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Legend Car Setup 2001
(Updated Edition)
J. Kevin Yeatts
Setting up your Legends car doesn't require a degree in rocket science. It doesn't require loads of money and it
doesn't require a lot of time. Best of all, YOU can set up your car and have a consistent, reliable, stable setup to
run competitively anywhere you go. The key to Legends racing (one of them, anyway) is to have a reliable car that
performs well everywhere you run and a good, baseline setup that you can come back to when you need it. Legends
(L/cars) chassis are a basic coil-over spring design and respond to the same inputs and conditions as the larger,
more evolved racecars.
In 2001, INEX instituted a new shock rule, which effectively eliminated many of the advances which had been made
in L/car setup. It also narrowed the window available to those who would stretch the rules by having the easily
modifiable Carrera shocks tweaked for better performance. "Cheating" the shocks not only gave those running
them an unfair advantage, it made it impossible to compete using off-the-shelf Carreras, which meant that if you
wanted to run up front, you had to go spend as much money as those who were cheating.
The Bilstein shock is a much better piece of equipment. There is no comparison between this shock absorber and
the Carrera, which was actually more of a shock dampener. Having said that, it soon became apparent that what
worked in the past with Carreras would not work with Bilsteins. The Bilstein is a much stiffer shock, and has 100%
more rebound than the Carrera. As with the old shocks, the objective here is to keep as much of the tire on the
ground as possible. To combat the rebound, we’ll try to overpower the Bilstein, while still taking advantage of it’s
overall superiority.
What You Need To Get Started
The secret to doing ANY job correctly is having the right TOOLS. Collecting the tools to do the job correctly is
probably the most expensive part of becoming your own chassis expert. There are some shortcuts, which we will
address, however, which will make your job easier at a fraction of the cost.
Below is a list of tools used by Yeatts Racing when applying a full setup to a L/car:
Scales ( go-kart scales are acceptable, as are bathroom scales - for best results, use digital racing scales
which are capable of following you up the divisional ladder)
Toe-in Gauge
Wheelbase Gauge
Camber/Caster Gauge ( digital or analog or bubble )
Tape measure
Degree Wheel (Available at most motorcycle shops)
Optionally, you may get a set of radius plates, which will also measure the degree at which a wheel is turned.
Another tool I have found invaluable is Todd Fennoff’s Pride Performance rear end square. 99% of these
cars can use this nifty little device and shorten squaring the rear end to almost no time at all.
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Legend Car Setup - 2001 http://www.angelfire.com/nj3/nightshadeink/kev/setuptext.html
The Place To Begin Is At The Beginning
Start setting your car up at the front wheels. Caster, camber, and toe are just about EVERYTHING as far as the
front wheels of these cars are concerned. Getting these dimensions correct, and keeping them correct week-in and
week-out are critical factors in your success or lack of success at the track. The first thing we’ll check is camber,
then caster, and finally, the toe.
Camber Your Angle of Attack
Camber is the angle of the tire relative to the ground. Early left-hand oval racers realized that they were losing a
good portion of their contact patch on the front end when they turned their wheels and the tires rolled over in the
direction they had been traveling. There is a mathematics equation that will explain all this, but I am a racer, not a
mathematician. Normally, tires will be cambered in the direction of the banking. If there is no banking, just
remember the tires should be leaning in the direction you will be turning. Measure the camber by removing the
center cap of the front wheel, and placing the camber/caster gauge on the hub where the center cap used to be.
If it’s a magnetic camber/caster gauge, make sure it fits smoothly and flatly on the hub. Straighten the wheel, and
adjust the camber gauge until the centering bubble reads 0. For the left wheel, read the camber line on the left,
"Positive Camber". For the right wheel, read the camber line on the right, "Negative Camber".
Basically, "camber" is meant to give your front tires a better chance of gripping the pavement while in the turn.
The way to check whether your tires require more or less camber is to take tire temperatures after a practice
session. Temps running hotter on the inside of the tire means you have too much camber in the wheel. Temps
running hotter on the outside of the tire mean you don't have enough camber. Regardless of what you hear
elsewhere, even tire temperatures mean your camber is perfect.
I have run as much as -5 ½ degrees of negative camber of the RF, but have never seen effectiveness past about
-5.0 degrees. Left side, positive camber effectiveness seems to peak out at 2 ¾ degrees.
*REMEMBER* Adding camber can add to the width of your car - too much width and you'll be starting in the back
after getting DQ'd in the tech line before the race!
Caster, Caster; What the HECK is Caster?
The best example of caster I can give you is the wheels of a shopping cart. The wheels are mounted in such a
manner that they are behind the point where the wheel bracket is mounted to the cart. This makes the wheel
follow the direction of the cart. Were a straight line to be drawn from the mount point to the center of the wheel,
the angle degree of this line would represent caster. If the caster in this case were to be the other way around,
the cart would be undrivable and grocery shopping would require a lot more muscle to get the cart around the store!
Grocery cart wheels need to follow the direction of the cart, because you are directing the cart with your hands,
and merely need the wheels to follow where you are directing the cart. The cart is said to have "negative caster",
because the focal point of the mount is AHEAD of the center of the wheel, making the general caster negative, like
a "/". With a car, it's just the opposite! You use the wheels to direct the car, and therefore most front wheels
have positive caster. Positive caster gives the wheels more stability and allows the front wheels to steer the car.
Positive caster would be like a "\". The angle of the caster makes quite a bit of difference in how the car bites
when you turn it.
For example, I was involved in an accident with my L/car one night where the left front shock tower was pushed
substantially forward. Not being familiar with caster at the time, I didn't realize it had been changed from the
fairly innocuous +1 degree to a hair-raising -8 degrees! Good thing we oval trackers turn left, because this car
wanted to turn left, and HOW! Whenever I would let off the gas, or loosen my grip on the wheel, ZZZZZIP!
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Legend Car Setup - 2001 http://www.angelfire.com/nj3/nightshadeink/kev/setuptext.html
Sharp left turn! The stability of the front end had been damaged because the left front wheel had acquired a
negative caster. The wheel wanted to turn whichever way the track's banking directed it - the higher the banking,
the more leftward it would go. Once we returned the wheel to positive caster, the stability returned and the car
became manageable again.
It is generally accepted that a 3 degree split from right to left is the proper amount. For example, if you have
caster set to 1 degree on the left front, the right front will be most comfortable at 4 degrees. A larger split will
make the car less stable but more willing to turn left. Also, the closer the left front wheel's caster is set to zero,
the more responsive the steering will feel on a left-turn oval. Many drivers, including myself, set their caster on
the LF to 0 or a little less, and their RF caster to 3 degrees or a little more. Again, the larger the split, the more
responsive the steering. There is a fine line between responsive and unstable. A safe caster setting to start with
is LF 1 degree, RF 4 degrees. As your skills progress, try moving the casters down the scale a little until you've
found a setting just on the brink of uncomfortable. It might not be faster, but it will certainly feel like it!
Setting your Caster
To check your caster, you must set your car on the ground. Shake it and roll it back and forth a little to make sure
the rubber on the tire is not binding. Remove the dust cap from the center of the wheel you are going to work on
first. In our example, we'll pick the right front (RF) first.
Turn the wheel 20 degrees in the direction away from the car. With your camber/caster gauge, set the center
bubble to 0. Turn the wheels until the tire is 20 degrees in the direction toward the car. The bubble in the gauge
will have moved, and this reading represents caster on the wheel. If it's more than you want, we need to move the
top or bottom wheel mount point to give the wheel a more upright angle. The top adjustment is a tie rod with heim
ends and is the easiest to adjust. The bottom adjustment is the heim joint at the end of you’re a-frame where it
connects to the chassis. Remember, reducing the caster of a wheel will LENGTHEN your wheelbase on that side.
Once you've made the adjustment, you have to start all over with measuring the caster. Once the wheel is the
proper caster, you need to repeat the procedure on the other wheel. The only difference is that you will first turn
the left wheel to the LEFT, and then back to the right.
Remember to check your wheelbase! Too long on the left hand side? You'll just need to try and move the rear end
up as much as possible (keeping it square, of course) and maybe moving the front wheel on the long side back as
much as necessary. Remember, if you move the front wheel back using the top adjustment, you'll need to make the
same change to the bottom adjustment. This whole thing is what's known as "the dance".
Not so fast! All we've really accomplished is setting up our wheels to track like we want them. We haven't even
set our toe-out! Toe out is the amount of difference in the direction of the front wheels. "Toe Out" means the
front tires are pointing away from each other in sort of a " \ /" configuration. Toe out is measured as the
difference in width between the front of our tires and the rear of our tires. A Legends car is supposed to come
from the factory with a toe-out of about 1/8". Any more toe-out and you will scrub off speed down the straight;
any less and you run the risk of having an unstable run down the straight. Of course, total lack of toe-out will give
you the most straightaway speed, but will cost you stability in the turns..
Setting toe-out involved loosening the jam nuts on the tie-rod and turning the tie rod either left or right.
Carefully watch the wheel and you will see it move inward or outward. Be careful not to turn the tie-rod too much!
Remember that every movement of the tie rod not only moves the front of the tire, but also the back of the tire,
so if you move the front outward by a quarter inch it will change your toe-out by a HALF an inch!
Once our camber, caster and toe are where we want them, the next step is to square up the axle housing, giving us
what is known as a "square rear". By "squared rear", I mean make sure that your rear wheels are facing forward at
the same 90 degree angle from the centerline of your car. A rear end which is slightly askew one way or another
will have opposite effects on your car, which you may find desirable as you become more skilled as a driver.
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Legend Car Setup - 2001 http://www.angelfire.com/nj3/nightshadeink/kev/setuptext.html
Starting out, however, you want YOU to be the only thing driving your car through the turns.
One of the best ways to square the rear end is to set your car on jacks about 18-24" off the ground. With your
car jacked up, disconnect your rear shocks from the bottom of the chassis. Place a piece of 2x4 under the housing
on both sides of the car (2x4 should be on it's edge). This will approximate the distance from the housing to the
chassis when the car is under load. Remove your front tires and find a straight piece of wood, such as a long broom
handle or even a 1x1 beam of wood. It needs to be long enough to be tied onto your front bumper and have the ends
extending past either side of your car. (Stay with me on this - if it gets wordy or confusing, re-read until it makes
sense).
What you should now have is your car on 4 jack stands, as close to level as you can get it. The rear wheels are on,
but the shocks are disconnected and the axle is resting on 2 pieces of 2x4. The front wheels are off.
Get 2 pieces of string (twine will work, or kite string) approximately 72" long apiece. Tie one end of one piece of
string to your rear bumper and attach the other end to the beam of wood attached to your front bumper. The
string should be taut and intersect through your rear tire at the level of the axle. Once the string is taut, go to
the front end of the car and move the string inward or outward until the string is touching the front and back of
the rear tire. The string should be in a straight line and any bulges in the string mean you need to readjust.
Repeat this process on the other side of the car with the other piece of string.
What you should now have is your car on 4 jack stands, as close to level as you can get it. The rear wheels are on,
but the shocks are disconnected and the axle is resting on 2 pieces of 2x4. The front wheels are off. There are
two pieces of string running from your rear bumper to the beam of wood you have tied to your front bumper.
Find a spot on your front clip and measure the distance from the string to the frame. Repeat the procedure for
the other side. The side with the greater distance from string to frame is the side on which your axle housing is
back the furthest.
To square your axle now, you must adjust the trailing arm lengths. After each adjustment, you must adjust your
strings to where they are touching the front and back of your rear tires. Keep adjusting until the distance from
string to frame is the same on both sides. Once the distance is the same, your axle is square.
Many of the faster people in the division run with the left side slightly longer than the right side. To accomplish
this, lengthen your left side adjustment no more than 3/16". Once you have your axle housing in the position you
want, you are finished. Tighten your trailing arm jam nuts and put your car back together. Even rushing through,
this procedure can take up to an hour.
An alternate way of centering is to simply set your car on jacks, remove the rear wheels and shocks, and place the
Pride Performance rear end square and simply use it’s components to measure rear squareness.
So What If I DON'T Square My Rear?
As mentioned earlier, an unsquared rear may have undesired effects on the handling and tire-wear of your car. If
you have your rear cocked toward the right, your car will tend to be loose in the turns. If the rear is cocked to the
left, your car will tend to be tight. Expert drivers prefer to have "bias" of this sort, but newbies really need to
learn to drive the car with the rear set straight. The choice is up to you! If you do start experimenting with bias,
try to keep it +- 3/16" of square. Any more and you'll just be losing power.
The Wait is Over, but the Weight has Just Begun
Most of the battle in making your car run like you want it to is getting the weight distributed over the wheels
properly. All the work we do on setups really comes down to making those 4 little contact patches of rubber as
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large and as effective as possible when we are on the track.
The three most important weight ratios in oval track racing are (1) Left-side weight, (2) Rear Weight, and (3) Cross
Weight. Cross Weight is the percentage of left rear and right front wheels relative to the total weight of the
car. The higher this percentage, the more the car will tend toward understeer, or "Push". When a car is pushing,
the front end is washing up toward the wall in the turns. When the cross-weight percentage is lower, the car will
tend toward oversteer, or be "loose". A loose race car seems determined to have the rear end in front of the front
end. Neil Bonnet once said that when the car is pushing, you see the wreck happening. When the car is loose, you
feel it happening.
Weight ratio adjustment can be changed by a number of things. Adding weight to different areas of the car is a
common method. Moving current weight on the car to more strategically located areas is another method. Coilover
adjustments only affect the cross weight ratio of a car.
Here's something to keep in mind: Changing the weight ratio via coilover adjustment also changes your ride
heights. Therefore, changing your ride heights by definition will change your cross weight ratio! This is something
that can be very helpful to know if you do not have a set of scales on which to weigh your car. Once you get a car
set up on scales the first time, you should have your ride heights (along with spring weights and shock settings)
written down. If you ever have to get your car reset to your original settings, simply get the car back to it's
original ride heights at all 4 wheels and the cross ratio will be the same as it was originally also.
Steps involved in setting a car's weights:
Get your air pressures as you want them at the start of a run.
Fill your tank with gas - do this before every practice session, also.
Adjust your car's ride height on each corner to the desired height. Remember, each adjustment on a corner
will affect the other corner's heights - move stealthily.
Once your ride heights are correct, put the car on the scale and adjust accordingly. Once your ride heights are
where you want them, the weight percentages almost always fall into line.
So Now What?
What we've effectively done is go through the basics of setting up your Legends car. Now we'll take to the track
and see what's going on with our setup.
Gee, Kev, the car is great into the corner, but...
What if we take to the track, only to find that our car is "monster loose" and keeps wanting to spin out on us
coming out of the turn? A loose condition out of the turn is symptomatic of having either too much weight on the
RR tire, or not enough weight on the LR tire. Conversely, a car that is tight off the turn could mean we have too
much weight on the LR or not enough on the RR. There are lots of things to remember when dealing with a chassis
at the track. I like to refer to my system of adjustments as
"X" - The Theory behind chassis setup
A race car chassis can be thought of as an "X". What affects the RR will directly affect the LF, and vice-versa.
What affects the LR will directly affect the RF, and vice versa. What you MUST keep in mind is that you cannot
make an adjustment to one corner of the car without taking into account what effect that adjustment will have to
the opposite corner.
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Legend Car Setup - 2001 http://www.angelfire.com/nj3/nightshadeink/kev/setuptext.html
The key to knowing what to do to a chassis to make it work is figuring out what it needs. Experience is really the
only teacher. If the car is pushing on the entry to a turn, chances are the right front needs to be softened up,
either through tire pressure, softer spring, or softer shock. Conversely, you may be able to achieve the desired
result by stiffening the left front, through tire pressure, a stiffer spring, or shock. In most cases, a car must be
adjusted at the front if it is pushing coming into a turn. This is because almost total control of the car's turning is
handled by the front end upon braking or deceleration. The weight shifts forward and at a 90 degree angle from
the turning direction. If the RF tire, shock and spring are not ready to accept the shifting weight, pushing will
occur.
Stability exiting a turn is controlled by the rear suspension. A car that wants to break the rear end loose may have
too much weight on the right rear wheel. The symptom may be corrected by either reducing the weight of the
wheel by softening the spring, adjusting the tension on the spring down, or by softening the RR shock or air
pressure. The same symptom may be corrected by stiffening the LR components, such as the spring, shock, or air
pressure.
Gee, Kev, all this sounds great but...
All the setup advice in the world will be of very little benefit without seat time. Learn your car, and learn the
tracks you will race on this season. If your car is showing signs of being loose exiting a turn and you've exhausted
all the setup tips, maybe the problem isn't the car, maybe it's the DRIVER! Have a crew member watch your line,
your pickup and break points from the pits AND the stands. Maybe your car has a push because your standing on
the gas too long into the turns, or too early leaving the turn. Maybe it's loose exiting the turn because you are
turning the wheel too hard to the left when you get back on the gas. Any slight adjustment in your driving style is
worth most any large adjustment on the car. If you can see your mistakes, or accept criticism (constructive,
hopefully) from your crew, fans, and competitors, you can correct the mistakes and you will see your lap times drop.
Click Here to View Setup "A" Table - a new window will open
Click Here to View Setup "B" Table - a new window will open
Notes on 2001 Yeatts Racing Setup
These setup has been derived over months of testing and has achieved tremendous success both for my customers
and me. Certain points about the setup merit further discussion. Note that the "B" setup is very similar to the "A"
setup. The "B" setup has really picked our program up. Car is higher in the front, and lower in the back, and seems
to require no change from track to track. The lighter springs in the rear allows the car to squat coming off the
turn.
The axle housing sits square in the car.
The pinion angle, measure in degree angle by many racers, is instead measured in terms of distance above the
rear cross member of the car. To measure, turn the rear wheels such that the driveshaft rear universal is
flat above the cross member. Measure the distance from the cross to the universal. Do not allow the
distance to become less than .75 inch. Any lower and you run the risk of having the driveshaft hit the cross
member under braking. Setting the pinion angle properly will require that you bring the center link
adjustment all the way in on both ends of the rod. You will then have to lengthen your rear control arms until
the driveshaft is the proper height above the cross-member. This will lengthen your wheelbase, so make
sure you check that everything is within spec. If you are too long, it is worth bringing your front end back
enough to get back into spec. Rear end trajectory is critical to getting off the turns.
Note that the left side wheelbase is longer than the right. With the left front wheel at 0 (zero) degree of
caster, it will sit further forward than the right front wheel, thus accounting for the difference in
wheelbase length. Do not stress if your wheel base differs slightly.
I have also tested with springs that are 10 lbs lighter across the back (165-175) with some success. The key
to getting the Bilsteins to work is to lighten the springs until the weight transfer mutes the stiffer rebound
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of the shock. I run 49% cross weight with my car because the soft springs demand less cross weight in order
to help the car turn with a degree of stability. The stiffer the springs, the higher the cross should be. Many
of my customers did not like the extra softness because they felt the car was too loose to race. I liked it
and have had no such problems.
I scale and measure my car without the driver in it. So long as you measure your car the same way every time
(full of gas, tires properly inflated) you will achieve consistency of setup performance.
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