One of the venues for the Indy series of races is Brazil. So how do you move 54 race cars and all of the associated equipment to Brazil? You pack two 747 aircraft with everything but the people.
Included in the shipment was the technical inspection crew and all of their measurement equipment. While I was at the track I spent some time talking with one of the inspectors and he showed me all of the templates and equipment they use to ensure parity between the cars. Right down to the silhouette of the cross section of the wings. The cars are all the same manufacture and the engines are all provided by Honda, the transmissions are the same and the tires are provided by Firestone, but there are still plenty of places where the cars can still be customized to a degree. Wing angles, suspension setup, spring rates, roll stiffness, and weigh jacking to name a few.
The firestone tires on the rear of the cars are 14 inches wide and are mounted on 15 inch wheels. The cold tire pressures can vary from side to side and will range from 20 to 40 psi. They are all filled with nitrogen gas and are mounted by the Firestone crew. The wheels also have TPMS (tire pressure monitoring sensors) mounted in them. The TPMS is in the “drop zone” of the wheel so the installed has to carefully orient the tire on the rim so as not to break the TPMS.
Fortunately the tires have a large sidewall so that helps the installer.
Once the tire is mounted the assembly must be balanced. This is done on a Hunter machine as well and stick-on weights are used so that they can be cut to size and placed in the best spot on the rim. Then silver tape is put on over the weight to ensure that it doesn’t come loose.
Tires are loaded on to electric carts and delivered to the teams garages and the teams then mark them for size, pressure, and what side of the car they will be mounted.
The wheels are held on each axle with a single nut. Not a nut in the conventional sense. It actually has flutes that match up with the guns used to take them on and off.
In the garage area cordless impact guns are used.
In the pits they are air operated by compressed nitrogen gas.
There are studs on the hubs that match the holes in the back side of the wheels.
The wheel nuts stay in the socket of the impact wrenches so they don’t get lost.
The guns are set to three hundred foot pounds of torque to put the nuts on and four hundred to remove them. A push button that moves side to side is used on the air guns in the pits so the all the tire changer has to do is drop the gun on its side and the pin is pushed so the gun goes in the opposite direction. That way it is ready to turn in the correct direction when he has mounted the new tire onto the hub.
The suspensions are designed to keep the shocks and springs under the bodywork and out of the air stream. Aerodynamics is most important these days as the suspensions really don’t move much.
Back when Jim Hall introduced a wing on his Chaparral race car the struts were mounted to the suspension so that the downforce was transmitted directly to the tires and wheels without going through the suspension. Due to some safety problems with that approach race regulations no longer allow that to be done. As a result of the rules change the down-forces must go from the wing to the chassis and then through the suspension to the tires. Over time it became clear that a suspension with a lot of movement was a problem as it would compress greatly under the forces and then the vehicle would bottom out. So today suspension travel is almost nil. There can be around four G’s of downforce that the suspension must handle and not bottom out.
So the suspension’s work is done primarily by the tires themselves which is why the sidewall on a race tire is so much larger than the low aspect ratio tires seen on many high performance road cars. They still have a suspension.
The adjustment of the alignment becomes critical with toe, caster, and camber setting becoming very closely held team secrets.
Aerodynamics is so important that you will notice that the tie rods are part of the upper control arms in the front suspension.
Wing angle plays a critical part in handling especially at a track like Indy. For qualifying a lot of the downforce is taken out of the rear wings so that there is as little drag as possible therefore keeping the speeds high as well as challenging the driver to keep these beasts under control.
It is a critical task of the team engineer to find the balance for the driver that allows them to get the most out of the car without going over the edge and hitting a wall.
For the driver it is a very cramped office. The seats are all molded to their suited bodies to the point that they have a little arm and leg movement and that is about it.
To keep the weight of the helmet from tearing their heads off their necks in the high G loads of turns there is padding (almost a solid) on the right side that helps support the driver’s head.
A steering wheel that cost more than many new cars is full of controls and displays all the driver information.
The rear of the car has a deformable structure that bolts to the transmission. The wing bolts to it. This is there to help expend the energy of 100+ G force when a car slams rear first into a wall.
The front has a nose cone that acts the same way.
The suspension is designed to also expend energy and the wheel hubs are attached by cables to the chassis so that an accident won’t send them off into the crowd at 60 miles and hour.
The fuel used today is ethanol.
On race day each car will have a fuel tank in their pit with a specific amount of fuel and no more.
They will have to manage the amount they use as part of the race strategy.
The ethanol used has about a third less energy per volume as gasoline, but it is part of the Indy series effort be conscious of the need to showcase alternative fuels.
In the past methanol was used. One of the benefits of switching to ethanol is your eyes don’t burn when they start up the engines in Gasoline Alley.
Enjoy the race folks and send me any questions – I might be able to answer them.