The Formula 1 category has continued to grow in popularity since the release of the F104 Pro. With this level of interest, there has been a steady release of hop-up options to further tune and improve the performance of the F104 chassis. With these available options, as well as all new options, Tamiya has released the F104X1 (Limited Production).

The F104X1 is designed to maximize traction, making it ideal for rubber tires on asphalt circuits. This is done with hop-ups such as the high traction T-Bar as well as all new parts like the X-Shaped upper deck and aluminum roll damper.

Full list of Hop-Ups and features include:

NEW for the F104X1

X-Shaped FRP upper deck (new part)

Aluminum damper mount (Titanium color) (new part)

Rear axle shaft counter weight fitted with ball bearings (black color)

F104 carbon reinforced gear case (new part)

Aluminum Roll damper (Black color) (new part)

Item 54129 TB-03D Aluminum Motor Mount (new color)

Item 54158 F104 Aluminum Diff Housing Set (new color)

Item 54159 Aluminum Horn for Hi-Torque Servo Saver (F104) (new color)

Item 54202 F104 Aluminum Upper Suspension Mount (new color)

Left Rear Wheel Hub (new color)

Other Included Option Parts

Item 53599 Fluorine Coated 5mm Aluminum Ball Nut

Item 53901 TRF Special Damper (F103GT) (Black)

Item 54154 F103 Carbon Reinforced Front Upright

Item 54160 F104 Titanium Coated King Pin

Item 54161 F104 Low Friction Suspension Ball Set

Item 54222 F104 High-Traction T-Bar

Touring Car Short Spring (Black)

Low Friction 5mm Adjuster

3x35mm Aluminum Turnbuckle Shafts (Black)

4mm Aluminum Lock Nuts (Black)

4mm Aluminum Flanged Lock Nuts (Black)

Specs and Features

Link-type front suspension

Front kingpin coil spring independent suspension

Direct drive solid rear axle transmission

Ball differential

Accommodates Tamiya foam or rubber tires

Fits F104 specific F1 body shells (sold separately)

Adjustable front camber

Adjustable front and rear ride height

Building the F104X1 is more of less the same as the F104 Pro (an article regarding the build can be found here: F104 Pro Article) so this article will focus more on the unique components of the F104X1 and elaborate on these features.

Key Feature Descriptions

One of the primary features of the F104X1 is the fiberglass main chassis and the X-Shaped upper deck (also fiberglass). Although fiberglass is less expensive than carbon fiber, it's used for the chassis material on the F104X1 because of its "forgiving" handling characteristics rather than cost. Not only is fiberglass more flexible than carbon fiber but it's the way it flexes and returns (lower frequency) that gives it a forgiving and predictable characteristic. Included are also a total of four chassis posts. These posts can be used or not used to increase or decrease chassis flex. The X-Shaped upper deck runs half way up the chassis and allows for additional flex.

As a side note, the two plastic electronics trays can be omitted and not conflict with TCS 2012 rules. This is because the use of the posts that hold the trays is optional. If the trays are not used, the electronics can be placed directly to the battery or chassis.

The rear damper system is also new on the F104X1. The dual disk damper plates are replaced with a shaft type roll damper. This damper controls lateral movement and allows the shock to focus on horizontal movement. This system is much easier to tune because the dampening is independent of one another resulting in less compromise and more potential traction. The roll damper is adjusted via grease or silicone (thicker increases dampening and softer decreases dampening).

Determining the amount of dampening will vary on conditions but generally, softer will increase rear grip/reduce steering response and harder will reduce grip/increase steering response. However in some cases, higher traction conditions can alter this effect. Once the body is selected, there will likely be modifications required to provide clearance for the roll damper. Be sure to cut away portions that interfere with movement.

The F104X1 features a steel counter weight and a steel axle. The purpose of using steel is to intentionally increase the weight to enhance rear traction. Adding weight to a race car may seem counterintuitive; however, in some conditions it can be an effective way to generate traction. The counter weight does double duty by offsetting the weight of the differential assembly creating a better left and right balance and is supported by ball bearings to minimize rotating mass.

To adjust the steering characteristics of the car, the aluminum upper suspension mount is standard. Camber can be adjusted from 1.0 degree to 2.5 degrees in increments of 0.5 degrees. When adjusting camber on the F104, caster also changes and this should be taken into consideration when making adjustments. Adding more camber reduces caster and reducing camber, adds caster.

Electronics Layout

A high capacity battery such as the Reedy 5500mah LiPo can be fitted if the plastic electronic trays are omitted. However, the trays can be used with minor alterations. Simply remove the protruding crescent loop on the top and bottom of each of the trays and they can be clipped on and off the chassis posts while providing clearance for the battery.

If you're using a high capacity battery, there will likely not be room to route the speed control wire as shown in the F104 build article (below the battery). It this case, the most efficient way is over the upper deck. Using the same heat shrink as illustrated in the F104 article, attach the heat shrink covered wire to the upper deck (as shown in the image). This allows access to the battery by removing the left front and right rear chassis posts (if they are being used).

The battery can also be moved (approximately 18mm range) to alter the weight bias and balance characteristics of the car. If using bullet plug type battery, turn the battery around so the plugs are towards the back of the car when shifting the battery forward (see picture). The battery can be taped in place using servo tape or a foam block can be placed at the back to stop movement.

Extras

The F104X1 also includes a full set of front and rear springs to make adjustments for a wide range of conditions.

Aluminum Motor heat sink plate in a matching Titanium Bronze finish is included. This motor plate requires a long neck pinion if used with a "silver can" motor.

This portion focuses on adjustments/settings and everything featured in this article is TCS legal for 2012.

There are two things that must always be considered when setting and tuning any car; Balance and Compromise. In other words, when you make a change to one end of the car, it can affect the other end. This is why you must compromise to get balanced handling so keep this in mind when making changes and adjustments to your car.

Tires -
Although there are both foam and rubber tires available for the F104X1, this article covers rubber tires (Foam tires were covered in the original F104 Pro article here). The choices are simple with two compounds to choose from front and rear.

The hard compounds offer the longest life but will have less overall traction. However, in very high track temperatures, the hard compound may have more consistent traction. For most asphalt surfaces, the best tire combination is usually soft compounds front and rear. At the Tamiya track in Aliso Viejo, this is what is used most of the time.

Inserts are just as important as the tire compound, especially in the soft tires. Inserts control the compliance of the tire as well as the overall contact patch on the track surface. Typically, a harder insert works better in high traction conditions and soft inserts usually are better in low traction condition. However, the stiffness of the tire must be considered when making your insert choice. For example, using an excessively soft insert in the soft rear tire can reduce grip because the carcass of the tire is already very soft. This can cause the tire to collapse during cornering, resulting in less traction, overheating and more wear on the tire.

Front
54198 - Hard Front Tire: Reduce front sensitivity and/or grip, high track temperatures. Running with no insert can work well in this tire to enhance traction due to its firm construction. This can be an "in-between" setting if you don't quite need the grip of the soft tire.

51399 - Soft Front Tire: High front traction and steering, low track temperatures. Trimming the corners of the insert is a common adjustment to allow a little more flex in the tire which improves steering. This tire can also be run with no insert in some conditions for maximum grip and steering.

Rear
51400 - Hard Rear Tire: Long wear, high track temperatures. This tire usually works best with no insert due to its hard construction.

54199 - Soft Rear Tire: High grip, low track temperatures. This tire should always be used with an insert due to its very soft construction.

The front tires usually work best when "scrubbed in". This means they work best after they are run for a few laps. This eliminates the "twitchy" feel and provides more consistent lap times. The rear tires are best when new.

Chassis & Suspension -

Front
The primary areas of adjustment on the front of the F104X1 are:

Springs - Three spring rates are included with the F104X1 ranging from soft, medium and hard. Choosing the spring rate should be based on several things such as amount of traction, track surface and how the back of the car is handling. High traction conditions may require a stiffer spring due to more weight transfer and a low traction condition may need a softer spring to allow more weight transfer to the tires. A bumpy surface may need softer springs to better absorb the bumps where a smooth surface could benefit from a stiff spring. Because everything you change will influence other areas of the car, a stiff front spring will transfer more weight to the back of the car than and a soft spring. For the Tamiya track, I found the gold spring (medium) to work for most conditions. With the gold springs, there is naturally about 2mm of sag. This is the amount the chassis naturally settles from its own weight. This should not be eliminated with shims because it provides the suspension with up travel and reduces chatter.

Ride height - Ride height can be adjusted via spacers above and below the steering knuckles. Besides the overall ground clearance this adjustment makes, this also will vary the rake of the chassis. For example, having the front lower than the rear will reduce caster. It will also lower the roll center of the front of the car in relation to the rear. This can make the front of the car more responsive.

Camber - Camber changes on the F104 platform is performed by moving the front pivot of the suspension arms in or out. This is achieved with Aluminum Upper Suspension Mount (Standard on the F104X1). Because only the front of the arm is moving in or out, caster is reduced then adding camber and increased when decreasing camber. Take this into consideration when making changes.

Ackerman and Toe - Ackerman and toe are the two most sensitive adjustments on the front of the F104X1. There is a myriad of ackerman and bump steer possibilities that are dependent of the servo position, the servo horn and the ball end location on the steering knuckle. I personally like to achieve a linear feel with steering response and this was best achieved with a Kimbrough Servo Saver and spaced as illustrated in the F104 Pro article. The toe setting also effects ackerman so the adjustment will vary depending on the amount of ackeman the car has. With my ackerman setting, toe out reduced initial steering and improved stability.

Rear

The primary adjustments on the rear end of the F104X1 chassis consists of:

Differential - The differential setting can affect steering and corner speed. It is ideal to have as free rotation of the differential with no slipping while driving. This allows maximum acceleration as well as a consistent handling car. A differential that is too tight can cause corner speed and steering to be reduced.

T-Bar plate - The T-Bar plate is an adjustment that affects compliance of the rear suspension over bumps and cornering roll. The T-Bar itself can be changed with three options to choose from; Black, soft and High-traction. Included with the F104X1 is the high traction T-Bar which is the softest of the three with Black being the stiffest. The tension of the T-Bar is set with the adjustment screw. The best setting will vary depending on the amount of traction as well as the track surface. Typically, tighter will reduce rear traction/increase steering response and looser will increase rear traction/reduce steering response. A good way to set a base-line starting point is to back off the screw so there is no compression of the o-ring. Then slowly tighten the screw just until you can feel the resistance from the o-ring starting to compress. Then back off the screw half a turn. Making adjustments from here should be no more than a quarter turn at a time.

Ride height - Overall ride height is adjusted by changing the rear shaft spacers. Like the front, making the rear higher or lower than the front changes the rake of the chassis. This is an adjustment that can fine tune the handling balance of the car.

Chassis posts - The chassis post control flex. Using all 4 included posts would be the most rigid setting. The more rigid the chassis, the more responsive it will be.

Shock and roll damper - Included in the F104X1 are three rates of shock springs. Where the front springs control the bump compliance and roll of the car, the shock spring only controls bump compliance so tuning this area should reflect this aspect. It should also be considered that the T-Bar is also a spring. Roll damping is controlled by the Roll Damper and this is tuned with grease or oil. I prefer silicone differential fluid because it's easy to find and there are more steps in viscosity available. 10,000 weight is a good starting point. The Roll Damper should be treated just like a shock in the way it controls the rate of weight transfer. The T-Bar selection and tension setting on the o-ring acts as the spring rate for roll movement. The tighter the o-ring setting, the heavier the roll dampening should generally be.

Weight -
Most of the time, it's ideal to minimize the weight of a car for the best performance. However, there exceptions such as low traction conditions where there just isn't enough weight transfer regardless of the chassis and suspension settings. This is the type of condition the F104X1 is designed for and adding ballast can improve the traction and stability of the car. However, placement of this ballast is equally as important because you want to add as little as possible. I found that the air box is a good place to add ballast because placement here basically raises the CG (Center of gravity) of the chassis which more effectively transfers the added weight to the tires during cornering. Considerably more weight would need to be added for an equivalent effect if placed low on the chassis and this tends to negatively affect tire wear, acceleration and cornering. For the Tamiya track, adding 20 - 30 grams in the airbox is a good starting point.

The steel axle and counter weight is standard on the F104X1 and provides more rear traction than using the carbon axle without the counter weight. Having said that, I preferred the light weight carbon axle (54162) and clamp type wheel hub 84196 (54240 blue) option here because it gave the car more steering and corner speed. The weight added to the airbox provided ample stability and cornering traction so this was a good compromise.

Conclusion -
The F104X1 is a very stable and easy to drive on low grip conditions. Only a few additional Hop-Ups are necessary. Because conditions as well as personal driving preferences vary, it's important to make changes to suit you and your car. This article is an aid to explain the general setting options of the F104X1 so that you can get the most from your car. Included is my base-line set-up for the Tamiya America track.

List of additional Hop-Ups used:

84196 Black -or- 54240 Blue - Clamp Type Wheel Hub

54162 - Carbon Axle

84115 Black -or- 54166 Blue - Aluminum Motor Mount

9805921 - M04 front shock spring (gold)

Here is a basline setup sheet for the F104X1, click to download.

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