TEST DRIVE EXCLUSIVE! Z-CAR ZMXT-8 RTR RTR NITRO OFF-ROAD THIS TRUGGY BREAKS THE MOLD WORDS KEVIN HETMANSKI kevinh@airage.com PHOTOS JOSEPH ARTHUR Z-CAR, A DIVISION OF SH ENGINES, is distributed exclusively in the USA by Global Hobby Distributors. SH has been making engines for many years and decided to get into the car market under the Z-Car name. Its first vehicle was the 1 8-scale ZMXB-8 buggy, and it now has a truggy version called the ZMXT-8. A trailingarm type rear suspension and rear-diff- housing-mounted disc brake are two unique features that really stand out. This truggy has many race features but will equally be at home in your backyard. It s causing a big stir on our forums; read on to see why. SPECIFICATIONS Type 1 8-scale RTR 4WD nitropowered truggy Price $500 (varies with dealer) Wheelbase 13.5 in. (343mm) Width 16.5 in. (418mm) Weight, as tested 9 lb. (4,100g) Clutch bell/spur 13/58 Final drive ratio 15.8:1 Chassis Aluminum plate Differentials Triple-sealed gear Suspension F/R Independent A-arm with pivot ball/independent suspension trailing arm Shocks Molded body with clip-on spacers FOR ACTION VIDEO GO TO RCCARACTION.COM/ZCARZMXT8 96 RCCARACTION.COM
IT S A GREAT TRUCK FOR BEGINNERS WHO WANT TO BASH AND ARE THINKING OF HITTING THE TRACK OCTOBER 2009 97
Z-CAR ZMXT-8 THE TRUGGY S REAR SUSPENSION INCREASES REAR TOE AND CAMBER AS THE SUSPENSION IS COMPRESSED, AND THAT INCREASES REAR TRACTION A high-performance Airtronics radio system is included with the Z-Car ZMXT-8 truggy. /////////////////////////////////// FEATURES CHASSIS. The base of the ZMXT-8 is a stamped-aluminum plate. There are cutouts for the front, rear and center diffs as well as under the clutch and the fuel tank to allow components to sit as low as possible. Molded front and rear chassis braces firm up the chassis plate, and a molded bellcrank plate adds more rigidity. ENGINE & ACCESSORIES. Power for the ZMXT-8 comes from an SH.28 Pro pull-start engine. Air is sucked into the engine by way of a 2-needle slide-type carburetor. It also features ABC construction, 3-port sleeve and knife-edge connecting rod. The engine is tilted slightly towards the centerline of the truck to improve handling. For an exhaust there is an aluminum header and tuned pipe. The fuel tank holds 150cc of fuel, and a splash shield keeps spilled fuel away from the brakes. DRIVETRAIN. It starts with a large-diameter flywheel and 3-shoe clutch. The clutch bell connects with a durable 58- tooth steel spur gear. The center, front and rear differentials are sealed and come packed with grease. One of many unique features of the ZMXT-8 is the front and rear brake setup. We re used to seeing a disc on each side of the center diff, but the ZMXT-8 has a brake on the front side of the diff, and the rear brake is mounted all the way back on the chassis on the rear diff input shaft. This basically tightens up the feel of the rear brake by bypassing some play in the drivetrain. When it s attached to the rear output cup on the center diff and you apply the brake, you must wait for the dogbone to contact the drive cup on the 98 MORE FROM THIS ISSUE AT RCCARACTION.COM
TEST GEAR BYRON FUELS 30% RACE GEN 2 FUEL XTM GLOW STARTER PERFORMANCE I broke in the engine and then headed to a local park for testing. As the body had no cooling cutout, I made a hole in the front windshield and increased the size of the opening above the engine to increase airflow over it. I had the needles on the carb fairly close after break-in, and the engine fired up on the first pull. After a quick tune, I bombed around to see what the ZMXT-8 could do. Steering is responsive and worked well on pavement, grass and in the dirt. The engine is crisp, and the clutch grabs well; acceleration out of the hole is impressive, and top speed is comparable to that of other truggies I have driven. I bashed around the park for a few tanks of fuel and beat on the ZMXT-8, and I am happy to report that I didn t have any durability issues. To see how well the truggy performed on a race track, I drove some laps at Pin Shop Hobbies in Oakville, CT. I fired up the engine and made a few laps to get the engine up to temp before I checked the carb settings; they were right on the money. The stock tires had plenty of grip for the hard-packed track. Traction increased through the day, as the track dirt was loosened up by the tires. By the end of my test day, the tires were hooked up. The Pin Shop track is the smallest track in our area, so it s important that the truck has good steering, and the ZMXT-8 held its own with the stock setup. I shut the truck down and increased toe-out in front and tightened up the servo-saver a little and went back on the track. Those two adjustments made a big difference in how the truck got around the track s tight corners. I made much faster lap times. The brakes work well, but I wasn t happy with the stock brake-bias setup. I like to run more rear brake in my 1 8-scale vehicles, and my test truggy was set up with more front than rear. Adjusting the brake bias was easy to do; thanks to the location of the brake linkages, there s nothing in the way. With increased rear brake, I was able to turn much better because the tires rotated more freely when entering the turns. Braking was smooth and consistent though my day of testing. The diffs come packed with grease, and that was noticeable on the track. You could see the front end diff out when accelerating down the straightaway, and the open diffs were noticeable when accelerating out of the turns. This is no big deal because the diffs are sealed and can be tuned to your liking; silicone in the diffs will increase forward bite when hard on the throttle. Just as with other truggies, jumping the ZMXT-8 was a pleasure. I was more interested in how well the truck went over the smaller jumps and small bumps in the track. There s one jump I ve taken many times with other truggies, and it always makes them kick the rear end in the air. This was less noticeable when driving the ZMXT-8. I could take that jump much harder and didn t worry about losing control of my truck on the landing. The suspension also felt very good going over the small imperfections in the track. INCLUDED ELECTRONICS & ACCESSORIES The RTR ZMXT-8 comes with a 3-channel Airtronics 27MHz radio system to control the truck. It features dual rate, 9-model memory, endpoint adjustment, ABS braking, expo and servo-reversing. The buttons on the left of the radio allow you to change dual rate on channels 1 and 2, while the buttons on the right allow other adjustments. Inside the truck are Z-Car servos to control steering, throttle and brake. A high-torque E9001 servo turns the front wheels, while S3001 works throttle and brake. The E9001 is rated at 128 oz.-in. of torque and has a startup speed of 0.16 second, which is up to the task of muscling those big front tires around. PLUS/MINUS + - Unique rear suspension Rear brake design Engine is powerful and reliable VERDICT No cooling hole in front of body The Z-Car ZMXT-8 RTR is a unique truck that works well and is durable out of the box. I really like the front and rear suspension design; it s easy to adjust and works well. The many changes you can make in the rear suspension alone is impressive. It s a good truck for beginners who want to bash and are thinking of hitting the track. There is a pro version of this truck that can be tweaked for improved track performance. I will have it on the track soon. SOURCES Airtronics airtronics.net Byron Fuels byronfuels.com XTM xtm.globalhobby.com Z-Car distributed exclusively by Global Hobby Distributors; global hobby.com center diff and the drive cup on the input shaft of the rear diff. Since the rear brake is mounted on the rear input shaft, it s directly connected to the rear ring and pinion. SUSPENSION. The front suspension features a lower A-arm and adjustable upper A-arm. The lower arm uses a pivot ball on the end, and this is where you make your camber adjustments. In the rear is a standard adjustable turnbuckle upper link, but the lower arms have an unusual setup. The rear suspension is referred to as a reactive caster system, and the inner front arms are attached to a single plastic mount that spans the width of the chassis and pivots on a pin with bushings; the inner rear of the arms rotate on a pivot ball. With this setup, the truggy s rear suspension increases rear toe and camber as the suspension is compressed, and that increases rear traction; and the location of the pivots allows the suspension to glide over bumps better than in the standard straight-line setup. Rear toe is adjusted at the rear hub, which, when it is changed, won t alter the wheelbase of the truck. Damping comes from four fluid-filled coil-over shocks. BODY, WHEELS & TIRES. The body on the ZMXT-8 comes painted, trimmed and mounted. A large high-downforce moldedplastic wing increases downforce in the rear of the truck, and the wing mount is adjustable. Soft-compound multispike tires come glued to dish wheels. The tread design is good for a variety of surfaces. OCTOBER 2009 99