by peter ‘mad pete’ gray w - cmldistribution.co.uk · to a cordless drill using a flexible...

Axial S

WX 2.2”

Rock Craw

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W ith the launch of the new SWX ‘Bender Customs’ competition chassis from Axial, I decided to update my now heavily used and abused Axial

AX10 that I entered in the 2007 Nationals and have run most weekends since! I first contacted the designer Brad ‘Bender’ Dumont and asked him about his background in crawling, and as the newly appointed head of Axial R&D I wanted to know what development had gone into this unique design and what actually makes a competition winning rig work.

62 WWW.RADIORACECAR.COM 02/09

By PEtER ‘MAD PEtE’ GRAy

AxIAl sWx 2.2" ROCk CRAWlER ChAssIs

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‘MAD’ PEtE INtERVIEWs BRAD

hIs MAIN POINts ON BuIlDING A GOOD COMP RIG ARE As fOllOWs:

• Fora4-linkedchassis,linkset-up,rideheightandshockangleplaythebiggestroleinhowarigperforms• Havetheupperandlowerlinksdoubletriangulated• Rideheighthastobesetsotherighasadecent‘breakover’angle(groundclearance),butstillsetlowenoughtoclimbsteepverticalfaces• Drivingstyle,aswellasterrain,canplayabigroletoo.Somepeoplepreferwheelspeedandsomepreferalotoftorque,oneset-upmaynotworkforbothsituations.Experimenttoseewhat’sgoodforyou!

• Ifyougetalotoftorquetwistinashaftdrivenrig,addastrongerspringandoiltotheoffendingrearshock,thentryitagain.Ifyoustillgettwistmovetheupperlinkmountingpointsonthechassisdownclosertothelowermountingpoints,andseeifthathelps•Thebest4-linkset-upisonethatcanflexwithlittlechangeinthewheelbase

BItE My shINy DElRIN skIDPlAtE!Brad’s notoriety and the respect he’s garnered from

enthusiasts worldwide all stems from his own product line that started with him competing in the 2.2" class in Colorado and Moab. These competitions evolved into him developing products such as the SW2, which Brad manufactured to sell to the general public under the name ‘Bender Customs’. The SW3 was the next chassis he designed which was essentially a no frills competition specification which went on to win the 2007 RCCRawler.com ‘Peoples Choice Award’ for ‘Best Chassis’. After a short break from manufacturing chassis, he designed the SWX chassis for Axial Racing’s AX10 kit. A culmination of four years of R&D, it’s by far the most compact and capable chassis he’s designed to date.

Here’s my interview with the man himself, his thoughts and ideas on what makes a good competition rig perform and his views on the ever-growing crawler scene:

Mad Pete: Where does the Bender in Bender Customs come from then? I’m thinking Futurama, am I on the right track?

Brad: You are correct, the name mainly comes from Futurama. That show cracks me up, and Bender is the best character on it in my opinion

So how long have you been into R/C rock crawling?

I’ve been R/C rock crawling since 2000, but became heavily involved with it when I stumbled upon RCCrawler.com in 2004. I won the 2006 USRCCA nationals with a rig I designed and built. Been competing all over the US for the last couple years. My first chassis design for the public was the SW2, which was designed to be a chassis that could be built with any axles out there. The next chassis was my SW3, which was designed to be strictly a 2.2 comp chassis. Then I designed the SWX

around Axial’s AX10, which they decided to buy the rights too. I interviewed with them shortly after that for a job as a product designer/R&D tester, which is now where I currently work in California.

So where do you see rock crawling going in the future?

For the future of R/C crawling I’d like to see the Super Class evolve more. I’m hoping more companies will start to support this class. Right now there isn’t much support for it as far as aftermarket parts go. I think that’s the biggest reason that the attendance numbers for comps are down in that class. The 2.2 class seems to be getting all the attention lately, which is great to see but the Super Class is what really kicked this aspect of R/C off, and now it seems to have taken a back seat to the other classes. I also think that the scale trucks are going to receive a lot of attention over the next year. I can see more and more competitions popping up for them. Especially now that Axial is releasing the new SCX10 ‘scaler’. The toughest part about competing with the scale trucks is having a set of rules/guidelines that keeps the playing field level, but still allows for all the creative ideas that people are coming up with. The wheelbases vary greatly too, and

that is a big factor on how capable a rig is. The wheelbase rule for the 2.2 class is what keeps it very competitive.

To dig or not to dig..? That is the question

I don’t see dig going away in the US. It has really taken the capability of the 2.2 class to a whole new level. There are so many situations where it is beneficial, and it allows us to run more technical/difficult courses then ever before. The USRCCA has also recently added a 1.9 class to the rules. I believe this class will grow very fast, because they are not allowing dig. This will let more new people that are on tight budgets to come in with relatively simple rigs and be competitive.

So what are you working on at the moment? Is there an essential hop-up or must have Axial add-on?

Axial is working on a bunch of new products for the 2009 season, but that’s about all I can say at this point without giving up any top-secret info. Right now I think the hottest hop-ups we have are the aluminium knuckles, aluminium axle C’s, the CVD’s. The SWX chassis also seems to be a pretty popular hop-up right now too, which is nice to see.

02/09 WWW.RADIORACECAR.COM 63

RRCi fEAtuREAxIAl sWx 2.2" ROCk CRAWlER ChAssIs

Left:Hardeneddifflockerstakeanything

youthrowatthem

Above:CDV’sgivetighterturningcircle

withoutbindingatfulllock

Right:TheSWXchassiskitinallits

darkgloryhastakenBrad4yearsto

develop

Left:RC4WDaxlehousingsin

superslipperyDelrin,note

rearrequiresnolockouts

Right:Subassembliesand

‘Punisher’driveshaftsbuiltto

takeabuse

With all these points in mind, and a new SWX Bender chassis in my hands, I started to collect all the components required to make a serious competition rig for the 2009 nationals and local competitions.My first stop was CML Distribution who had also supplied me the

chassis to review. I first upgraded the standard Axial diff lockers to the comp spec Axial hardened items. Next I swapped the standard front axle internals for Axial CVDs, allowing a better steering angle without any binding in the driveline, and I added hardened spool and pinion gears to each diff. I wanted a black on black look for the rig to match the chassis so chose the new Pro-Line Spider crawler shell and plain black Fastrax paint.Adding to the stealth look, I chose black Pro-Line Eight Shooter 2.2

beadlock wheels, Pro-Line memory foam inserts and the M3 soft compound Pro-Line Badlands 2.2 crawler tyres. I kept the slipper clutch assembly but replaced the slipper pads and spur gear that has lasted a year of crawling, as I wanted to start fresh! I lastly added a Novak Rooster Crawler Edition ESC and the new Venom 50T Crawler Spec motor, giving me slightly more wheel speed than a 55 or 60 turn motor and the amazing drag brakes that have made this ESC my favourite choice for any crawler build.I then travelled north to visit King Cobra to see their new range of

RC4WD Axial hop ups. I wanted to make this rig as bullet proof as possible across the whole drive-line so I chose a new aluminium transmission case and hardened steel internal gears, clock-able aluminium ‘C’ hubs and steering knuckles. I also used the RC4WD ‘Punisher’ steel driveshafts especially made to fit the Axial. I also added the new Delrin axle housings for a smooth and slippery surface to help avoid hanging up on rocks.My final addition was a set of the Losi 2.2 100 mm crawler spec

shocks. These have fast become the shock of choice in serious competition and are ideal for the SWX. With a threaded cartridge design, they are easy to assemble, fill and bleed. With Titanium Nitride

coated shafts, they are perfect for crawling and smooth in operation using the supplied soft white springs. These have been used by Brad himself in his own SWX builds, though he designed the chassis to also use the standard 120 mm Axial shocks mounted in different holes or indeed your own shocks of choice. That’s the great thing about a comp build, you choose everything that you want to bolt on and build to whatever spec, you want.

ClEANED, luBED, AND READy tO AssEMBlEThe donor parts from the original rig were the bearings, the diff spools

and rear drive shafts. I thoroughly cleaned and lubed the bearings by leaving them soaking overnight in oil. I also replaced all bolts, washers and nylock nuts on everything except the transmission case, as a year of wear and tear had taken its toll on the original rig’s hardware with some bolt heads almost worn half away!When rebuilding the diffs with hardened gears and lockers, I made

sure the cases were packed with quality LM grease. This also goes for the new transmission cases and hardened gears; I want longevity from this build with the usual RRCi philosophy of ‘Fit and Forget’. Once built correctly these sub assemblies should last a season or two and still be ready for more. My original Axial items have performed perfectly, and show minimal wear internally, but the lower plastic diff casings have taken a real beating so I thought it was time to give the Delrin RC4WD items ‘a day in court’. When both axles were finished I connected each built sub assembly

to a cordless drill using a flexible extension and turned them slowly to check everything ran smoothly and bed the ring gear to the pinion. The RC4WD Delrin cases do not need ‘lock outs’ on the rear assembly, as they are a straight moulding that captures the bearings for the output shafts internally. This will not allow you to fit 4WS as you can with the original Axial items, but as current 2.2 comp rules do not allow 4WS, it didn’t bother me.



Below:Pro-LineEightShooterbeadlockswithmemoryfoaminsertsreadytoassembleafteraddingweightstorims

Above:Anassembledweightof14ozforeachfront,and8ozforeachrear,readytocrawl

Above:RC4WDalloytransmissioncaseandhardenedgearsforhoursofmaintenancefreecrawling

Above:RC4WDalloy‘C’Hubsandsteeringknucklesallow‘clocking’tomaintaincastorandfullsteeringlock

Below:Completedrollingchassisreadyforelectrics,checkalllinksmovefreely

withoutbindingforsmoothshockmovementandbettertraction

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 BuIlDThe 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!)

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.

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 set-up 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.

Tap all the M3 holes on the skidplate first, as Delrin is a very hard material for screws to self-thread into.

Top Tip


RRCi fEAtuREAxIAl sWx 2.2" ROCk CRAWlER ChAssIs

Above:4-linkplateswithtoplinksmountedunderneathhelpreduce

torquetwistandaidstability

Below:Crawlerspecshocksby

Losimatchedwithwhite

springsseemtobethechoice

forseriouscompetition

Below:Tidyelectrics,withallweightkeptaslowaspossibletohelpreducetheCofG

sWx’y tOuChEsMounting 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 PERfORMANCEOn 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

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



ThePro-LineSpidershellgivesthefeelofafullsizetubechassis,almosttoogoodtoscratch

TheSWXtookonanythingwethrewatitandcamecrawlingbackformore!


RRCi fEAtuRE

QUICK SPECClass: 2.2” Competition Rock CrawlerType: Self-assembly Chassis KitManufacturer: AxialPrice: Axial SWX Chassis £69.99

EQuIPMENt usEDAxIAl – CMlCVD drive shaftsHardened diff gearsHardened diff lockersNovak Rooster CrawlerVenom 50T motorVenom 800 mAh 2s LiPo

PRO-lINE – CMlSpider shellBadlands M3Memory foams8 shooter beadlocks

RC4WD – kING COBRADelrin diff cases‘Punisher’ shaftsAlloy ‘C’ hubsSteering knucklesAlloy main gear caseHardened reduction gears

hORIZON hOBByLosi 4" Crawler shocksSpektrum DX3RSR3100 DSM2

DIslIkEsSkid plate holes very tightStraight bottom links

lIkEsNational winning designFour years real world R&DNarrow chassis design Virtually no torque twistLimiting articulation worksDelrin axle housingsAlloy hop-ups bulletproof Punisher’s drive shafts50T Venom Torque and Speed

CONtACtCML Distribution

Tel 01527 575349 or visit www.cmldistribution.co.uk

King Cobra Distribution Ltd Tel 01706 260502

or visit www.kingcobra.co.uk

Horizon Hobby UK Tel 01279 641097

or visit www.horizonhobby.co.uk


by peter ‘mad pete’ gray w - cmldistribution.co.uk · to a cordless drill using a flexible...

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