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Something I've have in mind for an absolute age but only just got around to starting - my take on a pro-mod WT-01 monster truck. The story begins way back in my early return to RC, the best part of 15 years ago, when I added a second-hand Blackfoot Extreme to my small but growing collection. It came completely stock but was missing the original Tamiya hardbody and was wearing a pre-painted Cross Tiger shell instead. I ran it as it was for a while, but I'd always planned on some upgrades. I was new to the hop-up world and what followed was a mish-mash of unmatched parts that turned the original BFX into something overweight, overdamped and overpowered. Unable to get the 14.4v 550s to play nicely with the Ho Bao monster wheels and axle wideners, I broke it up for parts and sold most of it on, promising myself that one day I would make something better. For a long time other projects took priority, but in November I went to my long-ignored monster truck parts bin and pulled out all the bits I thought I'd need to build another WT-01. Unfortunately I had only a fraction of what I needed, and what I had was badly worn, cracked in places and broken in others, so I figured the cheapest option was to start from scratch with a whole new kit. I found an NIB Mud Blaster II on ebay for under book price, and ordered a JConcepts F250 racerback body, on the basis that this was designed for the Clod wheelbase (10.5") and might look a little neater than the short Brat body over the WT-01's long stride. I already had a spare transmission with full bearings and a cracked case, an NIP case in which to put it all, and some lightly used dogbones and drive parts, plus enough new bearings to refit the new rear transmission and all the corners. As a matter of fact even the F250 is too long for the WT-01. I briefly considered making some staggered suspension arms on the 3D printer to shorten the wheelbase, but a recent post from top builder @IBIFTKH persuaded me to take the plunge and make some custom chassis plates. So - what you see here - and this really is just a teaser of what's to come - is my own take on the WT-01 shorty. The chassis plates are made of 0.5mm plasticard as a prototype / proof of concept / overall size check. If asked I will say that I chose 0.5mm because it's easy to shape and can be cut with scissors as well as craft knife for a very quick build, but the truth is that I had lots of it lying around but I didn't have anything meatier. I took an old cracked chassis plate and cut off all the protruding parts on the back so I could draw around it and mark all the holes. I kept the body post mounts in the stock location because I'd already cut the holes in the body. Then I measured that I'd need to shorten the chassis by 12mm at each end. The rear was easy - I marked the stock transmission holes, then moved them all forwards by 12mm. The front end was a different matter. I hadn't noticed until @Saito2 mentioned in the Cars You Once Enjoyed thread that the front of a WT-01 has no kick-up. The WR-01 has around 8 degrees in the dummy front suspension mount, but Tamiya didn't bother to make an alternative transmission housing or an asymmetrical chassis plate, so the 4wd version has that compromised front suspension geometry. So, rather than just bringing the front holes back by 12mm, I measured back by 12mm at the second-forwardmost of the transmission mounts, then angled the entire transmission back by 8 degrees. As you'll see from the photos this doesn't actually cost and ground clearance - it makes the centre of the truck lower but no lower than the centre of the diff housing. It would be an issue if I was building a crawler, but this truck will spend the majority of its runtime rooster tailing on the gravel lanes on the Imber Range or tearing up the astro at Robin Hood Raceway, so that extra clearance isn't needed. So - here's some rough teaser shots of the new chassis plates and the body in place.
I thought I already had a thread about this truck, but all I can find is something from back in 2016 when I first put it together, back before the Great Photobucket Treason of 2017 (may broken links rest in digital heaven). So here we go again, with a fresh thread and potentially only some rough ideas of what we had before. So - to recap - this started life as a Super Clod Buster delivered from an overseas hobby shop (either Tower or RCMart or something) back in the old days of the late 00s. I believe around summer 2007. My intention has been to build a scaler from the body and a stick-chassis crawler from the axles, but life got in the way, I didn't find the courage to paint the body and the comp crawling world moved away from sticks and into something else. The axles got fitted with 4-link mounts and axle-mounted servos and were used for a time on my TXT-1, before being consigned to a box on the top shelf for many years. In 2016 I refreshed the axles with new internals, converted from TXT wheels back to the original Super Clod, and built a budget racing clod up around a Reign K2-3S chassis. The end result was a bit of a pig to drive with 4S and Traxxas 550 motors, and again got consigned to the shelf while I tried to work out what to do with it. Last year, one of my first projects with my 3D printer was to make up some new servo mounts. These brace the servo against 3 parts of the axle instead of 2, so the transmission case screws aren't being strained and the servo doesn't flop around. With some 20Kg servos from Amazon, and some slightly revised geometry, it finally became driveable. However it was still a bit slow on 3S silvercans and a bit too hard to drive on 4S 550s. On its last outing it broke an RC4WD rod-end while bouncing over the grassy field at Robin Hood Raceway. For a while I couldn't work out why it broke, but then I took a look at the chassis and realised the geometry is all wrong for racing. You see, up until I started watching Trigger Kings videos a couple of months ago, I had no idea what a racing clod should actually look like. Now that I've been educated, I see I was still building my rigs like comp crawlers. Steep angle on the bottom link, horizontal top link, high middle for ground clearance and don't worry over much about the steering geometry. Now I understand a bottom link should be horizontal under static sag. For the best geometry, the top link should be parallel (when viewed from the side) and describe a marginally shorter arc than the bottom link (to maintain the correct caster angle under compression). I don't fully understand why the bottom link should be horizontal - maybe this is where the suspension is at its most neutral? - but I also wonder if the loading on the rod-ends is reduced with this geometry. When hitting a bump with a horizontal bottom link, the axle is free to move up and back. When hitting a bump with an angled bottom link, the axle must move forwards (towards the bump) as well as up. If my intuition is correct, this will increase the loading on the links and rod-ends. As you can tell, I'm kind of running on intuition here... Anyway - I can hardly make the rig worse than it is. So, with that in mind, and with my old metal-clad body looking a bit sorry for itself and a completely new JConcepts 1984 F250 body sitting around doing nothing, I figured a rebuild into a classic mid-80s monster truck style is on the cards. Righto - that is the talking done - now it's pics time! Here's a side-on view of the chassis as-is. K2-3S not really designed for Mod Clod builds but it's sturdy and tough. Geometry is more crawler than racer. Note tape around bottom links and endbells because of clearance with 550s. This view shows how much the bottom link wants to come down. I measured 47mm. Top links and wheelbase will be adjusted later.