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

[Mad Ax 9306]

So I had another idea about the transmission last night.  I was starting to think I'd have to pull the planetary transmission out of my long-stalled King Hauler drag truck project, which I didn't really want to do as I'm not sure how the gear ratios stack up between the Axial and the planetary, and I'm finding I spent longer and longer trying to work stuff like that out, which takes time away from actually building stuff.

Well, I mentioned about installing the transmission sideways (my original attempt to get it in had involved mounting it at an angle, but that didn't work so well).  Now I can't really get it in sideways on the RHS because the front prop and upper axle link are in the way.  I can flip the transfer case to move the front prop to the other side, and it seems I can move the upper axle link too without affecting the geometry.  Worst-case scenario is that I'd have to reverse the panhard rod, steering servo location and servo link, but all those parts are modular and reversible, with the slight exception of the panhard connection on the axle, which is moulded to only go on one side.  It'll work the other way, but will be very slightly out.  But I don't think I need to do that anyway.

So, hopefully, I've saved myself a fair bit of hassle getting the transmission installed.  Fingers crossed.  That means I can keep the stock servo mounts, and that means I can run a winch servo up-front, saving a whole lot of pennies on a winch and an aftermarket bumper to mount it on.

I also found some shorter, stiffer shocks to try in the rear, but on the highest available setting (without having to make all new hoops) the axle loses about 10mm of downward travel, and they're too stiff.  While it would make for a more scale rear-end and allow for a more realistic trayback, this is supposed to be a capable rock rig so I don't want to make it too stiff or low.  But it's still something to consider as I pull the back end apart again at the weekend.

As I'm planning to swap the SBK-1-style hoops onto the front, that will increase the ride height out front, so I need to do the same in the back.  Fortuitously, I drilled a slightly more upright rear shock position when I made my angled shock hoops, which will serve both to lift the rear end and to stiffen the stock shocks.  So maybe I can retain the stock shocks after all.  Alternatively, I could make some all-new front hoops and drop the front end down to match the shorter rear shock version...

There's a whole heap of options available to me here, the problem will be picking one and getting it installed and set up before I have to set off for the event in a month's time  

[Mad Ax 9306]

Updates!

I know you're all hanging up the big one - the update from Revival 2022 - but the week has not entirely gone to plan and I haven't had the time I need to sort through over a thousand photos, let alone wait for them all to upload to the net.  So instead you're getting the 6x6 update that should have gone out before I even set off for the Revival.

So, I started with this - the Big 6 project (which is actually its official title), with no transmission.

As I alluded to earlier, I was able to relocate the top link to the other side to clear space for the transmission.  In this arrangement, I'm connecting into the 1:1 drive on the transfer case, which will give me around 25% overdrive at the front axle.  I wasn't planning on doing it this way, but the general consensus is that 25% isn't too much and it's easier than flipping the transfer case around.

I got another offcut of 2mm aluminium plate and drilled it so it would attach on the standard holes in the chassis rails

aaand at this point I had to pack up and go in, as it was time to do...  er, something else.  I can't remember what now, it was pre-Revival, and as is normal for an RC camping weekend, most of what happened before is kind of a blur.

[Mad Ax 9306]

I was up super-early on the morning of Saturday 3rd.  My daughter was staying away until Sunday afternoon, so I had a day and a half to get in the workshop and hack at this monster project until it worked.

I started my mounting the Axial transmission onto the new side-mount plate.

In this angle, we see that the output shaft from the transmission is near-as-dammit inline with the input shaft of the transfer case.  I don't have the time or skills to CAD all this up or otherwise measure to see that it will be spot on, so there's going to be some trial and error here.

I started tidying up my side plate, so get it to sit neater against the chassis

then I redrilled and notched the top rail mount plate / shock mount plate on the middle axle - you will see why in a moment (and you won't like it)

 

[Mad Ax 9306]

My main concern - this being of the crawlery persuasion, heavy and with lots of 3S torque through a yet-to-be-purchased 5-slot crawler motor, is that my flimsy 2m mounting plate will basically wrap around itself as soon as the truck hits a tricky climb or sinks an axle into a hole.  So, I wanted to make a brace bar to stop the plate from twisting.

It was around this point when I started to have serious doubts about this installation.  Solutions should be elegant.  The old engineers adage says "if it looks right, it probably is" - therefore the reverse must also true.  If it doesn't look right, it's probably wrong.  A solution that doesn't look elegant may work fine, but something about this just looks wrong.

And here we are, with everything bolted in place.  Sort of.

At this point, we hit a snag.  I couldn't get the camera in the chassis to take a picture, but the output shaft of the transmission was no longer in line with the input shaft in the transfer case.  All the moving of the pieces as I cut and fiddled and spaced them around had pulled it all out of line.  Here I could have gone crazy and cut more spacers, or re-drilled the transmission mounting holes, but I was feeling deeply uncomfortable about this solution and decided to abandon it for a while.

Also at the same time, my neighbours went off out for a ride on their Triumph Bonneville.  My wife, standing in the sunshine watching them go, said "we don't have any childcare duties today, why don't we go for a bike ride?"

And so we did.  That was pretty much the moment when I realised this rig was unlikely to be ready before the Scaler Nationals at the beginning of October.  We're almost two weeks from that fateful moment, and it's still no closer to being ready, so at this point, unless I start pulling sickies from work, it really isn't going to be ready.

Which is a shame.  I may even paint the body and finish the trayback so I can take it along for display purposes only, but it's not going to turn a wheel on the track.

The bike ride took the rest of the day, and the next morning I had to do some work on my Revival racers before the crazy week-long packing process took place.

I managed to get a tiny bit of work done this lunchtime, so there'll be another update to follow when I've got the pics of the camera, but it's unlikely the rig will be ready.

But that's OK!  It gives me more time to focus on getting the other rigs ready for the big bad showdown.  Maybe - just maybe - I'll even see what's up with the Toyota trail truck and get that running, since it hasn't done a proper crawler event.  It's technically now a truescale rig, so it won't do much on the proper courses, but there's usually a little course specifically for truescale trucks, and it would be nice to see it run again after all the money I ploughed into it back in 2020.

[Mad Ax 9306]

One of the major bonuses of working from home is, during term time and when my wife has a work contract at least, I can get an hour of wrenching in the workshop while the sun is shining and there's a lunchbreak to spend.

I need to give the CFX-W a proper going over and a bit of a scrub before the Scaler Nationals in 2 weeks - it's still got dirt on it from the SST quarry day back in April - but first I wanted to pull out the transmission to see if it would fit in the Enduro chassis rails.

The CFX-W transmission is a fairly neat package, and while a little top heavy, certainly looks right for a scale-correct front-motor build.  It fits very securely in the CFX-W chassis rails, but there's a very slight design philosophy difference between MST and Element.

First problem - the pre-drilled holes in the MST transmission mount don't line up with the Enduro chassis rail holes, so new holes would need to be drilled.

Second problem - the CFX-W chassis rails are taller than the Enduro chassis rails (i.e. the channel is wider), so the CFX-W transmission mount won't slip into the Enduro rails without modification.  This isn't a showstopper, but it means once I've started I've compromised the CFX-W part, and would want to replace it with new (the mount bracket is separate from the transmission housing and can be unbolted and replaced separately) if I ever put the CFX-W back to standard.  Since this is only an exploratory mod, I didn't start filing away the mount - it's just loosely held in place.

[Mad Ax 9306]

This shows the UJ angle with the transmission mounted on the rearward of the available holes

This is a bit steep.  In fact just turning it over by hand, my dummy UJ threaded rod would unscrew instead of turning the opposite UJ.  So this won't work.

I tried moving the transmission forward, and although that makes it slightly better, there are issues with the mounting bracket fouling on the panhard rod mount.  Now, this alone needn't be a problem because the type-1 Enduro shock hoops have their own panhard rod mount (the type-2 is a separate adjustable metal mount bolted to the chassis rails) but also as the transmission moves foward, there's less space for a steering servo.  The CFX-w gets around this problem by using the older, slightly less scale solution of an axle-mounted servo, but that's not an option on the Enduro.

Now, there is an alternative option here, which is to install the transmission under the rails, by making some drop brackets.  This means I wouldn't have to cut the bracket to fit the rails, either.  This solution solves quite a few problems, but still doesn't leave much room for a steering servo.

Thumb not to scale.

The other big issue here is recommissioning the CFX-W after the transmission transplant.  The CFX-W has a neat transfer case mounted on the skid place, but the hole pattern is totally different to the Axial or Element transmissions (which are similar but not identical to each other).  Also the centre plate has some moulding pattern in the top to accept the CFX-W transfer case, but not any other transmission (except possibly the CMX?)  So there would be some work involved here.

Does this completely prevent the possibility of using a CFX transmission in the Element?  Well, no probably not, but it does make it somewhat more complicated, especially if I want to get the CFX-W running again in some way.

One option, as I mentioned in my Overthinking thread, is to buy the smaller CFX chassis, steal its transmission, and build it with the spare Axial transmission into a CMX.  But that's not an ideal solution, as the base plate will cause some added work, and it does mean having to justify a whole new chassis when I already have a lot of projects on and not that much spare cash.  It's a shame that MST don't sell modular parts - I can buy the parts to build a complete transmission, but I have to buy them all separately, and it's not cost effective.

Another option is to buy one of those cheap front-mount transmissions from Aliexpress, but they mostly seem to have their mounting brackets shaped to fit the curved front chassis rail like most SCX10 clones have, and I think that will make them awkward to modify or fit, and they'll probably have loads of slop (like the Aliexpress transfer box I'm using).

Finally, I could use the smaller, simpler planetary transmission used in some bigrig builds.  I have one (I think made by Lesu) in my long-stalled Drag King project.  I'm not sure how the gear ratios stack up, but it might not take long to pull it out of the Drag King and install it to find out.  I'll probably have a go at that when I have time, but the Drag King box is in an awkward place and I've not got a lot of time to get the Scaler Nationals rigs ready (especially as I now have to rebuild the CFX-W's front end, too!)

[Mad Ax 9306]

Another real quick update on this project, when I had a few spare minutes after working on the Scaler Nats rigs (of which this was supposed to be, and probably would have been, if a) I hadn't got side-tracked making a tray back and 2) I hadn't had so much trouble with the transmission install).

Anyway, one thing I really wanted to try was a planetary-type transmission.  Fortunately I had one, although it was in the Drag King project, which was right at the bottom of a stack of boxes on a really difficult place to get at.

Here's the assembly installed in Drag King.

And here's a very rough installation using an existing hole in the chassis.

The prop isn't connected in this last photo, although it previously was connected, but it came off during a test run.  The point is though, it did actually work, all the wheels were turning nicely and nothing was binding.

[Badcrumble 4201]

Good to see some progress on this after your recent issues. I'm not sure such as thing as a 'quick project' exists!

[Mad Ax 9306]

It's been a while since I worked on this project, for various reasons, mostly time-related but also waiting on money, parts and ideas.

I wasn't really happy with the planetary gearbox above, again, for various reasons, and I began to think that a pass-thru axle was the only sensible way forward.  I looked around for some TRX-6 or SCX10 6x6 axles, but they just aren't out there any more.  It's a real shame Element don't have anything for this, since it would be such a simple thing to have a pinion boss mounted in a diff cover.

I looked around for a 3D print file of the stock diff cover - it might not be that hard to add a boss for two bearings in there - but there's only one 3D printed diff cover available and it's a pay-for product, not a publicly-available file.

After much deliberation, I placed a purchase on Aliexpress for a set of metal 6x6 axles with a pass-thru.  At around £50 it seemed worth the punt.  It was only after "they" had been despatched that I realised I hadn't ordered 3 axles at all, just the rear one, and it was going to cost another £100 to get the other two I need to finish the project.

Anyway, the axle arrived on Friday, so I pulled it out of the box on Sunday and gave it a test-fit.

Here's the axle, fresh from the box.  It's a lot more chunky than the Element axle, looks pretty strong, and painted in black.

Unfortunately, like a lot of cheap stuff to come out of China it was terribly made.  The gears were binging badly, so I popped it open to take a look.  The crown gear doesn't run true, it's screwed onto that boss thing in the picture but it doesn't sit flat, so it tightens up and binds on the pinion once per revolution.

Damaged threads in the screw holes suggest it's been assembled by a ham-fisted oaf.

[Mad Ax 9306]

I spent a fair bit of time cleaning all this up and sanding down the boss to make it smooth and flat, but ultimately it didn't work.  I even tried "bedding the gears in" by filling the diff housing with polishing compound and running it at full blast in the electric drill for a few minutes, but although the diff looked like a Tamiya gearbox after 20 years with the stock pinion installed, it hadn't worn it down enough to run smooth.

I popped out the pinion and spotted this boss on the back.  If I could somehow take this off, it would increase the gear clearance and maybe prevent it from binding.

Unfortunately I don't have a lathe, so I used an electric drill chuck and a metal file.  It sort of worked, in that I managed to get a bit of the boss off, but there's a way to go to solve the binding.  I figured I would save this problem for another day and decided to see how the axle looked installed.

So, it fits well enough, and looks alright.  The links would need to be changed for the new geometry, but there's no reason why it won't work - if only it would, well, work.

[Mad Ax 9306]

I put the question out as to how I might go about solving this conundrum, and had a brilliant idea from @MadInventor that I put the transfer case between the rear axles.  So today I pulled the back end of the truck apart to test the theory.

Unfortunately, genius though the idea is, the axles are too close together to get a telescopic prop in place.  Close - but no cigar.

However, I'd also been hunting around online for inspiration, looking at some builds from before the TRX-6 / SCX10 6x6 days, and I spotted a conversion that used up-and-over props just like mine, with the transmission mounted at an angle.

I had previously discounted this idea, since I figured there will be some phasing is the driveline has a single UJ without a corresponding UJ to take the phase out again.  However, it the angle was shallow enough, or if the UJ was replaced with a proper constant velocity joint (I'm fairly sure Lesu make one, in fact I might even have one on the tipper assembly on my Grand Hauler tipper) then it might just work.

So tonight I went digging around in the box of Element parts, and found the crossmember that holds the battery tray.  Installed upside-down, there is plenty of clearance from the front axle and a nice angle to get the Axial transmission installed.  As luck (or coincidence, or design) would have it, the bolt holes for the battery tray are exactly the same as the mounting holes in the Axial transmission.  It fits, and it turns smoothly, even with a pair of cheap UJs installed just for show.  I think I can make this work with a single joint, although I'll have to come up with some sleeve arrangement to extend the output shaft.

[Mad Ax 9306]

So - there's a lot of decisions to be made and some new parts to fabricate, but it looks like I can get the Axial transmission installed after all.  Watch this space - the 6x6 show is back on the road  

[OldSchoolRC1 982]

Nice find on that axle, I tend to buy 2 SCX V1 axles and mod them for pass through - I had no idea you could buy one! 

[Mad Ax 9306]

Updates!  I've had a couple of long and busy days in the workshop on this project, but haven't had time to make updates until now.  And I'm timeboxed for 15 minutes, so let's see how much I can get done!

30th October was a good day to be in the workshop, because it's clock change day, and since I get up at 6am every as per my body waking me up at that time, that meant it was only 5am and I had a whole extra hour in the workshop.

I started with a piece of metal from my scrap tin:

I drilled some holes in it,.  As you can see, I didn't drill all of them in entirely the right place.  This is the "bit you don't see" when people like me are struggling to drill holes based on measurements.  I literally do this every time I'm trying to drill the mounting holes for a crawler transmission, because the mounting holes are blind.

Anyway, with the plate made, the trans was screwed in place on the front battery mount crossmember:

[Mad Ax 9306]

I used these real cheap UJs as a proof of concept, and it worked OK, but couldn't get enough purchase on the grub screws to actually drive like this.

The old 19 turn "race" motor was reinstalled for testing.  It's totally the wrong motor for a crawler but it's the right size, and that's all the matters right now.

I strapped a battery on the back and went for a test run.  It was literally dry all day up until this point, and it started bucketing down a few minutes after I got outside, but that was fine because the propshaft wouldn't hold anyway.

[Mad Ax 9306]

After that, it was time to modify some spare parts from those cheap Chinese propshafts to make something that fit better.

By installing the hex bar into a drill and running it in reverse against my bench grinder, I was able to turn down the end of the hex bar with the precision of an engineer's lathe, as you can see by the beautiful finish here.

Drilled and tapped an offcut of hex slider.

It's not perfect, but it's better than my bit of brass rod.

Sadly, it didn't survive my first attempt to crawl over my 1:10 scale mountain.  In fairness, for a rig with cheap tyres and a 19 turn "race" motor, it actually did very well at the earlier stages and only really struggled when it got a wheel stuck in an axle-breaker.  The spring-ring around the drive pin came off for some inexplicable reason, and the pin came out.

[Mad Ax 9306]

Apart from the pin problem, which will ultimately be solved by finding some better quality propshafts for the finished project, it was a very smooth drive.  Way smoother than I expected, as I thought there'd be some phasing from the primary prop, since the angles are unequal, but it was fine.  It has something like 24% overdrive to the front axle due to how I installed the transfer box, but that doesn't affect the smoothness even on grippy stone tiles.  It really needs that overdrive.

So my next plan was a bit of a tidy-up and finish-off.  I didn't want to hide the gorgeous black shocks from the Kit 2 version under the body, and since I'm not using any of the nice dark-coloured Kit 2 link bars on the back, I figured I'd keep the front ones too for another project.  In other words, I swapped over the entire front axle, shocks and links assembly from the Kit 1 version, and I reinstated the Kit 1 front shock towers, which have the panhard rod moulded in to the left tower, instead of as a separate adjustable piece.  Since I'm using all Kit 1 geometry up front now, the Kit 1 panhard rod is the right one to have.  I also fitted the project 20Kg servo that I bought especially for this project.

More to follow when I timebox my next 20 minutes of updates!

[Mad Ax 9306]

With the body in place, there was one slight problem: the transmission touches the body.  Gah!  To mount the body higher would leave the floor pan and chassis exposed, which will look silly.

Still, that's a problem for another day.  Let's do something else.

This is a super-cheap stinger bumper that I got from Aliexpress.  It's about as good as anything that comes from Aliexpress, but that's OK, because it's only a stinger bumper, so all it needs to do is sting and bump.  It's made from metal, in the same way that tofu is made from meat.

It fits easy enough.

Body isn't sitting quite right, right?

[Mad Ax 9306]

Leaving the body problem for another day, I turned my attention to the trayback I'd been making.  I had made the base from 2mm alloy, thinking it better for strength, but the whole thing was starting to get a wee bit heavy, plus it was too wide and was touching the shock tops.

Also the tyres touched it on full articulation.

I made a new, narrower base plate from 1mm aly.

As Duke Nukem would say, "aah, that's better!"

[Mad Ax 9306]

I wanted to finish the trayback, but I'd run out of the right sort of angle section to do it justice, so instead I figured I'd have a go at something I've never done before.  I'm concerned that the trayback will get a hammering, and being made from 1mm aly and cheap L-section it'll get bent out of shape real quick, so I was thinking of ways I could add some bracing to it.

This is some brass rod that I bought ages ago for this sort of thing.  It's a bit thick for what I originally bought it for, but it works perfectly for a roll hoop.

A good few years ago I watched a brazing demo run by CuP Alloys at the Bristol Model Expo, and I bought a starter pack of 5 brazing rods and a little pack of flux.  10 minutes with the MAPP torch (which I also purchased speffically for this sort of thing, but ended up using for many other devious things) and this happened:

Sadly the other side didn't go quite so well, but I'll re-braze it later once I've got it all cut to size.  It feels strong enough, I gave it a bit of a wiggle and it didn't come off, so maybe it just needs the graggly bit melting off.

It's gonna look something like this

or this.  Spur cover removed so the body sits more flatterer

[Mad Ax 9306]

That was quite a lot of work to get done in one day, but then I did have an extra hour spare thanks to the clock change.

Here's another photo, just because I like it so much.

Once the new month rolled around I placed an order for some brass sheet, so I can make mounting feet for the roll cage to screw it to the aluminium.  I considered trying to braze it on, but I don't think the flux will work and I'll probably melt the cheap angle bracket before I get the brazing rods to melt.

[Mad Ax 9306]

Some parts arrived last week.  Ruddog 5-slot crawler motor and servo winch from https://www.overlandrc.co.uk

I took apart the transmission mount and experimented with a dozen different options before coming back to what I'd started with.  With the body trimmed and mounted where I want it and the spur cover removed, there's a tiny amount of clearance.

I'm going to have to build a dashboard to protect the inside of the body, as this will take the paint off in a rollover.

With the transmission woes "sorted", I decided to install the winch servo.  Keeping the transmission away from between the chassis rails means plenty of space for the servos in the stock mounting positions.  However the winch drum catches on the diff cover, so I needed to space it up a little.  To do that, I needed to cut some spacers with my "hand lathe"

sorted

[Mad Ax 9306]

There's a convenient hole in the front bumper mount to pass the winch line through.  In this configuration the winch line will pull on the plastic, but I would sort this later by winding out the winch and winding it back in the other way.

The front bumper has a cast-in recess where a winch line might want to go, but it'll be hard to cut this out neatly and not leave ragged edges that will damage the line.

Ideally, it needs a fairlead.  I will buy a new one for the finished truck but for now I pulled this off the SCX10 Cherokee.

It was quite tricky to drill this out, as the drill bits wanted to wander once I'd put the first hole in, and my needle files are ancient and not particularly aggressive.  This is about as good as it gets - at least it's not sharp enough to shred the line on a chance snag.

The fairlead should keep the winch line away from the cut parts

[Mad Ax 9306]

Another one of the many little jobs that needed doing was installing the receiver.  I like these FlySky radios for their price, but they rarely fit in whatever waterproof electric box is included in the kit.  This one looked pretty close.

A few minutes with a tiny screwdriver and it magically fits

These aero radios have two antennae, and they're long and have hard metal parts in so they won't fit in the stock antenna mount.  Instead I used some rubber grommets and drilled out the top of the box.

Electrics installed and routed neatly

[Mad Ax 9306]

Next thing to investigate was the rock sliders.  Kit 1 and Kit 2 have different slider types:

The bigger rock slider with the body mounting channel is too wide for the body.  It's a slight shame, as this would make body fitting easier, but it's not going to work.  That's fine - they can go back in the box for another project.

Because the middle axle is mounted so far forward, the standard sliders will hit the wheel under compression.  Fortunately the other rock sliders were easy to cut and smooth off, oddly enough using the bench polisher that I use for aluminium parts.

Body in place, sliders fit nicely