Preparing your car

Once you’ve received your new Cool Chassis, check that the parts you plan to bolt on actually fit, because many components vary from brand to brand. It saves having to change something after the car has been powder coated.

The main components to try are wings and tail tanks, as these vary most between manufacturers. Once that’s all OK, go ahead and get the car powder coated or painted.

After powder coating, run a drill through every bolt hole and clean the paint out so it bolts together easily. Clean the paint out of all the nerf bar spuds too.

Assembly order

1. Fit the dash with the gauges already in it.
2. Fit the motor plate. It’s much easier to put the power steering pump and bell housing on the plate before it goes in the car.
3. Fit the master cylinder and make up the brake lines.
4. Fit the floor pan, then the pedals.
5. Fit the steering box and plumb the lines to the pump and the wing ram. The cockpit is now mostly finished.
6. Move on to the axles, front and rear. Connect the radius rods to the car and put torsion bars in the tubes, and you’re ready to get started.

Front axle

Put the front axle in the car and hook up all the radius rods. Set the axle up on blocks so the right-side radius rods are level with the bottom rail. You’re then ready to square the axle to the motor plate.

Squaring the axle

Run a tape measure from the back side of the axle to a straight edge off the front side of the motor plate.

With that measurement on both sides, set the panhard bar, which stops the axle moving side to side. Put a straight edge up from the bottom rail to the top rail and measure out to the centre of the king pin. Measure both sides and get the axle even in the car. That’s a basic starting position.

Camber

The two RF radius rods adjust the camber. With the car level, put a degree wheel on the RF steering arm. The basic setting is about 10–12° on the arm.

Once you have that setting, make sure everything is tight and your front end should be square.

Rear end

Bolt in the Jacobs ladder first, then put the torque tube up in the ball.

Once they’re bolted together, lift the rear end onto 6" blocks and set the birdcages on without anything connected to them. Fit wheel spacers and nuts to hold the birdcages in place so they don’t move around. Put the rear arms on the torsion bars and you’re ready to square it all up.

Squaring the rear end

It’s a lot like the front axle. Run a straight edge off the motor plate and measure back to the front side of the rear axle.

1. With that measurement on both sides, bring the ladder up and adjust the rod end in the birdcage so the bolt is free when it goes through the ladder. This stops the rear end moving side to side.
2. Connect the radius rods to the birdcage. Put a degree wheel on the bottom of the cage and adjust the radius rods until the birdcage is level to the frame. Check the bottom rail is level first. If it isn’t, level the car and do it again.
3. With both sides done, bring the arms up and adjust the rod ends so the bolt is free when you bolt them to the birdcage.
4. Tighten everything and check that the ball, the ladder and the arms are all free. If something isn’t free, it could be bent, or you may just need to go over it again.

After the rear end, the rest of the car can go together. Then you’re ready to put a setup in the car and go racing.

Torsion bars

Torsion bars are the springs of your race car. The bigger the number, the stiffer the bar and the harder it is to push the car down. The softer the bar, the easier it pushes down.

Starting setups

Rough track: use softer bars on the left to let that side down more easily, or stiffer bars on the right to keep that side up. Both help the car turn left more easily.

Dry or slick track: the idea is to get the car over onto the right rear and back onto the rear wheels for the most drive possible. That means a stiffer bar in the left rear and a softer one in the right, which lets the car roll onto the RR for more traction.

Torsion stops

Adjusting the torsion stops sets the ride height of the car and the load on the torsion bar. To fit the stops you need the setup blocks on the frame and under the axles, front and rear.

Setup blocks

The smaller the block, the higher the car sits. The bigger the block, the lower it sits. With a heavy car (a 360 steel motor, say, or a heavy driver), set up on smaller blocks so the car won’t bottom out all the time. A lighter car can use bigger blocks.

Lighter cars run the bigger blocks.

Through the meeting

Watch the track and adjust the car’s height as the meeting goes on. As the track dries, lower the car for more traction. Find a middle ground, though: go too low and you’ll lose side bite.

Stop bolts

Adjusting the stop bolts can either raise or lower that corner of the car, or load or unload the torsion bar.

• Loading a bar: most common with a reverse split (stiffer bar on the left, softer on the right). Load the softer bar so the car doesn’t just fall over onto that side.
• Lowering the left side helps the car get down into the corner.
• On a heavy track, raise the right side to keep the car from rolling over in the corners.

Shocks

Shocks are a very important part of a sprintcar. They’re easy to change and make a big difference. They determine how the car moves around the track, up and down with the torsion bars.

Valving types

Valving is measured on a shock dyno and labelled on the shock with numbers. The lower the number, the less resistance on that stroke.

In the examples below, the compression is written first, then the rebound. A single number is a straight shock.

Wet track (heavy)

Keep the left side of the car tied down, and the right side stiff enough to stay up and not fall over and get the car tight.

As the track dries, take the tie-down off the left side so the car can roll onto the right. If the track is really heavy and rough, use stiffer tie-downs to hold the car down and stop it rolling up.

Dry track

When the track has dried out or gone slick, get the front of the car up with the shocks to maximise traction on the rear wheels. This is where easy-up shocks come in. With not much tie-down on the left rear, the car can lay over onto the right rear.

Stagger

Stagger is the difference in circumference between the right rear and left rear tyres, measured in inches. Every inch is critical. Stagger helps the car turn:

Finding the right stagger isn’t always easy. It’s one of the most important setups on any night, because the racetrack is always changing.

By track condition

• Heavy, rough or fast: run a lot of stagger to keep the car turning left and stop it getting tight. Bigger tracks don’t need as much.
• Dry, smooth and slick: like the torsion bars and shocks, the slicker the track, the more you want the car on the right rear. Take some stagger off. The less stagger, the straighter the car stays. Don’t take off too much, or the car gets hard to turn.

Wheel positions & offsets

Along with stagger, wheel positions and offsets are a major part of the changes you make during the night. When you change the stagger to suit the track, adjust the wheel positions and offsets too.

Measuring wheel positions

With the car down on its wheels, measure from the frame rail (roughly just above the rear nerf bar) out to the centre of the tyre on both sides.

Offsets

The offset is the position of the hub in the wheel, measured from the inside of the wheel to where the hub bolts on. Rear offsets range from 4" to 6".

• 4" offset (3/7): for a heavy track. Most of the wheel sits out past the hub, so the centre of the tyre is further out and the car stays looser.
• 5" then 6": as the track dries out. A 6" wheel brings the centre of the tyre in towards the car, which tightens it up.

Starting combinations

Wing positions

The wing on a sprintcar adjusts in two ways.

Forward and back: the hydraulic ram

The driver adjusts this during the race as the track changes. For example, as the track dries out and the car gets too loose, pull the wing back to get more drive on the rear wheels.

Up and down: the rear wing tree

This works a lot like the ram. Early in the night run the wing in its lowest position, then raise it on the wing tree as the night goes on and the track dries out.

My setup sheet

Fill this in at the track and print it, or save it as a PDF, to keep a record of what worked. Stagger fills in automatically from your rear tyre sizes.