When the TC3 was released, it made an immediate impact on touring car racing. The A-team was stacked with talented drivers such as Billy Easton and Barry Baker, and the solid, shaft-driven platform proved to be a dominant force. Race after race, the TC3 took home podium finishes and numerous wins. The success of the TC3 inspired the then widely accepted notion that shaft drives must be best. Some belt-car brands even released their own shaft-driven touring cars. That was seven years ago; the touring car class has rapidly evolved and is even more competitive. In the last three or four years, belt-driven cars have started to crowd the winners’ charts, and this started the great belt- versus-shaft debate. Open-minded types recognize the significant benefits of each design, but in racing and the “Highlander,” there can be only one. Belt-drive cars have simply proven to be the best overall for racing. Team Associated, now in its third generation of touring cars, has gone back to the proverbial drawing board and reinvented how its touring car will get power to all four tires. Gone is the center shaft, and in is a pair of belts and a whole new design around them. Check it out.

Testing: Round 1
During a couple of photo shoots, I got the chance to run the TC5 on pavement and immediately liked what I saw and felt, but my main goal with testing for this review was to see how the TC5 handled on a real track, so I headed off to SpeedZone Hobbies in Rocky Hill, CT. This indoor track features Ozite carpet, and the store has recently been reconfigured to allow for more pit space. It’s a great place and my favorite place to run touring cars. The layout, especially the back straight, is somewhat tight, so I didn’t push the car too hard at first. I also wanted to get a feel for the car before I started ripping the throttle and slapping into the boards. After a few laps, I brought the car in to tighten the differentials. This is pretty standard practice on a freshly built car. The diffs were easy to adjust, so I was soon back out on the carpet. In the box stock setup, I found the TC5 to have an absolute abundance of steering. The turn-in was extremely aggressive, but the car was never loose. I dialed the dual rate down and just took it easy as I turned laps. With each lap, I pushed it a little harder, and it wasn’t long before I felt as if I was up to race pace and not that much longer before I was testing the TC5’s durability.

I slammed the TC5 into some corners pretty hard. So hard sometimes that I was amazed that it didn’t break. Touring cars are not known for their durability, but the TC5 was proving to be quite the tank. That’s a huge plus in my book. I should note that by this point I had switched to a stock motor. The LRP Vector X11 3.5-turn brushless is a lot more motor than I can handle on a tight indoor track. Down the long back straight at SpeedZone, the TC5 tracked true and didn’t get out of control no matter how hard I punched it sweeping onto the straight. This is a good thing because this lane is pretty narrow, and it’s easy to get out of shape and hit the boards at full speed. Through the corners, the TC5 again handled great. The turn-in is fantastic, and this is all with no changes to the stock setup. If there were any handling problems, I didn’t notice them; in fact, the TC5 carried a lot speed and seemed very precise. Even though I was a bit rusty, it was easy to get into a nice flow with the TC5. When I did have to use the brakes, the car stayed planted and didn’t as much as wiggle. I burned through a few more battery packs before deciding to take a break to charge some batteries and enjoy some bench racing.

Round 2
I was having fun, so I could have easily kept running laps, but I was lucky enough to have two local hot shoes trackside. I turned the controller over, and they both agreed that the TC5 was dialed and had tons of steering. One even said he would be building a new TC5 the next week.

Behind the Design: Team Associated’s Bob Stellflue

RC Car Action: How long have you worked at Team Associated? Which other projects have you worked on?
Bob Stellflue: I started during the Reedy Race of Champions three years ago. My first couple of days on the job were out in the sun at the racetrack—way too much stress! Associated has released a tremendous number of products over the last three years, and in some context, all of us in R&D are involved in each project. I’ve worked side by side with Torrance DeGuzman on the finishing stages of the TC4 and the 18T projects. We also worked together extensively on the Factory Team TC4.

RCCA: Which type of RC vehicles do you most enjoy designing?
Bob: I definitely prefer on-road cars. Before I went back to school to become an engineer, I worked for years installing custom car audio at a shop back in the Midwest called “The Radio Doctor.” This was right about the time that people starting tuning their “hot hatches” into street racers, and we were involved in these modifications as well. So touring car racing has always been sort of an obsession for me. During college, money was always short, so RC filled the space perfectly. I guess I’ve never looked back.

RCCA: Do you race?
Bob: I race as much as I can. I think that’s one of our biggest strong points at Team Associated. All of us in R&D race. It helps us to keep the passion about our work.

RCCA: Was it a hard sell to make the switch from shaft to belts?
Bob: Extremely hard—but for good reasons. It costs a lot of money to tool up molds for the plastic parts on these cars, and Associated had just invested most of its touring car budget on the TC4. When the TC4 was slated to be designed, the shaft car was still dominant at all the major races. We refined what we had in the TC3, creating the TC4. But during this design time, belt-drive cars started to come into their own, mainly due to the battery technology taking large strides forward in capacity. Selling the belt cars’ performance wasn’t as tough as trying to sell the belt car economically for the business.

RCCA: What is the major advantage of a belt drive sytem over a shaft drive system in touring cars?
Bob: When RC touring car racing was just starting to come about, battery technology was in its infancy. This meant the drivetrains of the cars had to be as efficient as possible in order to maintain good motor power throughout a five minute racing format—hence the TC3’s domination with shaft drive. The increase in drivetrain efficiency was worth more than the inefficiencies in chassis performance that it induced.
There are several disadvantages of a shaft drive system, and, contrary to popular belief, torque steer effects the car least of all of them. One of the biggest disadvatages of a shaft drive system is the fact the drivetrain is direct, with no damping. This means that whatever happens at the motor happens at the tires, sort of like a light switch, making the car harder to drive. When driving a shaft drive car, you have to be extremely careful when applying throttle so that the tires don’t break traction. Also, when braking (especially drag brake) the tires will easily lock up. Today’s batteries are far more powerful than they were even 2 years ago—powerful enough that they can overcome the inefficiencies of a belt drive system, and with that being the case, the chassis performance of a belt car over a shaft car starts to make a bigger difference. The belt systems are damped. When the driver applies the throttle, the belt will stretch a little bit and actually put up a fight before it moves. The power is then transfered smoothly to the tires making the car much easier to drive out of the corners. Likewise, once the belts are spinning, they don’t want to stop abruptly—again, especially in drag brake conditions. With a belt drive system the car will roll through off-throttle sections of corners faster. For most of us—heroes excluded—this means a belt drive car will be much easier to drive at a faster average lap time.

RCCA: In your opinion as the designer, what sets the TC5 apart from its competition?
Bob: There were very few design constraints for the TC5, but a major constraint was cost. I learned a lot on the Factory Team TC4 project, most of which was learning to design things that could be produced at a realistic cost. It used to be that anyone could be competitive with his $200 TC3; then we moved to high-dollar, complex pieces of jewelry that we were slinging around the track as fast as they would go. We tried to bring the cost back to a realistic level with the TC5 but still give it the “bling” that everybody now expects with this class of car. I tried to keep the parts count to a minimum and to make the pieces as cost-effective as possible. The rest of the stuff was just icing on the cake—thick icing, though. The TC5 has all the necessary adjustment to make any sensible guy’s head spin.

RCCA: What are some of the more subtle design elements that might be missed by a casual observer?
Bob: I carried over some of the anti-roll bar mounting system from the TC4. We have a threaded pivot ball that mounts the anti-roll bar drop link on the suspension arm, so our system is infinitely adjustable. The TC5 takes this to the next step by supplying a different anti-roll bar mount for each of our anti-roll bars, so there is no need to adjust for different-size bars at their fixed points on the bulkheads. We also have a pretty trick cam system on the diffs that allows belt tension adjustment and four different diff heights. We added options for outboard toe-in rear hubs as well—1/2 and 1 degree. The TC5 uses an arm mounting system that allows more flexibility for changing suspension geometry than the one we used on the TC4. The arm mount on the TC5 is fastened to the bulkhead, so we now have the ability to locate the pin width and angle to suit current conditions—very helpful at the ’06 Worlds in Italy, by the way.

RCCA: People have asked me—and I don’t have any idea—why the spur is gear positioned high when so much attention is paid to having a low center of gravity?
Bob: The TC5 is able to use a 2.5mm chassis and top plate to make an ultra-rigid chassis without any extra standoffs or stiffening devices, producing a lighter rolling chassis. This is in part due to the height of the top plate. Also, moving the spur gear up allowed the TC5 to hit gear ratios from 5.5 to 10.5 without changing the spur gear. The disadvantage of having a higher spur gear is that the CG of the car will also rise, and this is where the confusion is. The height CG of electric cars is predominantly determined by the heaviest components in the car—the battery, motor, and servo, in that order. All of these things are about as low on the chassis as they can go. The spur gear shaft assembly, top plate and any bulkhead material that are moved down, or up, will affect the CG height only minimally. Through my studies during the design process, I learned that if the TC5 had a top plate/spur gear combo at the same height as the competitors’, the CG would be 0.1mm lower, at most—about the thickness of a piece of paper. For this reason, I decided to put the top plate where it should be, rather than where the competitors “sell” it at.

RCCA: The TC5 is a radical departure from the TC3 and TC4; how different will the TC6 be?
Bob: I certainly didn’t dump all of my ideas in the TC5, but I don’t think that future versions will be too much of a departure from what we have now. The touring car class has become a mature racing class in which things are becoming highly refined. You see the same thing in other mature classes such as 1/8-scale on-road or buggy, where the cars all have the same features and essentially look the same as well.

RCCA:Is the TC5’s baseline setup for carpet or paved tracks?
Bob: The kit setup is geared for foam tires on carpet because that is where most of the TC market lies.

RCCA: On the TC5, what should racers adjust first when they feel they need to deviate from the baseline setup?
Bob: I think the question should be asked the other way around. Maybe you mean what’s the first thing a racer might change to get to his baseline setup. I mean, a good baseline setup is one that is well balanced around the track and needs no change. That’s why we call it the “baseline.” This is a very tricky question, so excuse me if I am kind of vague. If the setup you have on your car doesn’t suit the track conditions or your driving style, you really only have four options: pick the front or the rear, and make it stiffer or softer. The change that you make will definitely depend on the current performance of the car. The most critical components on the cars are spring/shock packages, as they will make the biggest performance difference on the track. Unfortunately, they are the messiest and most time consuming to change. It’s always a good idea to get this part of it dialed in first though, so it’s usually my first step. After that, roll-center heights and track width are both big ones as well.

RCCA: Which hop-up options would you consider must-haves for the TC5?
Bob: Foam-tire racers should be set out of the box. If you race rubber tires, the spool, or one-way, will be very important. The ITF chassis/top plate set is also critical in locking the rear end of the car in with rubber tires. Otherwise, most of the tuning options come with this Factory Team kit.

RCCA: When they switch from carpet to paved or vice versa, which things should drivers expect to change on the TC5?
Bob: This depends on what type of tires they use. If they use a racing rubber tire for asphalt, they should be 90 percent of the way to rubber tire on carpet. If they plan to race with foam tires on carpet, the setups are completely different. Again, the biggest difference is in the spring/shock package, as the foam-tire cars have a tremendously more traction than rubber-tire cars. An extra set of shocks for carpet would get most racers all they need for a quick change between venues. The added grip of foams on carpet means that the springs should be much stiffer, and the shocks should have considerably more damping. We try our best to get the team guys’ setups posted on our website at teamassociated.com, so I strongly suggest that people start with something from there.

RCCA: Do you see any major innovations left to be made in touring cars?
Bob: Again, this is a mature racing class, but I see power becoming a problem. Currently, we dump more than 325 watts continuously through these touring car chassis. At around 7 volts, that means that the speed control must pass a continuous 45 amps. Unfortunately, that is not all the batteries of today have to offer, so what is left must be burned up in heat. Heat in batteries, motors, diffs, tires, etc. This is wasted power because the chassis can no longer use any of it. The end result is that we have 3-pound projectiles being rocketed around tracks that are too small for their speeds. Moreover, the speed of the cars means that they can be controlled by only a handful of the best heroes—if they can manage to finish the round without burning up their electronics. This is not my idea of racing, and I think it needs to be addressed as in any other form of racing. I think the TC market will inevitably have to confront this dilemma. You can look at NASCAR, F1, CART, or almost any other organized form of racing, and they continue to cut back engine power to make more equal, enjoyable, racing. It isn’t that the cars will go any slower if we decrease the power—just that the racing will be more competitive and more affordable. The cars will be more controlled, and racers will be less likely to crash them. Overall, I think we’ll put on a better show for any audience, rather than seeing five out of 10 cars finishing the modified A-main at Cleveland as they did this last year.

RCCA: Do think current touring cars are too adjustable or not adjustable enough?
Bob: I have a bachelor’s degree in mechanical engineering, and I struggle to wrap my mind around all of the things we are doing with these cars. I can only imagine what someone without my education would think, but this is one of the most élite forms of RC racing, so complexity should follow. Seriously though, we are adjusting things on these current touring cars that full-size race teams would never think of going after. That’s one of the reasons RC is so unique: we can completely tailor the car for the track.

RCCA: There are more touring cars now than ever; do you see touring car racing growing in the future?
Bob: I’d like to think that the TC5 will help to change the on-road market. At this point, the cars are too expensive and too complex. The price point of the TC5 is excellent, and we are making serious efforts to support setups for this chassis so that customers will have good starting points. This way, they won’t tune themselves out of the ballpark before finding something that fits.

RCCA: Do you predict that touring cars will switch to 4 or 5 cells or even to LiPos? If you do, how will that change how these cars are designed?
Bob: As I said before, one of the biggest problems with TC racing is that we have too much power. Five cells are a must, in my mind, and if the battery technology keeps gaining at this rate, 4-cell will be necessary in about a year. Keep in mind that this is just to maintain the same speeds and to reduce electronic failures. As far as any industry 6-cell standard is considered, we used to run 7-cell hump packs back in the day when batteries really sucked. I think we need to take the next step, and the standard must change as the technology does—on-road and off-road included. I don’t see that LiPos have a spot in RC racing yet—at least, in a 2-cell configuration. This is the main disadvantage of LiPos: there are only two voltage options: 3.7 and 7.4. Don’t get me wrong; I love the durability of the LiPos compared with the current NiMHs, but they don’t seem to suit the current classes of racing we are involved in. Who knows? Maybe my next project will be based on LiPos.

Bob, thank you very much for your time. Congrats on the great TC5 design. We can’t wait to see what you and the rest of the A-team dish out next.