cornering and balance?

[Mike Usiskin]

Hi all,

question: when braking in a straight line, the weight (or Mass) transfers to the front of the car, so IF you turn in at this point do you benefit from greater grip on the front tires?

answers on a postcard please

If you keep the power on whilst braking does this then became the fabled left foot braking made so famous by the Swedes etc in the 60's 70's? and does it have any advantage in an 911 such as ours?

ttfn

Mike

[Bewildebeest]

Yes, no and it depends. At the risk of Talking Bull here's my opinion.
Yes you load up the front tyres and therefore get more grip but when you then turn the wheel you then load the tyres up even more and in a direction different to that in which they are rotating and therefore they are more likely to break away. Plus by shifting weight to the front you have unloaded the rears so that they are thinking about breaking away as well. Then when you turn the wheel all four wheels are on the point of losing grip and it's spin time. Hence the old maxim - Get your braking finished with before you start the bend. This also means that you can then get your right foot off the brake and on the throttle as the bend starts and start throttle steering through the bend which then means you are lined up ready to hoof it down the straight that little bit sooner.

Left foot braking ? Never understood it. Tried it, scared myself sh*tless. Did seem to get everywhere very quickly, usually before I was ready. Probably doing it wrong.
I think the idea of it is to keep the revs up ready for the next gear change - obviously while you are braking with your right foot the revs are dropping and will then take time to recover.

I think I'm right on the first point and quite possibly wrong on the second.
I bet you get a thousand different opinions.

[Bob_Salmon]

Well of course, I don't drive that fast, but..... acccording to Vic Elford in his 'High-Performance Driving Handbook' you can never get more than 100% from the tyres (pretty obvious really) so 100% while braking in a straight line is possible but the moment you start to turn that reduces. As for left foot braking, surely you are just trying to reduce physical time in order to speed up mechanical application?

Bob

[Helen]

IMHO, never a good idea to brake in a 911 while cornering especially if your eer pushing on a bit. if you feel it starting to slip then it better to put a bit more power on(if you have the balls) worked for me at Brunters when i hit a corner far to fast in my 930 slantnose turbo.....definatly something i won't be repeating in a hurry but the car made it with only the loss of rubber off the tyres and nail marks in the steering wheel now i know why the professional drivers wear gloves

as for left foot braking...haven't got a clue, im usually in a bit of a panic (on track)and use any foot that happens to be free at the time

[pmjt]

question: when braking in a straight line, the weight (or Mass) transfers to the front of the car, so IF you turn in at this point do you benefit from greater grip on the front tires?

This is obviously in a TRACK not ROAD context .

In an ABS equipped car (like a Cup car) one trick is to push the car into the start of the braking point so hard that, when you hit the brakes, the car will start to lock up - in a non ABS car this is NOT recommended . As the ABS attempts to control the car by 'stuttering' the brakes, there is an obvious front to back weight transfer BUT ALSO a side to side transfer - use of the steering wheel will 'fool' the ABS into thinking the weight is moving more - enabling you to change line very effectively while carying speed through a corner.

In a non ABS, RWD car the effects of hard straight line braking will be a radical shift of weight from rear to front - the obvious result is a light rear end and therefore less rear traction - the loading on the front means you end up with huge oversteer - so the trick is to brake so hard that the weight 'starts' to move, then lift off, then power on, then brake, then power on - ending up in the rear being pushed down WHILE the front is loaded up - you then can use the front traction to change direction - of course the obvious flaw in this is the increase in oversteer from the rear - which means you need to dial in some opposite lock - which means the car starts to fish tail - so the 'saw' action means you're pushing the front tyres to the point of breaking, then dialing oposite, then switching back to the other lock - the result being that AS the weight is moving the traction is being settled down - it's hard to explain by typing - easier to demonstrate in the car

If you keep the power on whilst braking does this then became the fabled left foot braking made so famous by the Swedes etc in the 60's 70's? and does it have any advantage in an 911 such as ours?

yes and now if you're entry is wrong - keeping the power on won't help at all!!! With front engined cars there is an advantage to entering the corner at a very different angle to a rear engined car - and using the opposite lock earlier than would be needed in a rear engined car - you can then get the power down earlier but as the corner tightens there is a need to abate more speed, and then correct the understeer with more power - so left foot braking becomes highly desirable to keep the car under control.

Left foot braking on a rear engined car is best used to correct mid corner - where lifting off completely mid corner results in the old song "you spin me right round, baby right round"

The ideal solution is a brake bias adjustment system enabling the driver to compensate for the amount of front and rear weight transfer needed - ABS cars came along and sort of ruined the fun - so drivers developed ways around it ABS 5.7 allows you to have all sorts of fun - but in a non ABS'd car of the same spec it will always be quicker.

Hope this makes sense - but probably not after the large bottle of Leffe I've just quaffed

Philip

[Helen]

no, you definatly NEED to demonstrate it to me

[pmjt]

no, you definatly NEED to demonstrate it to me

Track day season's now over I'll let you know next time I've got the cup car out in the new year

Philip

[Helen]

[Mike Usiskin]

Are there any track days being thought of in the new year?

mike

[impmad2000]

question: when braking in a straight line, the weight (or Mass) transfers to the front of the car, so IF you turn in at this point do you benefit from greater grip on the front tires?

This has worked an absolute treat for me in an Imp (but the navigator was very nearly sick!)... but with 34 BHP, you just can't slide the back end around on the "power" as you can with a 911. Secondly, in a 911, I found that I was approaching the corners Very much faster than in the imp, and so needed the 100% of the tyres just to stop me ! Again the 34 bhp of the imp is quite within the 155/65x13" tyres that it is fitted with !

If you keep the power on whilst braking does this then became the fabled left foot braking made so famous by the Swedes etc in the 60's 70's? and does it have any advantage in an 911 such as ours?

The sweedes of the 60's were doin this with Front wheel drive cars were'nt they ? And yes, left foot braking works an absolute treat in Front wheel drive. In the FWD case, it is just like trailing the hand brake a little, just to control the atitude of the car in a corner. For instance in my Mk1 GTi, barrel into a corner fast and the front just starts to push (understeer) away from the line you want to take, cover the brake VERY gently with the left foot and I could just change the attitude of the car to tuck the nose back in (by sliding the back out a tad) Plant the foot hard on the throttle and control drift of the back end with the left foot on the brake ....... Grin and do it again.
Now modern FWD cars, some have fly by wire and don't like this ! Be warned. Try this in my Audi diesel and the ECU thinks throttle pot fault and cuts the power ! Usually just when you need it ! Be warned.
All this stuff needs to be tried on the track... not on the roads!

Now scandinavian double flick...... Tee Hee
Tim

[IanMcLeod]

Here's what i aim for ...

pick wide late turn in point ... position car heading straight for turn in point ... wheels straight ... brake hard all weight to front ... get all heel and toe downshifts done without locking rears ... still straight ... start to ease off brakes but not right off ... just before turn in get off brakes onto balanced throttle ... car is nicely balanced now ... turn in slightly and feel front grip ... when confident front is turning then aggresively turn to get pointed at apex well before reaching it still on balanced throttle ... when you see you are pointed at apex throttle to floor ... unwind as exit corner to exit point ... all done as a series of smooth flowing actions

if you have taken too much speed into the corner you'll feel the front understeer ... and miss the apex ... stay on balanced throttle and hope car comes round enough to make the exit point ... tell yourself how crap that was all the way down the straight you are now going down slowly because your exit speed was so crap

if you have taken way too much speed into the corner ... tough ... remind yourself to take more care next time whilst sitting in gravel waiting for recovery

of course what i aim for and what is achieved are two different things

Ian.

[Mike Usiskin]

Now scandinavian double flick...... Tee Hee

Now your teasing......

is that Porn or driving or just driving porn

mike

[IanMcLeod]

if it's what I think it is then when you want to turn very sharp right start by first turning left ...

[sladey]

I was on a rally driving course a couple of years ago and for doing a 180 degree bend he had me doing the following:-

(It's a 180 degree right hand bend)

Hooning up to the corner and slamming on the brakes - braking in a straight line deep into the corner and past the apex (but not turning towards it or anything - so it almost looks like you've not seen the corner and are going to plough straight on!) - when the car was down to about 5 mph he had me do full right hand lock on the steering and floor the accelerator. Because the car was going so slowly it turn instantly and by the time the full amount of the torque hit we were heading for the exit at great speed. His words (when he stopped screaming at me) were that the slower the speed you got down to the faster the exist speed, which is what it was all about.

We did this in a mitsubishi evo 6

The course you end up taking through the corner is much more pointy, and not at all like smoothing it out and clipping the apex

Aside from that lesson, I've never tried this on a track but works a treat on GT4

Mark

[Helen]

Are there any track days being thought of in the new year?

mike

I have 7 places left on a Sprint day at Curborough (nr Lichfield) on April 14th 2007 at the cost of £40 per car... the day is limited to just 25 cars, (one car on track at a time) so you should get quite a bit of track time.