High Traction Track Tamer

Photos: Edwin Rodriguez

Words: Dean Berry

My first experience with a Yokomo radio controlled car was the YZ-10 back in the late 1980s. This 4wd off road racer was considered one of the absolute best vehicles of the era and in various forms won several IFMAR World Titles. Yokomo has always been competitive and is now to aiming to compete for national and world titles; only this time in the 2wd class with the YZ-2 CA and DT. Distributed by AMain in the United States, these 2wd machines are designed for the 2 main segments of 2wd off road racing that has emerged in recent years. The CA is intended high traction AstroTurf and carpet racing while the DT is made for racing on lower traction conditions, like dirt. Since my 2 favorite local tracks, R/C Madness and The Hobby Hangout, race on AstroTurf or Carpet I felt obligated to get myself a YZ-2 CA and give it a test drive.

REVIEWER’S OPINION

What can I really say, The YZ-2 CA is absolutely loaded in nearly every way. It drives like it was on rails, almost like a slot car, corners like a dream and is wicked tough! There really isn’t much Yokomo could do to improve this car other than perhaps include optional sway bars and a weight set.
Star rating (1-5) = 5+

ITEMS NEEDED
•Steering Servo
•Radio System
•Electronic Speed Control
•Motor
•Battery Pack
•Tires

ITEMS USED
• HobbyStar 120A 1/10 Competition Sensored ESC With Turbo
• HobbyStar 7.5-Turn 540 Competition Brushless Sensored Motor
HobbyStar might not be a house hold name within the industry just yet but their well-priced electronics and accessories just might change that. It is no larger than similar speed controls and has some spectacular features. I mounted the HobbyStar 120A ESC right behind the ProTek steering servo on toward the left hand side of the chassis. Wiring it up was fairly straight forward although I needed to get a few pieces of wire that were longer than the included pieces to reach the motor. HobbyStar even included a sweet flat sensor wire that was plenty long enough to stretch from the esc to the motor at the back of the YZ-2 CA . On track, the stock, out of the box settings were just about spot on. It has an exceptionally smooth power band and linear break. I ran the YZ-2 CA hard for about 6-7 minutes and throughout the run acceleration and braking remained consistent. When I pulled the YZ-2 CA from the track I decided to dial out some drag brake using the HobbyStar LCD Programming Box . The process took 2 minutes and the result was exactly what I hoped for.

The HobbyStar 7.5 Turn motor has a really good top speed that well complements the capabilities of the YZ-2CA . It is really smooth, has plenty of torque so it gets up to speed in a jiffy, and lots of top end to generate ample speed to clear big jumps, even with limited room. I also like the endbell has clear markings to easily adjust timing if need be.

HobbyStar 120A 1/10 Competition Sensored ESC With Turbo is well priced at just $89.99 and works like a charm. it also have plenty of adjustments to dial it in.

The HobbyStar 7.5-Turn 540 Competition Brushless Sensored Motor is fast beyond words!

Speedy, small and with plenty of torque, the ProTek RC 160T Low Profile steering servo is a great pick for any 2wd buggy

• ProTek RC 2S 100C Hard Case Shorty LiPo Battery Pack (5mm) (7.4V/4250mAh)
This 100C battery pack from ProTek RC has plenty of pop and with 4250mAh more than enough runtime for a 2wd buggy. It features 5mm female bullet connectors and a set of 5mm to 4mm adapters for those who use 4mm male bullet connectors. It is 2C capable so it can be charged at 8.5-amps and is also Hi-Voltage capable so each cell can be powered up to 4.35V (for a total of 8.7V) per cell as opposed to the standard 4.20V (8.40V) for a little extra pop.

ADDITIONAL ITEMS USED
• Pro-Line Racing Wedge Squared 2.2” Front Tires
• Pro-Line Pin Point 2.2” Rear Tires
• Spektrum DX4R Pro transmitter
• ProTek RC Yokomo YZ-2 DT & CA Titanium Screw Kit
• Paint by Scott Robert

HOP-UPS WE RECOMMEND
• YZ-2 Front Sway Bar Set (z2-412f)
• Yokomo Racing Battery Weight Plate (2) (25g) (yt-rw25)

FEATURE BREAKDOWN
Like its predecessor, the YZ-2, the YZ-2 CA uses a 2.5mm thick 7075 hard anodized aluminum chassis plate. Recessed pockets are precision machined through out to give it just the right amount of flex to help generate traction and so tuning weights can be easily added. Four screws attach plastic side plates to either side of the main chassis. They help keep debris out, act as part of the battery compartment and Velcro strips attach to them to hold on the body. Speaking of the battery compartment, it is designed to hold either a shorty pack, square pack or saddle pack. When used with a shorty pack, like I did, included foam blocks are used to hold the pack in place and move it forward or backward in the compartment to tune the weight bias.

The YZ-2 was one of the first vehicles to use what some call a backward or post forward steering bellcrank design. This positions the precision machined bellcranks that ride on smooth bearings very far forward. This helps save space so the servo can be mounted more forward on the chassis. The drag link, like the bellcranks, rides on smooth bearings and has horizontally mounted ball studs. This is done so shims and be added or subtracted as needed to fine tune Ackerman. A direct link attaches the servo horn right to the drag link for a near instantaneous steering response.

The shocks, and entire suspension package on the YZ-2 CA is second to none. The Big Bore X33 shock bodies are threaded, hard anodized feature a 12mm bore and thick 3.25mm shafts that can endure tough crashes. X type shock seals keep the oil from leaking out. Plastic shock caps have bleeder screws to make building the shocks perfect each and every time and Astro series springs are designed for high traction action. The front and rear shocks towers are made from super thick 4mm carbon fiber not only look great, they are designed to withstand the rigors of high traction roll-overs. The rear shock tower can be moved back on the tranny case with the use of an included spacing block for those that want to put a little weight toward the back end. The steering blocks height can be adjusted up or down, feature carbon fiber arms at the ends and hold the front wheels bearings. The C-hubs are rather beefy, feature sleeve inserts capable of 0°/2.5°/5° caster and feature a pair of tuning holds to really help in dialing the YZ-2 CA in to any high traction environment. The rear hubs have 6 positions to mount the vertically positioned ball stud and the rear camber link block offers 3 adjustment positions of its own.

Unlike the original YZ-2 that used a 4-gear mid-motor design, Yokomo opted for a laydown 3-gear design with a single large idler gear. This helps keeps the center of gravity as low as possible and makes for instantaneous throttle response. Inside the transmission case Yokomo went with a fluid filled gear diff that even came factory assembled. On the advice of Yokomo Factory driver Lee Martin I disassembled the diff and thoroughly cleaned it before filling it with 3000 wt oil that came with the kit. Yokomo employed a standard 2-disk slipper clutch design on the YZ-2 CA that is compatible with industry standard Team Associated spur gears.

The YZ-2 CA comes with a light weight cab forward body style that has more or less become the industry standard. This helps create downforce to keep the car planted at high speeds. I sent the body to Scott Robert for paint and he came up with a cool scheme representative of AMain and Yokomo . Velcro holds the body in place so there is no need to keep pesky clips on hand that tend to get lost anyway. A small front wing is included to add more front downforce on the front end if needed and is held in place behind the front shock tower with double sided servo tape. The kit comes with a pair of rear wings that have a few different cut lines for tuning preference and 12mm hex adapter yellow dish wheels. Tires are not included as these tend to vary from track to track.

Scott Robert put some some sweet paint on the YZ-2 CA body!

Let’s talk assembly. The YZ-2 CA went together like a piece of fine Swiss jewelry. Everything fit together absolutely perfectly and the instructions were spot on from page one until the final page, 26.

ON THE TRACK
STEERING Understeer Neutral Oversteer
Driving on the high traction carpet the mid-engine YZ-2 CA has well more than enough steering. In fact, it took me a bit to get used to how responsive the car was, thanks in part to the ProTek RC 160T servo and I had to turn the steering dual rate down on my Spektrum DX4R Pro radio. Once I was used to driving it and had it properly trimmed the YZ-2 CA could turn on a dime anywhere, at any time, making navigating the tight infield quite fun to drive on.

ACCELERATION/BRAKING – Poor Fair Good Very Good Excellent
At first the slipper clutch was a tad too loose there was a bit of a squeal so I tightened it a ¼ of a turn and it was absolutely spot on! The combination of the HobbyStar motor/esc and shorty ProTek R/C battery pack allowed the YZ-2CA to lunge forward and take off like a rocket when I grabbed for the throttle. The YZ-2CA tracked as straight as an arrow and the feel was smooth at high and low speeds. Ripping the throttle hard exiting corners, where many vehicles have difficulty, was a blast as the YZ-2 CA was responsive and stable. Braking response was smooth and proportionate too as I was able to stop hard if needed to avoid a crash and just a tap of the brake was needed to help navigate tight spots of the infield.

JUMPING/SUSPENSION – Poor Fair Good Very Good Excellent
The suspension set-up on the YZ-2 CA right out of the box is extremely smooth, plush and responsive thanks to the well-designed shocks. This enabled me to drive the YZ-2 CA into corners very hard because of how well planted the buggy felt. Likewise, I was also able to grab for the throttle very quickly when exiting a corner, increasing overall speed and lowering lap times. The various jumps, obstacles on the track were rather easy to tackle as combinations of speed allowed the YZ-2 CA to generate power quickly enough to clear jumps with little to no run-up and on landing the car settled instantly so I could rip back on the throttle again to be ready for the next corner or jump. With the very low center of gravity, and with most of the weight centrally located the YZ-2 CA had a near level attitude when tackling big air jumps. Now, there were some instances with if I didn’t hit a jump perfectly the YZ-2 CA felt a bit squirrely. I think this is because the car is so very light and the optional weight set might be the solution to help the YZ-2 CA stay planted.

DURABILITY Poor Fair Good Very Good Excellent
High traction carpet can really take its toll on a vehicle as crashes tend to be harder, more violent, the transmission takes more abuse and shock towers really get beat up on flips and the like. Even so, the Yokomo YZ-2 CA performed very well and just showed just basic signs of wear.

SPECS AND TUNING OPTIONS

DIMENSIONS
Length: 15.7” (398mm)
Width: 9.8” (250mm)
Wheelbase: 11.2” (285mm)
Weight: varies

BODY, WHEELS AND TIRES
Body: Cab forward style clear polycarbonate
Wheels: Yellow dish style
Wheel adapter type: 12mm hex
Tires: Not included

SUSPENSION
Type: 4-wheel independent
Shock positions: (F) 3-tower, 3-arm, (R) 3-tower, 3-arm
Camber: Adjustable turnbuckles
Roll: Adjustable ball stud heights
Wheelbase: Adjustable shims at rear hubs/arms
Ride height: Threaded shock bodies

STEERING
Type: Dual bellcrank
Toe: Adjustable turnbuckles

CHASSIS
Type: Machined plate
Thickness: 2.5mm
Material: 7075 T-6 Aluminum

DRIVETRAIN
Type: 2WD
Transmission: 3-gear
Differential: Fluid filled gear diff
Clutch Type: Adjustable slipper
Gear Pitch: 48 P
Gear ratio: Optional pinion or spur gears
Bearings: Full set of shielded

WRAP UP

Due to changing track design and conditions 2wd off road racing has evolved a great deal in recent years and the YZ-2 CA is without question a top contender when it comes to high traction racing. While it is very tough and durable and you may not need spare parts the YZ-2 CA is distributed by AMain so there will be phenomenal parts support for a long while. Coupled with an easy to wrench on design, the super low center of gravity and the ability to tune it so easily puts this car at the top of the podium more times than not.

LINKS