Axial SWX Crawler reviewed in RRCi - CML Distribution

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The front assembly was completed, by adding two M3 bolts to hold each ‘C’ hub in place. I realised when fitting these that the mouldings on the axle casings are smooth all the way around with nothing to key the ‘C’ hubs other than the two M3 bolts. This would allow you to ‘clock’ these hubs to any angle required just by re-drilling the two holes in a different position. If you make geometry changes in the future by altering link lengths the diff angle will change. Shorter bottom links or longer top links rotate the diff input shaft upwards giving a better angle for the drive shafts and extra clearance in certain situations when crawling. Just bear in mind that as you rotate the front diff housing, you need to clock the ‘C’ hubs to counteract the castor change induced, so the steering kingpin stays as vertical as possible (zero castor) thus giving you a better turning circle and more precise steering. A DARk BuIlD The last job was to bolt all sub assemblies onto the chassis ensuring you orientate the gearbox mounting holes in the skid plate opposite the cut-out vertical chassis plate for the motor (and yes I put it the wrong way round the first time!) Top Tip Tap all the M3 holes on the skidplate first, as Delrin is a very hard material for screws to self-thread into. The skid plate has a channel cut in the bottom face that helps stop you slipping laterally if you ground it over rocks or obstacles when running the rig. All bolts on the sides of the chassis are countersunk to avoid catching on rocks and the chassis itself is very narrow in comparison to the standard Axial item allowing you to squeeze through gaps not possible with a stock rig as long as your bodyshell will allow. As the motor and transmission are wider once assembled than the chassis itself, Brad has made the motor side of the chassis open without a top bar, and even though this looks weird at first, in use it’s not an issue and caused no hang ups or damage to the motor or its mounting plate. Below: Pro-Line Eight Shooter beadlocks with memory foam inserts ready to assemble after adding weights to rims Above: An assembled weight of 14 oz for each front, and 8 oz for each rear, ready to crawl Below: Completed rolling chassis ready for electrics, check all links move freely without binding for smooth shock movement and better traction RRCi fEAtuRE The geometry of the chassis allows you to fit shocks between 100 mm and 120 mm in length and still give good ground clearance while maintaining a low centre of gravity. The more you lay the shocks down, the softer the set-up becomes. Endless variations are possible with enough mounting holes to achieve whatever angle works for you. I opted to use the end mount holes as my shorter 100 mm Losi shocks fitted perfectly in that position and still allowed a good level of ground clearance. The supplied SWX links were a breeze to assemble, I used new plastic rod ends and made sure that when fixing them to the links that the balls were able to move freely and the rod ends were not over tightened. I then custom made a set of combination ‘4-link’ and servo mount plates from sheet Delrin to put the ends of the top links under these plates and remove the Axial Y-pieces from the assembly. Built as standard the Axial items work fine, but I have found a true ‘4-link’ more stable in use as it stops over articulation and once the shocks are setup correctly reduces torque twist significantly. I then turned to my wheels and tyres. I added lead ballast to the front Pro-Line Eight Shooter rims to make the total weight with Badland tyres and memory foam inserts 14 oz per assembly. The rears were left without weight at just 8 oz once built. This difference really helps a rig’s ability to climb ledges and descend very steep angles, by putting the balance point further forward. Different builders alter this weight bias, some even run without weighting their front wheels and concentrate weight forward by placing split battery packs on the front axles. In testing I’ve found that weighting the wheels gives me a more predictable set-up and once you learn what your rig can and can’t do, it’s your driving style and ability to choose the right lines that makes all the difference in a comp. Above: RC4WD alloy transmission case and hardened gears for hours of maintenance free crawling Above: RC4WD alloy ‘C’ Hubs and steering knuckles allow ‘clocking’ to maintain castor and full steering lock 02/09 WWW.RADIORACECAR.COM 65
AxIAl sWx 2.2" ROCk CRAWlER ChAssIs sWx’y tOuChEs Mounting plates were fabricated out of Lexan sheet to mount the ESC and LiPo pack fit to the top links. I was sure to check the cable ties were not over tight so the movement of the links would not be affected. Lastly I fitted a SR3100 DSM2 Spektrum receiver on another Lexan plate just above the transmission. To keep the wiring tidy and away from moving parts, I spiral bound everything to add a final touch to the electrical installation. I did the usual C of G test by standing the rig sideways on its wheels and it sat there fine with no sign of falling over. This is the simplest and best method of testing how a rig will perform on a steep incline. If it falls over the C of G is too high, with weight distributed in the right places you will be amazed how much better a rig will perform. Finally I added the newly painted Pro-Line Spider shell, and instead of mounting it through the sides, I opted to use longer body mounts and attach it through the top of the shell, so there was nothing on the shell that could hang up on rocks and I think it actually looks better aesthetically, keeping the lines of the shell uncluttered. I stood back and admired the completed rig, dark and moody…time to go test! ROCk sOlID PERfORMANCE On a usual British winter’s day, we took an RRCi crawling squad to Burton Dassett for a day’s testing in a good old session of ‘flow the leader’. I test here regularly and the terrain goes from easy climbs and sidehilling sections, to extreme near vertical ledges, higher than the wheelbase of most rigs. There is also a section of almost impossible descents with tight channels ready to trap and bind up a rig’s wheels and axles if the wrong line is taken. The SWX was a delight to run, as the low C of G really helps its stability. The rig climbed everything thrown at it, only grounding the straight lower links over certain ledges, and I’m sure the Above: 4-link plates with top links mounted underneath help reduce torque twist and aid stability 66 WWW.RADIORACECAR.COM 02/09 extra clearance that bent lower links would afford would make a world of difference. I must say that one thing I sometimes had a problem with on my old rig, were high drop offs, but the SWX just lapped them up. Holding the rig on drag brakes then letting it just drop slowly over the edge before giving it full throttle as it lands delivered a perfect result every time. Its ability to side-hill also amazed me, as it didn’t show any signs of wanting to roll over, it just sat there ready to go wherever you put it. The Pro-Line Badlands in the soft M3 compound and memory foam really performed well, with great levels of grip on most surfaces and only struggling if the tread filled with mud. Once cleaned and wiped dry they felt sticky again and ready for action. The whole package when combined with the bullet proof drive-train enhancements, CVD’s giving better turning circle and metal ‘C’ hubs and steering knuckles worked well together. I’m really looking forward to putting the SWX through its paces at the GB Models Urban Crawler Course and Black Rocks in 2009, so watch for the videos on my madpete98 ‘You Tube’ channel! Brad has done a great job with the development and design of the SWX and I hope that he takes the Axial brand and crawling to even greater heights of innovation in 2009 and beyond. If you are looking to upgrade your current Axial to something more competitive or are scratch building a rig, then you can’t go far wrong with the SWX chassis kit as a starting point. I would like to thank Brad for his thoughts and contribution to this article, and I hope to go to the West Coast of the US at some point in 2009 to crawl in the birthplace of the scene and to see what inspired him in the first place. RRCi Below: Tidy electrics, with all weight kept as low as possible to help reduce the C of G Below: Crawler spec shocks by Losi matched with white springs seem to be the choice for serious competition
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Axial SWX Crawler reviewed in RRCi - CML Distribution

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