Big 6 - Custom 6x6 Element Enduro Scale Builder's Kit

[Mad Ax 10826]

@Busdriver give it time and there'll be tank tracks to watch too - my FTX Buzzsaw is on the shelf behind me pending project start, and my Landfreeder QuadTrack should be here in an hour or so 

[bavee 1195]

12 hours ago, Mad Ax said:

Heavy rain was forecast for the entire of Friday 30th December, which would make for a cold and soggy day at the disused quarry where the Southern Scale Trail Pay & Play day was to take place.  Bedridden with a crippling sore throat, muscle cramps, headache and tiredness all week, I didn't fancy a day huddling in my waterproofs trying to stay warm, but as luck would have it, the rain dried out and my sore throat healed up just enough to allow me a few hours away from home.  As I'd pretty much been trapped there since Christmas Eve, it was nice to get out.

Good for you! Great pics of its maiden voyage!

[Busdriver 6532]

9 minutes ago, Mad Ax said:

@Busdriver give it time and there'll be tank tracks to watch too - my FTX Buzzsaw is on the shelf behind me pending project start, and my Landfreeder QuadTrack should be here in an hour or so 

4 wheels good, 6 wheels better, but tracks as well!!!! Ooooh heaven 

[Badcrumble 4422]

5 hours ago, Busdriver said:

I love the way this truck hugs the ground. There’s something fascinating watching a multi axle truck a bit like tank tracks!!

I agree!

Epic truck.

[BuggyDad 6375]

On 1/5/2023 at 9:07 AM, Mad Ax said:

Not a stupid question at all, and one I've asked myself multiple times recently.  The Kit 1 and Kit 2 shock tops and pivot balls are different, I think the Kit 2 holes are larger, as when I came to fit the Kit 2 shocks to the front of the 6x6 (where the blue shocks had been) they were more floppy than before, and I had to find the Kit 2 pivot balls.

This however does seem to be a thing with modern crawlers - the pivot balls are there because somebody on the design team saw them on another model and figured they were necessary, but had no idea how they actually worked.  That's my take on it, anyway.  At least, with Tamiya pivot balls, they press-fit into the shock tops - but obviously over time they wear out and pop off.  I totally understand that other manufacturers want to come up with a new way of doing this.  But they don't seem to have fully understood what they're trying to achieve.

Yes, the shocks flop around on the pivot balls.  It's odd.  Apart from mix-n-matching pivot balls and spacers to stop the shocks moving around, I'm not really sure what the solution is.  But I've decided not to care about it, as this isn't the only crawler in my fleet that has this problem.

Of course, it's entirely possible (in fact quite likely) that I am the most stupid link in the chain and I've overlooked something terribly obvious, and that nobody else has these problems.

Sounds like the answer is as you've done - don't care about it! 

Love the pics of your truck by the way. As @Busdriver says, the way those back wheels articulate it looks like that thing could climb up anything.

So you're not impressed with the tyres? 

[Mad Ax 10826]

Just now, BuggyDad said:

So you're not impressed with the tyres? 

It's hard to be sure - it was pretty slick at the quarry and I didn't run anything with Proline rubber for comparison.  I had a couple of big rolls when the rig slid sideways on wet rock, then toppled over - it's tempting to think that wouldn't have happened with Prolines, but I'll never know.  I might give the rig another outing next weekend if a local meet goes ahead, which might give me a better feel for the tyres.

It certainly pulls well enough over my 1:10 scale mountain, which is mostly made from broken shards of rough concrete, so it's very abrasive, but out on the trails where the rocks are smoother, the tyres lack a bit of bite.

I've just walked across the room to go squidgy-squidgy on the Chirax tyres, and they're squidgy enough, but then I squidged the genuine Proline Hyrax tyres on the CFX-W (which have an identical treat pattern) and the Prolines definitely feel more sticky.  The foams are smoother too, although it's worth noting that the previous owner of the Chirax tyres put holes in them for drainage, but the CFX-W tyres are mostly airtight (I actually punctured them with a needle valve and inflated them a couple of weeks ago and they held air for a few days).

I'd like to add - they're certainly not bad tyres in any way, they're soft, they conform, and they sure look good, but I think when you compare a £15 copy tyre to a £60 brand name tyre you're going to see more difference than just the packaging.  In that respect, the Chiraxes are good value for money.

I've just added another squidge-test on the GMade MT-1404 tyres that come standard with the BOM kit, and they feel almost as sticky as the Prolines - now that's a good value tyre, even if they don't match a genuine 1:1 tread pattern.  I personally think they look great on older-style rigs, with their big balloon sidewalls and wide, aggressive tread pattern, but purists don't like them for the same reason.

[Nikko85 3949]

Looks fantastic - well worth all the head scratching. I also really like the way you've but the two wheels roughly central to where on wheel would go, rather than just stick a wheel on the end.

 

[BuggyDad 6375]

1 hour ago, Mad Ax said:

It's hard to be sure - it was pretty slick at the quarry and I didn't run anything with Proline rubber for comparison.  I had a couple of big rolls when the rig slid sideways on wet rock, then toppled over - it's tempting to think that wouldn't have happened with Prolines, but I'll never know.  I might give the rig another outing next weekend if a local meet goes ahead, which might give me a better feel for the tyres.

It certainly pulls well enough over my 1:10 scale mountain, which is mostly made from broken shards of rough concrete, so it's very abrasive, but out on the trails where the rocks are smoother, the tyres lack a bit of bite.

I've just walked across the room to go squidgy-squidgy on the Chirax tyres, and they're squidgy enough, but then I squidged the genuine Proline Hyrax tyres on the CFX-W (which have an identical treat pattern) and the Prolines definitely feel more sticky.  The foams are smoother too, although it's worth noting that the previous owner of the Chirax tyres put holes in them for drainage, but the CFX-W tyres are mostly airtight (I actually punctured them with a needle valve and inflated them a couple of weeks ago and they held air for a few days).

I'd like to add - they're certainly not bad tyres in any way, they're soft, they conform, and they sure look good, but I think when you compare a £15 copy tyre to a £60 brand name tyre you're going to see more difference than just the packaging.  In that respect, the Chiraxes are good value for money.

I've just added another squidge-test on the GMade MT-1404 tyres that come standard with the BOM kit, and they feel almost as sticky as the Prolines - now that's a good value tyre, even if they don't match a genuine 1:1 tread pattern.  I personally think they look great on older-style rigs, with their big balloon sidewalls and wide, aggressive tread pattern, but purists don't like them for the same reason.

Thats great to get a bit more of a feel for. Thank you. 

"Definitely not as good as the best, but still good, and less than half the price" is bang on my sweet spot for the starting point for just about any part! It's nice to get a feel for what that is (and I'll probably wear it out anyway) before I judge whether to spend twice as much for better next time.

I wear out and replace bike parts a lot, and very often I find myself downgrading in similar circumstances (albeit generally not tyres).

I think if I head off down a modding track with crawlers, I will be following trails you've blazed. 

 

[Mad Ax 10826]

With the Southern Scale Trail just around the corner, and the Scaler Nationals not too long after that, I decided it was time to get Big 6 down off the shelf and give it a check over.  It wasn't ready for the trails until late December last year, and then it spat a driveshaft at the quarry meet, so it's never really had a proper run.  I missed the G6 this year as it was the same weekend as the Carlisle round of the Iconic Cup

Side story: I actually stayed in a hotel just 15 minutes from the G6 on the Friday night, and I could have taken a couple of scalers I could have spent all day at the G6, driven up to Carlisle to camp over for racing on the Sunday.  I decided not to because I was staying in a hotel for 3 nights after the Iconic Cup, and didn't want my van or my hotel room encumbered with big boxes and muddy trucks for my holiday, but in retrospect, I spent most of Saturday stuck in traffic and didn't get to the track until late afternoon - too late for any serious running.  Maybe next time...

Anyway, Big 6 has always had a squeaky back end.  I think mostly due to the angles on the rear shafts, and that they're cheap shafts.  Ideally, the whole lot needed replacing with something more beefy.

Here's an awkward shot of the bearing carrier that sits above the central axle.  The bridge prop is probably an old MST or Gmade one, I'm not sure, but it's been cut off very short and I'm surprised it's lasted this long without going pop.  The rear prop has a tendency to spit pins out, because it's a little over-stretched, and it also squeaks a lot.  It's a cheap one from Aliexpress.

Looking underneath, we can see another cheapo Aliexpress shaft on the front axle (right), and an old stock shaft (I think it's a cut-down Element one) on the middle axle.  These work OK but the front one could spit a pin under load, and the middle one is plastic, so it might snap if the wheel gets bound.

The fist job was to replace the front and middle axle shafts.  I bought this Boom Racing set, which were of perfect length, metal all-through, and have proper block UJs instead of those awkward pin-and-spring type joints.

These Boom Racing ones are pretty neat.  They actually come with some scale-looking rings that go around them, with bolts that can be screwed in for extra scales, but these "high clearance" bosses were also included, and they do a better job of filling space between pin hole and bearing, reducing the amount that the UJ is likely to wiggle on the shaft when under load.  Boom Racing also include a variety of different shims to go between boss and bearing, to give the best fit.  Cool.

This was especially useful on the transfer shafts, because there are no shims in the case to stop the shaft moving in and out, and it's got a heap of play in it.  (In fairness, I probably should buy a bulk pack of shims so I can fix these problems before I fit the case...)

[Mad Ax 10826]

Front and centre shafts fitted.  The centre shaft has a really steep angle, but the Boom Racing UJ seems to handle it with no juddering or binding.

Now, I'd originally ordered some individual shafts for the bridge and the rear, but they were out of stock, so I was sent this pack by Cross RC.  They would fit (the shorter one would need shortening) but unfortunately the don't have enough angle on the UJs.  Having had these pin-and-spring types fail on the trail before, I think I'd rather modify another set of Boom Racing shafts than try to wedge these on and having them explode on me.

[Mad Ax 10826]

Ugh...  The Money Pit strikes again!

So, after no joy finding appropriately sized propshafts in the UK, I went onto Boom Racing's website and discovered they do indeed make them in the right size for the rear axle, plus I had a big discount voucher to use courtesy of my SST tickets.  I placed the order and they arrived a week or so later.

Tuesday evening, I sat down to fit them.

Here they are - same as the front ones, just different lengths.

And there's where they need to be

And here they are fitted!  Since I now have matching propshafts all round, I decided to fit the more scale-appropriate bolt on ends.  I'll go back and refit them to the other shafts when I have time.  They're actually super-fiddly to get on, the screws are tiny and if you fit them without the boss being pushed over the end of the shaft, they can be in the wrong place and stop it from fitting.  So they have to be tightened up in situ.

[Mad Ax 10826]

After that, I went for a quick body-off test drive.  I was pretty nervous, since I'd spent a fair bit of money on these shafts, and they could break on the first ascent.  Well, nothing for it but to go for it.

Sadly, the truck really doesn't want to perform.  Its biggest problem, I'm starting to think, are the tyres - they look right but they don't have quite the same stickness as my genuine Proline Hyraxes, and even over the rough concrete of my 1:10 scale mountain they mostly want to slip and skip.  After a bit of persuasion I got the truck most of the way up the first climb, then it just got stuck.

Ground clearance seems to be a problem on these axles.  They're not exactly big pumpkins, but the track is wide, so there's less triangulation.  The pumpkins dragged a lot on the way up.  Admittedly my mountain isn't really representative of crawler event terrain, but my other rigs fare better.  I'd expected more from this.

And then it just got stuck.  I was giving it more and more throttle and it just wasn't moving.  I've been gradually tightening up the slipper all year because it won't stop slipping, but it's there for a reason...

[Mad Ax 10826]

I'm pretty sure this is the second time this has happened.  First time was way back when I got the truck mobile.  Yeah, it just span up and shredded itself.

It's a 48dp - 0.6mod would be much better, but there's not enough clearance to get one in and still have low gearing.  The 16/90 48dp combo is about as low as I can get it without redrilling the motor plate - it's right at the end of its adjustment.

But, of course, gearing is the issue here.  I had the transfer case rigged up with an approximate 25% overdrive to the front axle.  That means whatever my FDR is to the main wheels, I can make it 25% steeper up front.  That's a lot.  Ultimately, the rig is geared too high for the weight.

So, there was only one thing for it - flip the transfer case and abandon the front overdrive.  OK, it might have been nice for a bit more front grab, but I can counter that by fitting a rear steering axle at a later date - tbh it feels like it needs that to get it turning.  Reducing the overall gearing by 25% is more beneficial right now.

So - my Wednesday evening was spent pulling out the transfer case, flipping it 180 degrees, opening it up to swap over the outputs, and putting it all together again.  Not really a difficult job but the wiring routing is really awkward around that area and it was such a pain to do, I lost my temper with it a few times.

The end result, though, is a slower-moving rig that can climb without getting stuck, even with a smaller 86 tooth pinion installed (biggest one I had which was sort-of-just-about fit, the screw holes aren't 100% lined up).  It still didn't get up the initial climb as well as I thought it should, but maybe that's tyres, or maybe it's the weeds growing up around the bottom taking traction away.  Still, when I tried it back in December my review was way more favourable - so I don't know, I guess I need to see how it fares on the trails.

I've only got one 2200mAh battery that will fit the tray, so yesterday I ordered two more, plus a new 90T spur.  Fingers crossed it gives me enough runtime and enough gearing to survive the SST...

[Mad Ax 10826]

Quick update on this one - I never got around to fitting any of the scale parts to this attractive Carisma body, so I thought I'd get that done before its first outing at a proper gated event.

First item - mirrors!  These make such a different to a truck's appearance on the trails.

It's hard to see under the shop dust, but there are dimples in the body to match the mounting lugs.

However, the lugs are famously thin, and they won't survive a rough section on the trails.  They'll end up looking like this:

[Mad Ax 10826]

What I'm going to do next is not my idea - I got it from someone at the UK Scaler Nationals a couple of years back, who pointed me to this video, made by one of the UK Scaler Nationals regulars:

https://www.youtube.com/watch?v=YKKpM37Wkzs&ab_channel=MadMikeWorthington

I started by drilling 1.5mm holes where the pins used to be.

Then I fed some elastic through.  Typically I ordered some elastic from Amazon on Monday afternoon but this actually came from my daughter's new school shoes, it was used to tie them together.  And typically, those shoes, which were bought about 2 weeks ago in advance of the new school term, no longer fit :facepalm:

The stock mounting plate helps to spread the load inside the body and makes it less likely the thread will pull through

Mirrors stand up just like they should.  Bizarre alien reflection not to scale.

Boi-oi-oi-oi-oi-oing

[Mad Ax 10826]

I also added the chrome wipers, which don't sit entirely flat, and realised I'd never put the front window surround on either.  It didn't fit properly so I only put the bottom part on to hide where the coloured paint runs with up to the glass section.  No pics of that, but I'm sure I'll get some nice new photos once this rig hits the trails.  We're expecting our mini-heatwave to last right into the weekend, so there should be some lovely bright shots of this one.

[OldSchoolRC1 1090]

Genius idea for the mirrors! 

And my 11 year old goes through shoes every 3 months. It gets very expensive!  

[Busdriver 6532]

21 hours ago, Mad Ax said:

What I'm going to do next is not my idea - I got it from someone at the UK Scaler Nationals a couple of years back, who pointed me to this video, made by one of the UK Scaler Nationals regulars:

https://www.youtube.com/watch?v=YKKpM37Wkzs&ab_channel=MadMikeWorthington

I started by drilling 1.5mm holes where the pins used to be.

Then I fed some elastic through.  Typically I ordered some elastic from Amazon on Monday afternoon but this actually came from my daughter's new school shoes, it was used to tie them together.  And typically, those shoes, which were bought about 2 weeks ago in advance of the new school term, no longer fit :facepalm:

The stock mounting plate helps to spread the load inside the body and makes it less likely the thread will pull through

Mirrors stand up just like they should.  Bizarre alien reflection not to scale.

Boi-oi-oi-oi-oi-oing

Love the mirror hack. Like most good things “simple “

[Mad Ax 10826]

UPDATES!  Looks like I didn't really do much in the way of updates since Sept 2023, and no photos shared here from the Southern Scale Trail or the UK Scale Nationals in October 2023.

So I was about to tell you about a few fixes, when I realised there were photos left over from late September last year.

In short, the truck performed well at SST in September 2023, but the motor got very hot.  There's a lot of weight to carry around, a lot of angle on the propshafts which won't be helping drivetrain efficiency, and SST is a notorious truck-killer because the rocks are so crazy big and the gaps between them can easily swallow a wheel.  I break something every year, especially on the quarried stone sections.  The weather was stonking hot last year too, which didn't help, plus the motor is tucked in under a tightly packed hood, so it doesn't get much air.

At the end of the trails it was starting to cut out, and although it's a very nice rebuildable Novak FiftyFive, it's also pretty old - so I retired it and bought a new 5-slot instead.

I do like these 5-slots - they're definitely smoother, which makes low-speed control much nicer, and they feel like driving through butter.  They also seem to perform well when torque at low speed is a priority.  I went for the lowest turn I could get.

It made a huge difference, and the truck performed faultlessly at the UK Scale Nationals in 2023.  It got a fair bit of attention and was almost unstoppable on the trails - I really, really enjoy driving this truck, the motor has plenty of torque to get over the tough stuff, the traction is fantastic, the breakover angle is better than any of my other rigs due to the stubby middle axle location, and it never flips over on an ascent or descent, due to all that length and weight.  It's pretty good at sidehilling too, although it's a heavy truck and the suspension will cant over if given too much torque, and that can cause it to roll off a hill.

The only real problems it has on the trails are an increased turning circle - due to the length - and a reluctance to turn into some obstacles because there are two sets of rear wheels trying to push it forwards.

What it really needs is a steering rear axle, which would mean extending the axle out a little to give some swing on the rear tyres, but I think the difference on the trails would be night and day.

Naturally, of course, it had a few rollovers at the nationals in 2023, and the result was that the frame I made under the body got damaged, so it went on the shelf for a while.  To make matters worse, I bit off more than I could chew financially early last year, and couldn't afford to buy new ESCs for my summer race cars or a winch to replace the one that broke on another rig, - so Big 6, with its broken frame, got robbed of its electronics to make other cars run.

[Mad Ax 10826]

So, we fast forward a whole 12 months to the end of September 2024, with only a few weeks to go before the UK Scale Nationals, last big event of the season, and my first chance to run Big 6 on a proper course all year, having missed the May Nationals due to racing at Carlisle and the Southern Scale Trail due to it being right between loads of other events.

This is how the sorry thing looked when I got it down off the rack.  My wife has been doing lots of work with wood and resin this year, including some very intense sanding, so anything that isn't covered up gets covered in dust.

Under the body, the flimsy plastic frame got broke, the ESC is missing and the winch was stolen for something else.

I'm a fan of servo winches - they can usually be mounted neatly in the chassis, there's no fiddly extra electrickery box to install (they plug directly into the Rx like a regular servo) and they generally have heaps more torque than those little bumper-mounted scale winches, unless you want to spend a fortune on something from RC4WD.

Normally I would buy from Overland RC - they were local to me and were making winches out of TowerPro servos, but they stopped trading last year, so I had to go online and buy from Aliexpress.  Still, there's nothing wrong with these ones from Injora.

It's a proper 360 degree winch servo made specifically for the job.  Not to be confused with a "sail winch" servo, which technically is also 360 degrees, but is able to keep track of its rotation due to it turning a pot via a gear reducer, and will only make about 4 full rotations before it stops.  That's OK for operating your sail boat on the lake but no good for hauling your rig out of trouble.

 

[Mad Ax 10826]

Fortunately I hadn't lost any of the spacers I made, so it fitted in with no problems.

I wanted to route the cables neatly on this build (it's always been very tight under this body) so I changed the screw for the steering servo to give something to route around.

like so

A lot of modern rigs come with these nice waterproof radio trays, but it's always hard to get a FlySky receiver to fit.

[Mad Ax 10826]

I also replaced the ESC with a new 1080 v2.  These are awesome!  I didn't even know it was different until I opened the box.  As well as a slightly different form factor (now with captive threads for the fan instead of relying on the threads holding against the heatsink) the new model now has 2 additional wires to connect to your receiver.

One allows you to select reverse using a toggle switch on your transmitter - this means your back-stick is always the brake, regardless of which way the truck goes.  In turn this means you always have full control over how much braking force you apply, regardless of which way you're driving.  If you're running 100% drag brake the point is moot, because it's always on, but, here's where it gets better:

The other wire allows you to set the drag brake rate using a rotary switch on your transmitter.  This means you no longer need to have 100% drag brake all the time.  If you're in a technical section and you want the truck to hold position, turn it right up to max.  If you're on the hiking trails and you don't want it standing on its nose every time you let go of the go-stick, turn it right down and let it roll.

The price is pretty much the same as it was, but these little features are a game-changer for me.  I love these ESCs.

OK - now what about this interior?  Looks like we need a repair panel.

Something like this.

Lots of keying to give something for the cement to work into.

Blocks installed to cover the ripped area

New side-panel installed

et fin

[Mad Ax 10826]

So, how did it go?

Well - as it would happen, I had a minor operation 11 days before the Nationals and although I should have been fully back together by the time I left, things were actually starting to swell and become somewhat sore.  In fact I arrived at the Nationals after a sleepless night, almost unable to walk and in pain the like of which I have never known.  Turns out I'd contracted an infection during the op, although it wouldn't be picked up for a couple more days (it was being passed off as "some post-op swelling is normal").

However, within 30 minutes of parking up at the venue, my van had been completely blocked in by other visitors - so I could either sit in the van feeling sorry for myself until the venue cleared out, or I could hobble along on the trails and try to enjoy myself, so that's exactly what I did.

And this truck made it possible to enjoy it all the more.  Not having to keep bending over to sort it out was nice.  I felt the courses were pretty easy this year - Big 6 never really struggled at all on Course 1, and despite the rocks behind damp and the mud being muddy, it proved itself remarkable capable through the gates.  I wasn't really in the mood for a tough, technical course (I literally just wanted to forget I was alive for a couple of hours) so this was just what I wanted.

Cramped space under the body means I can only run tiny little 2200mAh LiPos, but one lasted for a complete 100 gate course and still had enough juice to get me back to the van.  I had half-intended to stay out for a second course (I had a fresh battery in my rucksack) but I noticed the front wheel was wobbling, which usually means the wheelnut has come loose.  My 3D printed hub covers look fab but there are 8 tiny screws to remove to get at the wheel nut, and that's much better done at the van than on the trails, especially when bending over is painful.

I didn't actually get as far as the van - the wheel fell off before I got there.  Capable as it is, it still got me to the van - but I couldn't be bothered to fix it, so I went out with the BOM instead.  That's always fun.

[MadAnt 596]

Good to hear it was a successful time out making the best of it. I hope you are doing much better. 

[Re-Bugged 11652]

A fantastic rig mate 👍🏻 Sorry to here the pain from your op took the edge off the day though, I hope it improves for you.