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Rear roll center tuning on the B7 plays a critical role in how the car generates grip, steering, and overall balance on carpet. Changes in rear pivot width have a direct effect on rear roll center height, with wider rear pivots lowering the rear roll center and narrower pivots raising it. Testing across multiple configurations showed that even small changes in rear roll center can significantly alter how the car behaves on power, through the corner, and over varying track surfaces.

The first configuration evaluated was the narrow rear pivot setup, which raises the rear roll center. This higher roll center produced a car with a large amount of rear grip when throttle was applied, but it limited on-power steering. The rear tires stayed heavily loaded, which made the car feel secure and predictable, particularly in sections of the track with bumps or uneven carpet. On tighter layouts or tracks that require frequent direction changes and short corners, this setup can be advantageous. The elevated rear roll center helps keep the car stable and minimizes unwanted rotation, but it also makes it harder to aggressively drive the car through the corner when maximum lap time is the goal.

Lowering the rear roll center by switching to wide rear pivots produced a noticeably different driving characteristic. With the rear roll center lower, the car gained on-power steering and became easier to rotate while still maintaining throttle through the corner. This allowed the car to be driven harder into the corner and pushed closer to the limit without becoming unpredictable. On higher-grip, flowing carpet tracks such as PDX, this configuration proved to be more effective. As the rear roll center was lowered, the car responded better to throttle input, carried more speed through the corner, and rewarded a more aggressive driving style. The improved ability to drive the corner rather than slow down for it made this setup particularly well suited for tracks where momentum and commitment are key to achieving fast lap times.

While the wide pivot configuration excelled on higher-grip surfaces, it did reduce overall rear grip compared to the narrow pivot setup. On surfaces where the carpet is worn or does not build as much tire grip, this reduction in rear grip can become noticeable. To address this, a third configuration was tested using wide rear pivots combined with a B7 rear arm and a -4 hub. This arrangement effectively created an intermediate rear roll center and track width relationship, blending characteristics from both previous setups.

This hybrid configuration added rear grip compared to wide pivots alone while maintaining more stability and consistency than the narrow pivot setup. On lower-grip or older carpet, where tires struggle for grip sometimes, this balance proved to be especially effective. The car maintained predictable rotation and usable on-power steering without feeling loose or overly aggressive at the limit. The result was a setup that could be driven confidently while still allowing the driver to push lap times as the track conditions demanded.

Overall, rear roll center tuning on the B7 should be approached as a track-dependent decision. A higher rear roll center from narrow pivots favors stability, bump handling, and tighter layouts, while a lower rear roll center from wide pivots increases on-power steering and allows the car to be driven harder on faster, higher-grip tracks. The in-between configuration provides a versatile option when grip levels fall between those extremes, highlighting how critical rear roll center selection is to maximizing performance on the B7 platform.

In modern 1/10 off-road racing, stiffness and durability was once the primary goal. Stronger, thicker, and more rigid parts were seen as the key to consistency and precision. While stiffness still plays an important role, today’s high-grip tracks have revealed its limits. A car that is too stiff can struggle to generate forward bite, feel harsh over bumps/jumps, and become unforgiving when switching directions. Instead of absorbing energy, the car deflects it, which often leads to lost grip and inconsistent lap times.

As tracks have become smoother and traction levels have increased, the demands placed on the chassis and suspension have changed. Cars are now required to generate lap times mechanically rather than relying solely on tire choice or raw talent. This has pushed designers and racers alike to look beyond stiffness alone and focus on how the car behaves dynamically under load. Understanding where and how a car flexes has become just as important as spring rates, shock oil, or geometry changes.

This is where controlled flex becomes critical. Properly engineered flex allows the chassis and suspension to work with the track rather than against it. When flex is intentional and predictable, it improves mechanical grip, helps the car settle through bumps and landings, and stabilizes behavior through the pitch axis without sacrificing response. The key distinction is that not all flex is beneficial, uncontrolled or accidental flex caused by certain geometry or weak mounting points introduces inconsistency and unwanted issues while driving.

At Factory Foote, flex is treated as a tuning tool. On our 2WD cars, we have run soft side guards for many years, as they increase overall drivability and forgiveness. This is a clear example of when additional flex can be advantageous, especially on high grip or technical layouts. However, flex must always be evaluated in context, as its location and direction are just as important as its amount.

On the B84, particularly in the rear of the car, there is a significant amount of side to side flex. This is likely due to the narrowing of the rear pivots and the D block no longer being mounted directly to the chassis. While this design can offer benefits in certain conditions, it can also introduce excessive lateral compliance in the rear. In some cases, the rear of the car can feel disconnected from the rest of the chassis, making the car harder to read and reducing confidence when pushing the limits.

This led us to develop an immediate solution. A two piece stiffener that mounts from the side guards to the front of the rear gearbox, limiting side to side flex in the rear of the car. By tying the rear end back into the chassis, this change helps the rear suspension work more in unison with the rest of the car. The goal is not to eliminate flex entirely, but to control it in a way that restores predictability and makes setup changes more meaningful.

This stiffener is just one step in an ongoing development process. As we continue to test and refine the B84 platform, we are evaluating additional ways to improve balance, consistency, and tunability without sacrificing speed. Every change is driven by on track feedback and real world testing, with the same philosophy in mind: Go faster.

Following the B7 design, AE released a new 4WD, the B84. The model has similar pivots and uses the same rear arm as the B7, with many parts interchangeable between the 2WD and 4WD. Parts like the internal diff gear, rear shock tower, rear arms, and rear hubs are shared. AE has seen great success on dirt tracks but hasn’t achieved the same results on carpet. Why might that be?

We haven’t had much time with the car yet. We got a couple of runs in on July 15, just a few days after receiving it and right before the Roar Carpet Nationals. Back in July, we didn’t have the parts needed to get it into proper race trim, which made it hard to gauge its pace. Instead, we focused on how the car felt and handled. Nationals was a learning experience in 4WD, but we took the data and used it to improve. Now, we’re looking to learn more about what to do when carpet racing.

The first thing we noticed was how rigid the front end was. I saw this while watching Brandon run the car. He mistimed a jump and had to plow the front on landing to get down as quickly as possible. The car’s reaction to this move really surprised me, I’d never seen anything like it from a 1/10 model. Luckily, I caught it on video. Brandon also pointed out how dramatically the car shifted its weight from front to rear when on the throttle.

While running the B7, I had a few thoughts. I figured the chassis jacking might come into play, so I focused on capturing video during long corners, knowing the car would perform well in hairpins.

At nationals, Brandon noted that the car was still transferring too much weight from front to back. He went through all the usual setup changes, removing all the caster from the front, adding as much anti-squat as possible—including a 1mm spacer under the D-Block—and standing the rear shock fully upright. This made some improvement, but not enough. We then began shifting weight in the car by moving the motor back. The car felt better, but still wasn’t quite where it needed to be.

Until now, I hadn’t really taken a close look at the car like I usually do. I made a point to do this a few weeks ago, and Brandon and I sat down to examine it. The first thing I noticed was how much higher the front hinge pin height was compared to the rear. Brandon mentioned that the B84 had more kickup than the B74.2, and I think that extra kick contributes to the higher front roll center. Removing all the caster or kick with the pills also adds to this because it raises the B-block pills to their highest position. I suspected the front suspension was extremely rigid, and it’s starting to make sense, high roll centers add stiffness to the suspension.

One drawback of narrowing the pivots is losing stability in the pitch axis while increasing stiffness in the roll axis. Shifting the motor and battery to the rear adds static weight there, so the car transfers less weight to the back since it’s already loaded. Adding weight to the front to dull steering feel follows the same logic. Like with the B7, the challenge is figuring out how to keep the car flat within this geometry.

On a small track with tight 180-degree hairpins, these effects are usually less noticeable. The same goes for running a stock 4WD buggy, as stock cars don’t shift weight like modified ones do. If long corners with clear entry, middle, and exit points are giving trouble, I’d start by lowering the roll centers, being pretty aggressive about it, especially in the front. I’d go lower until the front starts to push off-throttle from overload, then fine-tune the rear roll center to balance on-power steering and weight transfer. I’d also try a larger front tire, as it might help improve the front dog bone angle.

Regarding the chassis, this is a tricky situation. I’ve read plenty of posts and comments about it, and I’m not sure there’s much we can do with the current geometry. Narrowing the pivots and lengthening the arms has raised the roll centers, which stiffens the suspension. A stiffer suspension transfers more energy through all the components after the links. The instant center, where the roll is controlled, is now closer to the car, shortening the “lever” and making energy transfer quicker. This also makes it harder for the driver to control how fast the car rolls. With the chassis being so narrow, combined with the holes and countersinks as they are, it’s a perfect storm. I think the best approach is learning to tune within these parameters. Lowering the roll centers will allow more and slower roll, which will absorb some of the energy moving through the links and other components before it reaches the tire. This should help protect the chassis.

We plan to test these and other factors in the coming days and will share our findings afterward. These are my thoughts and ideas on improving the car’s drivability on high-grip carpet. One general observation is that lower grip requires a stiffer suspension, while higher grip allows for a softer setup. Controlling how much energy is transferred to the tires helps determine how much grip the car has and when it’s available.

Give it a try. We would love to hear your results!

This last weekend was the US Offroad Championships. Unfortunately, we didn’t attend this year. This is Scotty’s race, and the best carpet race on the circuit. The environment is unmatched by any other event in my opinion.

AE found some serious speed with the 2WD this weekend, and it was awesome to watch. I’m pretty sure they were testing different geometries. I had a hunch this might happen after seeing the video Aydin posted from RC One—his car looked totally dialed, especially the way it sucked into the corners, really “in the track.” He put down TQ runs in all three qualifiers and took wins in A1 and A2 in Cleveland, making it a perfect weekend. Curious about the pace, I dug into the setup and saw he was running what looked like a B6.4/B7 hybrid, with B6 front arms, a B6.1 transmission, and a wider-than-stock D-Block. Not sure what rear arms he had on there, though.

Timing is everything! Over the past couple of years, we’ve tested a lot, and most of this data has been shared with AE and our followers. When it comes to design and setup, one race always comes to mind: The Florida Carpet Championships. This event draws more talent than any other carpet race in the USA and demands the most from both car and driver. Driving “round” is essential here, and our European friends often excel at it more than we do. A few U.S. drivers have mastered it, but many haven’t. The culture at many American-style tracks is “hard in/hard out,” which usually isn’t the best approach at Beachline. Cleveland is another race were driving round can be critical.

We just released a 3-part series showing how the B7 can face challenges on these types of tracks. This is a perfect example of important the roll center on your car is. I’m thrilled AE has used the data to improve and go faster; that’s the ultimate goal. It feels like all the work we’ve put in over the past two years has been validated. Our customers played a big role in that, and for that, I’m grateful.

Thanks Again!!

Chuck

How many times have you heard this, “the car stays way flatter”? Most, including myself, instantly think about roll. I have learned that most elite racers are talking about the pitch axis. The pitch axis is the weight shift front to back.

Fast drivers excel at a many key skills, one of which is managing the car’s behavior along the pitch and roll axis. This is a crucial aspect of driving that often doesn’t get the recognition it deserves. The AE’s current geometry adds stiffness to the roll axis but not the pitch axis, causing the car to shift a lot of weight from front to back. This point will become important later in this article.

In rear-wheel drive cars, the rear roll center sits lower than the front, which matters because the rear tires push the car forward. The B7 geometry changes this front-to-rear roll center balance compared to other models, making it more like what you’d expect in an all-wheel drive setup. In a fast, sweeping corner, the rear should ideally roll first and more, hopefully pulling the front along with it. This balance between front and rear roll centers plays a big role in controlling weight shift along the pitch axis, and it’s one of the challenges the B7 geometry can present in certain situations.

In mid-2025, we had a few test days to try out different setups. We brought three cars: a B6.4, a B7 with B6.4 geometry, and a standard B7. On this day and layout, the B6.4 was the fastest, with the B7 close behind. The B7 took some getting used to because of its different driving style, while the B7 with B6.4 geometry was the easiest to drive but slightly slower. Both B7s were similar in performance, but the B6.4 was clearly quicker. Since that wasn’t an option, and we saw promise in the B7 if we could dial back some of its jacking and rotation.

This is where the B6.1 3-gear transmission came into play. I had some concerns about the B7’s 5-gear transmission. Reliability was one issue, but my main worry was the backlash it had. In the CNC world, backlash is called “loss of motion”, when a machine moves in one direction, then switches, and there’s a delay before it starts moving the other way. Elite RC racers are like CNC machines, hitting their marks on the track repeatedly, and any loss of motion can affect their ability to stay precise.

While I still think improving the throttle and brake feel was important, what we discovered might be just as crucial, if not more. The old 3-gear setup moved the motor back significantly, creating a new weight bias that balanced the car on its pitch axis with the narrow hangers and long arms. With the motor positioned farther back, the car didn’t shift weight as much. We believe this rearward weight shift helped the car absorb some of the energy that was causing the chassis to jack up, keeping it “flatter.” So far, this is the best performance we’ve seen from our cars with the B7 geometry.

In 2025, Brandon took part in five events, each with a different 2WD car and geometry. In Canada, we ran B6 arms front and rear with a brass front bulkhead. At RC One, he used a .050″ spring steel chassis and a 5-gear setup with B6.4 geometry. The April Fools Race was his only dirt event, and it seemed like he really enjoyed spending time with friends and running on dirt. I’m pretty sure he went back to B6.4 geometry for that race. The final two events were at Island RC—first with a modified B7 chassis, B6.4 3-gear, and B7 geometry, then at carpet nationals with our chassis, B6.4 3-gear, and B7 geometry. That setup has been our best yet for the current AE 2WD. While 2025 didn’t have much racing, it was packed with work as we designed, modeled, and tested many things, especially when it counted most, on race days.

Factory Foote began when a young boy set out to chase his dreams, racing against some of the fastest competitors in the world. Determined to even the odds, Factory Foote was born. The brand focuses on creating parts to help every racer, no matter their level. The mission is simple: go faster! With complete transparency, all secrets are shared. Victory should come from better driving, fine-tuning the setup, or maybe just a little bit of luck, nothing more.

Thanks for reading, Chuck

KPI is another important update in the B7 design. Like caster, it improves straight-line stability by keeping the front wheels pointed forward. Its self-centering ability is notable, and sometimes it’s better for the car to exit corners driving more “square”. This can be an issue if you need the car to drive more “round” on throttle. KPI can also affect scrub radius, but here the focus is on how it impacts the rear.

When combined with caster, KPI pushes the inside front tire down, adding to its load. This creates a “wedge” in the chassis that also puts extra load on the outside rear tire. This wedge can add to the “jacking” of the chassis. While this might seem like an advantage, it’s not always the case. In a fast, sweeping corner, extra load on the outside rear tire usually means more grip. So, the real question is: do you need more grip off-throttle or on-power?

“Square” = More grip on throttle-Car goes straight

“Round” = Less on throttle grip-Easier to turn on throttle

Our RC cars use an open differential, which directs power to the tire with the least load. This can lead to “diffing out” when the inside tire has less load but gets all the power, reducing the car’s forward speed. It can also make the car feel like it’s about to spin out or steer into the pipe. This is where the jacking of the chassis can be troublesome on some circuits.

As a result, many racers have gone back to using the B6.1 caster blocks and spindles, which are lighter than the B7 versions. On tight 180-degree tracks, more KPI can help improve rotation because of the jacking. If you’re running a lot of KPI, and need less rotation, lowering caster can help get rid of some “wedge”. The B7 parts also allow for a steeper front camber link angle, making turn-in more aggressive, but too steep can impact bump, so watch out for that. Overall, we’ve found the older front end delivers the most consistent, linear steering in most situations. If you prefer the B7 parts, the new T7 parts have the ability to run 0 KPI.

Next up, we will discuss “keeping the car flat”.

This is part 1 of a 3-part series explaining what we have learned about the B7 over the last 2 years. Part 1 will mostly cover the rear roll center. Part 2, we will talk about KPI. We will finish up talking about weight bias and controlling weight shift front to back. Hopefully you will take something away from this that help your carpet racing.

At the start of 2025, we met to talk about the setup window on the B7. After a year of running the car, we still hadn’t figured out a baseline setup for carpet and felt like something was missing. We decided to stop guessing and measure the car. First, we took one of our 2023 B6.4 models and measured the roll centers, then did the same for the B7. We fed that data into our CAD software so we could intersect lines and analyze the results, which is when we began modifying the B7’s geometry.

The big difference between the B7 and other brands comes from its narrow pivot and long arms. This setup raises the roll centers. In my opinion, this is what narrows the tuning window on the B7. Like everything, tuning the roll center is a give and take. Generally, a higher roll center makes the suspension stiffer. Any time you had stiffness or bind, you add potential for mechanical grip. On some carpet tracks, this is where we have an issue. A high rear roll center tends to “jack” the chassis and plant the outside tire in a corner. It also moves the “instant center,” the car’s leverage point for rolling, much closer to the chassis compared to the B6.2, shortening the lever. That makes the roll quicker but harder to control. It’s like using pry bars to lift a heavy rock: a short bar moves it fast but without much control, while a long bar lifts it more smoothly and with more confidence controlling that movement.

Why does the rear roll center matter? The rear roll center is arguably the most important part of the suspension setup. As a racer, you need to decide when you need more off power grip and when you need more on power grip. This is much easier said than done. I have a saying that I have been coaching for years, “slow in equals fast out”. I would argue that the most important part of the corner is the exit.

On carpet, sometimes you get full traction, where the outside tire grips, the suspension reacts quickly, and the chassis jacks up, lifting the inside rear tire. On a fast 180-style track, this can actually help by promoting rotation, but on a smooth, flowing track where you need to drive through the corner, it can be a real disadvantage. We’ve found that in almost every corner except a “dot 180,” the car jacks on entry and gets loose. To find grip, we pull the throttle, but then the car goes straight and won’t turn. To get steering back, you lift the throttle and repeat the cycle, turning an easy corner into a frustrating connect-the-dots exercise. It’s slow, and worse, it kills your confidence. Generally, this is when you need more off power grip and less on power grip.

A lower rear roll center will allow you to control the roll with more confidence. That roll is what loads the outside tire and makes grip. You could say you are controlling traction. This is when drivers are using the throttle and the wheel to steer the car. A lower rear roll center will jack the chassis down. This can have the feeling of “in the track”. The chassis jacking down takes the roll centers and the CG with it. In my opinion, you want the chassis as close to the surface as you can be without scrubbing speed from the chassis contacting the surface.

The B7 geometry can excel on tight tracks with a bunch of 180, and fast lap times. the B7 geometry works. The car jacks the chassis and makes the inside tire light which promotes rotation. This design works great on slicks, where side bite comes only from the contact patch. Getting the right tire load and contact patch is crucial for slick racing. However, it’s less ideal when the tire generates side bite, like on carpet.

This is why the setup window has become smaller on the B7. There are other aspects to the equation, but I believe this is the most important. To find your setup quicker, I would ask a couple of questions. Does the car need more grip early in the corner or late? If the car needs grip early. Lower the rear roll center. You need more downward angle on the lower link from the outer hinge pin to the inner hinge pin. You can achieve this by lowering the pills or lowering the rear hub. Both of these changes will have an effect on down-travel so keep that in mind. The most aggressive way of lowing the rear roll center would be using a wider hanger and a shorter A-Arm.

Part 2 will dive into KPI.

As artificial surface tracks gain popularity, tire strategy is becoming a lost art. I began racing on indoor clay tracks, where having race-ready tires was an absolute must.

If you’re on office carpet or CRC carpet, your tire strategy could set you apart from the competition. It’s free, so give it a try!

The top racers around the world start their setup around their tires. It’s that important.

First, take a look at the surface and layout. Some tires perform better on corner entry, while others excel at corner exit. Certain tires offer stronger forward drive, and others provide more rotation. For example, I went to RC Plus planning to run Nessi rear tires. After my first run, I felt the car was a bit edgy on the rear with limited rotation. I switched to Fuzz Bite rears, which gave more rotation and made the car easier to drive. The Fuzz Bite also felt stable on landings.

On carpet or turf tracks, new tires can often be faster, but speed can sometimes make the car harder to control. In my opinion, drivability matters more than setting a quick lap.

At Superior RC, I prefer tires that are broken in, usually putting 3-4 runs on them before racing. They seem easier to drive as they wear in. When they get too worn, though, they can lose some high-speed stability. Fresher tires are better if you make a mistake and need to protect your line, but worn ones don’t really drop off for me as long as I’m running my race.

Setup is all about give and take, and tires are no exception. Next time you’re club racing, come up with a strategy and stick to it. Worst case, a friend gets to brag for a week or so!