May 11th 1977, Tamiya releases their first Formula 1 radio controlled model car, the Tyrrell P34 Six Wheeler. 32 years later, interest in Formula 1 continues to be as strong as ever and Tamiya releases their latest Formula 1 chassis, the F104 Pro.

The successor to the popular F103 chassis, the F104 Pro brings more features and realistic dimensions of the modern Formula 1 car. Complete with a new late generation Formula 1 body, the F104 Pro is well equipped with the most desirable components and features.

As well equipped as the F104 Pro is, there is still an excellent selection of Hop-Up parts to further elevate the performance of the F104. These Hop-Up options offer a variety of benefits, such as increase durability, reduce wear, improve tuning potential and enhance performance. The following are just a few examples.

Building the F104
Because it's easier to add Hop-Up parts to a car during the build, have any additional Hop-Up items you've selected on hand prior to assembly. If you're unsure of which additional Hop-Ups should be considered, I recommend the soft T-Bar (54165), the Aluminum Motor Mount (54166) and a softer rear shock spring. I found the M04 front shock spring (9805921) to be a noticeable improvement over the kit spring under medium to low traction surfaces. The soft T-Bar and the M04 spring improves the cars compliancy and stability over bumps while the aluminum motor mount maintains cooler motor temperatures. One final item I recommend is a Kimbrough servo saver (standard size). In addition to protecting the servo gears from impacts, the servo saver effects ackerman and bump steer. With all the additional Hop-Ups and parts on hand, assembling the F104 is very easy. In fact, there are only a few areas that can benefit from extra attention during the build process.

Rear Pod
The rear pod of the F104 consists of 4 pieces, so it's important that they are aligned properly to avoid any twisting. Start by assembling all 4 components together as per instructions but do not completely tighten the screws. The screws should be just loose enough for the 4 pieces to move around a little. Place the rear pod assembly on a flat surface such as a set-up board and hold down only the left and right portions of the pod. While maintaining moderate pressure, gently begin tightening the 8 screws. Rather than completely tightening one screw at a time, tighten each screw slightly in equal increments and repeat this process until they're all completely tight. Lightly tap on the corners of the pod periodically to check alignment during the gradual tightening process to insure the pod isn't twisting.

Steering / Servo Position
The length of the servo saver arm and the angle of the steering links will directly affect the amount of Ackerman and bump steer the steering will have. I settled on the Kimbrough servo saver because it provided the steering characteristics I was looking for. On the Kimbrough servo saver, the two 5x5mm ball ends should be installed on the farthest row of holes (end of the servo arm).

When installing the servo, the instructions illustrate that the center of the servo output shaft should be 30mm from the chassis. I used a Futaba 9602 mini servo and raised the height to 32mm to reduce bump steer a little and this also affects the Ackerman slightly as well. The fore and aft position of the servo also effects Ackerman. For reference, I set a 1.2mm gap between the plastic ball end and the front of the servo mount. This is roughly a 5 deg. angle in the steering linkages.

(Your potential range in servo position will vary depending on the size of the servo used.)

When installing the servo, the instructions illustrate that the center of the servo output shaft should be 30mm from the chassis. I used a Futaba 9602 mini servo and raised the height to 32mm to reduce bump steer a little and this also affects the ackerman slightly as well. The fore and aft position of the servo also effects ackerman. For reference, I set a 1.2mm gap between the plastic ball end and the front of the servo mount. This is roughly a 5 deg. angle in the steering linkages.

Although installation of the electronics is easy on the F104, special attention should be placed on the motor wiring because it can affect the handling of the car. To begin, there are two areas to mount the receiver and speed control on the F104. The logical position of the speed control is on the left because the motor leads come off the left side of the rear pod. Rather than placing the speed control in a typical bottom down position, I placed it on its side with the wires pointing back. This enabled the battery and motor wires to travel in a more direct path.

Regarding wires, it's not necessary to have excessively thick gauge wire because it can limit free movement of the motor pod resulting in handling problems. To avoid this, I used 16 gauge wire to insure the motor pod moved with minimal interference. The receiver installation is straight forward. To allow plenty of clearance for the body, it was also placed on its side with the antenna pointing rearward. This creates a clean path for the speed control and servo wires to reach the receiver ports.

Due to the very scale nature of the F104 Pro's body, the receiver sits on the opposite side of the speed control with the battery running down the center. This doesn't make installation of the electronics difficult but the speed control wire typically goes over the upper deck to reach the receiver. I prefer to have this wire less visible so I routed it under the battery. Start by adding shrink tubing around the area that will be under the battery. This will avoid wear on the wire from installation and removal of the battery. Make sure to have enough slack in the wire next to the speed control to account for movement during battery installation/removal. Most Lipo batteries have slots on the bottom to lock into a chassis design for Sub C packs so with the heat shrink in place; use Shoe Goo to mount the wire on the chassis so that it sits between these slots. I also used heat shrink on the servo wire and used Shoe Goo to secure it down the right side of the chassis. The end result will be not only a clean appearance but a functional one.

Shock and Damper Plate
The rear dampening system on the F104 Pro consists of an oil filled coil spring shock for perpendicular dampening and a dual disk damper plate assembly for 360 degree dampening of the rear pod. Because the damper plate and the shock both control perpendicular damping and the T-plate is firm in this direction, I went with the softest oil and spring combination on the shock and light damper grease for the damper plate. Using the 3-hole piston, I used 200 weight oil in the shock and the front spring from the M04 M-Chassis (gold color). This improved the overall compliance over bumps. To control lateral movement of the pod, loosen or tighten the adjustment screw on the T-plate. A loose setting will generally provide more stability but reduce steering (good for low traction surfaces). A tighter setting will increase response and provide more steering (good for high traction surfaces).

On the rear friction damper, add a 3mm o-ring above the preload collar after assembly. This keeps the preload setting from moving. In rare cases, the preload collar can completely unthread itself without the added o-ring, so it's a good way to avoid this from happening.

Tires & Gearing
The F104 Pro is equipped with the Tamiya Type A foam tires. These are a relatively soft compound with a moderate amount of rubber content. The optional Type B is a bit harder but with more rubber and this typically generates more traction. For medium to low traction surfaces, the Type B will most likely be the best choice between the two.

For carpet or high traction surfaces, the Type A may be better. Once you've selected your compound, the diameter is very important because it affects your ride height, gearing (rear tires), and overall handling. A smaller diameter tire tends to be more responsive due to less sidewall flex but can have less overall grip than a larger tire. In general, try a larger tire for low traction surfaces and a smaller tire for high traction surfaces. A good starting diameter for low grip surfaces is 60mm and 57mm for medium and higher grip. For very high grip such as carpet, 55mm would be a good starting point.

Deciding on the gearing for your F104 will depend on the motor you'll be using, the size of the track and the diameter of your rear tires. The F104 Pro includes two spur gears sizes, a 104 tooth and a 93 tooth. For motors such as a "silver can" and the Formula Tuned, the 93 tooth spur will be ideal in most cases. For high powered motors, the 104 tooth spur may give you the proper gearing range. With your tire diameter determined, you can select your gearing. The best way to calculate gearing is by "roll out". This is the distance the car will move per one rotation of the motor armature/rotor.

General Roll Out Range:
"Silver Can" - 53mm to 56mm
Formula Tuned - 57mm to 60mm

Chassis
The F104 includes two optional chassis posts. If used, they must be installed after the battery is installed and removed before the battery can be removed. The purpose is to make the chassis flex characteristics symmetrical. I found that on medium to low traction surfaces, the benefit is marginal. However, a high traction surface may justify the use of the optional posts.

Differential
The differential is a very important component of any direct drive car so it's important to use the right differential grease. Differential grease has a unique characteristic in relation to typical grease. It lubricates the differential yet resists slipping on the differential rings. This allows for a free rotating differential that is resistant to slipping. If conventional grease is used, the balls will slip on the rings requiring and excessively tight setting resulting in a poor handling car. For this reason, you shouldn't use just any kind of grease. My personal preference is Associated Stealth Lube.

The setting of the differential will also be determined by grip level and the power of the motor. The higher the grip level and or powerful motors, the tighter the differential may need to be to avoid slipping. In general, a differential that is too tight can cause sudden loss of traction on a low grip surface yet in some cases, under steer on high grip surfaces. A setting that is too loose will slip excessively reducing drive exiting corners and will also create inconsistent handling. For this reason, the setting will need to be tuned to each condition. Typically, you want the differential to spin relatively freely but not loose enough to cause slipping while exiting corners.

Tire additive helps enhance the grip level of the tires. There are a variety of options made specifically for hobby use. If you are unsure of which additive to get, the most commonly used additive is Paragon Ground Effects. This additive works by softening the foam and is suitable for tarmac or carpet tracks.

The other recommended additive is sun block. This may sound unusual but sun block has been used for outdoor foam tire racing for as long as I can remember. Of course, there are a lot of brands of sun block out there so I would suggest starting with Coppertone SPF 30. Sun block tends to be used mostly on low to medium grip conditions and is applied after the primary additive such as Paragon has been applied. When using additive, the amount of time it is left on the tire determines the level of effect. Apply additive to the full surface of the rear tire for maximum rear grip but only the inside 1/4 of the front tires. The amount of additive applied to the front can be increased or decreased depending on the amount of steering desired. Also, experiment with the duration you let the additive sit before wiping it off and running. The longer the additive is left on the tire, the softer the tire will become and the depth of absorption will also increase.