Pre-braking terminology and other braking points, braking late versus braking early Options

[nine14cats]

I've heard Brad talk about the pros braking early going into the track or "pre-braking" to settle the car. What does this mean?

Also I see the merits in driving hard into a turn and out-braking a competitor to make a pass. But during qualifying or timed runs where the lap time is the opponent, late braking doesn't appear to be the answer for a momentum car.

What is the proper technique for brake points during qualifying laps and Time Trials?

Thanks,

Bill P.

[Brad Roberts]

Several turns at Fontana (and other tracks) the entry is VERY bumpy and unsettles the car as you enter the braking zone under braking. This is not good for your brain.

Think of "settling" the car much like pre-loading a motorcycle before a jump. After the jump they use the brakes on a motorcycle to control the angle. Tap the rear brake to drop the rear of the bike.. tap the front to lower the front. They balance the bike this way. You dont have control over the individual brakes on the Boxster, but you can lightly tap/hold the brakes going into a turn to "pre-load" the suspension instead of loading the suspension in the corner. Just like a bike coming off a ramp when pre-loaded.. the car will "explode" out of the corner. You will be on the brakes longer but using less pedal pressure. It also causes people around you to back off..lol

The people who raced momentum cars really have this technique down. The first time I saw it in data acq.. I started asking questions about it. I couldnt figure out why the "Pro" was hitting the brakes 50-60 feet sooner and using less pedal pressure. He was still on the gas using left foot braking. I also noticed he only did it on the rougher sections of track where the entry really un-settled the car. His shock readings looked VERY smooth with the brake lights lit up.

B

[Rough_Rider]

Come on Bill, your asking one of those un-answerable questions!

Every track, corner & situation is different. How much curb to take, track temp, tyre temp, car capability etc.

In general as JP would say Seat time & more seat time. You need to really know your packages capabilities inside out.

The pro's technique of early braking has payoff's in a longer sprint race or endurance environment. Where conservation of equipment is beneficial. Braking earlier means your not braking as hard, not wearing out pads, not upsetting the car, as much as harder braking.

In AX I tend to accelerate up to a early braking point, hit the brakes at maybe 60-70% effort then transition off the brakes smoothly before turn-in.
On turn-in i'm coasting through till slightly before Orat apex where i feed in the throttle.
IMO thats standard cornering technique.

Alternatively you can brake later & harder. Come off brakes at turn-in. Just be carefull of the weight transfer.
Or brake even later & simultaniously turn-in while backing off brakes. Requires left foot braking & goot car control.

The only time's i've heard of pre-braking is in 2 cases. (A) pre-brake on long straights to verify to driver that brake pedal is still there. Required with floating rotor design as pistons can back into caliper, meaning a really big scare to driver when entering the next turn. ((IMG:style_emoticons/default/cool.gif) Entering a flat out corner a dab of brake helps settle the springs for the turn.

Sorry Bill thats probably as clear as mud.

[Brad Roberts]

Dont confuse this with the pro's who perform a "bake pedal tap" at the end of long straits. You'll see a blip on their data and see the brake lights light one time quickly before they actually stand on the binders. This is their method for telling their brain that the brakes are still their and will slow their car. If the "tap" occurs and the pedal isnt there.. they know what to do..LOL



B

[nine14cats]

B,

I'm getting some Hoosier R6's to try out on the Speq car. The Kumho's come as 245/45's in the front. The Hoosiers can be ordered in either 245/40's or 245/45's.

I'll get 275/40's in the back.

Have you tried both sizes? Any insights with handling other than the shorter diameter?

Thanks,

Bill P.

[Brad Roberts]

I have not tried both sizes. I ran the taller ones. I beleive it would be easier on the power steering with the shorter tire and effect how the brakes "come on" under braking.

Do you have REALLY good intial bite when you stand on the brakes Bill??

I recall telling you how important it was to "bed" the brakes, but dont know if you ever had a chance to do it properly. If they are bed correctly.. you can stand the car on it's nose and the intial bite will stretch you against the belts.


B

[nine14cats]

I have not tried both sizes. I ran the taller ones. I beleive it would be easier on the power steering with the shorter tire and effect how the brakes "come on" under braking.

Do you have REALLY good intial bite when you stand on the brakes Bill??

I recall telling you how important it was to "bed" the brakes, but dont know if you ever had a chance to do it properly. If they are bed correctly.. you can stand the car on it's nose and the intial bite will stretch you against the belts.


B

The brakes are bedded fine! (IMG:style_emoticons/default/laugh.gif) I did the 100mph runs to 30mph brake dives on the expressway next to my house. The pads are biting big time....

Maybe I'll try the 245/40's up front. See how that goes...

Bill P.

[DanT]

255x40s up front? (IMG:style_emoticons/default/smile.gif)

[nine14cats]

255x40s up front? (IMG:style_emoticons/default/smile.gif)

Actually, I've got Ken J's 255/40's on the 8.5's in the garage. I can bolt them on and drive around the neighborhood and see what it feels like....

hmmmm..... (IMG:style_emoticons/default/idea.gif)

[Brad Roberts]

Not a bad thing having a semi "street" legal car!!

Back to the question:

TT line= yes
Race line= yes
Rain line= yes

Mid-engine car line = yes
Rear engine car line = yes
Heavy car line = yes
Light car line = yes

Do they differ much.. not really, but beleive it or not.. this is a game of inches. The kart guy's figured this out AGES ago. I beleive it is a matter of moving your apexes back and forth and adjusting to track conditions (temp/weather) which will effect your trackout point.. which is determined by your turn in point...LOL

Instructors typically ask that newbies be consistant. Do the same thing every lap every time.. you are passed this and have been for awhile. You should be experimenting with every corner every lap until you pull it all together. That can be two sessions or 20 for some. Sometimes I totally get off "the line" and change it up. You have seen me post the difference between Pro and amateur when arriving at a new track in a new car. The pro has it nailed in 3 laps. He "views" each turn and tries to compare it to another turn that he has ran 100's of times. Turn 10 at Sears feels/looks like turn XX at track XX.. so I will do XX like I do at track XX.

You get the idea. I seriously need to do a real download session with you and the data. If I fly into Sac. for Dec Thill can you pick me up? Sac airport is on the 5. You skip the airport when you take 505 from Bay area.


B

[nebreitling]

bill, speaking of.... have you gathered up any karting experience?

[jhadler]

One other item regarding a brake "tap" at the end of a straight is to get the brakes ready. Some cars can have a tendancy to suffer knock-back, where the pads and pistons back off a little under heavy vibration, and can give you a real eye-openeing experience entring a heavy braking zone... (IMG:style_emoticons/default/ohmy.gif)

-Josh2

[nine14cats]

bill, speaking of.... have you gathered up any karting experience?

Hi Nate,

I've only been in karts a few times in my life. It would be interesting to talk with you and see how the momentum of karts translates to driving a momentum car.

Thanks,

Bill P.

[nebreitling]

i only mention because it seems that you're on track to road race the spec boxster. NOT that i have experience racing cars w2w, but i've learned ass-loads about racing in general having been in karts. given the number of crashes i've personally been involved in during kart races, i have easily saved what would have been $30 or 40k in cars (though we're probably much more aggressive/stupid then most prc/nasa/scca racers). it teaches you to be comfortable in extremely tight traffic.

[Chris Pincetich]

Kart racing rocks! I want to go back to that place on Belmont or whatever with the 3 indoor tracks. Nothin like being inches off the pavement with no suspension travel to "feel" the input of different driving styles. For people like my friend who I went with last time, with MX racing skills sore knees and disposable income, the experience ends with "I want to go buy a racing kart right now!" Once we all start going crazy this winter, a group 914club trip to the indoor kart track is in order! (IMG:style_emoticons/default/beerchug.gif)

[grantsfo]

Karting certainly has all the basic elements of 4 wheel driving and gives you immediate feedback to your inputs. I'm planning to spend some time in karts next year early in the season to brush up on my reaction times etc.

Speaking of momentum. The ultimate momentum sport is cycling. One can learn a lot about momentum and being comfortable with traffic when you're bumping shoulders through a 40 MPH turn on less than an inch of tire with 4 people on each side of you. I use tons of cycle racing experience in driving my 914 on the track. Except you can get away with a lot in a car or a kart that would put you on the pavement on a bike. Cycling elements such as being smooth, executing proper lines, attacking corners, etc translate very well for me. My first time on the track just felt like a downhill bike race with 100 times more HP and 50 times more tire.

Biggest difference between cycling and motorsports is power and weight transfer. ...I never prebraked in cycling races, but I did lots of trail braking! (IMG:style_emoticons/default/biggrin.gif)
(IMG:http://republican.assembly.ca.gov/members/124_keene/images/pic19_nevadacitybicycle.jpg)

[sww914]

I've heard about some brake pads that will barely work until they're warm, some guys will tap the brakes at the end of a long straight to warm them a bit before trying to limit brake.
I use Porterfields, they seem to work at the end of a straight just fine, I think the limiting factor is me.