Tamiya TRF 415 MS-H Special Custom

THE IDEA
The crack team of engineers at Driftmission.com have put together their first custom CS modified drift chassis. This chassis was originally a Tamiya TRF415 with the TRF415 MS upgrade kit. This chassis originally destined for a Rear Wheel Drive project. After consultation with the Drift Mission Team, we decided that weight-shift counter-steer was a better direction for this chassis. Our goal was to custom modify a Touring Car chassis for better weight distribution for RC Drifting.

The TRF 415 MS-H modifications are not the first of their kind, they have already been done by a few others in the RC Drift community. The front horizontal battery mount was originally performed by Hiracchi san from Japan and Tokeyo83 from CSJunkies; they originally modified their Hot Bodies Cyclone TC chassis now called the TC-H. This is where the inspiration for the TRF415 MS-H came from, so thanks to Hirrachi san and Tokeyo83 for the idea. There are a few other small modifications along the way, but we will share those insights as they come up in this custom build. This is the first TRF415 that has gone through this kind of surgery so at least it is unique in that respect.

THE HISTORY
This chassis started as a touring car which was purchased 2nd hand by a member of the Driftmission team. The total cost of the chassis shipped and delivered was $75USD for the TRF415MS which was missing several parts (front CVDs and dampers being key components), which are later replaced with third party option parts.

This is our attempt at creating a unique drift oriented chassis, so we present the Tamiya TRF415 MS-H: A Drift Mission Special Custom.

The first order of business was to install the new battery holder in a horizontal position across the middle-front section of the chassis. Four holes were drilled on the corners of the chassis and the battery holder was mounted with 4mm spacers to lift up the battery. The battery holder is now floating, to accommodate for the front belt that will now pass above and below the battery. We also created an idler/tensioner pulley behind the battery holder to keep the belt from interfering with the battery mount. The battery holder and tensioner mount was purchased from R2 Hobbies, the tensioner pulley was a spare plastic 18T from an old HPI RS4 Nitro RC.

Chassis and Bulkheads
The original Tamiya TRF415 suspension arms were replaced with a set of new reversible suspension arms, now common on new Tamiya cars. The new suspension arms are narrower than the previous version and also with greater damper mounting positions for better damper configurations. The front suspension arms have also been modified with a pair of ball-cups, this will be used to remove the C-hub. This modification is commonly known as the ‘C-hub delete mod’, where the C-hub is removed and replaced with an extra turn-buckle for stability and adjustment. More pictures of this modification will be shown below when the steering arms are installed. The new TRF415MS bulkheads are easier to work with compared to the original one-piece solid bulkheads.

The Differentials
The Front One-way was included with the chassis and came with original 35T pulleys, which we replaced with an Eagle 37T front pulley. An Eagle 14T centre one-way was used to replace the original 16T center one-way. The 23T direct rear center pulley was purchased from R2 hobbies. The rear spool/direct-coupler is a 3-racing TB-03D spool, it fits nicely with a couple of shims on each side. We did manage to fit a genuine Tamiya TB-03D spool in there without a problem, however due to the rear pulley we chosen; the 3racing spool was a better fit. The rear pulley is an Eagle 28T strong pulley, made for the TA05 GRT but will fit on the TB03 spool easily. The Spur gear is the stock 102T 64 Pitch Tamiya TRF415.

The Steering Design and Components
As mentioned before, the C-hub will be removed. An extra linkage was added to stabilize the upper suspension link and also provides adjustment for castor angle. The stock TRF415 steering wipers did not provide adequate steering angle so they were replaced with Eagle Racing TA05 GRT V1 steering wipers. The new wipers were installed on a wider position originally on the chassis for mounting the front upper chassis plate. The TRF415MS upgrade package eliminates the old upper chassis plate so these holes are not used for the 415MS. The new steering wipers improve the steering angle significantly, where it was once 20 degrees maximum, they can now extend up to 50 or 60 degrees. The only thing left limiting the steering angle are the damper positioning.

Steering Angles

The Dampers
We had a spare set of 3racing HPI/HB threaded dampers available for use on this chassis. These dampers were modified using ‘Hamster’s dual rate damper modification’. This means that the dampers would compress at a faster rate than they expand, which results in a dual dampening rate. This modification is a very useful one and costs very little to replicate. We have been trying to get in contact with Hamster for permission to display this specific modification on Drift Mission, so look for it in the future.

Electronics
With the battery situated horizontally across the front-mid section of the chassis, the servo no longer has anywhere to mount. The new steering wipers are also operated in a different way. Even if the battery was not there, the original servo position would not be able to utilize the new steering system properly. This requires a whole new mounting position and method for the servo. First we obtained a low profile servo, the Futaba S9550 to mount on the right side of the chassis directly beside the motor. Mounting the servo required some creative thought, but we manage to get it together without too much carbon fiber modification.
We used a small 35A esc and 12T brushless motor to power this chassis. Luckily the 35A ESC was small enough to be able to fit right on top of the servo without any interference. We also added 20g weight to the servo side to balance the rear weight distribution.

Conclusion and Review
The Tamiya TRF415 MS-H custom modification was a success! This chassis behaves like no other that we own at Drift Mission. The balance of the chassis while drifting behaves much like a 50/50 drifter, but with a 2.17CS ratio (117% Overdrive), it can still counter steer! This car is very ideal for chasing, as it is well behaved and easy to control.

After several battery cycles, everything seems to be functioning properly. The belts are still running free and clear. The steering mechanism has gone through some turn-buckle adjustments for better steering geometry. Ackerman angle was eliminated when this was first built but we have since restored some of the Ackerman angle; due to the large castor angle, we find that the Ackerman angle does help with steering.

While performing the “castor hub delete modification” we noticed a few small problems. If you run a larger castor angle, approximately greater than 8 degrees; the front wheel will turn into the lower suspension arms, causing some rubbing. This problem was solved by adding some kick up to raise the front of the suspension arm away from the inside of the tires. This “Castor Hub Delete Modification” is an easy one to perform, but you will need to be prepared for unanticipated problems. It took some time and small modifications to get it to function properly.

If we were to perform the same modification again, we would get new carbon fiber and create a new chassis. The NiMh battery slots are troublesome when it comes to drilling and mounting the battery holder. Creating a whole new main chassis plate would be ideal to reshuffle different parts. This was an after thought, we never knew it would be this much fun to modify a chassis.

When working with carbon fibre, drilling, cutting or even sanding. Extra attention needs to be taken to ensure that you do not breathe any of the carbon dust. The carbon dust is hazardous to your health, please refer to the Materials Safety Data Sheet (MSDS) for information before you proceed to do any carbon fiber work. Always use safety equipment whenever possible!

If anyone has any comments and/or suggestions, please do not hesitate to comment below or contact us. Thank you for checking out our Tamiya TRF 415 MS-H Special Custom chassis.