Axial Crawler Tuning Part 2

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Axial Crawler Tuning Part 2
Tony Arnold - StampedeProject.com

Last article we tested how good the stock Scorpion could be just with key tweaks and the right electrics. I even showed what the rig could do in a couple semi-lame YouTube videos (see videos on my site), but there were hardly any "upgrades". That first round of tuning greatly improved performance and made the Scorpion a real crawler, but we had a lot of work still left with CG, tires, clearance, and tightening the turning radius. This month I will install a box full of competition level upgrades that will make our Axial Scorpion one nasty little arthropod. I even consulted with some of the rock stars of rock crawling for some tuning pointers.

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Tips from a Pro
BenderCustoms' Brad Dumont - Low CG and stickier tires such as Losi's Rock Claws or Proline's M3 tires are the most critical upgrades in improving crawling performance. Heavier oil will make the chassis less reactive and moving the upper link mounting inward on the AX10 will reduce torque twist and increase chassis stability.
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The Axial Arsenal
Matt Kearney at Axial knows a few things about crawling, after all he designed the AX10 chassis. Matt suggested some Axial branded upgrades that increase durability, clearance, and lowered CG. The front battery servo tray allows us to mount all the electrics low and up front. Bent links give the rear some much needed clearance. To up durability Matt suggested Axials's aluminum shock bodies, and heavy-duty front & rear differential gear sets. Matt shared some other good news - Axial finally has a full set of spring rates to tune with.

Driveshaft Crushing Torque
The brushed Axiom/Tekin Rebel 2 combo last month was great, but... I gotta go brushless. Medusa Research has a very torquey 1300Kv Afterburner motor that works extremely well for crawling when paired with a Mamba Max brushless ESC. Since the Afterburner motor delivered enough torque to snap a driveshaft yoke in initial testing, I used Axial's new driveshaft rings on the replacement axles to prevent yoke pop offs and future damage.

RCPCrawlers
RCPCrawler.com owner and top crawler competitor, Brian Jones suggested some of his RCP line of beautifully machined black anodized aluminum AX10 accessories. I used the Max Clearance knuckles for much tighter tuning, rear Solid Stainless Steel Straight Axles and Adapters to clear up the rear for a ton of extra clearance and "Clockable" front axles for a little adjustment and strength.

Pro Line Crawling
Pro Line is on top of the crawler scene with new narrow offset 2.2 Beadlocks and a Rock Star USRCCA spec approved body. The beadlocks accepted the M3 Moabs perfectly and narrow the overall track by about 3/4". The lock rings on the wheels are made of a heavy alloy so you can omit or limit extra wheel weights. No more guessing when to stop cutting and still be USRCCA legal with you body, Pro Line has the smallest USRCCA legal bodies available and assures snag-free wheel travel and overhead clearance.

Parts, Pieces, & Tweaks
The Spectrum RX/TX, JR Servo, and A123 pack stay put on the chassis. Both Brad and Matt suggested RCCrawler.com's Axial phase 2 modification. The modification moves the rear upper link mount inward via new drilled holes to cut down on torque roll and rear steer, however I engineered a no-drill option with similar results. Using the short stock steering link or the new AX1315 35mm spacer to extend the upper links to reach and mount up at the body mount location just about matches RCCrawler.com’s link geometry modification. I also cut the stock servo mount plate in half and used those for the two rear ESC and RX mounts. Another key tweak was a full set of Red Kreepy Krawler tire memory foams that add weight and greatly increase traction. The best part is installing the foams as is - no trimming.

Testing
Just as before, I did before and after testing, however this time performance took a big jump forward. Throughout Phase 1 testing, I could see the drivetrain straining and once I went brushless, a yoke broke. The durability upgrades obviously did little for performance but drastically strengthened entire drivetrain. The swap to sticky M3 Moab tires with Kreepy Krawler foams all bolted into some of Pro Line's new narrow offset beadlocks made the most obvious difference. I even skipped the wheel weights. The combination of the RCP Maxx Clearance hubs, wider low CG battery tray, and the narrower offset Pro Line beadlocks did create some rubbing at full locks, however more steering and 3/4" more gate clearance room is worth the annoyance. The Mamba Max powered Medusa Research 1300Kv motor powered through the worse I could throw at it without a hiccup. The new Pro Line Rock Star body allowed plenty of snag-free clearance and provided a good experimental canvas for trying out my new Iwata Revolution airbrush. The CG changes again mad a measurable difference with increased off camber and direct approach angles, the tuning radius decreased by almost a foot, the near elimination of torque roll, the bent rear links and RCP fixed rear axle made a noticeable difference in clearing obstacles - overall a much more confidence inspiring chassis.

Conclusion
Matt, Brad, Brian, and the rest of the gang were a huge help with all the tips and allowed me to transform our little Scorpion into a real completion rig. So you think we are done with upgrades? Not even close, we have a couple chassis to test and a host of new and exciting Axial upgrades, and I may even break out my new Proxxon Mini-mill for a few custom parts all in an effort to make our little 2.2 class scorpion crawler even deadlier. See you on the rocks.

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Sources: Axial - www.AxialRacing.com, Tekin - www.TeamTekin.com, Castle Creations - www.CastleCreations.com, RCP Crawlers - www.RCPCrawlers.com, A123 Racing - www.A123Racing.com, Medusa Research - www.MedusaProducts.com, JR Servo - www.JRradios.com, Pro Line - www.Pro-LineRacing.com, Great Planes - www.GreatPlanes.com, Spectrum - www.SpectrumRC.com, Bender Customs - www.BenderCustoms.com, Kreepy Crawlers see www.RCPCrawlers.com, Iwata - www.Iwata-Medea.com, RCCrawler.com

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Scorpion Phase 2 Upgrades
Axial Low CG Battery Mount Plate
Axial Bent Links
Axial Aluminum Shock Bodies
Axial Heavy-Duty differential gear sets
Axial Soft springs - Front
Axial Driveshaft Rings
Medusa Research 1300Kv Brushless Motor
Castle Creations Mamba Max
A123 Receiver Pack
RCP Crawler Max Clearance Knuckles
RCP Crawler Rear Solid Stainless Steel Straight Axles
RCP Crawler Straight Axel Adapters
RCP Crawler Clockable Front Axles
Pro Line M3 Compound Moab Tires
Pro Line 2.2 Narrow Offset Beadlocks
Pro Line Rock Star Body
F/R Upper Link Mount Move
70wt Shock Oil
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