Building the Ultimate 2.2 Competition Crawler

Building the Ultimate 2.2 Competition Crawler
By Tony Arnold - StampedeProject.com

Sure Axial blew us all away and gave use a stunning crawler platform, but for crawler competitors, the AX10 was simply a good starting place for fabricated performance enhancing upgrades. Now with readily available upgrades there is no need to fabricate, we can bolt together our own Ultimate RC Car Competition Crawler with the best that aftermarket crawling upgrades have to offer.

BEST OF THE BOLT-ON'S

DRIVETRAIN - RCP Crawlers was one of the first retailers to have high performance billet AX10 parts. Now bundled in their Axle Upgrade Kit, their rear fixed axle kit cleans up the rear, increases clearance, and greatly strengthens the drivetrain. Up front, the included RCP Clockable Hubs and Max Clearance Knuckles increase turning angle and up durability.

BEADLOCKS - Eritex, Inc. lead the way several years ago with some of the first and still some of the best beadlocks on the market. I choose their new heavy competition set for this build. The beefy beadlocks are CNC machined from solid Derlin blanks and finished with thick lock rings that lock tires in more securely than any beadlock I have ever tested.

CHASSIS - In June, Visionary Fabrication, released the Axial AX10 Slingshot chassis kit and quickly became a preferred competition chassis due to it slim clearance increasing design, low CG, improved geometry, and tuning options. Made from 1/8" aluminum with a slick Derlin transmission mount, the chassis features improved four-link geometry with supplied Derlin high clearance bent links ready for E-Maxx rod ends. Screw everything together and you are a full chassis swap away from drastically improved performance and slipping past obstacles you never thought possible. We also used VF's front and rear upper link mount plates that provided a huge variety of upper link mount and tuning options and completely eliminated any torque roll.

POWER - Tekin's tiny postage stamp sized 3S rated ESCs has become the favorite for rock crawlers due to its power and size. Tekin only rates the FX-R Pro to 3S, however Tekin requested I push the envelop a little with a total of 13.2 volts from dual A123 1100Mh 2S receiver packs and it easily handled the voltage during the low current and low speed demands of crawling. The extra voltage really isn't used unless we get stuck and need momentary fast wheel spin.

Holmes Puller shown with a 1/8^th scale Hacker Emaxx Motor]

We couldn't use just any standard 55T motor for our Ultimate Crawler so we grabbed the legenary Holmes Hobby Puller motor. A beast of a motor with investment case face plate, machined can, seven pole, and Cobalt magnets for power that will blow away most 10^thscale brushless systems - yep brushed more powerful than brushless in this case. At $80 it isn't cheap, but delivers both super buttry smooth high torque at low speed and stunning wheel speeds with the blip of the throttle even with just a 2S pack attached.

BODY & TIRES - Pro-Line has been at the forefront of crawling with tons of tires, bodies, and accessories, and the newest Helios seemed appropriate with M3 Hammer tires providing the grip. The Hammers are an outstanding all-purpose tire for almost any surface and looked the part for our Japanese Anime themed Helios paint job complete with hand painted Japanese Kanji characters. If my Internet sources are correct the multiple square characters are the number "four" and the flanking characters on each rear fender state "Big Electricity”. Easiest pain job I have ever done - paint Kanji in red, back in white, and spray the body black and then apply copious stickers. Initially I wasn't all that stocked over the Helios body design, but after use it all makes sense and is now my favorite crawler body. Pro-Line's new gate markers kept me honest during my testing with the added challenge that a real competition would provide.

AXIAL - Axial of course has more than a few upgrades. The Axial slipper clutch is in my opinion the best upgrade for any crawler and literally ends drivetrain damage. Axial's driveshaft sleeves also greatly increase durability if the slipper is a bit to snug.

CAN YOU "DIG" IT?
" Dig" is a drivetrain engineering feat only occurring in rock crawling. A typical front "Dig" setup allows the rear driveshaft to be "shifted" remotely (3-channel Rx/TX) via servo from standard 4WD (4-wheel drive) mode, FWD (front wheel drive) with rear wheels in neutral, to FWD (front wheel drive) with the rear wheels locked/braked. This allows shifting from a standard 4WD to a FWD only mode. FWD allows the front wheels to grab traction and pull the car upward without the rears pushing the truck off your line. Probably the coolest Dig trick is locking/braking the rear driveshaft to turn. This allows the crawler to literally pivot on its rear axle for near 90 degree turns - especially handy when you get bumped off your line. Another benefit of rear lock/brake is when descending - the front slowly pull you forward and the rear just drag along and lessens tip-overs. Typically a fabricated contraption, VF came up with a Dig unit that bolts right on to you stock Axial transmission and happens to be one of THE upgrades for competitors and we certainly couldn't leave that off our Ultimate Crawler build.

Dig units do take some tuning to get the servo and Dig engagement points right. If I would have had/used a Spectrum 3-channel system, it would have been easy with EPA adjustments. If however you use a standard 3-channel RX/TX like the Traxxas TQ-3 I used, you will need some extra help from a ServoCity Servo Extender. The super handy $20 Servo Extender allows setting of mid, and end points all independently and worked perfectly tuning our VF Dig system. Now by flipping the thumb switch on my lightly modified TQ-3 transmitter allows easy shifting between 4x4, FWD, and FWD with rear lock.

EXTRA TWEAKS & CUSTOM TOUCHES
Stock Axial shocks would have worked, but for a little lower ride height upside down Revo shocks were used loaded with 100 weight oil, but re-sprung the rears with soft Yellow Jato shock springs and left the fronts in a springless droop setup. The beadlock/tire combos were weighted to a total of 11'ish oz. per front and 8.5oz each on the rear. The front tires received Pro-Line memory foams with the rear retaining un-cut stock foams to prevent tire wadding. I couldn't complete our Ultimate Crawler without at least one of my own fabrication tricks. Although the A123 packs could be mounted with copious amounts of tape and zip ties, I decided to fabricate angled aluminum mounts for a cleaner install. I simply cut two thin 4"x1" brushed aluminum rectangles and bent the first 1" around 75 degrees to form a backward bend, drilled holes to mount to the axle, and topped with Velcro for secure battery mounting.

GET READY TO ROCK
As a proud owner of seven crawlers and counting, I have a few opinions of what a crawler should include and this build nailed even my highest expectations. This build represents some of the best competition level upgrades available for the thousands of AX10 owners who want the ultimate in performance with super low CG, outstanding traction, high durability, control at low speed, and high wheel speed. Most importantly, our Ultimate RC Car crawler was highly predictable even on very challenging lines. Our Ultimate Crawler is amazing compared to any other crawler I own and continues to amaze delivering line after line that I thought were previously impossible. The flexibility of the VF Dig system allows some mind blowing maneuvers and recoveries, however after over a year of attempting to set up my lines so I can hook a tire to make a turn, it's tough to remember that same capability is just a thumb flip away. Adding a Dig system definitely takes crawling to an entirely new level. I could make a huge deal individually over each and every component, however they all just worked, no fuss, no pain, just endless hours of high performance without failure and I would personally recommend each and every component.

CONCLUSION
Like any other segment the "ultimate" comes with a price attached and our build beginning to end topped out at about $1200, but if you want the best those expenses are easily justifiable. Let's face it, Axial just bringing out a crawler just over a year ago was a big deal and having large companies stepping up with mainline upgrades was a big move for a new untested market. What was a surprise, was that we also have custom upgrades from smaller companies that have been fully engineered, designed and released all in that same year. If we are already at this level of performance now, the question is, what will next year bring with the second generation of crawlers and parts? See you on the rocks... I'll be the one "digging" it.

------CALL OUT------------

Axial AX10 Upgrades
Axial Crawler Kit
VF Slingshot Chassis
VF Heavy Motor Mount
VF Upper Link Mounts
VF Dig Unit
Hitec 225MG Mini Servo
JR Sport Servo
RCP Solid Diff Lockers
RCP Billet Axle Upgrade Kit
Tekin FX-R Pro
Dual A123 2S 1100Mh Packs
Traxxas TQ-3 RX/TX Modified
ServoCity Servo Extender
Holmes Hobbies Puller 7T Motor
Axial Slipper Clutch
Axial Driveshaft Rings
Eritex Competition Beadlocks
Pro-Line Helios Body
Pro-Line Hammer M3 Tires
Pro-Line Body Clip Pulls
Pro-Line Gate Markers
Custom Battery Holders
Total $1200

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SOURCES: Axial - www.AxialRacing.com, Pro-Line - www.Pro-LineRacing.com, Tekin - www.TeamTekin.com, Holmes Hobbies - www.HolmesHobbies.com, VF/DNA Engineering - www.VisionaryFabrication.com, Hitec - www.HitecRCD.com, RCP - www.RCPCrawlers.com, JR - www.JRRadios.com, ServoCity - www.ServoCity.com, Traxxas - www.Traxxas.com, Eritex - www.EritexInc.com, A123 - www.A123Racing.com.

I decided to pull the chassis apart for a rebuild and put a little shine on the chassis with a little elbow grease and Flitz metal polish.