Track Tac

Racing, handling, karting adjustments and lap time improvemets

R

robox45

New member
I think this is a very important subject that may have been talked before, but i could not find all these things before.

Lets talk about racing. In racing, half of things and results are up to you and your driving skill, but the other half is up to your karting. You could be the best skilled pilot out there, but without a good karting you can't show the best possible results.

And this is the place were i want to talk about setting up your karting for the best results on asphalt track racing.

few weeks ago ended my last championship stage. I did won and i have won few other races as well, but i have no knowledge about adjusments. after that I'm starting to wonder about all the adjustments and setups that changes the handling of you kart. So im just going to fire all my questions right away:

1. tire air pressure. we all know that too much air pressure in your tires can and will make your back wheels to spin out and make you drive corners in drift (oversteer). But whats if the tire pressure is too small? can it make your kart to drive corners in oversteer? And how about wet tires? i have driven in wet track only two times. the first, my kart drove in a huge understeer, but the last time it took corners like in the tokyo drift movies. can too small air pressure make the kart in to a massive oversteering device?
2. how much does changing the width of the front and back affect driving the corners? cornering is one of the most important things in racing. whats the best width adjustments? is it better to make your kart tires as width as possible, is it better to make the front wider than the back, or the opposite?
3. I have been hearing guys talking about chassis. they say that they have changed the chassis to a new one and it drives completely different and better. is it true? does chassis become soft in time and how does it affect your driving?
4. center of gravity and seat position. in car racing, the best GC ratio is 50/50, but does that apply the same to kartings? and how much does changing the seat position (to front, to back, up and down) affect your cornering?

And what are your other experiences in adjustments?
 
Almost nothing in Car Racing applies to Kart Racing.
Drift is not oversteer. Drift is all four wheels losing traction.
Oversteer is the back end coming around with a set amount of steering input which causes you to make a tighter turn than the
steering input would indicate.
Understeer is the opposite. It takes more steering input to make a turn.
You'll need to post your kart manufacturer and all your weight %.
Front, Cross, Left.
Oval or sprint.
 
Probably the reason that you can't find "all of these things" together here is because it takes books plus experience to answer your questions. Not knocking your questions - they are good - just saying that there is not enough space in these forums, and too many variables related to your kart / track / class / driving style to give simple direct answers. There are good karting chassis books available and advertised on this web site. But in general...

1. Low tire pressure allows the tire to act softer, which can increase grip. But there is a limit here: without enough air the tread and sidewalls aren't supported enough, causing them to buckle and lose grip. Many karters notice significant grip changes with half pound pressure differences... some can feel even smaller increments. Wet conditions are different - that effects grip that the tire tread gets against the track, aside from whatever air pressure you use. Yes, too little air pressure can cause a push (understeer) if there isn't enough pressure to support the tire (keep all of the tread in contact with the track, and keep the sidewalls stiff enough that the tire doesn't just flop over).

2. Changing front and rear track widths can have a major effect on cornering. Basically, it determines how much and how fast weight transfers which in turn effects tire loading which in turn effects grip. Generally, track width effects are opposite for dirt tracks vs. paved tracks. Track width adjustments are usually very coarse adjustments - a little can make a big difference. Ask your chassis manufacturer for their suggested track width starting points; generally it will be narrow for dirt or wide for pavement. Road courses are trickier than ovals as far as setup compromises... generally I try to optimize my setup for the part of the track I feel is most important for gaining time or minimizing losing time.

3. New chassis can drive differently due to change in design and / or the old chassis could have weakened. Kart chassis flex, and that does cause them to eventually wear out. However it is hard to measure because it is affected by design, overall weight, horsepower, track conditions, etc. I've experienced an older kart that was raced only at one track and only in the same class (weight and horsepower) that "took a set" (bent) to that track - which optimized its handling for that set of conditions. So a chassis that becomes "soft" in time isn't necessarily bad... but because design keeps improving older karts eventually become obsolete.

4. By design karts rarely achieve a 50/50 front/rear weight split, due to the driver and engine located toward the back of the vehicle (those are the two heaviest items except for the chassis itself - in adult classes the driver weighs more than the kart). Because the driver is a significant weight, seat position is critical - and so is its ability to hold the driver so his weight doesn't shift while the kart is moving. Seat mounting effects weight transfer in the corners - not only how much, but also when.

My experience in adjusting boils down to:
a) Obtain a baseline from the chassis manufacturer.
b) Experiment with settings via advice first from the manufacturer, then second from TRUSTED experienced racers.
c) Expect newer chassis to respond more noticeably and consistently to changes than older chassis. One way you can tell that a chassis has worn out is when you make large changes but cannot feel much difference in how it handles. Experienced setup guys may notice this on their scale readings.
d) Always evaluate changing track conditions and the driver's reactions to them when evaluating chassis adjustments. They can effect each other.
e) When you have a setup you like, make it your new baseline. Also note how changes effect feel and performance.
f) When you think you have it figured out, prepare for a new monkey wrench to be thrown in and having to work through all of this again!
 
Good Answers!

Someone ... said:
Probably the reason that you can't find "all of these things" together here is because it takes books plus experience to answer your questions. Not knocking your questions - they are good - just saying that there is not enough space in these forums, and too many variables related to your kart / track / class / driving style to give simple direct answers. There are good karting chassis books available and advertised on this web site. But in general...

1. Low tire pressure allows the tire to act softer, which can increase grip. But there is a limit here: without enough air the tread and sidewalls aren't supported enough, causing them to buckle and lose grip. Many karters notice significant grip changes with half pound pressure differences... some can feel even smaller increments. Wet conditions are different - that effects grip that the tire tread gets against the track, aside from whatever air pressure you use. Yes, too little air pressure can cause a push (understeer) if there isn't enough pressure to support the tire (keep all of the tread in contact with the track, and keep the sidewalls stiff enough that the tire doesn't just flop over).

2. Changing front and rear track widths can have a major effect on cornering. Basically, it determines how much and how fast weight transfers which in turn effects tire loading which in turn effects grip. Generally, track width effects are opposite for dirt tracks vs. paved tracks. Track width adjustments are usually very coarse adjustments - a little can make a big difference. Ask your chassis manufacturer for their suggested track width starting points; generally it will be narrow for dirt or wide for pavement. Road courses are trickier than ovals as far as setup compromises... generally I try to optimize my setup for the part of the track I feel is most important for gaining time or minimizing losing time.

3. New chassis can drive differently due to change in design and / or the old chassis could have weakened. Kart chassis flex, and that does cause them to eventually wear out. However it is hard to measure because it is affected by design, overall weight, horsepower, track conditions, etc. I've experienced an older kart that was raced only at one track and only in the same class (weight and horsepower) that "took a set" (bent) to that track - which optimized its handling for that set of conditions. So a chassis that becomes "soft" in time isn't necessarily bad... but because design keeps improving older karts eventually become obsolete.

4. By design karts rarely achieve a 50/50 front/rear weight split, due to the driver and engine located toward the back of the vehicle (those are the two heaviest items except for the chassis itself - in adult classes the driver weighs more than the kart). Because the driver is a significant weight, seat position is critical - and so is its ability to hold the driver so his weight doesn't shift while the kart is moving. Seat mounting effects weight transfer in the corners - not only how much, but also when.

My experience in adjusting boils down to:
a) Obtain a baseline from the chassis manufacturer.
b) Experiment with settings via advice first from the manufacturer, then second from TRUSTED experienced racers.
c) Expect newer chassis to respond more noticeably and consistently to changes than older chassis. One way you can tell that a chassis has worn out is when you make large changes but cannot feel much difference in how it handles. Experienced setup guys may notice this on their scale readings.
d) Always evaluate changing track conditions and the driver's reactions to them when evaluating chassis adjustments. They can effect each other.
e) When you have a setup you like, make it your new baseline. Also note how changes effect feel and performance.
f) When you think you have it figured out, prepare for a new monkey wrench to be thrown in and having to work through all of this again!
Click to expand...
 
Great answers, really. Makes me wonder how my kart can drive that well without all this knowledge. I have a feeling that I would need a free, full day for different tests.
 
robox45 said:
Great answers, really. Makes me wonder how my kart can drive that well without all this knowledge. I have a feeling that I would need a free, full day for different tests.
Click to expand...

Thats why most tracks have Test and Tune . We try every thing we can think of just to see how the Kart will react . Sometimes we do stuff that we know should slow the kart down and we prove are self wrong . Get out to your local track and test . Start with a note pad and wright every thing down you can think of . Make sure you know where your base line is so you can always go back .

Good Luck and Have FUN !!!!
 
4. Seat position. a small change can take a last from understeer to oversteer .how you can prove that? Go to am arrive n drive place where the karts have adjustable seats. Moving the seat front or back an inch can take you from having no rear end grip to having no front end grip.
 
I don't have a single model kart. how do I put this... its built from different parts. i bought it used. Chassis is form Birel, but it looks like some older model if i compere it to the newest design. when i will be near the kart I will check the year. Engine is a tuned honda gx270. it weights about 165 KG.
 
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