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Spec Class Overkill – Building Yokomo’s BD10 for USGT Racing

Spec Class Overkill – Building Yokomo’s BD10  for USGT Racing

We all love a bit of on-road racing in our RC lives. I mean for me, it comes down to having a love for all things automotive, which is part of what drew my attention to RC in the first place. One of those real-world inspirations is high-performance GT touring cars. There’s just something to be appreciated about a beautiful car that’s been built for performance racing. Luckily, there is an RC analog that looks just like the real thing; the long-established USGT spec class.

For those that aren’t familiar, USGT is a 1/10 electric touring car class that emulates real world GT racing in scale format. All cars must be 1/10 scale 4WD touring kits, and must use a realistic style GT body, spec tires, a 21.5T USGT spec motor, a ROAR-approved ESC, and a ROAR-approved 2S LiPo battery. Besides those few main requirements, there’s a whole list of ways you can make the car your own, from the base car kit choice to the body used, individual electronic component choices, and even a good selection of spec wheel styles to choose from. Once I saw this class in action a few years back, I had a plan to get into the action myself one day. And finally, that day has come.

Built to Last, Designed for Performance

First decision for me to make was which kit I’d base my build on. Now, there are quite a few high-end touring car kits out there, but to me I had my eyes set on something with a long racing pedigree along with great parts support, and if possible, something that might be a little overkill for spec racing. This goal meant I needed something with an industry-leading design, and world-class performance. So, after some thought I pulled the trigger on one of the latest kits on the market, the Yokomo BD10. Yokomo is well known in RC for their top-notch manufacturing quality and excellent designs, and I can tell you that the BD10 does not disappoint.

Initially when opening the box, I was greeted with bags full of precision molded parts trees molded from high-quality plastics, CNC machined aluminum bulkheads, and that beautiful woven carbon fiber main chassis, along with the carbon fiber shock towers. Right away I was hit with that feeling of joy and appreciation that comes with buying a top-of-the-line kit, ready to be assembled. As can be expected from Yokomo, the fit and finish quality is hard to beat. Every piece of the BD10 kit is not only machined to exact tolerances but fits snugly in place without need for any shaving, filing, or other modifications. Exactly right, right from the start.

The BD10 is a serious racer, with tons of fine-tuning adjustments that can be made across the entirety of the chassis. Different toe blocks, pill inserts, tons of shock mount and camber link positions, a precise cam adjustment system to change drive belt position and tension, and even several flex tuning points on the center bulkhead and top deck plate. The BD10 draws inspiration from Yokomo’s previous BD9 design, even using some of the same small parts, like drive cups, along with a handful of option parts. Although similar, the BD10 starts to break away from the previous BD9 design with the most notable change being the BD10’s mid-mounted motor center bulkhead and isometric front and rear belts.

This major design change completely smooths out the driving characteristics of the car by placing the majority of the weight more central to the chassis, effectively creating a better driving car. The shocks on the BD10 have been totally redesigned by AXON, a heavyweight in the Japanese RC touring scene and include a new dual o-ring design, HVF internal coating for reduced internal friction, and new progressive rate springs. The BD10 also features 2mm longer suspension arms front and rear for stability and traction, and AXON anti-sway bars front and rear for improved handling. The BD10 ticks all the boxes in the on-paper performance department.

A KO Propo BSx3one-10 Grasper steering servo was chosen for its balance of precision, strength, and extreme speed.

The tub chassis of the Fazer Mk2’s wheelbase is about half an inch longer than a typical standard touring car chassis. This helps give more realistic overall proportions to the Elky.

The Gravity RC USGT spec 21.5T motor is powered by a Hobbywing XR10 Pro Stock ESC, chosen for its excellent BEC output and overall performance.

Spec’d for USGT

With the BD10 being chosen as the base foundation, it was time to choose components to make this USGT build a reality. USGT rules require the use of the Gravity RC 21.5T USGT spec brushless motor, along with Gravity RC’s USGT spec wheels and RIDE semi-slick tires, which keeps the playing field fairly level on two of the more major component choices. I opted to power the 21.5 USGT motor with Hobbywing’s XR10 Pro Stock Spec ESC, a ROAR-approved 80A brushless spec speed controller with a high-output BEC for optimal performance.

To keep the car on track, I opted for the KO Propo BSx3-one10 Grasper steering servo, a high-performance brushless servo with a nice balance of speed and torque. KO Propo’s 418KR receiver was chosen due to its compact size and extra response speed when paired with the Grasper servo and was linked to my trusty KO Propo EX-II radio. Providing power to these components is an IP Intellect 7200mAh 2S LiHV race pack.

Since I can’t really ever leave anything stock, even if it’s a kit as good as the BD10, I chose a few extras to throw on for good measure. The first option part that caught my eye was Yokomo’s Graphite Battery Holder. This set replaces the original plastic components with woven graphite parts, improving the rigidity of the battery tie down. Yokomo’s titanium turnbuckles were fitted in place of the stock aluminum parts for a bit of added strength.
Lightweight aluminum drive cups were installed front and rear for drivetrain weight reduction. A Hiro Seiko Lightweight Titanium screw kit was mixed in with the Yokomo screws to give me just that extra bit of tunability when needed. To top off the upgrades I opted to throw on a set of X-Square Kevlar low-friction belts to further reduce drag on the driveline, plus they look pretty dialed.

After choosing the major components of the car, along with some extra goodies, it was time to decide on just how I wanted it to look. There are so many sources of inspiration out there in the world of GT racing, so it took some time to home in on just what I wanted. After some thought, and reading over the approved body list several times, I finally decided on the Bittydesign AGATA. This sleek 190mm GT body design looks to be inspired by a certain Italian automotive manufacturer who competes in modern GT racing. Painted up in a striking fluorescent yellow-green, this body was perfect.

All in the Drive

Belt driven cars have always had the benefit of feeling buttery smooth, and the BD10 surely continues that tradition. I don’t even think the word smooth does it justice, it’s that good. First impressions of the BD10 motor layout change are that it’s very predictable. While testing I noticed the weight transfer is very tight, and not unwieldy. The chassis just sails through corners, with almost no feeling of oversteer. Granted, with all the possible tuning options on the BD10 chassis, you can introduce oversteer or understeer as you see fit but going by the very neutral instruction manual settings the chassis feels extremely tame.

For anyone looking at using the USGT spec RIDE semi-slick tires, it takes a few laps to get them to stick on asphalt, but once they wear in a little, they do a great job of keeping the car planted and on track. The USGT spec 21.5T motor has a great powerband for a 21.5 motor, thanks in part to the Hobbywing XR10 Pro Stock ESC, and a change in spur and pinion gears to get just the right gear ratio. When tuned to ideal settings, the Yokomo BD10 flies. Even with a 21.5T motor, the car feels fast, and that fast feeling is just what I was looking for. Something that may not be a break-neck speed like 5T modified car, but still has enough get-up-and-go power to keep me excited. The more I drive this car, the bigger my smile gets, knowing full well that it was money well spent.

and can handle 2-3S LiPo or 6-8-cell NiMH packs. Ours was run primarily on Kyosho’s own 2200mAh 7.2V NiMH pack, but some extra performance can be had with higher cell counts.

The new BD10 design features isometric front rear belts. Gone are the days of having to lug around 2 different sized belts for maintenance.

Final Thoughts

I’d say if you’re looking to build a new touring car, then you can’t go wrong with the Yokomo BD10. The large list of tuning options, plus the high-end racing pedigree that Yokomo bring with their years of experience really shows in the quality of the BD10 design. I know for me personally, I’m very pleased with the driving feel and performance of the car and can’t wait to hit the track for some wheel-to-wheel USGT racing.

If you’re interested in a new touring car class to race, then give USGT a look. The spec rule set mixed with the large amount of chassis options means you can build yourself a car that is just for you, something you put heart and soul into that makes you smile every time you take it out to the track. And it’s at the track where this BD10 build will live. I’m sure I’ll see some of you out there so until next time, happy racing!

The BD10’s shocks are newly design by AXON for optimized smoothness and consistency and come outfitted from the factory with newly designed progressive springs.


 

More About USGT
USGT is a popular touring class across the nation and has even seen growing popularity internationally. The core ethos of the class stems from enjoying more realistic looking GT bodies, while keeping the racing relatively accessible. Although my BD10 build may be in the higher realm of the price range, entry into the class can be as simple as picking up a used 4WD touring kit, installing the spec motor and tires and enjoying. If you’re interested in finding a fun, accessible form of 1/10 electric touring racing, check in with your local track to see if they run a USGT class.


Text & Photos by: Lauren Short

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Updated: May 18, 2021 — 10:38 AM

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