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Mad Ax

Project Top Secret - Element Enduro Scale Builder's Kit

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OK, back to the build.

This isn't a great photo, but you can see the bulge in the transfer case.  I needed to trim that off the centre plate to get it to mount flat.  Again, the hole spacing here was just slightly off, but putting a 3.5mm drill through the centre plate sorted that.

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Those of you who are paying attention will notice that I drilled the holes on the wrong side.  At first I didn't realise the transfer case isn't a 1:1 ratio, so I had to swap sides to get the drive directions where I needed them.  For a while I wondered if I could overdrive the front, but the ratio is around 20% and that feels like way too much.  This way, I'm dropping the gearing a little, which is no bad thing from an old SCX10 transmission.

The transfer case is a neat little thing.  It's easy to open up and flip the gears around so the output shafts are where I want them.  Important, as I want the rear axles to have counter-rotating props, so the cancel out any torque twist.  I haven't yet decided if the front axle should match the rear or the middle axle.

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My next plan was to work out how to mount the motor and transmission, and how to connect it to the transfer case.  I found a space that looked about right, but it would need a super-short prop, with UJs.

In my stash I had a few sets of these: basic budget metal propshafts.

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I like that these are a modular design.  Unscrew the male and female sections, and you get some dinky little things.

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For reasons that mortal man is not meant to have the what of, these two ends are not of equal size.  The female part is under 6mm, the male part is 6.1mm.

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I had to use the trusty drill press and a 6mm, then 6.5mm, carbide drill bit to get the two parts to mate together snuggly.  A 6.1mm drill would have been a luxury in this instance, the 6mm was simply too small, it was never going to fit.

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By this time, Workshop Sunday was coming very close to the end, in fact I was overdue my end time and should have been getting changed for a night in the studio.  Just to prove the concept, I tightened up the grub screw on the modified mini-prop - it doesn't fit entirely square, but I can fix this later by drilling through the male end and using a screw pin to make it more secure

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et, voila!

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OK - so it's only roughly held in place by mine own hand, but there is space, there is a surface to mount the transmission on (or at least, there will be) and the propshaft turns freely without binding.  It looks like it's going to work!

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So, there's only one more complicated challenge to overcome - routing the rear propshaft.  It's going to need a bearing carrier, as there's no clear run between the middle axle and links.  I'll have to go up-and-over, but stay forward enough that the UJs don't bind on full articulation.  A bearing carrier is on order, and may require a little bit of re-fabrication once it arrives.  But we'll see.  There is space for it, the challenge is mounting it at the right angle.

Watch this space!

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Updates!  It's been a crazy day in the workshop, up around 33 degrees C all day so a pretty sweaty place to be (at least for us soft Brits who typically don't see much about 26 on a good day).  With lots of manual cutting and sanding to do, it's been something of a challenge but it's been worthwhile, as I'm running out of days to the Scaler Nationals in October.

This arrived a couple of weeks ago, but I haven't had time to open it until today:

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It's a Lesu bearing carrier.  Cheap and delivered fast from Ebay.  There's not much to it really - a small but attractive aluminium body, with some nice details, two 540 bearings and a shaft with some E-clips.

Here it is slotted neatly onto the diagonal chassis brace that holes the rear link mounts and middle shock mounts.  It's a perfect fit here, but it needs to be horizontal, otherwise the UJs won't work.

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A point to note for later - this is yet another blind-drilled lug hole.  I'll need to drill that out later, then...

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So, we kind of want the bearing carrier to fit here somewhere.  I experimented with mounting it under the diagonal, but there was too much stuff in the way (mostly the rear link mounts).

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This is a lump of 10x10mm square alu bar that I'd kept from another build.  It fits neatly into the diagonal brace.

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To get the diagonal that I needed, I had to cut down through the bar with a hacksaw.  In 33 degree temps, this was something of a challenge.

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This is what I finished with.  It's a bit rough as I had to come at it from the other end when my sawblade started going off line.

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After a lot of filing and sanding, far more than I wanted to be doing on such a warm day, I ended up with this.  Note the filed out recesses at either end to help locate the bracket into the recess in the diagonal brace.

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Mocked into place (not bolted):

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It level

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Next, it was necessary to drill some big holes and cut threads in them, so I could screw it into the diagonal brace from beneath.

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The bearing carrier has M2 threads already cut into it, so all I had to do was drill some 2mm holes for the screws to go through.  I had to recess them slightly as the finished bracket needs to fit flush on the chassis brace.  This was done by convincing my drill press that it is a milling machine for just long enough to get the holes cut.  Note that I only drilled 2 holes - I don't think there's enough meat for the additional 2 holes with recesses.

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Woop!

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Remember those blind grub recesses I mentioned earlier?  Here's me drilling them out.

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To get at the underside of the diagonal brace to screw the bearing carrier bracket on, I had to remove the links for the rear axle.  That gave me an opportunity to do something I've been meaning to do since I started on this project.

First, I opened the diff cover and pulled out the half shafts.

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Then I said a magic word and snapped my fingers

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And hey-presto!  The diff is in the other way around.

So, if you have an Element Enduro and you want to run a conventional forward-timed motor, don't fret about the silly backwardsness of the gearbox.  Just turn your diffs upside down!

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While I was in the process of putting everything back together, I replaced the screws for the rear lower links for a single threaded rod with a spacer in the middle and locknuts on the end.  This braces the link mounts together and should make it more rigid.

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After that, it was time to hook up the driveshafts.  I had a bit of fun trying to get the stock shafts to fit, but they weren't inclined to do so, so I opened up another cheap aluminium ZD Racing slider from Banggood.  For some reason that is beyond the ken of what humankind is meant to have the what of, ZD Racing put their grub recesses in the wrong place so it is physically impossible to run them in phase.  I had to file another flat and drill another recess to fix this problem.

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Et, voila!

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The next thing for me to turn my heat-sapped attention to was the transmission.  This marks the final super-complicated step in the project (and I've only been on it for two days :o ) - everything else is just fabrication.

The real problem with the transmission is packaging.  Swapping the Element stealth transmission for the old Axial one was a good move, as it's a bit shorter, but it's still a very tight fit.  It won't fit between the front chassis rails, like a CFX or other front motor transmission, and I didn't really want it there anyway because I want a winch servo there alongside the steering servo.

After a lot of mocking up, I settled for this:

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A standard can won't fit - even swapping the Axial plastic propshaft out for a smaller ZD Racing metal one, the shaft rubs on the can.  Lifting the transmission causes the drive to the transfer box to bind.  I plan to use a mod motor in this one anyway (maybe one of those Reedy 5-poles) but the 19 turn TC motor is a good placeholder for now.

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I made this little plate from 2mm FR4 sheet.  It's fairly sturdy, but it will have to withstand the full torque of the transmission, so I might have to brace it later.

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With everything fitted, I slapped in some temporary electronics and span up the drivetrain.  There's a lot of lash - pretty much every component (especially the aftermarket propshafts) has some lash in it, and over so many shafts that equates to the wheels not running entirely smooth.  The imbalance in the tiny little shaft from the transmission to the transfer case probably doesn't help as it's adding some vibration into the whole of the rest of the drivetrain.

I figured it was time to put it on the ground and go for a test-run.  The 19 turn TC motor isn't the right tool for the job, and I only had a 2S pack ready to go, but at least it would prove if the whole thing was going to work.

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So, how did it go?

Pretty well, actually!  There's buckets of steering angle on the front axle, so even with the longer wheelbase and middle axle adding all that extra turning drag, it still spins around in a small space.  This has long been a problem on the really tricky, technical parts of the UK Scaler Nationals, where you have to do a 19-point turn to get a truck pointed the right way between two gates.  Lots of angle will really help here.

I haven't worked out the gearing yet.  I stuck an 18t pinion on, which feels about right - it had a bit of speed in the garden, with more to come when it gets a 3S pack, but a crawler motor will be much slower.  I can experiment with pinions later.

The rear shock mounts aren't a permanent solution and were liable to come loose if I tried any serious crawling with them, but that's what I did anyway.  Sadly though I couldn't do much more than drive around on the flat, because I'd run out of the pin screws for securing the little prop to the transmission, and was using grubs instead.  They didn't have enough purchase and slipped any time significant torque was applied.  I'll have to order more of those to finish the build.

So, all in all, this has been a tremendous success and it's well on the way to having a functional test-drive.  The next big hurdle (although probably the smallest of all the big hurdles) is fixing the rear suspension mount and back end of the chassis.

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I've devoted a lot of my thought time over the past two weeks to the rear suspension, chiefly the rear shock towers.  I really like the SBK2-style hoops with the adjustable shock mounts, but sadly the conventional hoops for a truck-style build are taller than the hoops for the Gatekeeper, which I used for the middle axle because the positioning was just too good to pass up.  This means either having to adjust the shocks to work at different lengths (which will look odd, because the shocks will be at different heights) or using the SBK1-style rear hoops for the back (which will look odd because the designs are different).

I've been considering replacing it all with a single strip of aluminium (one for each side) incorporating both shock mounts with various mounting positions, for tuning.  But that might not look very good either, and might not be very strong in a roll over, as it could bend.  As all this will be visible, I wanted the final product to look right.

While I was having my breakfast this morning, an episode of Dirt Everyday appeared on Youtube featuring a new factory-fresh Ford Bronco, which Fred and Dave tore apart, cut off the back of the body and fitted a tray.  It looked so awesome, I started to think about building one myself after the 6x6 is finished.

And then I thought - wouldn't a home-made tray cover up anything that doesn't look right with the rear shock hoops?  Well, yes, it would, but the tray couldn't be very deep because it would have to clear those shocks.

Then I decided to go take a closer look a the chassis, because I had an idea...

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There is another issue with running two rear axles, and that's that the weight is spread over two axles.  Which means the rear springs need to be softer.  It's yet another expense (in time and money) to have to find some softer springs to regain the balance.

Well, one way to soften up a spring is to lay down the shock.  Indeed, when I went to take a look at the chassis, it struck me just how gangly it looks at the back - all tall and spindly and not really what I expect from a chunky off-road truck.  Those 90mm shocks standing right up are most of the problem.  But there's loads of space between the axles to lay the rear shock down so much that it attaches directly to the chassis rails.  Same with the middle axle, although I'd have to fabricate an extension because the chassis rails drop away for the centre section.  But that's no big deal at all.

Dropping the shocks that much might be too much - they might end up super-floppy, like the BOM's cantilever rear end, which is way too soft despite having springs harder than Vinnie Jones - but it shouldn't be hard to make up a rail extension with a variety of shock mounting points.  Plus it shouldn't be difficult to find harder springs if I need them.

And all this means a lower rear deck, for mounting a tray back onto :o 

Before writing this update, I was watching Youtube vids on brazing aluminium, so I can make my own tray...

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On 8/15/2022 at 5:04 AM, Mad Ax said:

I've been considering replacing it all with a single strip of aluminium (one for each side) incorporating both shock mounts with various mounting positions, for tuning.  But that might not look very good either, and might not be very strong in a roll over, as it could bend.  As all this will be visible, I wanted the final product to look right.

Looking good! First 6x6 Element I've seen. 

I used some L bracket sourced from my local hardware store, and finished the top with a rectangular strip. It let me lay down the shocks a bit, stiffens the chassis and gave a nice clean look. It's a little tall, but I had originally planned a flatbed.  Very strong setup, the rear does not flex at all. 

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@OldSchoolRC1 that's an awesome rig!  I hit "like" because we don't have a "love" button!

That's pretty much what I had in mind, I hadn't actually considered L-section but I've got a lot lying around from other builds, looks like I could use it to make the shock mounts plus something to mount the bed onto.  Thanks so much for the idea.

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On 8/2/2022 at 3:40 AM, Mad Ax said:

I'm now tempted to go and pull apart an axle and flip the diff just to make absolutely sure it will work

Long as the diff does fit into case both ways... yep it’ll work!

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1 hour ago, WillyChang said:

Long as the diff does fit into case both ways... yep it’ll work!

yep, it worked :D

after being excited about it for so long - and posting on here about it so much - I was suddenly worried that either the diff wouldn't actually fit for some completely spurious reason, or that I'd somehow managed to get my engineering all wrong and was still going to drive the same way.  Or maybe in both ways at the same time.  Although this may only be possible if driven by Chuck Norris, or fitted with a Conrad.

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With just over a month to go before the Scaler Nationals, and the long weekender of the Iconic Revival in just over a week taking up an entire weekend of my time, getting this rig has become Priority Alpha.

So, here's what I started with:

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My first plan was to brace the rear of the chassis with some angle section, onto which I could drill new mounting holes for the rear shocks, to lay them down, reduce the spring rate and get more space to add some detail on the back end.

I wanted to keep the ride height exactly where I'd set it, so I put the original shock towers back in place and put the shocks back on.  I had to flip the shock towers left-to-right to do this as there's a little lug that rests over the chassis rail.

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Then I suspended the chassis from the rails to get full extension

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after which I could use a compass to mark where the shock would be if it was angled forward at full extension

oh...  Looks like I made my extensions too short...

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Try again with another length:

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This shot isn't entirely clear, but it's looking down the chassis rail / extension from the back of the chassis.  There's not enough space to get a nut in above the chassis rails, so I'm going to have to drill the stock chassis rails to accept a nut from the shock top mount.

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and, done.  except, now that they're in, that angle looks waaay to shallow.  In fact there was precious little tension at all, and it only got softer as the axles compressed due to the reducing angle.  So I'd have to make some new shock mounts after all...

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Screwed on a piece of plate:

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Drilled some mounting holes for a variety of shock position options.  Yep, despite countersinking everything and using a drill press, sometimes it still goes off-centre for some inexplicable reason.

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Two rough plates installed

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et fin

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This setup now gives massive amounts of articulation, due to the increased motion of the axle for the same compression of the shock.  I'll have to put spacers on the shocks to limit the travel, as that's going to be too much.  I'll probably have to add stiffer springs too.  In fact I might even go to my parts tray and find some shorter, stiffer shocks altogether and go back to mounting them on the rails.  We'll see.

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After sorting that, I wanted to have a go at making a trayback.  I saw an episode of Dirt Everyday where they put a Toyota trayback on the back of a brand new Bronco (they chopped the body up with a sawzall), and I thought it looked so cool I wanted to have a go at making one.  I started with some 2mm alu sheet.

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This is as wide as it can go and still allow some articulation from the wheels.

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That's as far as I got on Saturday, as I ran out of time and materials, but I had a free afternoon on Monday so I stopped by the hardware store and bought some more alu section

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Using more 2mm alu sheet, I build up some fender risers

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Risers added on both sides now.  I'm going to widen it a bit more, then add sides.  If I decide to fit shorter shocks on the back, I can lower the tray down a little.  I'll probably also swap out the 2mm sheet that makes the bed floor for 1mm, as it's getting quite heavy.

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I had a few spare minutes tonight, so I figured I'd give the truck another test-run.  My last test run failed because I didn't have any pins for the propshaft from the transmission to the transfer box, but I found some at the weekend, so it was time to give it a try.

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Something wasn't quite right straight away.  It jerks around a little, as if one of the shafts is binding or out of phase.  Probably that tiny little shaft from transmission to transfer box.  After a few short runs around the garden it popped the drive pin from behind the coil spring retainer, then the spur gear shredded itself.  I thought I'd found a 48p pinion, but I think it was some other random thing, and it span up and ruined the spur.  So my test has still been an epic failure, and now I don't have a spare spur that will fit on this transmission.  I can get another ordered, but, I'm concerned about that joint angle - tbh I'm starting to think the whole transmission setup isn't going to work.

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I'll have to pull it all part at the weekend and see what I can do.  There's possibly a way I can flip the transfer case around and mount the transmission sideways, or maybe I just pull the servo off the front of the chassis and re-install it sideways later, so I can move the transmission out front.  It's starting to feel like a bit of a challenge to get this ready for the Nationals, which will be a shame, but there's no point in rushing it to get a rig that will fall apart after 10 minutes anyway.

My other crawlers are in good shape, except the MST CFX-W, which needs an interior making.  That's 3 good rigs for the weekend, so I should have a good time without the 6x6.

I also realised another mistake - if I'm not going to use the post SBK-2 style shock hoops on the rear, I probably want to pull the SBK-2 style hoops off the front too, and just use the old SBK-1 style hoop.  That way I can use all the nice ones together on another rig.  But the SBK-1-style hoops are lower, giving a taller ride height, and that's now how I lined up the back end when I drilled the shocks.  Also that's now how I had the truck set when I tested the driveshaft angle.  So maybe I'll have to limit the downtravel on the front shocks if I swap the hoops over.

In other news, today I found a complete unused rear axle on Ebay for half the price of a new one, so I impulse-bought it.  That means I now have enough parts to build a complete new Element Enduro rig.  I'm not quire sure what I'll do with it yet - I might build it as a stock-ish Enduro with a body I have already, or buy a whole new body online and do yet another scaler build, or maybe I'll put the Enduro axles on my old SCX10 and use the SCX10 axles to build a monster truck.

But that's a story for another day...

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So frustrating, @Mad Ax after you had made such progress. I sympathise having had pinion / spur / transmission issues on my Skeleton crawler recently. Why is it that solutions involve spending more money?!

I like the long term monster plan!

Hope you manage to get the rig ready for the Nationals.

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