Wednesday, December 24, 2014

Lets call this the Christmas special

A recent question from Bryan caught my attention: 

"Amazing the variety in subtle spec changes even between teams. In regards to gravel, what tread width and block cuts were more efficient for the different gravel surfaces?"

In 2005 on gravel we always used the same tread pattern called "Z" but we sometimes cut it to half "ZA" or full "ZA". Except in Cyprus where I used something called a "GW" pattern which was designed for rough events. I am not sure about the tread width anymore...Anyway it was the standard width for the 15 x 7 inch gravel wheels, perhaps 185mm tread width. 





A full "ZA" cut tire looked like this:


Full ZA cut (left tire)


Just for reference, the triangular shaped blocks sit on the outside edge, once mounted on the car. In this particular photo the tire on the left is a full cut but not the right one! Compare the second row of blocks from the outside. 

As you can see the transverse grooves that run across the tire have been opened up and the inside edge blocks have been cut in halves. This sort of cut is helpful for muddy conditions; sandy roads where the hard surface is broken up and loose as in for example in the Fafe area in Portugal; you could perhaps use this also on New Zealand stages on the first pass if you are among the first 3 cars on the road and its damp; or also on Finnish style roads if it's very wet. In Wales you should use a "Z" if its dry whether it's loose or not because from my experience a cut tire will overheat quickly due to the hard surfaces and the fast nature of the stages. If it's damp, do a half cut and only a full cut if it's pouring down. A "half" cut would be: to open up the transverse grooves from the outside, going until the fourth row of blocks. Nothing else is touched

Generally speaking, you need to be aware that fast stages generate lots of tire heat. A cut tire will tend to create more unwanted movement on hard-ish surfaces for a given compound. Mainly because 1. there is less rubber in contact with the ground and 2. the blocks move due to overheating. It will cause loss of general performance, precision and confidence. Back in 2005 I drove the "Halfway" stage (18,85 km) in Wales with an 8 compound full cut "ZA", thinking it was going to be wet. It was dry and the result was a 10 second loss. 



 For the second pass the tire choice was correct.


At the end of the day it's all a matter of compromise between performance, endurance and confidence. 

Having said all this it's important to remember that, just like on tarmac, the most important factors are your tire constructions and compounds. Back in Mexico 2005 I was running shakedown and it was our first gravel rally of the season. Michelin had just come out with a new 9 compound development tire called the "L". Toni, Roman and Dani had them in their tire pack but not me. I ran the older "M" type. 

The shakedown stage was rather long, a nice uphill climb followed by a downhill climb. All that on a hard surface covered in sand and lasting some 8 kilometers plus. We did our runs and stabilized the clock around the same stage time each run, literally within tenths of a second. No way to go faster. Toni was within an arm's reach but no way to match him. Then came the moment back in service where the tire guy did me a favor and let me have Dani's set of used "L" for a go. Off I went for one final round. I had a clean run. The time was 8 seconds faster, just like that, easy. Suddenly this put me in front of Toni and even got me a thumbs up from Loeb. What an amazing tire. I was all smiles. Needless to say I was begging for more of these tires! 


Happy Holidays!




Friday, December 5, 2014

The tire conundrum

I have been getting requests to discuss tires. I can understand the curiosity as I was indeed also very interested in this particular subject when I drove competitively. These rubbery things are, after all, the link between your car and the road.

This read is going to be a bit heavy for I have included lots of details and anecdotes and I might even get carried away... I apologize in advance.

For the sake of this post we’ll concentrate on Michelins which I have experience with. When I was active in the WRC, there were many types of Michelin tires rolling around the service place. First of all, one has to be aware that in those days there were two main categories of tires:

1. Customer tires.

These were tires available for sale to privateers. A limited variation of different compounds and constructions were offered and they were products of the past years of development. For example, a dry weather tarmac tire would be marked with a big “N22” on it. This was typically what heavy 4 wheel drive cars used. It was a “number 2” compound which was rather “hard” and resistant to heat and abrasive surfaces. "N" meant it was a “slick” tire. Another example was the "T04" which was a “0” (zero) compound intermediate for wet tarmac. The "B00" was a "zero" compound full rain tire for tarmac which was absolutely amazing. Stephane Sarrazin used those to set some awesome times on the wet with his private Subaru.



Ok let’s go back a bit and answer some of your thoughts. The Michelin compound scale for tarmac went from 0- (zero minus) to 2+ (two plus); 0- being the softest and 2+ being the hardest.  The gravel scale went from 7 (softest) to 9+ (hardest). As I remember, a typical gravel tire was marked, for example, “ZR8”. This was an asymmetrical design tire “Z” and R meant it was for the right side wheels; 8 was the compound category. I mentioned tire construction, which is extremely important for performance and confidence. The construction of the sidewall of the tire is flexible to allow distortion. Basically more flexibility will help in slippery conditions but will move a lot when lots of grip. I’ll get back to this later…

2. Development tires.

These were reserved for factory teams, who tested them and selected the ones they wanted for competitions. Michelin continuously came out with newly developed or improved compounds, there were many tires to choose from and they ranged from greatness to, well, I’ll let you guess… Once or twice, I heard some privateers saying they were happy to have received some development tires from Michelin… I thought to myself: "well I hope you know what you are getting because if you don’t it’s Russian roulette." Except in this roulette there’s one empty chamber out of 6! That’s because the good (and fresh out of mold) development tires were reserved for factory teams and for some privileged privateers who had the right connections. These tires had no particular markings on them but if you’d look carefully you’d find a small engraving in the rubber (on the sidewall). This was a long code made of various digits and, as far as I remember, one letter. In any case, the interesting part was the letter and the two or three digits before it. After every tire fitting, all the factory team’s tire guys would use a grinder to, you’ve guessed it again, grind the code off the rubber. Secrecy was imperative and nobody except you and your tire guy was aware of what you took. Asking another driver what he had and getting an answer like “n°2 compound” meant nothing to me because as far as I was concerned there could be at least seven different “n°2 compounds” which had varying constructions and compounds. And these seven were just the ones I knew of; I had no certainty that another competitor, for example Citroën, had chosen exactly the same tires as Ford had.  

Here’s an anecdote to illustrate my point:

Back in Catalunya 2005 we had just taken 20 seconds off Alexandre Bengue in a stage. The stage was bone dry and the next was full wet. I was running on what I thought was the best solution in my list of choices: “183D”. This was an old type of “0+” compound slick usable on slightly wet roads or very cold dry tarmac. I had run the stage smoothly, caring for my tires, avoiding overheating. They had worked well. Bengue was surprised at the time and came up to me. He asked what I had. I said “D…and you?” He replied “J”. I replied “ok” but thought to myself “wtf”. I thought “is he sh*ting me?” The only “J” tire I knew was the “380J” which is a hard slick. We ran the next stage, in full wet conditions, and we lost 20 seconds to him. Later I understood that Skoda was running with something called the “183J”. This “J” had a “softer” construction which made a big difference on cornering.

Accelerating and braking on wet roads with the “183D” was ok. You could feel the grip well and the threshold of grip-loss was progressive. Confidence was there. When cornering, however, it was different. The soft compound alone wasn’t enough and the rather rigid structure made the loss of lateral grip rather sudden. Apart from the lower overall cornering performance it was difficult to be confident about the grip level and therefore the times suffered.

A similar story happened to Loeb in Catalunya 2003 where Markko Märtin used an intermediate called “74F” and set amazing times in the wet. Loeb was on an intermediate tire called “74V” which had a more rigid structure and he said afterwards that he wasn’t aware of the "74F"! Needless to say they had it for the next event.

In 2001, before starting the Rallye du Var in France, I visited François Delecour and asked him about tires; we had two types of slick tires: “N22” and “N04”. He said “do you have some “248D”?” I replied “huh?” He had left Peugeot a little while ago and back then “248D” was the thing to have on dry tarmac. By the time 2005 rolled along, all the factory drivers were running on something called “380J” for dry tarmac. So what does all this mean in practice?

Delecour, San Remo 2001

In a comparison test between a “N22” and a “380J”, you’d find on the first corner that the latter rendered your steering extremely precise. The front wheel’s reaction to steering input was twitchy and immediate. Why? Because of a more rigid structure. You would have also noticed a slower rise in temperature than the “N22”; meaning it took more work to get it ready for max attack. The big advantage was its longevity. Once it started working, you could drive and drive endlessly without performance loss, so to speak. This tire had been developed for the evolving rally format of having mostly longer stages. In 2005 it had become rare when a tarmac stage was less than 20km. Needless to say that this tire was useless and dangerous on wet roads. Nowadays with the new “all purpose” tarmac tires, Michelin has had to compromise heavily therefore it’s normal to hear drivers say things like “...yeah my tires are moving a lot” on dry tarmac.

In some cases it was difficult to choose the right tire. We had occasions when we knew we’d have dampness in the stage but not enough to justify going softer by one whole step. In this particular case the solution was to cut up your tires and make thin grooves with a knife. A 3 cm cut every 5 cm, perpendicular to the tire, on the outside edge. These thin cuts helped the rubber move and it kicked the rubber’s temperature up a bit faster than normal.

By 2005 Michelin had developed many different tires. For up and around 70% of dry in a stage I’d use a “050C”; this was a "2-" compound which worked well in mixed conditions. It was also a good choice on a fully dry stage made of very smooth tarmac but the “050E” was better for that. If the next stages were very long, dry and twisty with abrasive tarmac, I could use a "2+" compound called “050B”. If you really needed a very soft "2-" compound the “050L” was a choice. We had a bunch of cold weather dry and wet condition slicks which we could use. The softest were the “248F” and the “465T” (0-) of which the latter worked well on low grip types of tarmac. The “130K” was a “0” compound, versatile. The "0+" compounds were “183D” which was useful in dry and the “132C” which was useful for wet conditions. Bear in mind these were just the slicks I knew about!

You have probably noticed that I am constantly speaking of using slicks on wet roads and you may find this awkward. I did as well when I began driving. I quickly noticed that all top drivers always pushed for using slicks on wet roads simply because they performed better. In fact as long as there is no standing water on the road, no need to break out the intermediates or full wets.

Finally I’d like to quickly discuss tire wear. In 2003 and 2004 when we had to make do with our own diff maps, I had big differences of tire wear on gravel between front and rear wheels. Also, in general, my tires seemed to wear very fast. The problem laid in our diff mappings. It turns out our diffs were loose and this meant lots of uncontrolled wheel spin. The result was excessive tire wear, especially on the front. For more on diffs see Differential extravaganza

2002 Focus

Apart from that and generally speaking, the geometry was always spot on and the wear was even across the tire. My 2004 Focus ran -2.0° of camber on the front with -1.2° on rear and the tracking was 0 on front with 2mm in on rear (all this for gravel). The car was evenly balanced as far as weight went and this meant the front was wearing only slightly more than the rear.

You may ask why Ford ran with a 2mm in track on the rear. From my experience this helped keep the back steady on straights under high speed and perhaps also helped counteract over-steer in corners. Alternatively if your car suffers a bit from understeer you may opt to change the front track and open it up a bit to 1 or 2mm. this will help with turn in, but be careful because it will also cause your car to “snake drive” a bit on straights. Another way to help with turning in is to do a “Solberg Subaru”. Remember Peter’s Subaru, with the low nose and high arse? Lowering the nose is in fact something you can try to fix inherent under-steer.

This post was about tires and here I am getting carried away about geometry… Let’s continue this subject on another day!

Wednesday, September 24, 2014

Space jump or car setup?

I was asked by a reader to write a little more about setups and what to do in certain instances when a car does something awkward.

“I know you've talked before about car setup, but could you please right something a bit more general. What I mean is that you could write saying things like: "if the car's oversteering, then you can make changes to the damper rebump", "if you have understeer, maybe you could have a change in the diffs preload".”

Ok, let me take a crack at it…

Setup is crucial if you want to get the most out of your car, we all know that. But it’s not only about theoretical performance (engineer’s calculation of optimal setup), it’s also about which setup gives you confidence to push more! It’s important to understand that the best performing teams have understood they need to find a compromise between the two. 

Do you remember the “energy drink” space jumper guy? Well, guys like him drive rally cars as well; I bet you’ve seen them! They are fearless, can push it to their maximum, driving whatever, and sometimes (more like often) don’t make it far into rallies because there's just too many hazards. I will focus on the other type of driver, who needs to feel good with his car to perform at his best.

Back in 2004 we were running with a 2002 Focus WRC and I had some confidence issue with taking jumps flat out. The problem was that I knew if I jumped much there was a very high risk that the car would nose-dive into the ground. Luckily I got some advice from François Duval, he was driving a factory Ford at the time. One day he told me that tightening the rebound on the rear dampers would help with the nose-dive issue. Problem solved, thanks François. You’re gonna ask me why a loose rebound? Easy: For maximum traction! If the rebound is loose, the spring will extend easily when the wheel wants to lift off the ground. This means the wheel will keep in better contact with the ground, hence more traction. The down side to that is when you are about to jump and the wheel starts to get light, the spring extends freely and catapults the back of the car in the air, resulting in a nose dive! Nowadays things have changed a bit because there is a second rebound adjustment, I believe first invented by DONERRE sometime around 2004-2005. They are specialized in off-road dampers. The system is called "DETRA" for détente rapide, or "fast rebound". 

courtesy of Donerre

The damper can sense the difference between sudden loss of contact with the road and “normal” movement. It will release the rebound control and let the spring extend quickly as soon as the wheel is off the ground. As a WRC driver you have to deal with that adjustment as well. 

I’d like to add that the Swedish Rally was a good example of a loose rebound rally. The reason being that stages are very smooth, slippery, fast and flowing, with few jumps. You need as much traction as possible and making the damper rebound very loose is necessary to allow the wheels to follow the terrain. As soon as you start driving on rougher roads, for example Argentina, you need to tighten up the rebound. Why? Because of the jump issue for one, and especially to prevent the wheel from falling into every rough hole. A colorful way of putting it is you want your wheels to fly over the really rough stuff. I know what you think so I’m just gonna say it: yes, obviously, this only works when you drive really fast over the rough stuff. With the advance of technology, huge travel and bullet-proof strength of today's WRC car dampers, world rally car engineers don’t mind so much the rough stuff. The result is wheels follow the terrain nicely, especially thanks to the "fast rebound" system.

I can speak more about my experience with dampers in another post if you’d like. The Reiger shocks we had on the Fords were really interesting pieces of tech.

Back to our eggs… Somebody once asked me what to do with a problem he had while driving his rally car. He had what I believe is a rather common issue: under steer going in the corner and too much over steer coming out. He felt like he was losing time especially in tighter corners. There are various things you can look at and sometimes many things need to be looked at. I’m going to explore one specific and very common source of problems: 

Pre-load on a mechanical rear diff

I had conversations about that subject with my team back in the days when I was driving a Gr.A Celica and the Corolla WRC. I remember that some of the rear diffs out there had outrageous pre-load settings and some people were driving with 80N of pre-load. Let me be very clear about what this amount of pre-load would feel like in terms of driving, as one of my mechanics used to say:

“Having a locomotive pushing against your arse each time you lift off gas.”

He was a Finn, by the way.

You’d feel it really upon turning into corners. For those of you who don’t know about pre-load : It’s what keeps your diff on a determined amount of tightness when off-throttle. Why would you want that? Simply because it will give the rear some stability under braking and prevent the wheels from locking too early, as well as give you a better feeling and confidence. It’s important but having too much pre-load for a given characteristic of stage will mean under steer on corner entry.

Why on earth would some of these diffs have such high pre-load settings? Word on the stages was Didier Auriol had been driving with that stuff but I don’t know if it’s true. Our Celicas were unaffected; they were built by Toyota Team Sweden (TTS)*. The Corolla which came from Cologne (TTE), on the other hand, needed some adjustment… If I remember correctly the pre-load setting I was driving with was somewhere in the 10-30N for the rear. As a comparison the Markko Märtin maps we got, later in 2005 for the 2004 Focus WRC, were generally with the same pre-load philosophy.

I can see you coming with the next question…

“Ok Antony that’s really nice and all but where does the over-steer come from?”

It comes from the botched up corner entry. Our unlucky driver has much work to do, dealing with that effing locomotive. He gives huge steering inputs and throws the car in, with lots of excessive momentum being created. All that momentum will result in excessive over-steer on the way out. His car is out of balance. The basic rule of thumb is you can have more pre-load on fast roads, less on twisty roads. How much exactly is up to the driver and his technical team to find out. I'd say not far from zero on twisty gravel, and double that amount of fast gravel is a good point to start from. 


*TTS was a satellite team of TTE. Based in Sweden and run by Leif Asterhag. They ran cars for Thomas Radstrom, Markko Märtin and Marcus Grönholm among others. Their cars originated from TTE but they had their own setups and "developments" on them.

Friday, September 19, 2014

A group incentive

Have a look at this group if you have 30 seconds to spare in your in your life as a motorsport lover:





The group's object is:


"The World Rally Championship is on the cusp of a dramatic change, a change that is completely out of touch with the sprit of rallying. The team bosses and promoters are proposing to make a massive change to the format of events.

Basically the drivers and cars will battle over the unforgiving terrains of the world for 100's of miles for 3 whole days and no matter how big margins between them are, the final stage will decide who wins. Crazy hey!?

1st-3rd position will fight it out, and their overall result will be based on the final stage time, even if the 1st placed driver is 5 minutes in front of 3rd. This will happen for 4th-6th position, 7th-9th etc, etc.

The WRC drivers have already voiced their opinion and rejected this plan and the World Motorsport Council are not happy with it either, but the teams and promoters are convinced it will happen is some form or another.

The protagonists and creators of this idea believe that it will increase television audiences, and thus car sales. OK, yes they are all in it to sell cars, but if the fans think its a ridiculous idea then who will watch and buy the cars?

Basically, the fans need a voice! If we can grow this group and show the teams and promoters that we disagree with their idea, and whole heartedly support the drivers, then how can they argue?

After all, we are the ones that they are trying to sell the sport to......and more importantly their cars to!


Please like and share, especially any drivers as you have the biggest following and voice."


I liked the initiative therefore I joinded.

Thursday, August 28, 2014

TRIVIA: The good'ol days of Finnish Mafia

(joke, no offense to Finns!)


1. Name all of them from left to right.

2. Which manufacturer did each one drive for at time of photo ?


BONUS: 

On which rally was this photo taken ?

Wednesday, August 27, 2014

Explanation request answered

I got asked from a reader to explain this: "°". I mean degrees as in angle degrees.
As far as I can tell Loeb's corners follow this logic:


He also has slower corners like hairpins, etc. but I omitted all that to keep it simple.

In practical terms this is how it applies:



From top to bottom: left 130 short onto right 130 half-long
left 144 tightens 130 short. green color is racing line.
If you assume this is a blind corner, the "left 144 tightens 130 short" example shows a very basic example of how handy his notes are. He knows the severity of the entry corner, how much space he has to brake, the severity of the tighter corner and its exact racing line.



A pace note side note

Hi everyone,

It’s been a long time since my last post and it’s great to have some motivation to write a bit more on this blog ! I hope you will enjoy it.

There has been some interesting discussions on this forum from time to time: http://www.motorsportforums.com/forumdisplay.php?14-WRC-World-Rally-Championship

Today I’d like to focus on this thread:

Where I asked:

It's a shame that Mads (Ostberg) isn't able to go faster than what he is currently showing. 


It seems to me that he has the gift of driving, and the adequate balls, not even mentioning the experience...and car. 
I have a feeling that his pace notes are not precise enough. I am just looking at his driving and cannot understand his Norwegian notes so not sure...but that's what it looks like to my eye anyway. 

I mean by that:

1. the excessive sideways driving
2. the lack of commitment on specific fast entry corners into dead slow ones (when it's blind only).

In my view these are signs of a good driver who is unsure about EXACTLY what the upcoming corners are like and/or the distances between them (exact racing lines and braking points).

Maybe a bit of coaching would do him good.

That's my two cents.

Any ideas?



What I’d like to do is go over Sebastien Loeb’s pace notes system and share what all that gibberish means in terms of driving (as far as I can understand). For this example we’ll use the first few km of stage 14 from ADAC Rallye Deutschland 2011. This stage is located in the Baumholder military area. There are lots of surface changes, junctions, rough sections, high speed sections, hinkelsteins, etc.

You can find the in-car here: http://youtu.be/kI-9lIEa4YA


START

Droite a fond long et long ciel tout droit

Flat right long (apex far into corner) and long crest keep straight

250 metres gauche 140 moins mi-long pas corde entrée léger gravette sortie

250 m left 140° half-long (apex a bit around the corner) don’t cut at the corner entry and there is light gravel at exit

100 metres attention à la flèche droite 156 ferme 100 mi-long

100 m caution at the sign post (turn arrow) right 150° over 60 m (this means the corner runs for 60 m) tightens to 100° half long

et gauche a fond long

And flat left long

sur droite a fond 100 metres

Onto flat right 100 m

droite 140 plus long fond

Right 140° plus long flat (flat out corner)

et gauche ferme 140 bon long pas corde

And left tightens to 140° ok (good corner although it may look weird from driver’s perspective, this is to prevent him from lifting off) long don’t cut

et droite 140 bon long

And right 140° ok long

et gauche 140 mi-court corde frein pour 60 metres face fleche gauche 100 corde max

And left 140° half-long cut braking over 60m until in front of sign (arrow) left 100° maximum cut

et droite 60 long pas corde

And right 60° don’t cut

sur gauche 80 moins rasé glisse

Onto left 80° minus go very close to inside (there is a rock) slippery

sur droite a fond long tard frein pour gauche 100 mi long 50 metres apres fleche

Onto flat right long late braking for left 100° half long 50 m after sign

et gauche a fond

And flat left

et droite 90 plus tard elargis

And right 90° plus late apex let the car go wide (this means the road is unusually wide and he should use it)

sur gauche ferme 140 moins long

Onto left tightens 140° minus long

sur ciel et attention a la fleche bleue droite 145 bon ferme 130 bon

Onto crest and caution at the blue sign right 140° over 50m then tightens to 130° ok

130 metres gauche 110 mi-long début dalle

130 m left 110° half-long start of concrete slabs (this is useful to know because it's more slippery smooth concrete)

200 metres attention droite 149 bon frein pour gauche 90 mi-long derriere paille

200 m caution right 140° over 90 m ok braking for left 90° half long behind hay bale.

sur droite a fond long

Onto flat right

et attention gauche 110 tres long tard corde legere

And caution left 110° very long until apex small cut

et droite a fond sur gauche 130 plus plus mi-long corde fond ouvre

And flat right onto left 130° plus plus half-long cut then opens flat (flat ou corner)

et droite a fond corde legere sur attention 70 metres gauche 130 moins long tard rail sortie

And flat right small cut over caution 70 m left 130° minus long late (late apex) narrow clean line for wheels only at exit (rail sortie) (this means stay in the clean tracks)

sur droite a fond pas corde sur gauche a fond et attention droite 154 ferme 130 mi-long béton

Onto flat right don’t cut onto flat left and caution right 150° over 40 m tightens to 130° half-long concrete (change to better grip level)

et attention gauche 124 moins frein corde ok pour droite 80

And caution left 120° over 40 m braking cut ok for right 80°

250 metres …

250 m …

There is a lot of detail and sometimes his co-driver has little time to say it all. It gets even worse in twisty mountain roads.  Loeb focuses on describing what the shape of the corners are like. You may think this is elementary!

Oh, but it is not! 

Many do it the other way and rely mainly on speed indications with some description of road conditions and apex location through words like short, half-long, long, very long, etc. Petter Solberg's notes are a good example of speed notes with notes like "5 right minus half-long", 5 being the gear and minus meaning it's a bit lower in rpm's, half-long meaning the apex is a bit around the corner. I know you're gonna say it's pretty straight forward and you don't need me to tell you all of that. Well, you are right and that's exactly my point! In speed note cases it is often straight forward. 

Loeb’s system is primarily descriptive, with sometimes some speed notes. By speed notes I mean “plus” and “minus”, “flat” additions, “brake points”, etc. When necessary he will also give some notes about where to position his car on the road. In this case we are talking about where to be on a blind crest, letting the car run wide on a corner exit, how much to cut, etc.  Others do the same to a certain extent but he puts more effort into describing very precisely the corner combinations, how long corners are in terms of meters and where he should brake! This is paramount information in blind corners. Many top drivers simply don't do that.

You will hear things like "very long 6 Left tightens into 2". Unless the driver has intimate knowledge of the stage this information is simply not enough to be "balls out" in a reliable way. 

You will notice on the in-car footage that a "flat" corner (a fond) for Loeb is only used for corners which have almost zero angle to them (they happen to be flat out, mostly, yes). My point is if he comes out of a dead slow hairpin and into a 90° left he will call that corner a 90 left and not a flat left, even though it's on full acceleration.

For a driver the advantages behind the descriptive system are the following:

1. after getting used to it your brain will automatically understand exactly what is coming up and you will instinctively adjust the speed, even though there are few speed indications. 

2. the descriptive system is independent of weather or road conditions.

3. almost completely independant of your car's performance level.

4. very useful in reduced visibility.


Point n° 1 is a question of work, patience, dedication and understanding but n° 2 & 4 are the real biggies and when rallies have new stages and/or are fought in changing conditions these will really pay off.

I believe that his note system was pivotal in his success. It permitted him to use his skill to the fullest whilst being able to keep the risk taking to a minimum and hence his very limited amount of accidents. It also enabled him to set-up his cars for precision driving and he could focus solely on achieving maximum traction and speed out of corners. 

This guy's driving was in my opinion a dream come true for his engineers.