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TOPIC: Art's Advice - Revisited |
| Eric G
May 31, 2005
3:56:08 PM
Entry #: 873643
| I posted this also, but they're mixed in with the other stuff. Here's a series of articles written by Art Carbonell. It's some of the most useful stuff you could read. Read it even if you don't feel you're at the level of what he's talking about. It will make sense eventually. For those of you who don't know who art is, think of him like our Yoda. He's a former WORLD Champion and a great pioneer of Nitro Rc Racing. He's at the track every weekend, and unless he's super busy, he's always willing to lend a helping hand or give advice. Some of this info is from other specific cars, but the general ideas are the same. Hope this is helpful to some of you.
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| Eric G
May 31, 2005
3:56:42 PM
Entry #: 873646
| Driving - A State of Mind
Driving is all mental. You have to set your mind to what you're going
to do in the race. And if you can do it, it's something very exciting.
This all depends on the situation, your car, the track, the setup.
The main thing is if it's a short race, or a long race, you try to set
your car accordingly. Let's say you have a short race, you don't want
to start your race with big tires, because you're going to be pretty
slow through the whole race. You should have an idea when you qualify
how much tire wear you're going to have. You almost always go a little
bit more than that. Let's say you start with 68mm tires and they wear
down to 67mm in five minutes. You now know that you're wearing 1mm in
five minutes. You have to remember too that the bigger the tire, the
less wear you'll have, for the same amount of time. So, in a 20-minute
race, that's 1mm per 5 minutes, or around 4mm tire wear in a 20-minute
race. So, you might want to start with say, 69mm tires so you stay in
the right range.
Some people run too big a tire. For example, if they used 70 or 71mm,
they wouldn't have the speed or the handling with this big a tire, and
because it's bigger, it will take longer to wear the tires. I usually
like to set up the car in qualifying pretty close to the setup for the
Final. So, I usually run a little bigger tire in qualifying, just to
see how the car works and handles. If the car doesn't work with these
tires, or if it isn't as fast as it could be, in qualifying you can
always run smaller ones, but then your car will be different in the Final.
A lot of people go the other way. They run very small tires in
qualifying, feeling that they're going quick, but in reality, it's
slower than if they had used the right size tires. Of course, your
stopwatch should tell you the truth.
Getting back to driving, there's qualifying where you try to go as fast
as you can in five minutes, of course, avoiding wrecks or traffic if you
can.
Traffic is something that is very frustrating. A lot of times you think
they get in the way, but it's not their fault. It's something you have
to deal with. The better drivers try to anticipate what the traffic is
going to do. Unfortunately, this only comes with experience, and using
your head - it's all mental!
Anyway, when you finish qualifying, for the Final it's a little
different strategy. You try to set a pace that you're comfortable with,
and if you can maintain a fairly good lap average you'll be surprised as
to what happens at the end! Again, you have to deal with traffic, same
situation. Usually a lapped car will give way, but sometimes not. But,
you have to deal with that. If you're fighting for first place, it's
still very important to maintain your pace. You can go a little
quicker, but then you take a chance of making a mistake or breaking your
car.
I've been in situations where at the start of the race I was in last
place, but by maintaining my pace, I was able to win the race. By
maintaining your pace, you are also saving tires, saving fuel, and
saving the car. That's important, saving the car for the whole race,
not just five minutes. If your pace isn't quick enough to be in the top
three, let's say, it's still important to maintain it, because who
knows, whatever happens in the race you could end up being second or
first just by finishing the race!
Anything can happen in a race. The guy running in first or second can
break or not finish for any number of reasons. It's not always the
fastest guy that wins the race - you have to be there at the end to
collect your laurels.
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| Eric G
May 31, 2005
3:57:22 PM
Entry #: 873649
| Handling and Settings...
HOW BRAKES EFFECT CAR SETUP
The biggest thing about how brakes effect car setup is when you brake in
the wrong place or at the wrong time. Your car may do something you had
no intention of doing. If you set your car up properly, you can get the
most out of your car's braking ability, while at the same time
minimizing the chance that your brakes will cause your car to do
something you didn't intend for it to do.
DRAG BRAKES vs. PUSH BRAKES
Drag brakes can upset the car in a turn. You may want to coast through
the turn. If you decide you're not on the right racing line, and let off
the throttle at that point while the car's turning, the brakes will come
on, and it may upset the car, possibly throwing the car even more off
the racing line, which not only hurts you in the turn you're in, but
also puts you on the wrong line for the following turn. Push brakes
won't do that, because when you let off the throttle, your car will
coast. If you're using push brakes, you can brake deeper in the turn,
and still take the turn at the desired speed.
REAR DROOP SETTING
To allow you to effectively get the most out of your car's braking, you
have to adjust your car's "droop setting". When you're braking, if you
have too much droop, the front of the car will lower, the rear of the
car will go up, and the car may go into a slide. Remember the cartoons
in the movies of cars braking very hard, with the front end of the car
so low it's scraping on the ground, smoke coming from the front tires,
and the rear of the car way up in the air? The correct droop setting
will minimize this.
REAR TOE-IN
To allow you to get the most out of your car's braking ability, you have
to adjust your rear toe-in. A little rear toe-in makes your car more
stable under braking. Start with 1.5 degrees on each rear tire. If the
track is dirty or "loose", you may want to use a little more than that.
Without any rear toe-in (and if you also have no rear camber) the car
will go perfectly straight. When you apply the brakes, because of
"weight transfer" from the back of the car to the front of the car, the
back of the car gets light, and can move off-line either way. With a
little toe-in (or camber) even when the back of the car gets light due
to braking, you have a little more straight-line stability. More rear
toe-in also gives the car a little more traction coming out of the turn.
(Less rear toe-in gives you more rear steering and higher straightaway
speeds.)
REAR CAMBER
Camber has an effect on car stability similar to rear toe-in. If you
have more rear camber, your tires will wear in a "cone shape". We're
only talking one or two degrees here. The cone shape simulates stagger
on a real car. Take a cone shaped part, such as a paper cup, and tip it
on its side, then roll it. You'll notice that it wants to "curve" in an
arc. When the tire is coned such that the diameter at the inside surface
of the tire is approximately 2mm less than the diameter on the outside
it's about right. This much camber has a stabilizing effect on the car
under braking, to help keep the car going in a straight line. Also, with
the proper adjustment of the car's "droop setting" (see above), there is
a limit of how far the rear of the car can lift. If the camber of the
rear tire has been set right, and the tire has worn into the proper
"cone-shape", when the rear end of the car lifts, more of the tire is in
contact with the ground, which also tends to make the car more stable.
Don't use too much though - with too much camber, you'll spend too much
time only running on the inside edge of the tire.
OVERDRIVE RATIO
Overdrive ratio also effects braking. On a four-wheel-drive car, if you
have a one-to-one overdrive ratio, your car will seemingly coast
forever. With more or less than a 1:1 ratio, one end of the car or the
other will be "dragging", which produces an effect similar to drag
brakes. If you want to use a lot of braking, you have to compromise on
many of the settings to make the car more stable. You have to find the
best compromise for good braking AND good top end (straightaway) speed.
I'll have a lot more information on overdrive ratios in a future column.
USING YOUR BRAKES
If your car spins out every time you hit the brakes, don't brake so
hard. If the car is set up properly and still spins out, just use less
brake. Remember that a tire only has so much traction. You can use this
traction for acceleration/braking, or for turning. If you're using the
traction for one of them (such as turning) and simultaneously try to use
it for the other (such as braking), you'll overload the available
traction for the tire, and the tire will start to slide. For maximum
braking effect, brake while going in a straight line, and NOT when
you're turning.
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| Eric G
May 31, 2005
4:02:18 PM
Entry #: 873674
| How do you go about Setting up the Car?
Some people get the car setup information, but they don't bother with
it; they just look at it, and go and do what they want to. For their car
to work at its best, they should take a little time and follow the steps
the car manufacturer recommends in setting up their car. Go through step
1, 2, 3, etc. Everything interacts with everything else. So for example,
for step 5 to work the way it should, steps 1 through 4, and 6 on, also
have to be right. I set my car up in the same order as shown in the
setup guide. He also knows that for the whole setup to be correct, all
the individual steps have to be correct, not just some of them.
The setup sheet you get from the car manufacturer is really a "starting
point" to teach you how to go about setting up the car. Unfortunately, a
lot of people finish setting up the car, put the tires on, put the car
on the table, look at it, (perhaps looking at the ride height), and
change something (such as lowering the car with the shock collars), but
in doing this they have just re-arranged (shot) their whole setup. If
you have a Serpent car, you should have a Serpent setup sheet. If you
don't have a setup sheet, call the car's manufacturer or ask a local
racer for a copy of theirs.
Car setup is something you have to learn. Once you're familiar with it,
and have more running time, only then can you make changes,. By then,
you'll realize what else is happening. For example, when you're new to
RC car racing, you might not realize that changing the ride height also
changes the roll center. Start with factory recommended setup and go
from that. (For the example listed here, instead of raising chassis,
maybe you should use larger tires). By the way, in all these initial
setups, if you don't have the mechanical part done right, all the setup
time in the world won't matter. Your car MUST have a freely working
suspension, properly built shocks, and so on.
Another thing to remember is that maybe instead of changing springs,
damper, etc., start by changing the simple things, like tire compound,
wings, spoilers, diff tightness, and your driving style (brake
adjustment, etc.). Also remember, the type of body you're running makes
a difference
Different track conditions require different setups. Once your car works
the way you like to drive, you're probably close to a setup for
different tracks. When you go to a different track, most of the time you
don't have to make many changes. There also isn't usually enough time to
make too many changes. Some people arrive at a new track, and from then
on "chase the track", by constantly changing the car. It helps to
realize that most tracks start off "loose", with little traction, and as
the day goes on, and more cars race on the track, traction improves. A
lot of people have this problem - they go out and can't drive the track,
so they come back, and make many changes at a time. They keep changing
the car to match the track, but the track keeps changing, so they're
constantly changing their car. This "chasing the track" wastes time. If
you're more experienced, you might make changes anticipating what the
track will be, but even an experienced racer may get caught up in this
"chasing the track". One suggestion: as soon as you feel comfortable
with your setup, don't make major changes. Also, write down this setup,
so at least you know you can always get back to it.
Some other suggestions:
a) Pay attention to all the details, so things work like they're
supposed to.
b) If you start getting lost in the car setup, go back to the beginning
and start over.
c) Check all the "small" details, things you may tend to forget.
Last weekend I ran good, and the car was strong. This past weekend,
it was not right. Most of the time when this happens, it's because
the track conditions have changed.
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| Eric G
May 31, 2005
4:02:43 PM
Entry #: 873675
| Adjusting to a new race car....
When you get a new car, replacing the car you've been racing, you have
to learn what's different. You have to learn (or relearn) a few things,
due to the different design of the car. Keep an open mind - the new car
may be very similar to your old car, but don't assume that it will
respond to adjustments in the same way that you're used to.
If the new car is a fairly good design, mostly you'll be learning how to
adjust the new car - how the different adjustments effect the handling
of the car on the track. For example, you have to learn how to adjust
the sway bars.
Usually if you soften the front sway bar, it helps a car turn better
going into the turn. Of course, some cars don't act that way - its
something you have to learn. You need to learn what the car likes, in
order for you to make changes, so that you can run fairly quickly.
Another example is the caster setup; change the caster and see what it
does. An important thing to remember when doing any of this, is to ONLY
MAKE ONE CHANGE AT A TIME. Also, write everything down - make a note to
yourself, so you don't forget. If there are other racers at the track,
and they all have the same car that you do, you can all learn from each
other a little, but be careful - don't depend on the other guy
completely.
If you don't have time or a track on which to do this testing, it's more
difficult. Different tracks will require different setups. Most of the
manufacturers give you a starting point for car set-up. From there you
can try different things. Be careful - make sure the track isn't too
bad, or at least is similar to tracks you've run on before.
Traction: If traction isn't that good, you compensate for the traction
on the track - that's OK, but it's not the way to go fast. Make sure the
track is fairly clean, and your times are respectable lap times. You
have to have a base to start with.
Tires: Different tire compounds have the biggest effect on car setup and
handling. You can try different tires and so on, but before you try
them, start with the basic kit setup. You may want to try combinations
of 35 front / 30 rear, or perhaps 40 front / 35 rear. I like to run the
hardest rear tires I can get away with. If it's too difficult to drive,
I back off a little, and go to a softer compound. Don't go from a 35 to
a 25 - that's a big change.
Body: You should run the body that you normally run with that car, so
that it's the same as before. That's one less thing to take into account
when comparing the new car with the old.
Fine-tuning: You're looking for what the changes do to the car, if you
change something a little and it makes a big change on the car, write it
down, so when you make this change somewhere else you won't forget how
big a change this will make on your car.
Gear Ratio: If the car has got different gear ratios you should set the
ratios so they're reasonably close to the gear ratio you used to run. Do
that for both first and second gear, so both ratios are the same as what
you used to run.
Spring Rates: You might want to try different spring rates, but again,
one thing at a time. Try changes to the front, see what happens, then
put your original spring back on the front and change the rear spring
and see what the car does. It's basically a trial and error situation.
Once you get more information, and you run the car more, you learn how
to adjust it to different conditions.
Overdrive Ratio: If the car has different overdrive ratios start with
the factory setup. On the Vector that's a 25 or 24 tooth pulley (the
front middle pulley). The factory recommends 25 tooth pulley to start.
It's a 1:1 overdrive, using the recommended tire sizes, which makes the
car neutral. If you go to a 24 tooth pulley, that makes the front pull 1
1/2 percent more than the rear, giving you more front drive. It again
depends on track conditions. I prefer the 25 tooth pulley so far. It
makes the car more neutral.
Engines: On some tracks your engine is very critical to your car's
handling. You're using power to turn, and the power makes the car turn
better. Note - if you have a new Serpent engine, the heat sink is
different, the way the center hole the top of the hole design is
different, and the temperature reading will be different. It all has to
do with how far the probe is from the glow-plug. Also remember that the
Raytek temp-probe is different from the Exergen. The Raytek focuses at
6", so it doesn't matter that much how close it the temp-probe is from
the glow-plug. The Exergen actually touches the spot where it focuses.
The color of the heat sink also makes a difference - an aluminum heat
sink isn't good for a reading, because it reflects. Black is best for a
truer reading. Speaking of engines, the biggest thing you should learn
if you want to be competitive, is to tune an engine without a temp
probe. You need to learn how to read the engine without a temp probe,
judging things by the way the engine feels, the way it runs, the amount
of smoke (which in turn depends on the fuel you're using). Normally you
can tell how lean the bottom is; if there's no smoke in the turns, the
engine is probably too lean at the bottom. A future column will describe
how to tune engines without using a temp probe.
Mechanical Setup: The biggest thing on any car, is the mechanics.
Everything must be done properly, and in good working order. The
mechanical components must work together on the car. The setup is the
last thing you do, only after the car is built properly. A good setup
can't compensate for bad shocks, binding suspension, binding sway bar,
etc.
Unless I have problems, I move all my electronics over from the old car
to the new car. I try to a set of servos for six months, then change to
another set, keeping the old ones for backup. Never use a brand new
servo for a big race - it might work well for 15 minutes, then fail.
This happened to me at the World championships in Japan.
Don't expect miracles just because you've got a new car. Don't assume
that you'll automatically go two laps faster. If you're lucky, you'll be
faster - but it's all feel, driving style, getting comfortable with the
car...
Once you're comfortable with the car, get a stop watch, time some laps,
and see how the new car compares to the old car. Remember that when you
ran the old car and had good times with it, maybe traction was better
that day compared to your test day with the new car.
Lap times can be different (better or worse) for lots of reasons. You
have to take a lot of things into account, the track, conditions, the
weather, etc.
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| Eric G
May 31, 2005
4:03:05 PM
Entry #: 873677
| Driving in Traffic...
It's not easy to drive in traffic. When new drivers start out, they
don't have very much control of their car, not to mention all the people
screaming at them "Get your car out of the way!". These new drivers get
all kinds of advice.
I think that if you're just starting off, you should drive your own
line. Supposedly the faster guys should be able to drive around you.
It's difficult, when you have "tunnel vision", only seeing your own car.
It's hard enough to keep an eye on your own car, let alone ten feet in
front (or behind) you.
It's hard to realize (even for a so-called "expert") how fast you are
going. It's easy to be doing 90KPH in the length of a straightaway just
from a standing start! It's easy to overshoot the turns, especially in
the beginning. New drivers are happy enough to make the turn, let alone
miss someone else.
When you're driving with these people, you have to anticipate what is
going to happen. I try to complete the pass when I first come up on a
driver (if I can). If not, the problem is the guy will be aware that
you're there, and get nervous. But lots of times you have to follow and
wait for an opening. Always try to pass on the inside. Try to set him up
for a pass as soon as you can, but sometimes you have to be patient.
Unfortunately, some guys want to race you, even if they're a lap down.
However, since you're all on your own clock, this is silly. Most of the
time the fellow you're trying to pass ends up against the wall, upset.
Eventually you can only hope they learn to let the faster guy by. This
doesn't apply if it's a Main, and you're racing for a position. In that
case, the other guy has every right to try to block you, and prevent you
from passing him. A lot of times you both end up going a little faster,
since you're pushing each other.
I think the thing to remember - if you know the other racer is better
than a beginner, he is trying to go faster, but doesn't know what line
to take. That's the person to worry about. His car may be as fast as you
when you do pass him. Try to leave enough room to make the next turn
before he gets to it. He'll come up alongside you and hit you, usually
on the side. So, stay inside for the next turn (usually not a good line
for going fastest) but safest. This is the typical reaction. He is
better than a beginner, but has enough speed to be dangerous. It's
experience - and you're going to be frustrated, but you've got to learn
to anticipate what is going to happen. If you're coming up on good
people, then it becomes intense, and a lot more enjoyable You've got to
remember, you started on their level and that it's a learning process.
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| Eric G
May 31, 2005
4:04:48 PM
Entry #: 873685
| Racing Strategy...
Racing is a mental game. This applies to any kind of racing. It doesn't
matter if you're inside the car (full size cars) or outside (R/C cars).
It's not only a mental game, but also an emotional game. You have to
control your emotions, and know your limitations. You need to try to
optimize the limitations to your car, so you can make the car easy for
you and your particular driving style, so you can do consistent laps and
make the final at a big race.
There are two racing strategies, one that is a qualifying strategy, and
the other that is the actual racing strategy. In qualifying you want to
be as quick as possible. You have to be aggressive, and set up your car
accordingly. It might be hard to drive your car set up that way for more
than five minutes (the typical length of a qualifier), but it is very
important at big races to try to make the final. If you can't get the
setup quite right for qualifying, if you finish the qualifier right, you
can still make the final. You might not make TQ, but getting into the
Final is what's most important.
Finals
For the final, there are a couple of ways to look at it. Of course, you
always try to finish first, but in some cases you know you are not as
quick as the other guys are, so you go for consistency, to run the
distance. You have to set the car up accordingly, so you can drive it
for the length of the race without wearing out either yourself or your
car.
Again, there are a few different ways to set up the car. A lot of people
just drive - they always set up the car for qualifying to go fast for
five minutes. However, when you go to the final, it's at least 30 to 40
minutes and maybe even an hour-long race. If you run your qualifying
setup in the final, it makes it very difficult.
You're also going to wear out your tires more. You might start out with
softer tires, but in the final you need harder tires or they're not
going to last. You have to look at overall tire wear, and maybe even
make some practice runs. The practice runs will allow you to get used
to the harder tires (which you'll probably need to run if it's going to
be a long race).
What to do if you make the final at a big race.
What do you do if you make it into the final at a big race? Let's say
your car is working fairly well. Maybe you're not the quickest, but now
you have to drive the whole race. You have to set a pace for yourself.
Start out with a pace that's comfortable for you. I personally try to
run that pace, knowing I can go a little quicker if I have to. I know
that if I do run quicker, it will be easier to make mistakes. Not only
that, by running quicker I'll wear out the car and the tires, a little
more, and the engine will be a little hotter. It's important to take
everything into consideration.
The biggest problem some people have, myself included sometimes, is
having a consistent pit crew, a guy who works with you all the time and
knows what you like, etc. it's very difficult to find someone like that.
In the old days, just by finishing the race you'd usually win the race,
but now it's so competitive that you can't do that. You have to go
quick, and you also have to have a good pit crew. Both are a big part of
the sport. Try to get a guy to be your pitman that's fairly quick at the
pit stops, but even more importantly, one who doesn't make mistakes.
Maybe your pitman might be a second slower, but it's even more important
that he doesn't overflow the tank, getting fuel on the tires, etc., and
that he's aware of what's happening in the race. Pit stops are very
important. If you run five minutes in the qualifier and barely make five
minutes, it's better to make that first stop a little under 5 minutes,
maybe at 4:45. Your pitman can then pick the car up and look at the tank
and see how much fuel you have left. It might take a second to do this,
but then you can plan accordingly.
Just because everyone takes 5 minutes between stops, that's not the
thing to do necessarily. Maybe you're a little smoother, and you have a
minute additional running time, so you might gain at the pit stops,
which is important at a race.
You also try to be aware of what's happening around you, especially if
you're racing with someone very close. You have to be aware of what's
happening with them, with the driver and with the pit guy. Personally
this knowledge helped me win the US Nationals last year, by doing just
that. I was behind a little on the track, but I knew my pit crew was a
little better than the other person's, so I purposely came in at the
same time as the other racer. Until then, we were pitting off sequence;
I was coming in a lap later than the other racer. On my last pit stop
(and his last pit stop) I purposely came in at the same time.
Fortunately I had a pit crew that was aware of what was happening.
Although there was no communication, I purposely came in at the same
time, knowing my pit crew was better, putting additional pressure on the
other guys pit crew. What happened - the other racer's pit crew spilled
or overflowed the fuel while refueling. They had trouble, and I took
over the lead and won the race. That's just one example how "race
strategy" and "race psychology" can help you win a race.
Another example is the last World Championships. Unfortunately I was
watching the race, and not directly involved. It was very disappointing
for me, but this example shows how important the pit crew and timing is.
I was watching one of the teams - they had to pit at exactly 5 minutes,
barely making it. Then one time that they went one lap too many. I saw
it coming - the guy drove past the pits. I said "that's it, they're not
going to make it". They ran out of fuel, blew a plug, and the rest is
history, the other fellow won the race. That's racing - anything can
happen, but the pit work is as much a part of the racing scene as the
actual driving on the track.
There's other example I know of. I don't want to mention any names, but
this person should have won the World Championships two or three times
already. He was usually the fastest guy on the track, usually TQ, but
when it comes to the final he always has problems. It's hard to point
what happened. One race he got behind at the start and he got knocked
around a little, but it's an hour race so there's time to come back. He
tried to push so hard to make up that time in 5 minutes that he broke
the car. There are similar examples in other races. He's one of the
fastest guys, but it just doesn't work out. Unfortunately, it's always
his driving style or something mechanical.
You've got to learn how to win races. It's not just going fast. It's
analyzing things and driving accordingly, and being aware of what's
happening on the track at all times, and controlling your emotions.
A lot of times I talk to myself on the drivers stand - I do dumb things,
and I tell myself to focus, to get back on track, and to settle down.
Again, you have to win races. It's not just going fast.
One race I remember I wasn't the fastest car on the track but I knew I
needed to keep up a good pace. I was way behind at the start, but I just
stayed there and drove consistently, and ended up second at the end of
the race. I didn't win but it was better than finishing third or fourth.
Another example was at the World Championships in Austin, Texas. I
qualified 9th. In the Final I ran at my own pace, and let everyone go. I
looked around on the driver's stand, how many new guys who had never
been in a World Championships final before. There were three of them. I
thought that they'd probably not finish the race, as this is a very
emotional race. I know how emotional it is, because it happened to me
when I first started. I let them go, and they got almost half a lap on
me at the beginning. I was 9th for the first ten minutes, I was 6th at
the 15 minute mark, I was 5th by the 25 minute mark working on 4th. I
got up to 4th, working on 3rd with twenty minutes to go in the race,
with a good chance of catching second. Unfortunately I had a big radio
problem then. It's hard to say if it was the radio or if someone else
turned a radio on, but I was out for the race, a big disappointment.
Just the same, this shows what you can do when you drive consistently
and know the pace you have to drive on so tire wear isn't too bad, you
get good fuel mileage, and don't use up the car or make mistakes.
In the Cincinnati Nationals that same year ('91 or so), I was again
running at my own pace. It wasn't as quick as a couple of guys in the
race, but I knew that tire wear was high at this track. In the US, we
don't even think about changing tires, which can be good or bad.
Sometimes you just have to plan on changing tires. Basically, everyone
there ran with no tire changes. We were equal in the pit stops, but I
kept the pace up so much that they had to run hard enough to keep ahead,
that they wore their tires out. I ended up winning the race because of
this.
This just shows you how you have to think what's happening around you.
Your car isn't perfect all the time, so you just have to drive it the
best you can. Again, it's a thinking sport. A lot of people don't think
so, but as in any other racing, NASCAR, Formula-1, whatever, you have to
be aware of what's happening.
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| Eric G
May 31, 2005
4:05:54 PM
Entry #: 873690
| Overdrive Ratios
The following information concerns gear ratios, particularly the
overdrive ratio. Although this is written for the Serpent, the general
principles apply to any four-wheel-drive R/C car. (With two-wheel drive
cars, you don't have to worry about this.)
Selecting the "best" overdrive ratio is something you have to try
yourself, to get the best overdrive ratio, tires sizes, and tire
compounds. The overdrive ratio has a big effect on the handling of the
car. That's why the tire size and the pulley ratios are so important.
Usually the more overdrive you have (the more front drive you have),
makes it a little easier to drive the car - but the car will not be as
fast as if you set the car up with less overdrive in the front (closer
to 1:1).
The reason the car is slower with more overdrive, is that even with the
one-ways, the car still is dragging a little with a lot of front drive.
If you want to see what kind of drag you have on the car, just roll it
on the ground with the brakes off. Roll it forward, and you can tell if
you have a lot of overdrive - if so, it will feel like you have the
brakes applied - the car won't want to roll freely. Reduce the overdrive
and try it again (roll the car again) and the car should roll for a
longer time. (This doesn't mean that it's better because it rolls
freely, it just means you have less drag on the car. )
A lot of tracks here in the states require a little more front drive
than on European tracks. With European tracks in particular, speed is
usually more important. Normally US tracks are a little tighter than in
Europe; you need a little more front drive to make the car easier to
drive.
More front drive gives you a little less steering going into the turn,
but where it helps you the most is in the middle of the turn. The
overdrive helps bring the nose of the car around, when you apply power.
Coming out of the turn, more overdrive will make the car tend to push a
little too, making the car a little more stable coming out of the turns.
Setting up the car the other way, using less overdrive, gives you more
steering coming into the turn, making the car turn in a little sharper,
but as soon as you apply power, the car wants to push a little, because
the front tires are not helping bring the car around. Coming out of the
turn (as soon as you come out) you have a little more steering, commonly
referred to as "throttle steering". This happens as you apply power, but
it also makes the car a little unstable. If you apply too much power,
the car will want to spin out. It's not really harder to drive the car
this way, but it does take more control. Some people like a car to
handle like that.
On most tracks here in the states, it's a little better to run a little
more front drive, either by changing pulleys, or by changing tire size.
You can set the desired overdrive ratio either way. Changing the pulleys
makes the biggest change in overdrive ratio. Changing tires makes a
smaller change.
Remember that during a race, the effect of gear ratios on overdrive
remains constant, but as your tires wear, this can effect the overdrive
ratio, which may constantly change as the tires wear. If you wear your
tires evenly (wear 2mm off the rear and 2mm off the front), then it's
probably pretty good.
If you have a Serpent, the standard Excel kit comes with 19:23 gearing
for the two side gears. To increase the overdrive (put more front drive
on), you can change the 23 tooth pulley to a 22, giving you a 19:22
ratio. You can also go 20:22, which gives you even more front drive. On
a Serpent Excel, one thing you want to keep in mind when you run more
front drive, is that you have to keep an eye on the belts and on the
pulley, especially the little 16 tooth pulley in the front. You have a
16:24 drive ratio on the front belt. When you have more front drive,
there is more drag, so more load on the pulleys, so you tend to strip
them out more often. If you have to change the belt because it's
stripped, make sure you also change the 16 tooth pulley, even if it
looks good. The pulley is a lot cheaper than the belt. Remember, it will
wear out faster with more front drive.
You can also change the overdrive by selecting the appropriate tire
diameters. This is important because you want to keep the overdrive
ratio constant through the race. If you change it by pulleys, and then
check your tire diameters, and find the front wears 4 and the rear wears
only 2, it's going to change the overdrive quite a bit. You either have
to run a harder compound in the front so it wears less, or use less
overdrive ratio, so it remains more constant for the duration of the
race. This is something you have to try out on different tracks.
I like to run with the least overdrive I can get away with. That way the
car is fastest. But, in some cases I have to run more overdrive because
of track conditions, (or the way you have to drive the track). With more
overdrive, you can be a little more aggressive on the track, which
sometimes helps if you're in traffic, because the car is more stable.
You might make a very quick lap with a neutral car (with the overdrive
set 1:1) but that might be the only real fast lap out of ten laps. With
a little more front drive, your car might be not quite as fast for that
one lap, but it will be probably be a little faster consistently for the
other laps.
Try out different amounts of overdrive on different tracks, and keep
notes on how your car responds. This will help you select a good
starting point when you show up at a new track that you haven't yet
driven at.
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| Eric G
June 1, 2005
6:55:12 PM
Entry #: 876285
| bump
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| Eric G
June 9, 2005
12:43:48 PM
Entry #: 889855
| bump
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| kakapoopie
June 10, 2005
3:42:52 PM
Entry #: 892437
| awesome post i think i got more out of it this time around than when i first read it
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| Eric G
June 10, 2005
3:46:18 PM
Entry #: 892445
| Well now that you've been driving more, you know what half of that stuff means. I'm glad it helped.
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| joe
June 10, 2005
3:57:53 PM
Entry #: 892478
| kakapoopie
are you going to run that max or did you get another motor? andrew told me you bought a new one. if you are not running it, i would like to have it back and i will put a new piston and sleeve in it. let me know.
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| joe
June 12, 2005
9:08:24 PM
Entry #: 894610
| kakapoopie please read above
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