"OK TC" - Land Rover Defender 90 Truck-Cab (Winch Challenge truck)

JMo

V.I.P. Member
2021 - latest update

This is not a new build, rather an evolution of what I consider my first true scale build after customising a number of Tamiya [chassis] based RC vehicles for many years...

Having bought a cheap RTR crawler back in 2013, I was immediately hooked and ultimately by 2017 wanted to build something more scale, using a traditional ladder chassis... and since then it has continued to evolve, not least once I'd discovered the scale crawling community and been further inspired.

I catalogued the initial build and evolution on the TamiyaClub forum in detail at the time, and now I feel it has reached it's realistic conclusion - ie. I've finally run out of further ideas to incorporate... well, other than a rear winch too perhaps like I did with the Ghetto Vanquish 4Runner here on SBG - will endeavour to summarise the key attributes and details here for posterity, and hopefully in turn inspire some of you too!


photo. 'Winch Challenge' style Defender 90 track-cab - the body is an D90 station wagon, and I chopped the rear of the roof to create a pick-up, in much the same way as some 1:1 Defenders are converted into a small 'extra cab' style pick-up.


model name: "OK TC" (Defender 90 Truck Cab)

driver: Jack (customised Jack Osbourne figure, modified to fit in seat with Tamiya Wild Willy legs)

body: eBay/RC4WD Defender 90 Station wagon (roof chopped to truck-cab pick-up style, with scratch-built load-bed)

chassis: Injora RC4WD style Trailfinder/Gelande style ladder chassis

wheels: 2.2 size Axial Trail-Ready bead-lock (plastic) with Locked Up RC scale hardware and SLW aluminium hubs.

tyres: 2.2 Mad-Gear Cliff RTR (130mm diameter)

motor & transmission: RC4WD 27T motor, 5:1 ratio planetary gearbox and 2:1 transfer case

axles: XtraSpeed Currie F9 style portal axles (1:1 portal ratio)

suspension: Gmade RSD 90mm shocks and custom links (4 link rear, 3 link and panhard front)

wheelbase: 280mm

track width: f: 204mm / r: 204mm

overall width: 255mm

overall length: 465mm (inc. nudge-bar and tow shackle)

overall height: 270mm (including roof mounted light-bar and cage)



Originally this build used the majority of running gear from a RTR Mad-Gear Cliff crawler - wheels and tyres, axles, suspension links, motor and servo etc. mounted on an aluminium ladder chassis I bought from eBay, pitched as suitable for a 'Defender 90' and is in effect a copy of the RC4WD Gelande/Trailfinder II chassis, with multiple mounting locations for either leaf or 4-link style suspension. True to their word, it did essentially line up with the widely available (at the time) Defender 90 body from China, which is essentially the same as the one you used to get from RC4WD.

Over the years, all of that previous running gear ended up being replaced and upgraded to the extent the only thing left now is those original fat 130mm tyres - even the 2.2 size plastic wheels are now Axial Trail-Ready bead-locks, complete with aluminium hubs and scale hardware.

The motor/transmission combo is a budget brushed 27T RC4WD motor, coupled to a 5:1 planetary gearbox, in turn connected to a central 2:1 ratio transfer case - the slow speed crawling is impressive, and now it runs on a 2S LiPo, still has just about faster than walking pace as a top speed.

In converting this vehicle LiPo recently, I swapped out the original Mad-Gear budget ESC (which was really impressive for slow speed running) for an Axial AE-5L, which includes power tails for front and rear lights, meaning I could eliminate the separate Axial light controller I'd been using before. Of course it turns out these latest ESCs require different LED light strings than their previous kits, so those needed to be replaced too. Ultimately there are just a pair of 5mm red LEDs at the rear, and 5mm orange at the front for the turn-signals/running lights, while the headlights are taken care of by a full width LED light-bar on the roof.

I had previously swapped the original Mad-Gear 9Kg servo with a 20Kg version, and most recently have now fitted an even more heavy duty 35Kg version, in an effort to beef up the steering action on those huge tyres - not that it struggled particularly, other than in a full lock bind situation where it could be difficult to re-centre the steering until the weight was unloaded slightly?

I've also added and revised a few of the scale details - paint, stickers, and some additional accessories - and I'll let the following photos and captions describe the overall build now:



photo. wheelbase is 280mm , and coupled with the huge 2.2 wheels and tyres (130mm diameter), ground clearance is impressive - there is 80mm under the belly (to the radius arm mounts) and minimal front and rear overhangs.



photo. I recently replaced the oversize plastic Mag-Gear axles with these all-metal Currie F9 style portal axles - further improving ground clearance, and at the same time narrowing the track width by 8mm each side - the vehicle is now 255mm wide to the outside edge of the tyres.



photo. my most recent detail changes include painting the existing raw aluminium checker-plate (on the sills, bonnet and rear wheel-arch boxes) the same colour as the body (genuine Land Rover Arles Blue), and then sanding it back slightly to represent wear and to highlight the textured tread-plate finish. I also added an RC4WD working scale Hi-Lift jack to the bonnet, mounted using quick-release pins in the same was as I had on Ozzy's YJ Jeep.



photo. because of the size of the tyres, I ended up having to chop away the rear arches (to allow clearance even at full articulation) and completely removed the front wings - it's a pretty extreme look, but again, similar to some of those Land Rovers you see in UK/European winch challenge events. The side rails along the rear body bed and the screen/roof cage helps to protect the body when sliding against rocks.



photo. the new axles and more narrow hubs have tucked the wheels in under the arches as far as they can, while still allowing decent steering lock at the front - it might not pass an MoT test, but looks less cartoon like than before. note the Problem/No Problem sticker... most people would put this the other way up for the traditional joke, but this is a Land Rover of course ;o)



photo. scale accessories in the full-depth load bed include a welder (necessary), Warn accessory box and ARB tow-strap, spare fuel and a milk crate full of old oil-soaked rags (leaky Land Rover axles), cutting discs (worn Dremel wheels), and a mallet for when you want to get all John Cleese on the bas*ard! The sand ladders double as a cover for the battery compartment behind the cab.



photo. I left the rear window out on purpose, so you can always put an action camera through there to get a driving view. note the folded map in the centre console is a real piece of Ordnance Survey LandRanger map (of one of my favourite places in Wales). Driver Jack [Osbourne] is also toking a doobie.



photo. when looking for a driver for this build, I was so pleased how well the Jack Osbourne figure (at least his top half) fitted in the interior - his bent right arm being perfect for a casual lean out of the right-hand-driver window. His torso was mated to the seated legs from a Wild Willy driver -painted to replicate his original legs. And yes, that is a a Lego spanner in his hand.



photo. one more shot of the interior - scale snacks, soda, map and fire extinguisher accessories added to the already well-detailed body-kit interior - it didn't even need painting, just a genuine layer of dust over the years.



photo. part of the reason for the axle swap was to also incorporate a proper panhard rod so that the chassis mounted servo didn't jack the [soft] suspension so much when turning. The custom panhard link and mount was made from various brackets and rods I had, and the geometry works well, with plenty of articulation, even though the portal axles required 10mm shorter shocks (now 90mm all-rounds), to maintain the original ride-height.



photo. this vehicle has ridden on a lot of different shocks over the years, from a series of cheaper eBay options in 100mm length, to these slightly less cheap Gmade RSD shocks (90mm in conjunction with the new axles) which are my current favourite from a price vs. performance point of view. A set of four is around $50 and you assemble them yourself, and they don't appear to leak, which is nice. The only issue is that the supplied springs can be quite stiff - although the majority of my builds are quite heavy vehicles anyway, and there are softer optional springs available.



photo. some people love portal axles, others not so much. I was particularly impressed with these I got from eBay/China - the anodised finish* is really good, and once I'd replaced the chintzy silver hardware, really like the way they look and the ground clearance advantage they offer. Best of all, the reduction gearboxes on each end are 1:1 geared, so there is no further reduction in overall gearing - you just have to remember they run backwards now so you need to flip the switch on your transmitter or reverse your motor wires. Note also how the 2.2 wheels fit perfectly around the portal gearboxes, allowing the track width to remain narrow - I like that!

*note. be aware I have subsequently bought another set of these style axles from a US based retailer, and although dimensionally the same, they came powder-coated rather than anodised, and some of the cast lugs and hardware location are not quite to the same machined standard. They are not bad, just note quite as nice as these.




photo. admittedly there are very few Tamiya parts on this build... just Jack's legs, plus this rod-end and ball joint to mount the 12mm Axial spot lamp. I think that still warrants a window sticker though!



photo. the dramatically modified front end meant the headlights were initially replaced with a pair of 18mm spot lamps on the bumper bar (until those broke off in a forward roll), and now forward lighting is handled by the the full width light bar on the roof instead. Traditional Lucas style front indicator lenses (and the rear tail lights) are glued to Axial housings with 5mm LEDs inside. That is a genuine RC4WD 9.5CTi winch (together with a wireless key-fob style remote control) wired to run off the main vehicle battery as required.



photo. a compact footprint plus loads of clearance and articulation means it's a very capable trail-rig/crawler cross-over.

Overall I'm really pleased with how this vehicle has evolved over the years - it's always been impressive to drive, even on the previous axles and suspension links, but now it really has the scale detailing to compliment it's performance. I admit the oversize tyres means it is a little more extreme than some of my other scale models, but that is kind of the point - it would be dull if they all started to look the same wouldn't it? And ultimately, I don't think it too unreasonable to think that this sort of vehicle in real life would not have essentially 47" tyres (approximately, at 1:9 scale) on it once you'd modified the body to such an extent...

I hope you like it!
 
Last edited:

JMo

V.I.P. Member
Oooops, I forgot the almost obligatory flex photos of course!





The articulation is not quite as extreme as it was on the previous 100mm shocks (since these 90mm shocks have shorter shaft length, but use the same mounting locations), but overall it still offers impressive performance considering it's short wheelbase, combined with huge clearance and minimal overhangs. I trust the [stiffer] Gmade springs will also bed-in a bit too over time.
 

cooper

Active member
looks cool and fun to drive. Like what you did on the front under the hood. Never seen that before
 
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