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The " Art " of driving in the rain

Question ?
The " Art " of driving in the rain
 
Answer !

Rain is the best fun - Really hones your driving skills.

Many drivers hate driving in the rain, others love it. The ones that love it have an advantage going into a race because they are prepared for it and are looking forward to it - and they usually think they are very good in the rain, while the ones that hate it often think they aren't great. It's a good idea to learn to love it and practice in the rain as often as you can, nothing beats seat time to figure out how to drive in the rain.

(below - Martin driving in the rain - the BEST FUN - a few years back )

 


Race gear:

A rain suit is a good idea to keep yourself dry during the race. The suit is worn over your normal suit, and is there to keep you dry. Remember that if you don't wear a wet suit you might end up carrying a few extra kilograms of water around with you that'll slow you down (on the cool-down lap it might be a good idea to open the zipper on your rain suit to let in as much water as possible to bring up your weight if you know you're close on weight - just don't tell anyone what you did). In cold climates the water will make you cold enough to not be able to affect your concentration. Clear rain suits are best especially if you have sponsor logos to keep visible - or use the Red SQ Racing rain suit - it promotes us :)

Plastic over-boots are used by some to protect and keep their kart shoes dry, but might make you lose feel for the pedals. Plastic kitchen gloves can be used over your normal gloves but it's down to driver preference. Now you might look like you have done the washing up, but at least you stay dry and feel comfortable.

You need vision to win:
"Turbo-Visors" can be used to keep visibility clear, and require you to use a clear visor that has been cut-out to provide a clear view. The other option is to use anti-fog products or good quality anti-fog visors, and on the outside some drivers like to use Rain-X to have the water flow away quickly. Visors that have some kind of anti-fog treatment over them are a lot better when they are new - over time they become less effective - so if you have a new clear visor and you're about to race in the rain it's a good time to put it on your helmet.

 

Driver input:

Getting on the throttle smoothly is even more important on a wet track. One thing that isn't as smooth is turn-in with the steering. An almost violent quick jerk of the steering wheel to full lock (or almost) is used to turn the kart into a corner - this should not make the kart spin but rather it should induce a bit of understeer because with the quick steering action the tyres exceed their traction limit, but still make the kart turn in nicely because the violent action forces the rear-inside wheel up otherwise the kart might not generate enough force to do like it does in the dry. By lifting the rear wheel the kart is able to turn in nicely without understeering off the track. It takes a bit of confidence to try this technique but once you've tried it you'll realize how it can work. Of course in gradual turns or certain corners the quick turn-in isn't going to work. Braking can also be better if you are a little bit more violent at the very initial point of braking than you would be in the dry so that you know where the limit of grip is, and you can feel the tyres biting into the track.

Aquaplaning:
This is when there is so much water on the track that the wet tyres are unable to cut through it and contact the track surface, but instead skims across the top of it. The best thing to do is to avoid puddles that are this big, but if that isn't possible then when driving through a large area of water it's best to do as little as possible. Getting off the throttle a tiny bit if you were on full throttle can be a good idea as staying planted on the throttle might result in wheel spin which generally throws the kart sideways as one wheel will get better traction than the other. Getting off the throttle abruptly or braking is also not a good idea as the change in weight transfer can really unsettle the kart and make you lose control. The main thing to do is to have the steering straight when you come out of an aquaplaning situation because if you have your wheel turned the front tyres will regain traction before the rears do making the rear tyres step out and throw you into a spin.

 

The racing line:

The fastest racing line usually changes considerably from a dry track to a wet track. The part of the track  that is used in the dry is smoothed out by all the karts running over it and it gets all the rubber laid down on the dry line which is grippy when dry, but becomes extremely slippery when wet. The best grip in the wet is usually found everywhere else but the dry line. You can see this quite clearly when watching Formula 1 races as the drivers take very strange looking racing lines because they are trying to drive where the best grip is. This is compounded on a kart track as chain lube builds up on the race line, and once the water hits the track, the oil lifts to the surface. This is why you can drive right around the outside of someone in the rain. You have grip, they don't

TBelow is an example of a slow hairpin turn that requires braking both in the dry and wet. The dry line (in RED)  shows a line close to a geometrically perfect line that is taken in the dry by drivers and that is where most of the rubber has been laid down. The wet racing line (in Blue) slightly avoids the rubber and oil that has been but down in the braking area so that maximum braking is achieved, and then crosses over the dry turn-in point and keeps going to the edge of the track where a more abrupt and much later turn-in is used where hopefully there is a lot of grip compared to the wet rubber line on the inside. The line also allows for the kart to be straightened out as soon as possible and the dry line is once again crossed with the kart straight to avoid wheel spin and oversteer when the throttle is applied.


Here's another sample of how a wet line can be very different from a dry line. This corner is almost flat in the dry, with only a slight lift required on turn-in. In the wet the driver needs to apply the brakes for a short time to slow the kart for the corner. The driver brakes quickly just as he has passed over the main rubberized section of the track and then after the braking is done in a straight line the turn-in is quick and the driver stays on the outside where he has found the most grip, and builds up speed. The driver then finally cuts across the dry line again with his kart already almost completely straight and he gets on the throttle again.


Note that the above examples are just that, examples. Track conditions, kart setup, driver preference, and many other factors will change what the ideal wet (and dry) lines through a corner are. These examples are to show how dramatically different wet driving lines can be, so go out there and find the grippiest part of the track in the wet! Knowing what happens when the rain starts falling can be a really big advantage over your competitors, particularly during the first few laps of a wet race!

A general rule is that the newer a track is, the less used it is and the less rubber and oil has been laid down which makes the wet line closer to the traditional dry line because the advantage from going off-line is reduced. But even with a brand new track that nobody has ever run on the line will be different, because you have to start getting that power down in a straight line, and the entry has to be violent enough to lift the inside-rear wheel so emphasis is placed on squaring the entry of the corner to make for a more direct exit

 

Tyre Characteristics:

The loss in grip of wet tyres compared to dry tyres is less longitudinally (traveling straight) than it is laterally (sideways). What this means is that in the corners you will have a fair bit less sideways grip, but especially under braking (when going directly straight) the loss of grip isn't as bad. So when you are driving your braking points might not much earlier than you thought. You will already be traveling slower down the straight than you do in the dry because you exit the previous corner at a slower speed than you would in the dry and because of more drag from standing water. Your braking point might only be a meter or two before your dry-braking point, if that. Another characteristic of wet tyres is that they give less warning before losing grip, which is why the earlier advice of abrubt steering input on turn-in makes sense - because you reach the grip limit of you front tyres right away they can't surprise you by suddenly losing it. Constantly keeping the kart near the point of losing grip (just barely sliding) is a good technique because the tyre won't surprise you by suddenly giving way, but the technique takes a lot of seat-time in a kart to master.

 

Other Considerations:

One thing that changes from a dry-setup to a wet-setup are the tyres. Remember that rain tyres typically weigh less than dry tyres so don't be caught out by being underweight when you finish your race! Although this article doesn't focus on wet weather setup, it's important to remember to use a rain-box over the engine air intake to avoid flooding the engine with water (check the first picture in this article and you can just see a high tech BUCKET over the air-box on the engine).

The Very Best Advice:
Practice at 110% - find your limits and race at 95%.. to win ..first you must finish and the final thing to remember is that karting in the rain can be even more fun than in the dry!


Now go out and get soaked!


Martin
(and other internet sources)

 
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