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ARC18 Setup Instructions

Thank you for your recent purchase of an AFCO race car (ARC18). We hope you find the following information helpful in achieving success. Races are won in the shop during the week and proper preparation is essential. The information provided here is a basic guide in ensuring your AFCO car performs as it should. In this setup manual, we will show you the following AFCO car setup techniques: setting the jacobs ladder, squaring the rear axle, setting the front  suspension, setting the caster/camber/toe, setting the wheelbase, and scaling your car. We wish you the best of luck and if you have any questions, please do not hesitate to contact us.

Download the setup manual as a PDF by clicking HERE.

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Radius Rod Positions & Lower Control Arm Pivot

Before you get started, confirm positioning of the following mounting locations.

1.  Left rear radius rods should be in the fourth hole from the bottom in both locations as indicated by the red dots.

2.  Right rear radius rods should be in the fourth hole from the bottom in both locations as indicated by the red dots.

3.  Right and left front lower control arms should be bolted in the top mounting location of the lower control arm tabs as seen in the photo.

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Setting the Jacobs Ladder

The left-to-right placement of the rear axle is determined by the location of the rod end in the right rear bearing carrier.

1.  The jacobs ladder straps should be in the center holes on the chassis.

2.  Screw the provided rod end all the way into the center hole of the bearing carrier. Attach the jacobs ladder to the rod end through the center hole of the jacobs ladder. Be sure that the rod end is vertcal.

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Squaring the Rear Axle

1.  The first step in squaring your ARC18 car is to install all 4 Longacre alignment plates. Be sure to note the position/corner laser etched on each plate. Insert the ½” x ½” cross bars into the front and back plates.

2.  Install the steering box centering tool at this time.

3.  Finally, place 1.5” ride height blocks on the right side and 7/8” ride height blocks on the left side. The front blocks should be placed under the lower inner rear control arm pivot. The rear blocks should be placed directly beneath the axle. 

One end of each shock will be unhooked from the car for this process.

4.  Next, the bearing carriers need to be timed. Check the LR Birdcage timing by using a combination square and
the provided set-up block. Adjust the left rear rods until the square is flush against the front flat on the bearing
carrier.

5.  Check and adjust RR Birdcage timing by using a combination square and adjusting the RR radius rods until the square is flush with the brake caliper mount. Place the square on the front of the brake caliper and check that the square touches both bosses.

6.  The next step in the process is to square the rear axle in the car. Using one combination square and a ruler, measure from the back of the rear axle to the back of the rear cross tube. Take this measurement as far out on the axle on the right side as possible. This measurement should be 7”.

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7.  Repeat this measurement on the left side. Take this measurement as far out on the axle on the left side as possible.

If an adjustment is needed, adjust the rear radius rods by turning the top and bottom the same amount so you don’t lose your bird cage timing.

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Setting the Front Suspension

The first step is to adjust the right front lower control arm until it is parallel to the rear axle.

1.  Place the ride height block provided to help measure the distance from the control arm cross tube to the rear set-up bar.

2.  Measure to the most inward point on the control arm tube to the rear set-up bar (Point A to B).

3.  Measure to the most outward point on the control arm tube to the rear set-up bar (Point C to D).

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4.  Adjust the strut rod length until step 2 and step 3 measure the same.

*Special Tip: the direction of the arrow in the AFCO logo (highlighted red) on the rod is a directional indicator. In this
instance, turning the rod towards you would lengthen the rod.

Once the right front lower control arm is squared, the caster and camber will be set. A small 2” x 2 ” digital angle finder can be used for this step.

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5.  First set the right front caster to +3º by lengthening or shortening the upper control arm rods.

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6.  Next, set the right front camber at - 4º b y adjusting the upper control arm rods equal amounts. This method helps maintain the caster that was previously set. Always re-check caster after you set the camber.

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Next, the left front caster and camber will be set. Again, a small 2” x 2” digital angle finder is handy for this step.

7.  First, set the lower control arm at 90 degrees to the frame using a ride height block. You may have to lengthen or shorten the left front lower strut rod.

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8.  Next, set the left front caster to 0º by lengthening or shortening the upper control arm rods.

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9.  Finally, set the left front camber at +3º by adjusting the upper control arm rods equal amounts.  This method helps maintain the caster that was previously set. Always double check caster after you set the camber. See step 6 for help with camber angle orientation.

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10.  Right front rod ends should be angled out as shown in photos A and B.

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11.  Left front rod ends should be vertical as shown in photos C and D shown below.

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Setting the Wheelbase

Once the rear axle has been squared in the car, we can use it to set the front axle. Simply measure from alignment bar to alignment bar on both sides of the car to determine if the wheelbase is equal on both sides. Always adjust the left front lower control arm when working towards this goal.

1.  On the right side of the car, measure from the rear alignment bar to the front alignment bar and note your measurement.

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2.  Next, on the left side of the car, measure from the rear alignment bar to the front alignment bar and note your measurement.

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3.  Reference the online setup sheets or contact our Quarter Midget Department for specific car measurements. Be sure that the left side measurement matches the right side measurement. Adjust the left front lower strut to do this.


Setting Toe

The ARC18 is typically run at zero toe.

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1.  First, using the upper measuring slot on the right front plate, determine if both front and back measurements from outside of the setup plate to the frame are equal. If not, adjust the tie rod accordingly. This operation should be done on the left front as well.

2.  Next, using the bottom slots, measure across the front of the set-up plates and repeat for the back side. This measurement should be equal. If not, lengthen or shorten the left front tie rod until this measurement is equal.

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3.  Once the toe has been properly set, be sure to remove the steering box centering tool you installed during step 2 of Squaring the Rear Axle.

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*Re-check caster and camber at this point in the process.


Scaling and Set-up

After squaring your car, it is time to put on the tires and wheels.

1.  Be sure to measure the spacers behind the hubs. The right front should measure 3/4”, the left front
1/8”. Note that the long side of the front hubs point in toward the center of the car. On the rear, the
right rear typically starts out with a total of 2” of spacer from the snap ring. The left rear is adjusted
out until a straight edge placed on the left rear wheel clears the left side nerf bar. This is a rule
requirement for the QM sanctioning bodies and should be checked each time you set up the car.

2.  Hook the shocks back up to the car before proceeding to the next step.

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3.  Below are the recommended starting points for shocks and springs based on the driver’s weight.

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Now that your ARC18 car is all squared up and has tires on it, you are ready to set ride heights and set it on the scale pads.

It is important to have a baseline setup to come back to if you have made adjustments to your ARC18 and seem to have lost the handle.

4.  Set tire pressures at 11 PSI in the right front and right rear, 6 PSI in left rear, and 9 PSI in the left front.

Now have your driver get into the car for the next few steps.

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5.  We recommend a starting point of 1.5” ride heights on the right side and 7/8” on the left side. You can measure this under the rear axle from the bottom of the frame rail to the scale table.

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6.  For the front, the same measurement is taken below the inner pivot of the lower control arm cross tube.

The final step in setting up your ARC18 is scaling it out, with the driver in the car. When scaling your car, it is important to remember that left side and rear percentages will not change by turning the adjusting shock collars. Moving ballast is the only way to achieve the desired percentage of left and rear.

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While the ideal percentages will vary, we recommend starting out with maximum left side and 54% rear for low HP classes and 56.5% for higher HP classes. Move your ballast around in the car until you achieve the desired percentages. Once you have the desired numbers, it is a good idea to recheck your ride heights to see if they changed before setting your cross weight.

It is important to note the bell cranks will need to remain parallel to the scale table during this process (notice how the red line is parallel to the table in the photos above). If they are not parallel, either lengthen or shorten the push rod and re-set the ride height with the shock adjusting collar.

Everyone’s optimal cross weight will vary, but a good place to start is 60%, measured with the driver in the car. When adjusting cross weight, it is important to use the X method. If you do the same adjustment to the left rear and right front and the opposite adjustment to the left front and right rear, your cross weight should change without ride heights changing.

  • Be sure to settle the car in the same manner each time you make a change.
  • Always go back and check ride heights and the bell crank positions after achieving the cross weight.

If these are satisfactory, tighten all of the jam nuts and shock collar set screws.


At The Track Changes

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