Pierre Gillet Posted January 15, 2001 Share Posted January 15, 2001 So who is REALLY : 1) DDCing on the road ? on the track? 2) DDCing AND braking + Heel & Toes? Pierre Link to comment Share on other sites More sharing options...
AndreK Posted January 15, 2001 Share Posted January 15, 2001 Sorry Pierre, No to all. I thought that this technique was for old Leyland (or Saviem for you?) lorry drivers with 'crash' (non-synchro) gearboxes. I can just about do this on a 'normal' car but on the 7 with the extra speed and the closely spaced pedals, I would be pushing my luck. Is the Ford (4,5 speed) or Caterham (6 speed) synchromesh that bad? Link to comment Share on other sites More sharing options...
Number Six Posted January 15, 2001 Share Posted January 15, 2001 On road, yes. Sprints - no. Want to save that extra millisecondteeth.gif But do use heel and toe all the time, road, track and sprint Track - maybe, if I was racing - no. Anyone ever tried left-foot braking? Andy Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 16, 2001 Share Posted January 16, 2001 1) Me. Me. 2) Me My passengers appreciate the smooth ride on road. On track I am smooth and balanced and can get into the appropriate gear without risking a loss of control. Paul Ranson argues that although heel and toe is vital, a DDC H&T is unnecessary. He is right to a degree, but the practiced skill costs me no extra mental effort or time in execution - data logs show DDC H&T downchanges in 0.2s - so I will presist in the knowledge that I am also sympathising with the machinery. The time of execution is also close to being irrelevant as these gearchanges are being performed during deceleration. In analysing the data logs you are more concerned to see that the longitudinal deceleration is maintained at the limit of grip. The cheat's single declutch H&T, which uses the blip to spin up the engine but uses the synchro to spin up the layshaft, is a minimum basic skill for track driving. To persist in track driving without acquiring this skill, once the need has been pointed out to you, is perverse. H&T makes driving safer (able to balance the car on the power by being in the appropriate gear; don't have to stop braking to downchange), smoother and faster. This is why the RACMSA "Go Racing" ARDS pack includes instruction in this skill in the video. On the road an early H&T downchange on approach to a hazard (intersection/roundabout) gives you more time to observe and decide on whether to accelerate into the clear or brake to a standstill. The latency surrounding the decision point is kept to a minimum by being in the right gear to accelerate should your decision fall that way. This is patently safer than not using H&T. The distraction of perfecting the technique will make your driving less safe for a while, but the benefits in the long term outweigh this. I think that the margin of safety afforded by this technique is equivalent to driving at a significantly slower speed (~10mph) under many circumstances. Car's designed with the presumption that this skill is not going to be deployed (most recently experienced with a Honda S2000) preclude access to this extra safety margin and suffer a reduced active safetly level for all drivers. By the same token, all cars with automatic gearboxes are unable to reward a skilled driver with such safer high speed progress. As for Number 6's question, left foot braking can only be used with RWD to promote understeer in a trail-braking situation. Under most circumstances, more control is achieved by relaxing the steering input. In FWD left foot braking can be used to reduce understeer (tuck in the nose) under acceleration through fast corners - its applicability to RWD is academic. Edited by - Peter Carmichael on 16 Jan 2001 04:11:51 Link to comment Share on other sites More sharing options...
Graham Perry Posted January 16, 2001 Share Posted January 16, 2001 DDC:-not really but I am a throttle 'blipper' between gears. Heal & Toe;- always on a downshift where high engine revs are needed to avoid a spin. Left foot braking: yes to reduce understeer at high speed, BUT, you must keep the throttle hard down (This exercise is not for the faint hearted and shouldn't be practiced on the road) I find it works reasonably okay on my Caterham with not too much instability (but I have spun doing this) , but it is best on FWD cars where it is very predictable what will happen Link to comment Share on other sites More sharing options...
Marius Posted January 16, 2001 Share Posted January 16, 2001 Obviously I´m the only "looser" here. I just don´t get that heel&toe managed in the 7. Maybe my feet are too small but I have to stand on the very outer edge of the braking-pedal to get somewhere near the loud one. I´m already thinking about changing something on the pedals ´cause of that. What do I do wrong sad.gif???????? H&T works well in the 911, pedals are floor-mounted and easy to reach. Marius Link to comment Share on other sites More sharing options...
Peter Carmichael Posted January 16, 2001 Share Posted January 16, 2001 Graham, You are deluding yourself regarding the effect of LFB on an RWD car. The only way you have reduced understeer has been by slowing the car down below the limit state of grip - readily demonstrable by a simple friction circle analysis. With the throttle hard down and the brakes gently applied, a net braking force is applied at the front and a reduced accelerating force produced at the rear. Compare this to the situation where the brakes are not applied, and the same net acceleration is being applied to the car (reduced throttle/same weight transfer): The fronts are now purely available for cornering and have their full grip circle to deploy to this end. The only way that this situation would generate worse understeer would be if the rears also had the accelerative use of the friction circle reduced by an even greater proportion than the fronts, but even then the grip at each end would be better than in the LFB scenario. i.e. you would be generating more lateral G and cornering faster without the LFB input. Roll stiffness and rear steer would have the final say in whether you understeered or oversteered. Compare also to the situation where more throttle is applied to the point where the grip circle at the front is reduced in size to the point where it is the same size as the remainder left over after the braking force has been deducted in the LFB scenario - some Pythagorean mathematics need to be imagined so it is not a matter of straightforward subtraction. The relationship between centre of gravity height and wheelbase requires that the force at the rear tyres to achieve this is quite a lot larger than the resulting weight transfer. In turn this guarantees that the rear tyres will have proportionally reduced grip despite the weight transfer and the car will tend to oversteer compared to the LFB scenario. If the purpose of the LFB was to neutralise understeer it has failed. In a FWD car, the situation is much different. The weight transfer under acceleration is working to reduce the grip of the front wheels, causing understeer. At full throttle, with a light dab on the brakes, a slightly reduced accelerative force will be applied to the car. The grip circle at the front grows because of the reduced weight shift to the rear; the net use of the grip circle at the front for acclerating will be reduced because the engine torque will have the brake torque applied against it - more grip will be freed up to generate cornering force; the rear grip circle will reduce in size because of the weight shift; the rear grip circle will give up some of its grip to the light braking force being applied; overall the front will have more grip available for cornering and the rear will have less grip, neutralising understeer. The only way that a RWD car can mimic this consistent, determinate behaviour under LFB is to reverse the regime of weight shift. i.e. instead of looking at acceleration where the weight is shifting onto the driving wheels you have to look at braking where the weight is shifting away from the wheels over which you have an independent control in the form of the throttle. Under braking, modulated application of the throttle can be used to neutralise oversteer, effectively altering the brake bias. Edited by - Peter Carmichael on 16 Jan 2001 09:41:26 Link to comment Share on other sites More sharing options...
Marius Posted January 16, 2001 Share Posted January 16, 2001 question.gif Link to comment Share on other sites More sharing options...
Number Six Posted January 16, 2001 Share Posted January 16, 2001 Wow Peter, you've given us a lot to think about. However there is one man that might disagree with you on the usefulness of the technique... I've heard him hint broadly in interviews that circuit racers up to Grand Prix teams use his LFB technique... Quote "They all left foot brake!!!!!" -- but then Pentii would say that wouldn't he teeth.gif Pentti Airikkala at http://www.leftfootbraking.com Andy Link to comment Share on other sites More sharing options...
gee_fin Posted January 16, 2001 Share Posted January 16, 2001 I've often found left-foot-trailbraking into an apex helps to promote oversteer (obviously not trailing a throttle mind you) - weight transfers to the front, less weight on the rear, light rear pops out, oversteer..... I use this technique every time I go to Curborough to get the turn-in at the hairpin as it alows a setup that can still be nicely balanced through the first left hander. Just my two cents. _______________________________ www.fluke-motorsport.co.uk Link to comment Share on other sites More sharing options...
Pierre Gillet Posted January 16, 2001 Author Share Posted January 16, 2001 Well I think that DDC/ H&T is really part of the fun especially with the Seven. I figure that a lightened fly wheel increasing the responsiveness of the throttle would even be better.I have been doing that all my life, and yes, Andy, while racing my Renault Gordini in the early 70's ( your parallel with Saviem is quite right to the point!) at Montlhery. I had the opportunity to make a few laps with former Formula 2 Matra Grand prix racer, Jean Pierre Jaussaud, now in charge of the maintenance of 1.6 K Seven at the training track of Pont L'évêque in Normandy, and I was amazed by the smoothness of his drive , as Peter noted for his, and the lightness of his foot while kicking the gas pedal. I am afraid I am more brutal !!! Pierre Link to comment Share on other sites More sharing options...
Pierre Gillet Posted January 16, 2001 Author Share Posted January 16, 2001 Sorry, please read "Pont L'Eveque" as this site does not take French ponctuation smile.gif Pierre Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted January 16, 2001 Share Posted January 16, 2001 Peter, I am confused. To fully utilise the grip circle, one has to brake up to the apex and power out from the apex. This is an act of genius. Stirling Moss, Mansell and Michael Schumacher drive this way. More classical drivers brake in a straight line and turn in later (Senna, Prost). As I understand it, the idea is that as the car turns in early, the tyres are required to supply lateral grip, but not 100% until the apex due to the tighter profile of the line chosen. Therefore the closer to the apex you get, the less you can brake to keep the tyres at the edge of the grip circle, but you can be using the brakes up until that point, keeping the tyres at the edge of the grip circle throughout the corner, and meaning you can brake later and therefore be good at overtaking - like Mansell, Moss and Schumacher. This is why these drivers don't like any understeer in their cars as they drive in a way that just needs the car to not understeer. They will look after the twitchy rear end with their driving skills. What classical drivers do (brake earlier and turn in later to try and create a constant radius corner) requires going from 100% grip into braking, then no grip being used for a millisecond, then rapid progression to 100% lateral grip. What I don't understand is what this has to do with LFB as practicioners of both driving styles can be RFB's or LFB's. Also, does braking up to the apex increase the size of the grip circle by creating in effect downforce? Alex Wong www.alexwong.net _________ / / ___ _/______ /_ ___ / (_) (_)/ /`-'/o/ _______ o/`-'/ / /// ( VDU7X ) \/ / /___/--_________/--/___/ Link to comment Share on other sites More sharing options...
Graham Perry Posted January 16, 2001 Share Posted January 16, 2001 Peter makes a good point as usual. I only use this technique when it looks like I am about to understeer onto the grass. If all you do is hit the brakes you spin instantaneously, but I find that by holding the throttle down and LFB'ing I don't spin and nor do I end up on the grass on the exit to the corner. Instead what happens is that the nose jinks slightly towards the apex and often solves the problem. But as Peter says its probably could just be delusional and all that is happening is that I am slowing down, and holding off rear wheel lock by putting power through the rear axle. I am certainly no Prost or Senna, but it could just be a characteristic of my car. When I finally get to drive my car in the spring having made numerous suspension changes it will probably handle completely differently and I will have to start again, learning how to drive around various handling problems. . Link to comment Share on other sites More sharing options...
Rory McLeod Posted January 16, 2001 Share Posted January 16, 2001 As a novice to this fast driving thing, I am interested in anything that smooths/improves my driving, increases control etc. At Anglesey there is a short straight followed by a hairpin. I was using rather savage late braking with a DDC and BANG on the throttle to get the revs high enough to get down a gear. This was patently engine & clutch unsympathetic and uncontrolled as I was doing too much in too short a time half a second off the brakes is a lot of distance. Having had heel-toeing explained to me today, I am practising it in my Fiesta (honestly) as this would patently smooth the whole approach to this particular set of circumstances giving more time for concentrating on other things (like the tyre wall 20 feet in front of you)! If this is the wrong technique for this obstacle let me know - I cant afford a second clutch - I have to replace the current one. Edited by - Rory McLeod on 16 Jan 2001 19:27:10 Link to comment Share on other sites More sharing options...
Number Six Posted January 16, 2001 Share Posted January 16, 2001 Rory -- 2 books you should definitely buy... ok, make that three. 1. "The Porsche Driving Book" by Martin Beck-Burridge and John Lyon (of HPC fame) pub. 1988 by Porsche GB Better still, do the HPC and or Cadence introductory courses. 2. "Competition Driving" by Alain Prost and Pierre-Francois Rousselot pub. 1989 by Hazleton 3. "Secrets Of Solo racing" by Henry A. Watts pub. 1989 in the USA by Loki, Sunnyvale The third is an absolute goldmine if you are into sprints and hillclimbs Andy Link to comment Share on other sites More sharing options...
mark.hall Posted January 16, 2001 Share Posted January 16, 2001 Number 6 Do you happen to have the ISBN no's, particularly for the "Secrets Of Solo racing" book, or alternatively a web-site where I might locate them/it. Thanks. Link to comment Share on other sites More sharing options...
elie boone Posted January 16, 2001 Share Posted January 16, 2001 LFB is generated in a rallycar to set up the car for the next corner in oversteer(ask the Finn's), in a FWD and AWD car the effect is far greater because the most traction is at the front wheels and because of the wheight transfer the back becomes light and swings rond to the outside of the corner= oversteer.On circuit it is usefull in fast corners to scrub off some little speed while holding the pedal to the metal this is faster in action and more stable than ease off a little bit on the trottle. Unless you have the clutch on the steering wheel it is useless for any corner where you have to shift down. About DDC, if its your pride and joy ok but the guys in Formula Ford do not even use theirs in the heat of a fight because there is only one place that counts n°1 and if the box breaks they will say if only my box held together.... But it is verry handy on the motorway when somebody is to close on your bumper then with your left food just light them up and he will ease off. wink.gif Link to comment Share on other sites More sharing options...
Rory McLeod Posted January 16, 2001 Share Posted January 16, 2001 Andy: Well I have done the thousand quid course with John L but we didnt get on to heel toeing - I think he reserves that for his Race Techniques course. The other books - off to the library on Saturday! Link to comment Share on other sites More sharing options...
Number Six Posted January 16, 2001 Share Posted January 16, 2001 Chater and Scott have a web site, unfortunately I don't have it handy. 1. porsche = isbn 0-9513737-0-6 2. prost = isbn 0-905138-80-5 3. solo = isbn 0-9620573-1-2 tel usa 408-245-4040 also Amazon.com later Andy Link to comment Share on other sites More sharing options...
mark.hall Posted January 16, 2001 Share Posted January 16, 2001 Number 6 What kept you!!!!!!!!!!!!!!!!!!!!!!!!!!!! Mucho thankssmile.gif Link to comment Share on other sites More sharing options...
Number Six Posted January 16, 2001 Share Posted January 16, 2001 Elie "But it is verry handy on the motorway when somebody is to close on your bumper then with your left food just light them up and he will ease off." Also useful in shaking off the same idiot when approaching lights just turning to red - LFB and accelerate on through! teeth.gif Andy Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted January 16, 2001 Share Posted January 16, 2001 I read Paul Frere's book and watched Mario Andretti's video but although it was interesting to see the theory, it didn't really help with my driving. There is no substitute for time in the seat. Practice is, IMHO the only way to drive faster. Oh, and being driven by faster drivers! Link to comment Share on other sites More sharing options...
Number Six Posted January 16, 2001 Share Posted January 16, 2001 A Nitrous button helps Alex teeth.gif Andy Link to comment Share on other sites More sharing options...
gee_fin Posted January 16, 2001 Share Posted January 16, 2001 For some further info with regards to LFB/heel and toe in FWD/RWD/AWD go to http://www.drivingtechniques.co.uk and look in the techniques section. Lots of interesting theories/information. Cheers, Graeme. _______________________________ www.fluke-motorsport.co.uk Link to comment Share on other sites More sharing options...
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