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Following! If you want to protect / strengthen those links, get some metal brake line at an autoparts store - works great! 

 

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I marvel at the work that has gone into the chassis and suspension and I reckon that finished shell looks like it is a straight copy of a 1:1 - your decals are really cohesive. 

It has been a great build thread, I'm going back to re-read it now.  

I love 'have you flown a Ford lately?'!

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8 hours ago, SteveUzi said:

Following! If you want to protect / strengthen those links, get some metal brake line at an autoparts store - works great! 

That's a neat idea.  I've got some alu tube that slides neatly over the links but I've still managed to bend them on my Clod.  Steel brake line should be a lot tougher.  I'll see if I can get any - straightening bent links gets quite tiresome...

7 hours ago, BloodClod said:

Really like the look of this truck. Any vids of it running? :)

Not yet - I could probably pull the ESC out of Fifty-Fifty, or find one of my old spare twin motor ESCs from something else, and give it a blast on 2S, but I don't have a lot of spare time and would rather spend it putting things together than taking them apart.  Depending on how my May RC budget goes, I might order a new Hobbywing ESC and some hot-ish motors at the end of the month, especially if there's the possibility I can take the truck out to some bigger spaces in June.  It's too big for my garden track.

4 hours ago, Badcrumble said:

I marvel at the work that has gone into the chassis and suspension and I reckon that finished shell looks like it is a straight copy of a 1:1 - your decals are really cohesive. 

It has been a great build thread, I'm going back to re-read it now.  

I love 'have you flown a Ford lately?'!

I think that decal must come from the 1:1 monster truck world, as it's on the JConcepts decal sheet that came with the body and the Ford decal sheets from MCI.  I tried to keep the design cohesive.  I don't have any qualifications in graphic design (or design of any kind) but I try to follow what real-world designers do.  So after coming up with the name and the warlock face design (see earlier in the thread), I settled on a colour scheme and font.  Colours were an easy choice - the warlock face needed at least 3 and had enough detail that it could support a monochrome look.  Early-on I had envisaged a black body with luminescent green graphics and text, reminiscent of an old 80s VDU, but I think the white works better.

I found the font by searching a free fonts page, then decided to mix up the shades (using the same shades from the face design) to give it some more life.

With both font and colour settled, I sat down with a ruler and scaled my designs to fit in the appropriate places.  The SCRAPSpeed designs are an existing design that I put on all my cars, they just needed to be scaled to fit.  I already knew I wanted a black load bed, so the obvious choice was to re-colour the warlock face into metallic silver (already used on the beads in his braided beard).  I lost a little detail doing that but it was a price worth paying.  After that, the challenge was getting all the graphics onto a single Letter-sized page for printing.  MCI Designs have a really good submission form for printing custom decals - the only drawback is the delivery time from Canada.  MCI also do a huge range of generic monster truck sponsor decal pages and some Ford-specific monster truck pages, which I re-coloured (using the order page) into the same dark grey as the main body of my designs.  I could have had a friend print my designs locally but there's no guarantees the colours would match so well.

In short - that's how I got a cohesive design.

There were actually some last-minute changes after the decals had been ordered.  The body came with a racerback that covers part of the rear bed, but when I put it all in place unpainted it made the extra cab look too long and the bed too short.  It just didn't look right.  I'd already intended to have a warlock face graphic on the side of the racerback, and had sized the load bed graphic to fit over the smaller load area (and not be lost under the racerback).  So at painting time, I opted to leave the rear quarter windows unmasked so they could take the warlock face intended for the racerback.  It meant I had a lot of space to fill on the load bed, and given this is supposed to be a race truck, the sort you might see at Monster Jam, it needed some space for sponsor decals.  The monochrome design doesn't work too well for sponsor logos so having a dedicated space on the load bed made a lot of sense.

I learnt a lot of this from building Fifty-Fifty earlier in the year.  The results were so much better than I expected that I decided to expand on the ideas for Spellbreaker.

Normally I'd be too busy going racing or bashing or generally going about my life to do stuff like this, it's nice that I've had some things to direct my time and energy towards while we're working through this somewhat unpleasant period.

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Did a bit more work yesterday.  I spent a lot of time procrastinating and a few hours fitting shelves in my studio, but still got a bit of time to finish off the TXT build.  As far as I am concerned this is 99.9% done now, which is as close to done as anything ever gets in my workshop.  I can't immediately think of anything else I want to do.  Maybe once I hit some badder terrain I'll realise my links are too weak or my motors too slow or my propshafts too fragile, but until then I'm just going to enjoy looking at it.

An order arrived last week with a pair of Etronix 19T motors and a Hobbywing 880 ESC.  These are a perfect match on 2S.

I made a radio tray from plasticard.  I'd have liked to use thicker card but I seem to be running out.  This is a bit flimsy but it's easy to cut.

P5240125.jpg

P5240126.jpg

Messy pre-installation wiring

P5240127.jpg

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Motor wires bound up with spiral wrap - this makes such a difference to the finished article

P5240128.jpg

P5240129.jpg

These motors seem to be pretty good for the money and are readily available from Wheelspin at the moment

P5240130.jpg

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Also fitted a pair of Traxxas 15T pinions.

So how does it go?  Well, it's not super-fast.  I think I expected a little more, actually, but it runs.  Motors are 0 timed at the moment but there's more to add if I need more speed.  I think the gearing will handle it.

Steering is spot-on.  I'm glad I put the time into the geometry because it just works.  It lifts an axle under acceleration but not overly-so, and there's more preload to add if it becomes a problem once I'm running in larger areas.  It feels pretty solid, although I've put a lot of time into it and now I'm nervous of breaking something.  I sneakily suspect either a propshaft will fail or a link will bend, or a servo will strip.  I should probably make some link covers but that's a job I can do during a lazy pitstop at an outdoor event once such things are viable again.

I still need to do a showroom entry and I need to decide if I'll take new photos on location while I'm out with the family tomorrow, or just use the ones from earlier in this thread.

So, for now, that's all, folks :)

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On 5/27/2020 at 1:54 AM, TenzoR said:

were you able to resolve torque twist?

Torque twist isn't "solved" in that a truck like this will always lean under power.  I could add some preload to fix it up, but that would affect the spring rates when landing from jumps or taking bumpy surfaces.  Either way it's not an ideal situation but in actual fact the truck drives reasonably flat for what it is.  The springs are tougher than stock and the inverted transmission, forward-mounted battery tray and lightweight LiPo battery all help to make a nicer drive.

I took it for a spin on a gravel track earlier this week, I got a video and will upload when I have time to edit off the "Dad, I'm hungry!" from my daughter who was sitting in the back seat at the time.  Apart from her I was alone, so only a static camera shot.  I keep meaning to make up a transmitter-mounted camera cradle but I just don't have the time.

Anyways, it will wheelie under throttle but only if provoked - I like that, it's nice to be able to put the power down without it dragging its tail.  It gets off the line fast.

The big wheels stay under control over bumps.  That's good.  A standard TXT will flap its axles like a spaniel's ears once it gets up to speed.  Watching the Trigger Kings videos must have helped because it feels like I have a very good setup already.  Horizontal bottom links and parallel top links make for a controllable truck.

Amazingly, a full-speed both-axles U-turn won't unsettle it either.  I was expecting it to roll with the slightest provocation, but no, it wants to stay on its wheels, hook up and come racing right back to me.  Result.  I only actually turned it over once, and that was when my 3 year old had the throttle and left stick (rear axle steer) and I had the right stick to keep it out of the hedge.  We ended up going off the road and over some big pre-apocalypse berms made by full-size 4x4 adventurers back before the rains dried up and the country turned to a dustbowl in the wake of the pandemic.

I feel like this would be a pretty solid race truck.  Here's hoping we can have some bashing before the good weather goes away, even if we are dressed up like extras in a Mad Max spin-off to do it.

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Been a long time since I put any updates on this thread.  Mostly this truck has stayed up on the shelf since the last post.  Actually I think the last time it got any more than a token run up and down the lane was when I made the video that I referred to in the above post, way back at the end of May, when we were only a month away from the lifting of Lockdown 1.0, the Second Wave was just scaremongering and we hadn't even heard of the London Strain.  Well, here we are, still dressed up like extras in a Mad Max spin-off, although the rains have returned not quite apocalypse style but definitely English winter style.  Incessant, damp and annoying.

That said, Sunday was mostly dry, so I set off to the coast for a bit.  I stopped at a place called West Bay, which is famous for its shale banks.  After eating some Fish & Chips (see my MST CFX-W thread for more details of English cuisine) I pulled out the TXT-1, squoze* in a 3S softie and went to play on a huge shale mountain right in front of my van.  See pic.  Sadly the run lasted about 2 minutes before it spat out not one but both propshafts.  I didn't have enough tools to effect a full fix so I quat** for the day and set off to run my CFX-W in the mud.

PC200074.jpg

*past tense of "squeeze" - "I squoze it so hard it popped"

**past tense of "quit" - "I got so annoyed I quat the game"

 

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This evening I had nothing better to do, so I pulled the TXT apart to fix the propshafts.  Here's where the front axle attaches.  The grub screw has worked loose again.

PC220001.jpg

The obvious solution to stop this happening is to drill through the stub on the UJ and put a pin through, a la Axial.  This is how I fixed the other end to the input stub on the axles.

Here's the components of the propshaft, with an Axial pin.  Note complete and total difference in thread.  The thread in the shaft outer is M4; the Axial pin thread is M3.

PC220002.jpg

Now, I could drill a 4mm hole through the stub, but that wouldn't leave a lot of meat left and this rig puts through a lot of torque.  So I flipped the prop outer around and drilled the other end.

Marking the place to drill:

PC220003.jpg

Centre-punched and secured in a drill vice

PC220004.jpg

Successfully drilled with a 2.5mm hole

PC220005.jpg

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Stub centre punched

PC220006.jpg

and drilled

PC220007.jpg

test-fitting the pin to make sure everything lines up

PC220008.jpg

thread tapped and pin inserted

PC220009.jpg

PC220010.jpg

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Now repeat for the rear.  Hold to, that's not normal:

PC220011.jpg

that's a fair bit of torque right there...

PC220012.jpg

Still, never mind.  With a steady hand it was possible to drill the stub.

PC220013.jpg

After that the truck was reassembled and ready to run.  I even had some charged 3S packs left over from Sunday's jaunt.

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Earlier today, in another thread, I'd complained that I never drive my rigs in winter because it's always dark.  Well, I figured, I've got outside lights - why not have a quick blast to see how it holds up?  What could possibly go wrong?

Well, as it turns out, my garden isn't really big enough for a full-size monster truck.  One slight graze against the wall broke the front servo horn.  In fairness it was only a plastic horn supplied with a servo, I really should get something better on there.  Well, I'll have to now, won't I?

Unfortunately this pic isn't very good - it looked alright on the camera screen but obviously trying to hold the truck with one hand and the camera with the other wasn't such a good idea after all.

PC220014.jpg

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Nice work on fixing the shafts.  I end up doing that a lot, I hate grub screws and they never seem to hold properly.  Your image of the rear shaft is case & point.  

Your servo mounts are nice too, I did the exact same thing on my TXT-2 and love them.  I ended up using 2mm carbon fiber sheet but they look nearly identical to yours.  I originally bought some behind the axle mounts from Thundertech Racing and didnt like their setup so made my own.  I usually prefer to buy parts if I can to make my life easier, but I usually end up having to make them anyway to get things how I want them.

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Just read throug the beginning of this thread and I'm impressed, this is a very cool TXT.  I'll bet it handles wonderfully with the new 4-link geometry.  I must have missed it when I was away from the site for a while, awesome work.  Love the body as well.  

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Yes, handling isn't bad for a heavy monster truck.  I think it's a little bit shorter than stock wheelbase as the shock rods are angled the "wrong way", made worse at the front because I angled the axle backwards for more caster angle.  I didn't want to have to relocate the cantilever mounts since it's not really a big deal.

It definitely needs some sway bars, early next year I'll order some piano wire of various thicknesses and have a go at making some.  This was my first big monster truck build after playing around with the mod clod way back at the end of last year, and the first time I realised I needed to be aiming for horizontal bottom links to get any kind of stability and reliability.

As always with a big monster, the steering is one of the worst problems.  I'm running hi-torque Alturn servos with plastic horns - I've tried Kimbro servo savers but they introduce too much wobble and make it undriveable.  I really liked the Power HD 25Kg servos on the mod clod, so maybe I'll bag a second set of those.  They come with aluminium servo horns which hopefully will be more robust than the plastic one I snapped last night.

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Yea, getting the bottom links parallel with the ground is ideal in any 4-link monster truck for predictable handling and lower COG.  I could imagine sway bars would help out a lot as well considering you're using the stock cantilever setup.  Piano wire or spring steel rod will work well clamped to the lower arms.  

As for the steering, I am running the 25kg servos with Kimbrough savers on my TXT-2 and the steering is great, even at high speeds the truck is nice and stable.  I did have issues early on when running the stock Tamiya links, but since upgrading to 1/4" 6061 aluminum tube for the steering links it has been perfect.  I think having strong links is key (especially on the rear), but yours look plentry strong so that shouldnt be the issue.  

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I finally had a chance to do some running with the TXT a week ago.  The sun was shining and the weather was warm and we'd finished painting the ramps, so I went out onto the concrete behind the garage and did some jumps.

We then went into the garden to do some higher jumps on the grass, in the hope that the grass would be softer.  The truck managed OK for about 5 minutes but it's hard to drive straight without sway bars - the geometry is good but there's still some inevitable torque steer when the axle lifts and that sends it off-centre.  The end result was a bad landing and a broken servo gear.

P2280048.jpg

The servo is a Power HD 20Kg, model number DS 3218 MG, using an alloy (solid) servo horn.  I've seen a lot of recommendations for "Power HD servos" here and elsewhere but had never noticed there are various different models.  The MG model has brass gears, but there's also a PRO model with steel gears - it's strange that most of the ads selling either model make absolutely nothing of this, and the price difference is minimal.

So last week I ordered two new DS 3218 PRO servos on the advice of @87lc2, along with some Kimbrough 124 servo savers.

Here's the two servos side-by-side - the new PRO model with the steel splines and the old MG model with the brass splines.

P3070011.jpg

My intention was to fit the servos with the Kimbrough savers, but alas my BTA installation won't allow that without some fairly serious re-thinking.  (OK, technically it might be possible if I made some extensions to the Kimbrough servo saver but that's a job for another day).  However I did notice I had a lot of throw on the servo horn, and had dialled the endpoints right down as the TXT axles don't have a lot of lock.  This was putting a lot of unnecessary load on the servo.  I moved the steering link to a lower position on the solid horn and turned up the endpoints to compensate - on top of the stronger servo, that should make it more robust.

It's a real fiddle getting these servos in and out without removing the axle but it's doable.

P3070012.jpg

P3070013.jpg

P3070014.jpg

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I figured I'd replace the rear servo at the same time, instead of waiting for the inevitable breakage.  That gives me a spare high-power servo that I can use in a low-impact area.  Assuming I can find spare gears for the broken one, I will have two spare servos.  These are probably great in crawlers although I've been using Alturn 780s for those.

While I had the rear servo post out I noticed the driveshaft had been rubbing.

P3070015.jpg

There seems to be a lot of play in my rear input shaft, so I might have to pull the axles to check them anyway.  TBH I think there was a lot of play when I put this together back in February last year, but I guess it's worth checking before I destroy the axle.

After that I figured I would try using my TC setup parts to centre the steering.  It's always difficult to set the trim on a 4ws truck and it's even harder on a solid axle rig when suspension movement will inevitably cause some degree of bump steer.  Well, I managed to get the wheel plates roughly on, but there's too much play across the chassis to make an accurate setting.  Also everything on this rig is hand-made - from the holes drilled in the axle mounts to the 4-links themselves, so there will always be some inaccuracy.  The end result is I get an equal measurement in one spot and it goes out somewhere else.  So I gave up, made a best-guess effort by eye, and went out for another play.

P3070016.jpg

At least I now have a functional TXT again, although I desperately need to sort out those sway bars.  I guess I have to decide if I will try to bend some piano wire into a U-shape and see if I can thread the ends to mount the droplinks, or if I will have to find or make some arms that clamp onto the piano wire with grub screws.  I can make some arms out of square stock but they wouldn't be pretty.  Alternatively I could replicate the stock sway bar design and mount them directly onto the links, assuming I can bend the wire without weakening it.

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Hopefully the DS3218PRO servos work out for you.  I have been using them on my Clod-sized tire trucks for a while now and have yet to break one, fingers crossed :)  I use the regular DS3218's on my crawlers and they're great, haven't broekn one on a 1.9/2.2 tire crawler yet.  I agree with what you said on the rear wheel steering end points.  I usually run hardly any rear steer at all on my monsters and just use the rear to help pull the front around rather than actually steer the truck (that's why good servos are important, so the front can actually steer).  I was just messing with my LMT yesterday and have the front steer at 60% and the rear at only 30% and it turns on a dime without letting the rear get too out of shape.  

You definitely need some sort of sway bar system on that truck when running a cantilever shock setup, I imagine its a handful to drive.  Would be great to attach them to the chassis if possible, but I've had good luck just tying them to the lower links.  Not as good as a chassis mounted setup, but will at least making it drive straight.

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Yes, sway bars are the next part of the plan, I think.  I need to order some piano wire next week so I can finish the last piece of the puzzle.  There are holes in the chassis that might work nicely for feeding the sway bars through, but then I have the fun of getting them to attach to the links or axles somewhere.  I'm sure I'll come up with something, tho.

It is indeed a lardy pig to drive without them.  Give it full beans and the body rolls right over - it's not as bad as a stock TXT, which lifts a paw at the merest hint of throttle even on 2S with silvercans, but it still makes it hard to drive straight.

All my solid axle rigs run off my stick controller, so I control the rear axle with the left stick.  That way I can steer as much or as little as I want.  I had my Clod running off a wheel controller with a switch to run rear steer on/or off from the wheel channel, but I couldn't get the coordination right to flip it on in tight bends and leave it off in wide ones.  Maybe I'll experiment with channel mixing and run less steering on the rear but off a single channel, as I'm not as smooth as I'd like to be on the left stick.

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Quick update on this one - I found some missing piano wire so I decided to have a go at those sway bars.  I couldn't be bothered to come up with some crazy through-the-chassis mount setup, so I just cable tied them to the lower links.

I only had enough for one sway bar, so I started at the front end.  That's more tricky because my inverted transmission puts the motors below the level of the lower link pivots, so a conventional setup won't work here.

sm_PA010429.jpeg

I hand-bent the wire in the bench vice, but in typical Me fashion I got it absolutely wrong and made a twisted sway bar.

sm_PA010430.jpeg

Fortunately a bit of twisting and swearing got it straight again.

sm_PA010431.jpeg

Cable-tied to the lower links, this seems to work OK - there's enough stretch in the cable ties to allow for the slight change of geometry with the axle twists, but plenty of tension in the sway bar to keep the axle mostly straight.

sm_PA010432.jpeg

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Tidied up the cable ties

sm_PA010433.jpeg

Not the best angle, but most of the twist is now in the back end, the front is being held in check by the sway bar.  But give it a sudden twist and it will flex, which is exactly what we want!

sm_PA010434.jpeg

It wasn't really a fair test when I ran it up and down the lane, as the torque twist is mostly affecting the rear axle.  The truck went back on the shelf while more piano wire was ordered.

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A week later, my new piano wire order would arrive so I could crack on and fix the rear axle as well.

sm_PA080487.jpeg

sm_PA080489.jpeg

Static articulation is now reduced, but the truck is much better behaved on the concrete.  It'll still get out of shape when it wants to, but it drives nicely on a 2S battery and looks fantastic.  And now, when I point it towards a ramp and hit the throttle, it actually goes towards the ramp, it doesn't shoot off in some random direction and go upside down.

sm_PA080490.jpeg

Setting up the radio for full-time 4WS was a good move, too.  I've had to reset all my multi-channel cars due to my FlySky radio dying a few weeks ago, so I've been taking the time to set them up properly.  Just a little bit of rear steering mixed into the front steering channel really makes the difference, the truck now steers nicely around tight spots but doesn't get out of shape under throttle.

While I had the truck on the bench, I drilled some new holes and did a wire tuck, to keep it all neat and tidy.

sm_PA080491.jpeg

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