direction (no lifting). Track out to the runout patch on the left, straightline the track from there to the turn in point at T5 (coming across the track near the emergency lane on the right).

The Carousel at M.O. is tricky because of the big bump in the middle of the apex. That tends to separate ribs if you're not careful. We tend to go through T12 hot, flatfoot on the throttle, then brake in a straight line right before the turn in for T13, double apexing it as opposed to a single apex specifically because of the bump. End result is you lose .1 second on that corner, but you keep your ribs intact, and since T14 comes up quickly, the speed you lose through T13 actually helps give you time to set up for T14.

I should be there in two weeks for the WKA National. I can get some on kart footage and post it if you want.
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  #33  
Old 06-08-2011, 10:50 PM
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Default Re: How To Brake?

Quote:
Originally Posted by bman View Post
In my experience, T12 at Mid Ohio is indeed tricky if you hold the brake as you approach the apex. As you describe, the track flatens and falls away but has positive camber on the approach. Keeping the front end loaded with the track falling away equals

http://www.youtube.com/watch?v=pLXIyiCfTmo
Wow, what a fun looking track with some challenging turns and lots of elevation change. Too bad it's so far from CA!

IMHO the guy lost it primarily because of the brow he was going with too much steering lock on. To make matters worse he seemed to apply the brakes as well.

I was taught to momentarily straighten the steering when going over brows in a turn. It unloads the tires for a moment until the car settles again on the other side of the brow. It's the short version of making it a double apex.

-Christian
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  #34  
Old 06-08-2011, 10:58 PM
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Default Re: How To Brake?

NickW, could you comment on the difference between driving karts and cars. It seems that a lot of your racing experience is in karts, but in limited experience with serious karts I found them to be completely different to drive. The main difference being that karts don't really have a suspension, so the weight transfer happens much more quickly than in a car suspension. I was driving kart without a rear differential, so you really had to use the brakes to lift u the inside rear wheel to get the kart to turn in. You pretty much had to do a slight amount of trail braking into most turns.

But I'd love to hear your thought on the differences ihow you have to drive these very different beasts. It's a bit like driving a front wheel drive vs rear wheel drive. You use the throttle with quite different effect in turns. but what about karts vs a Porsche?

-Christian
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  #35  
Old 06-09-2011, 12:42 AM
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Default Re: How To Brake?

Christian-

I can probably discuss this on another thread, that is quite a bit off topic and although some of my posts have been on the periphery of the subject, a discussion just on karts and karting dynamics probably isn't appropriate.

There are some things that apply though- my discussion on the traction circle and how it expands/contracts depending upon polar moment and weight bias, etc. The concepts are very similar and in some cases even magnified- you learn very quickly what is and isn't important in setup and driving.
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  #36  
Old 06-09-2011, 01:35 AM
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Default Re: How To Brake?

Quote:
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a discussion just on karts and karting dynamics probably isn't appropriate.
I cannot think of any discussion that is inappropriate for this web forum, except the usual stuff. Discuss all you want please.
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  #37  
Old 06-09-2011, 09:07 AM
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Default Re: How To Brake?

Quote:
Originally Posted by NickW View Post
the big bump in the middle of the apex. That tends to separate ribs if you're not careful..

I can get some on kart footage and post it if you want.
I know what you mean! It's pretty nasty in a car and can only imagine how rough it must be in a kart.

Yes, please! I'd like to watch.

Quote:
Originally Posted by csmarx View Post
Wow, what a fun looking track with some challenging turns and lots of elevation change.

I was taught to momentarily straighten the steering when going over brows in a turn. It unloads the tires for a moment until the car settles again on the other side of the brow.
It's a blast to drive! I would strongly recommend it for any track junkie. It's also, IMO, a track that will test your braking skills. It requires several techniques; if you want to be quick

Check out the turn before the spin, turn 11. It's exactly the type of turn where you need to open the wheel as you crest a "brow". It's awesome!

I've only been to Mid Ohio twice, most recently last month. It's such a unique and fun track that on my 7 1/2 hour drive home, which is normally a drag, I found myself smiling, seemingly for hours, as I reflected on the weekend. I can't recall ever doing that before
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  #38  
Old 06-09-2011, 10:22 AM
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Default Re: How To Brake?

The Boxster spins because he/she is braking too hard with too much steering input - too much traction on the front, while the rear has hardly any weight on it. Look at the attitude of the car as it begins to enter the corner - it looks to me the driver thought they were carrying too much speed into the corner, and tried to fix the situation with progressive braking - adding more pressure as they continued to turn the wheel - look at how fast the car with the camera in it catches up to the quickly, and progressively slowing Boxster. Unfortunately the back end also gets light because of the slight crest in the middle of the turn - this exacerbates the situation. but the spin actually begins before the elevation change.

IMHO, one needs to use very different braking techniques for each kind of corner... if you're trying to threshold brake at each corner, no matter it's configuration, then you're using your brakes too much, and probably over-slowing the car in many instances.
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  #39  
Old 06-09-2011, 10:23 AM
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Default Re: How To Brake?

Mid Ohio and Grattan are the two most technical tracks in the Upper Midwest and the most fun to drive. I would put either of those up there with Barber, Road Atlanta, and Laguna Seca as technically difficult to master AND fun to drive.

There are other tracks here too within a 4 hour radius (that I have run), GingerMan, Putnam Park, Waterford Hills, Blackhawk Farms, Autobahn Country Club, Mikwaukee Mile etc. but those are either not that fun or not that difficult. There's a little known "favorite track" to some old time F1 and Indycar pros called Meadowdale Raceway that is defunct too. Fun stuff...
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  #40  
Old 06-09-2011, 11:23 AM
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Default Re: How To Brake?

With all this discussion, I am pumped up, I am going to VIR again today!
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  #41  
Old 06-11-2011, 09:38 AM
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Default Re: How To Brake?

VIR was awesome. Mercedes/Audi/BMW clubs had the Marque Madness event, They were very kind to accept me for Friday, and weather was perfect. They really put out a great event, there were may be 45-50 cars, so we got a lot of track time, nearly 3 hours.

More importantly, I got to test a lot of what has been talked about in this thread. One distintictive conclusion I reached is my biggest problem is not how apply the brakes, but how I release them. I worked on that specifically, to release the brakes without upsetting the balance of the car, and I think during my 4th and 5th sessions, I could consistently do so at every corner. I am not sure if I was any faster, but the car and I were cooperating much better
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  #42  
Old 06-11-2011, 10:46 AM
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Default Re: How To Brake?

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VIR was awesome.

how I release them. I worked on that specifically, to release the brakes without upsetting the balance of the car
I thought you were kidding about heading to VIR yesterday. You just went down for the day? You've got a problem!

What change did you make in the release? Earlier? Which corners in particular?

Also, did you try different lines and braking thru T3?
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  #43  
Old 06-11-2011, 01:01 PM
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(Christian, you should trademark the term "sinusodial driving" )
Hey, if I could make a living from any kind of driving instruction I would!
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  #44  
Old 06-11-2011, 02:54 PM
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Default Re: How To Brake?

Quote:
Originally Posted by bman View Post
I thought you were kidding about heading to VIR yesterday. You just went down for the day? You've got a problem!
I never kid about VIR, and no doubt I have a (or more) problem(s)

Quote:
What change did you make in the release? Earlier? Which corners in particular?

Also, did you try different lines and braking thru T3?
Actually I was releasing a tiny bit later, but gentler, especially in T3, T4 and T10. I tried your line in T3, which worked better in entry, the car was more stable and controlling the brake pressure was easier as I broke slightly earlier with less pressure and I could more consistently take the turn. The preliminary result of doing so is... I am not sure what the word is frankly; I was significantly slower in entry, but slightly faster past the apex. The significance of this is that the conditions were much less favorable than in March or May; it was between 100-105 deg heat with very high humidity, the track was very greasy in many corners, all corners generally lacked grip, top speeds were also lower by 3-7 mph. Even so, my best was 2:11.7 in the morning, when it was about 92-95 with moderate to high humidity.

There is much more to look at in the data before any real results can be drawn, but I love that stuff and I have quite a bit of data to play with

I might put my notes in another thread as I look at data.
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  #45  
Old 06-17-2011, 09:38 PM
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Default Re: How To Brake?

When I hired Chris Hall for coaching at Sebring he told me after a few laps with me that I'm the last of the late brakers...he could not believe how deep I got the Carrera into the brake zone. He said this is not the way to go fast and take car of equipment. Slamming on the brake as late as possible on every turn is wrong and Chris drove my car and proved it. Also there are some turn were you get off the brake early and balance the car and sail it into the turn and then get on the throttle. My whole lesson was about brake release and modulating after he got me to brake slightly earlier and softer. I can't wait for some more lesson later this year.
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