We Drive It First! Team Associated RC10B5 and B5M

We Drive It First! Team Associated RC10B5 and B5M

Armed with four cars, each painted as a replica of four of their biggest stars, Team Associated invited RC Car Action’s Aaron Waldron and Joel Navarro to SDRC Raceway in San Diego, CA for an exclusive opportunity to drive AE’s first new 2WD buggies in over a decade! Accompanied by B5 project engineers Bob Stellflue and Kody Numedahl, Aaron became just the sixth person on the planet (and first outside of a small circle of Team Associated’s designers and team drivers) to log laps with the new rear- and mid-motor platforms.

After dominating the 2WD buggy category since the original RC10 was released over 30 years ago, particularly during the B4’s untouched reign of terror that included five straight IFMAR World Championships, the B5 and B5M platforms have high expectations to meet. We’ll have to wait to see how they do in top-level competition, however – one of the first things that we learned during our test day is that AE’s team drivers will not be running the new buggies at this weekend’s Reedy International Race of Champions, citing a lack of kits and parts, as well as testing time, as the reason to hold off on debuting the car on a world stage. Looks like we’ll have to wait until the Cactus Classic in March!

Here’s Aaron driving the RC10B5 and B5M, sharing his first impressions on how the cars worked on the sticky surface and tight, twisty layout of SDRC.

Team Associated engineer Bob Stellflue discusses the challenges and successes of designing the new B5 and B5M buggies during an exclusive test day at SDRC Raceway. Bob lends insight into the choice to make separate rear- and mid-motor buggies, the design tweaks made to each car to suit the platforms, and how each will behave on the racetrack.

Team Associated engineer and IFMAR Worlds finalist Kody Numedahl discusses his role in the development of the new RC10B5 and B5M buggies, what he feels are the car’s biggest benefits, and the process of replacing the most successful buggy in history.

Here’s a closer look at some of the cars’ features:


The rear-motor B5 is what Bob and Kody both called “a facelift” for the successful B4 platform. All new molds had to be created, and both buggies are now exclusively outfitted with metric hardware. The rear-motor B5 retains nearly all of the B4’s geometry, with subtle refinements found all over.


The mid-motor B5M was designed specifically around the central mass placement of the motor location and four-gear transmission, which was necessary to reverse the motor’s direction to take advantage of its gyroscopic effect.

The most noticeable differences between the B5 and B5M are their chassis and front arms, but there are reasons for both. Team Associated felt that plastic composite was the best option for the rear-motor car, not only because of cost but also its resilience (plastic doesn’t bend and stay bent – it returns to its normal shape) and durability (scratches don’t look as bad as they do on an aluminum). When the motor is hanging out of the back of the car there is plenty of room to add ribbing to the plastic chassis in order to change its flex characteristics in both longitudinal bending and torsional twisting, but the mid-motor car doesn’t have such luxury – which is why the aluminum chassis was necessary.


The gullwing arms pictured on the B5M aren’t platform specific – rather, AE’s engineers insist that the arms and shock tower will be used as a tuning option.

Keen observers of Team Associated’s press photos for the B5 and B5M noted the upward sweep of the front arms of the mid-motor car, immediately assuming that they were necessary in order to make the buggy work properly. Bob Stellflue, however, explained that the gullwing arms, and wider front shock tower that accompanies them, will instead be a tuning option – and that they’ll most likely be used on the rear-motor car more often. Whereas the straight front arm design increases the progressive feel of the front suspension, making it “stiffer” as the car rolls during cornering, the gullwing arms maintain a much more linear rate as the shocks compress, which makes the front end of the car feel “softer” and increases the car’s steering response.


Check out the blue anodized aluminum thumb nuts, which now use an o-ring to keep them fastened securely. No more threadlocking your battery strap!

Neither the B5 nor B5M will fit a full-size stick pack – in order to keep the weight of the car close to its centerline without using an upper tray to raise the car’s heavy electronics above the battery, the receiver and speed control are tucked either behind (rear-motor) or in front (mid-motor) of the battery. To fit ROAR rules, both the B5 and B5M can be fitted with a standard saddle pack, though “shorty” batteries and Reedy’s square pack will also fit.


Because of the way that the front and rear suspension bolt to the buggy’s main platform, there are significantly fewer screws on the bottom of the B5’s chassis, which makes the car easier to work on – they won’t pack with dirt or be ground down as the chassis wears.

The B5’s chassis is significantly narrower than the B4, a product of the mass centralization efforts explained above. Bob Stellflue stressed how important it was to make the B5 easier to assemble and maintain than the B4, and it shows in how few fasteners are used to hold everything together.


The servo mounts are bolted to the top of the chassis, rather than the bottom, which reduces the number of screws on the bottom of the chassis and makes it easier to remove the servo.


A special one-piece spacer is used to determine the mounting angle of the wing.

Unlike the B4, the wing mounts of the B5 are not keyed into the transmission and remain in place when disassembling the rear of the car – a big improvement over its predecessor’s design. The transmission case itself assembles differently as well – the motor plate is bolted to the right side of the case, rather than relying on long screws that hold the whole thing together, which means that the left side of the case can be removed independently to service the tranny’s internals.


Both cars that we drove were outfitted with Reedy’s yet-unnamed prototype racing speed control, which felt smooth and controllable even with serious modified class horsepower on tap.

Despite the tight compartment set aside for the receiver and speed control, the B5 and B5M were designed to accompany electronics of all sizes. Special attention was paid to how the electronics would install into the car – note the antenna mounts on each side of the chassis, allowing the builder to configure the car to his liking.


The mid-motor B5M uses the battery strap as a brace to provide extra rigidity in support of the chassis.

Since the battery compartment for the B5M lies between the speed control and receiver, a channel is built under the battery for the sensor wire to pass. A similar channel is built into the front of the buggy in order for a small AMB receiver to be fitted near the steering assembly.

What do you think of the new buggies? You can find out more information in an upcoming issue of RC Car Action!

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Updated: July 21, 2015 — 3:36 PM
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