Scania Rally Truck

[Mad Ax]

I drilled out some weight-saving holes and (badly) countersunk the bottom mounts

I did sort of mess up a bit when I was lining up the holes - I had meant to line the top of the bumper up with the top of the lights, but I forgot, and lined it up with the top of the mounting bar instead.  So it's a little lower than planned

Still, I think it looks awesome

[Mad Ax]

Serendipitously, mounting the guard slightly lower gives more clearance for the cab to tilt - I expect I would have had issues if I'd mounted it where I'd originally intended

And that's how it looked at the end of Sunday.  Pretty gosh-darned awesome, I think  

[Mad Ax]

My transmission arrived in the post yesterday.  It's something I've been worrying about for a while, as although there's plenty of space under the cab and under the cargo area, I want to fit the cab interior and I wend the cargo area to be free for all my trail-specific stuff like extra battery packs and tools.  So I was hoping the transmission would fit nice and low under the cab.

This is what I got.  It's an Inajora 2-speed unit, plus a HPI 35T crawler motor that I've had lying around for a while.  Transmission comes with a steel pinion included.

I'll need to strip it down fully and check it over before I run it hard, as it feels a bit notchy, and I found a bit of swarf stuck to one of the planetaries with I fitted the motor.

Speaking of planetaries, here's where the pinion goes.  These types of gearbox always amaze me, they're generally very strong and should be smooth and quiet, although this one isn't - I expect the problem is in the 2-speed, which is more like a conventional transmission.

Fully assembled, it's a very compact unit

[Grumpy pants]

Very nice, coming along well 👍

[Mad Ax]

Sadly, it doesn't come with any kind of mount for a truck chassis.  In fact the mount is fairly specific for the Inajora chassis, which has a curved design over the front axle like an SCX10.

Here's how it looks roughly plonked between the rails

With the body mount in place, it needs to go further back.  If you're wondering why the gloves, it was a little over 2 degrees C in the workshop.  I had just lit the log burner, but it was taking a while to get going.

This is the standard motor mount, screwed to some ubiquitous 15x15 L-section.  I would use it as a template to make my new mount.

 

[Mad Ax]

I had to file a notch out for the motor mount screw

then I had a new problem: the supplied screws have very small heads, but even they catch on the casing when screwing in all the way.  I had to do quite a bit of filing to get them in properly.

Here we go

These are some brackets I made to fit the new transmission mount to the chassis, but it was all so tight the screw ended up right on the edge.  This isn't really ideal, and I'll have to use some bigger L-section later, but this makes a good prototype / proof-of-concept.

So, it's sort of going to go in like this

[Mad Ax]

And here's the prototype

I think it'll work out too flimsy on the trails, so I'll remake the longitudinal brackets longer and wider, and a new crossmember that can capture the lower screw seen in this photo.  Then the transmission will be held in 4 places with no twisting force applied to the thin alu brackets, so it should be very sturdy.

I've had to do away with the stock body mount, but that's OK as there will be plenty of places to lock it down once the whole thing is finished.  Transmission pokes out in just the right place for a scale look, although this will be hidden under the box.

That's all I had time for tonight.  I've possibly got a bit of time on Thurs afternoon, and some time Saturday morning, but it's all got to be reassembled in time to be displayed at the truck meet.  The mounting brackets need to be remade for more sturd, the floor needs cutting around the transmission, the transfer case and props need to go in.  And then all the side panels need to go back on, and I've got to think about how to make the roof.  Then I can throw in some electrics and give it a test run, although not over any hard terrain, as the rear shock hoops aren't properly mounted yet.

 

[Re-Bugged]

5 hours ago, Mad Ax said:

Still, I think it looks awesome

Here, Here 👍🏻 Sure does mate. 

[Shergar]

I’m loving this keep up the good work @Mad Ax 👍

[Mad Ax]

More updates!  I finished work early today, so I threw some logs in the fire and attempted to kill the winter chill.  This is the thermometer on the paint bench.

Following on from my last update, I wanted to add a second set of legs to the transmission.  I made these two little brackets.

As seen from below.  Rest assured the two new brackets are on the same plane as the old single bracket.

I also replaced the small transmission mounts on the chassis rails with these bigger ones.

[Mad Ax]

I had to cut and file away part of the bracket to clear the transmission.

Other side made

Final fitment now complete

I decided tonight wasn't the night for fitting the transfer case, although I will do that next time I have a long run in the workshop.

[Mad Ax]

My low roof arrived earlier this week, so I thought it would be a good time to test that out.  It came from Aliexpress, and was one of the few places I could find one in stock.  The mouldings look good for a cheap product, and it's just what I needed.  It also came with roof bars and vent cover in black.

It doesn't fit without some modification.  It catches on the bosses where the standard highline roof goes.

These ones

First I drilled those bosses out to 7mm, which got me this far

[Mad Ax]

Then I cut part of the boss off completely

Perfect

After fitting the transmission, I wanted to get the floor back in - I knew I would have to cut around the case, so I measured it up and cut out a chunk

Fits nicely now

[Mad Ax]

Finally I put the sides back on so I could check out the profile with the new roof.  I think the sides are too high.  I'll keep watching the Dakar footage to decide exactly how much to take off, but I've already got some great ideas for how to do the roof.  It needs to be sturdy but also needs to be easy to open (and leave open) when I'm on the trails.

[Grumpy pants]

Impressive progress 👏

[gogsyfinnie]

Really enjoying this thread, it’s looking great but my favourite thing so far is the wee epicyclic box!

[ad456]

Another wicked build @Mad Ax!

I’ve been weighing up getting one of those 2 speed boxes for a 2wd SCX10 Proline Baja build I’ve started. Do you think it is strong enough for that kinda scenario?

[bRIBEGuy]

Great thread so far. 

It feels like a million years ago that I sourced all the body parts from a Thunder Tiger MAN Nitro Race Truck with the intention of using it on a similar Dakar-style build... I still have it all (and it's in the build cue somewhere...), so hopefully I'll get to it sooner than later.  Watching your thread (and the concurrently running Dakar event...) is kinda making me want to get going on it...

[Mad Ax]

On 1/19/2024 at 9:20 AM, ad456 said:

I’ve been weighing up getting one of those 2 speed boxes for a 2wd SCX10 Proline Baja build I’ve started. Do you think it is strong enough for that kinda scenario?

I don't see why not.  A local guy started an FB group specifically for budget crawler builds in the Inajora was one of the favourite chassis on that group.  Build quality certainly isn't up to Axial standards but the planetary design is intrinsically strong.

The issue I always have with gearboxes from China is that they aren't as smooth as the big brands, there's always the sense that they're grinding slightly but I can never find exactly where.  I guess the parts just aren't made to the same tolerances.

[ChrisRx718]

V. Cool build. One thing I'm always impressed by when watching the Dakar trucks is how stable they are - they defy all logic because they look tall and relatively narrow, yet they don't topple over nearly as easily as you would expect!

Were you not tempted to go down the route of the Rally Legends bodyshell? I hope you don't roll the Tamiya body... I can't imagine it will be very forgiving!

[Mad Ax]

On 1/22/2024 at 9:56 AM, ChrisRx718 said:

Were you not tempted to go down the route of the Rally Legends bodyshell?

Good question.  The answer is no, for various reasons.

1) I didn't think of it at the time.  I had heard of Dakar body sets in the past but wasn't sure who made them or if they were still around.  I didn't bother to search.

2) The project didn't really start with "I want to build a Dakar truck - what options do I have?" - it was more a combination of "I want to build a hillwalking truck with a big load area for carrying batteries and tools" and "I have a Scania R470 kit minus rear axles, what can I build with it?" 

Looking back on it from this stage in the project, I'm happy with the path I took.  I've managed to build a Dakar-style skid guard and light assembly, I've used loads of stock body parts that came with the Scania kit, plus the body mounts and cab tilt are all part of the kit too.  It's saved me heaps of time making new rails or retro-fitting an aftermarket cab to Tamiya rails.

On the other hand, the point about the fragility of the shell is perfectly valid.  Actually the shell itself should be fine, it's pretty solid.  The weak parts will be all the extra details like mirrors.  Actually the headlights are the most fragile part with now, I'm even nervous about damaging them on the workbench.  I'll have to build a frame around them using brass rod to stop them getting torn off on the trails.  I expect those parts will be expensive and/or hard to find, I don't know if Tamiya make many spare parts for big rigs since they don't get hard use.  How many people in the history of that bodyset have broken a light unit..?  So my intention is to build a partial roll cage from brass rod.

Also, while a roll is certain at some point in the future, this truck won't be driven like a rock crawler or a Dakar racer (unless it's on the sand dunes in a very scale way).  It's going to trailblaze my way across the hills when I'm out walking, and largely avoid the tricky stuff that could tip it over.

I'm thinking I'll put a lot of weight low down, too.  The transmission is mounted low, the batteries will be right above the chassis rails.  I'll mount the electronics high to keep them dry but otherwise the weight should stay low.

 

[Mad Ax]

I couple more thoughts on this project, while I'm here.  I've spent a lot of time on the roads last week, much of it in an area where we have a lot of quarries, and therefore, a lot of older rigid trucks.  Scanias are popular.  I'd noticed that a lot of our trucks have totally different lower bumpers to the R470 kit, and for a while I wondered if that was a cheaper, more robust option for trucks that have a hard life.  I did a lot of searching for various R-series models, but all of them had the taller bumper and generally looked taller than our quarry trucks.  Then I spotted the key difference: most of our rigid trucks are P280s, not R470s.  The P-series trucks are quite a bit smaller, and although they have the same design ques and probably share a lot of parts, there is a clear difference.  I'm guessing the yellow Dakar truck I posted earlier is actually a P-series, hence the differences between it and my R-series cab.

Anyhoos, none of this matters, as I've got the R-series looking just right on the chassis, I just thought it was interesting to note.

[Mad Ax]

Last Friday I went out to fit the transfer case.  This is the final step in getting the truck mobile under its own power, so I can see how it drives for the first time.  Well, it didn't go entirely well.

The 2-speed transmission came with a 6x6-style transfer case with a gear reduction.  I used the same thing on my 6x6 Element Enduro build, and it's a good-enough piece of equipment, but it's way too bulky for the truck chassis rails.  I had planned to order a smaller transfer case, same as I have on my leaf-sprung monster truck, but cash is tight, so on Friday I pulled the case out of the monster truck and tried to fit it in the Dakar rig.

Well, that didn't go to well either.  Although it's way smaller, it was never designed to fit the big rig chassis, so it doesn't fit.  If it had been machined differently it would fit really well, but it hasn't, and all the meat where I could have drilled some mounting holes has been machined away.  I couldn't really find a good way to get it in that would be secure, look right, and clear all the 4-link mounts.  So the only option here was to buy a new transfer case designed for 1:14 trucks.

Except cash is tight in January, so nothing has been ordered yet.  Kind of annoying since the parts for this rig are strewn over 3 flat surfaces, I don't really want to put it away or lose momentum, but even after I place the order later this week I've still got a 2-week lead time from China before I can start work.

Well, OK, there's more to do - the entire rear area needs work, there's bodywork, lights, electronics, battery mounts, and even finishing off the rear suspension mounts (the rear hoops are kind of floating at the mo because the rails aren't long enough).  It just would have been nice to get all the mechanicals done.

In other news, I started work on my ScalerController for Arduino - this has been on my mind for years, but this weekend I've actually got a rudimentary system working.  I'll post up another thread when I have time.

[Badcrumble]

On 1/29/2024 at 8:11 AM, Mad Ax said:

Also, while a roll is certain at some point in the future, this truck won't be driven like a rock crawler or a Dakar racer (unless it's on the sand dunes in a very scale way).  It's going to trailblaze my way across the hills when I'm out walking, and largely avoid the tricky stuff that could tip it over.

I'm thinking I'll put a lot of weight low down, too.  The transmission is mounted low, the batteries will be right above the chassis rails.  I'll mount the electronics high to keep them dry but otherwise the weight should stay low.

Oddly enough, I saw a little video of a Dakar truck earlier and the top cover looked to be fabric, not rigid like the sides. To reduce the CoG, I guess?

[Mad Ax]

4 minutes ago, Badcrumble said:

Oddly enough, I saw a little video of a Dakar truck earlier and the top cover looked to be fabric, not rigid like the sides. To reduce the CoG, I guess?

I was paying close attention watching the Dakar coverage this year, and the construction seems to vary but canvas is a popular choice.  Some rigs have canvas sides, although that isn't immediately obvious unless there's a close-up.

My plan is to make the horizontal part of the roof from plastic, and mount the sensitive electronics under there so they are protected from puddles and rain, and to make the sloping part from fabric mounted on rails, so I can slide it down to get to the inside.  I'm hoping I can find a local sign printer to make a canvas roof out of banner material in a custom size, but that will have to wait until I've chosen a livery and sponsors.