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Team LCOC
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Newsletter

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Chassis Setup

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Wheelbase

All cars must compete with a 73" wheelbase plus/minus 1/4 inch on either side
(72 3/4" to 73 1/4").  The width of the car may not exceed 60 inches and the car must roll freely through a 60" wide by 48" high opening.   The horizontal rear end offset is measured between the rear frame rails and the inside edge of the brake drum as the car sits without the driver in the car.  Their must be a minimum of six inches between these two points.   On my car, I can only achieve about 1/2" of difference between the left and right side.

Shocks

In the year 2001, INEX has chosen to switch from the Carrera Shocks to the Bilstien Shocks exclusively for the Legends Series, and must be installed by July 1, 2001.  These shocks being Mono(single) tube shocks means, no dents in the body, or the piston will not move in the tube.

Shocks may be turned upside down and/or the upper end of the rear shock may be mounted on either the inside or outside of the frame.  Shock bumpers are permitted.  Changing or altering the fluid inside the shock is illegal, and will result in a six month suspension for both the car owner and driver.

Springs

All Legends Cars must use a 10" or smaller length spring. Any spring weight combination and aftermarket springs are acceptable. Only one spring per shock, and no spring rubbers are allowed. Minimum ride height at the lowest point of the frame rails (not measuring at a weld point) is 3 1/2".  

Pinion Angle

Use more downward angle for short tracks (more bite). Less downward angle for long tracks (more speed).  Also use less angle on dirt tracks to leave more room for travel between the rear of the driveline and frame cross member when going through bumps.

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Basic Setup Information

Finding out how your going to setup your race car in any class of racing is a big challenge when your just getting started.  I searched hard for info on the internet about setting up a Legends Car, and was able to find some information that was helpful.  Everything good I've found is on my 'Links' page.   Staying in-touch with the Yahoo Groups Legends category is always enlightening.  The book 'Dwarf Car Technology' (#S225) by Steve Smith is full of good information that is easily understood through his style of explanation. 

All this information combines to gives you a foundation to work from.  Developingcaster-sm.jpg (15315 bytes) your base setup is derived from a range of allowable adjustments that can be applied to your car, controlled by physical tolerances that cannot be exceeded without major performance loss.  It is my attempt here to give you a competative but safe starting point, so you can then fine tune the combination to work best for you.  Actual car setup is as diverse as the drivers themselves, and is always a subject for debate.  I believe the three area's you'll work with the most from track to track are 'Ride Height' on each corner, 'Tire Pressure', and 'Spring Rate' on each shock.  The next in line will be Caster, and Camber and Toe-Out.  It's helpful to remember this order on these adjustments.   If you adjust Caster, it will affect Camber and Toe-Out.  If you adjust Camber, it will affect Toe-Out only.  Toe-Out can be adjusted without affecting either. 

For paved oval track, these cars like a lot of right front wheel negative camber tocamber-sm.jpg (17384 bytes) keep the front end from pushing in the turns.  Your caster setting will affect how easily the car turns left.  A good starting point for caster will be Left Front (LF) pos+ 2 degrees. Right Front (RF) pos+ 3 degrees.  A rule of thumb is a 'one degree split' between sides with a right side bias.  For camber, start with LF pos+ 2 1/2 degrees, RF neg- 4 1/2 degrees.  Check out Longacre Racing for good front end setup equipment.  Adding camber will affect your overall width, so check that you can pass within the 60" limit.  Stand the left front up more if your too wide, adjusting to LF pos+ 1 1/2 degrees if necessary.  Your toe-out should be at least 1/16", with a maximum of about a 1/4" for most tracks.

The spring rates on each corner of the car is difficult to define for an individual driver, and affects many of the factors you will be monitoring such as individual wheel weight when the car is scaled, ride height, and how the car reacts and feels under race conditions.  crosswt.jpg (20498 bytes)I believe the best procedure to follow is to start by knowing what percentage of weight each corner of the car is carrying against the overall weight of the car full of fuel.  You will need to acquire (beg, borrow or steal) a set of Computerscales to find this out, but it is worth all the trouble.  At this point it is important to say, "Document Everything You Do To The Car!"  Find a Chassis Set-up Sheet and use it every time you set-up or make changes to the car.  It will be nice to have once you find that sweet spot, and makes your performance much more consistent from track to track.  You want to note the cross weight, left side bias, and rear bias.  My method, not that it's the right way or the only way, is to set-up without the driver in the car to dial it in, then to note the final effect with the driver in the car.  Although their will be a change, usually in the range of one percent in each of these three areas, the driver weight is a fairly constant factor you can estimate while achieving the final setting.  I measure cross weight by the percentage of the RF and LR weight combined.  This is usually the higher number of the two cross percentages.  According to this rating method, a higher percentage of cross weight will eventually cause a push in the corner, a lower percentage will cause the car to be loose.  The different Legends Car chassis styles (Coupe and Sedan) will require different overall percentages to yield a balanced feel, but I believe most should fall in the range between 51% to 60% crossweight for best performance.  Adding a stiffer spring to one corner of the car or screwing the coil-over nut in towards the spring will increase the weight load carried by that corner, which in turn increases the overall weight percentage for the corners being measured. Adjust for your need to eliminate understeer (push) or overseer (loose).  The left side bias can be improved by adding lead weight to the left side of the chassis.  By the rule book, you can not exceed 52% left side bias.  This helps to stabilize the car in the turn by reacting against the centrifugal force of the left hand turn trying to lift the chassis, causing the left side tires to loose traction. The design of these cars and the amount of lead weight you can actually fit on the car should yield a range of left side weight bias between 49% and 52%.   Rear bias is also improved by adding weight, again not to exceed 52% rear bias by rule.  This improves overall rear traction.  Finding a balance on where to place the weight is the challenge, and should probably be applied as fine tuning after you get a comfortable setup on the car without it.   

Here is what I call the 'School Car' setup.  Our Legends Cars dealer, Randy Shearer of Team Legends Cars of California, runs this setup on the cars he rents out for his 'Arrive and Drive' program.  People that have never driven a race car can get into one of his cars, drive fast, and keep it off the walls.  Before I purchased my first Legends Car, I went to a few races to note the lap times of these cars.  I then ran one of his school cars, and was running fast enough to make the field at our local track, the Cajon Speedway.  This made my mind up on whether to get a car.  He has told me that he will give this setup to anyone that asks for it, so I am posting it for your benefit.  This is for a paved oval race track, and I'm confident you could take this setup and run it almost anywhere.

Spring Rates (lbs.)

LF - 200

RF - 240

LR - 180

RR - 160

Tire Pressure (psi)

LF - 15

RF - 25

LR - 10

RR - 35

Ride Height

LF - 3 3/4"

RF - 4"       

LR - 3 7/8"

RR - 4 1/8" 

Use the caster, camber, toe-out and pinion angle settings suggested from the above.   If you try this setup, and it feels right for you, I suggest that you print out 'Kev'sCorner Quick Fix Guide' and use it to tune for your needs. 

One last thing that should be mentioned is the squaring of the rearend, and the offset adjustment using the 'panhard bar'.  Set the wheelbase up initially so that when you check your wheelbase length with the standard 'go, no go' gauge, your length would be at 73" in the middle of the variable (72 3/4" to 73 1/4") half inch of play.  I then check for square each side of my rearend housing from the front 'cross-member/shock tower' to the front face of the rearend axle tubes close to where the frame passes under them.  You can do this by hanging a weighted string off of these two points on each side of the car.  If the rearend is square off the front cross member, your front wheels will be square as well.  It is good to be aware of Rear Roll Steer, and possibly compensate for it if necessary to keep the car from being too loose in the turns.  The right side of the car will squat more than the left side going though a turn, creating 'Rear Roll Oversteer'.  To offset this effect and keep the car from becoming loose as you corner to the left, you want to (shorten) adjust the right side in slightly to compensate for the trailing arm extending the wheelbase on that side of the car as it squats going through the corner.  arc.jpg (6096 bytes)The effect is cause by the trailing arm sitting at a slightly downward angle when the car is going strait, but as you turn and the right rear of the car squats down, the trailing arm connection at the rearend travels upward in an arc becoming more parallel with the chassis. This creates a longer distance between the point 'A' connection at the frame and point 'B' connection of the trailing arm on the rearend and pushing the right side of the rearend back.  This adjustment can be used for fine tuning, but being too far out of adjustment can affect handling dramatically.  Remember also, if you change your pinion angle, you should check for changes in your wheelbase and rearend offset.  The panhard bars on these cars are hard mounted, with no vertical adjustment for tuning the rear roll center. But you can get a slight effect in a similar fashion just by raising, or lowering the rear ride height evenly.  Details on this type of fine tuning can be extracted from the pages of the book 'Dwarf Car Technology' (#S225) by Steve Smith.  This book is a very good investment for setting up scaled cars. The horizontal rear end offset is measured between the outside of the rear frame rails and the inside edge of the brake drum as the car sits without the driver in the car.  Their must be a minimum of six inches between these two points.  You set this adjustment as close as possible to 6" on the left rear, to maximize your left side bias.   This information is still just a part of what affects the handling on one of these Legends Cars.  Hopefully it will help to keep you pointed in the right direction and moving forward in the field.  

Questions or Comments
legends@abac.com