BigGinge's TRX4 Trail Van Build Thread

[BigGinge]

So, I figure I should probably start a build thread to cover the evolution of my TRX4 trail van build.

 

As a quick background I've wanted to build a crawler/trail truck for a while now but have been fancying something a little different to the normal pick up/jeep/defender. A while back I came across the van rendering shown below and thought it would be a very nice thing to aim for in a build but had no idea how I would go about creating a body like that for myself. Then, not too long ago now, Carisma came out with their Prairie Wolf body and it looked like just the sort of thing that might let me build up the trail van I've been thinking about.

 

 

So, to get the build going I decided to make a start with a Traxxas TRX4 Chassis kit (with a 12.8" wheelbase extension), the Carisma Prairie Wolf body and a bunch of other bits that I've picked up here are there (I'll put a full parts listing for the build in at the end of this post).

 

So far in the build I've mounted up the Canyon Trail tyres that came in the TRX4 kit to some steel bead lock wheels, build up the two speed gear box, and started on some of the chassis assembly. I've then also checked that this will all fit into the untrimmed body to give myself a little reassurance that I wasn't aiming for something that I couldn't achieve. The next steps are to get the differentials, axles and shocks built up and mounted on the chassis so that I can get a better idea of how to mount the body shell and have a look to see what I can do with the bumpers and side skid plates that came with the kit.

 

 

After that I will have to have a proper think about what to do for a paint scheme on this build as its looking fairly unlikely that I will be able to get a good match to the colours on the render above. I may be back for advice on what to go with here as I'm very much stuck overthinking my options at the moment.

 

Build Kit List:

• Traxxas TRX4 Chassis Kit
• Carisma Prairie Wolf body shell
• Traxxas 8215 body post/mounts (I will need two high mounts when I think only one is provided as standard with the kit)
• Traxxas 8057 Chassis conversion kit, short to long (to end up with a wheelbase of 324 mm, or 12.8", to match the body shell)
• HobbyWing quickrun 1080 ESC
• FlySky FS-BS6 6 channel receiver (to pair with my FS-GT5 transmitter)
• White steel beadlock wheels from Aliexpress
• JX HV7032MG 32 kg metal gear, IP66,  servo (that might be waterproof enough to use in a crawler)
• 11 turn Rocket 540 plus V2 five slot brushed motor

[Lone-wolf]

Nice should be a decent trail van once done

[BigGinge]

Had a chance to sit down with the boy tonight and put the rear axle together. I was a bit surprised how involved the axle build was with all the work going into the lockable diff and portal.  Then I guess if I’d actually thought about it before starting it probably wouldn’t have been that surprising as there is a lot going on in there compared to my previous truggy build. 
 

One thing I’ve not been sure of while building is how much grease to try and pack into the diff, portals and axle to try and keep water out and things running smoothly. So far I’ve put a lot more in than the build instructions specify but I’ve not tried to fully pack the housings out.  If anyone has experience with trying different amounts in there it would be interesting to hear what  you find works best. If it makes any difference I’ve been using Mobil XHP 222 grease for the build as it’s nice and sticky and doesn’t wash off easily. 

 

 

 

Apart from the confusion about how much grease to put in while building everything else seems to have go together pretty smoothly just as indicated in the instructions. Though I did almost loose the e clip that holds the diff lock control cable in place when it slipped out of my pliers and pinged across the room. 

 

Edited December 3, 2021 by BigGinge

[Lone-wolf]

Those e clips are the very work of the devil

[Redback]

They keep the water out pretty good if you have used a reasonable amount of grease inside the portal housing, also stick the shafts in the grease as you feed them into the axles the grease will help seal the main axles from filling up.
Dynamite marine grease i used throughout along with corrosion x on each bearing.
Our trx4 is (used almost every weekend for 4 hours +), It was regularly in water so should have been serviced a bit more often but overall i think you will be very happy with the durability of the rig. 2 failed bearings i can chew on.
2 failed micro servos is a bit more sad, just dont touch them and they should work dandy for a good period of time.
 

 

[BigGinge]

I didn’t get any time to spend on this at the weekend but made up for that  by spending a few hours on this tonight after a stressful day at work. 
 

I’ve managed to put the front axle, shocks, and suspension linkages together which I think finishes up all of the big subassemblies. Hopefully this means I can put the tube of grease away for a little while as I seem to be starting to spread it around a bit too much on the dining table. 
 

 

 

After that I managed to get the front and rear axles mounted up onto the chassis along with the steering servo and the body mounts. I also found my first oddity in the build instructions (it has all been a bit straight forward so far which just isn’t as much fun as needing to work some things out for yourself); these were instructing me to use some 25mm screws to mount the upper rear linkages to the chassis but there didn’t seem to be any in any of the bags I’d opened. I finally figured out I had two spare 27mm screws and these seemed to fit without any trouble, so I guess they have just updated the kit to remove a screw size but forgot to change the manual. 
 

 

 

Once the axles were on the chassis I stuck the wheels and body shell on to see how this will all sit when finished and I’m happy to say that it is all looking pretty good. The 12.8” wheelbase is spot on for the wheel arches in the body and the inner fenders are a very good fit across the width of the body (sitting pretty much flush with the side panels) and line up well with the top of the arches in the position I would expect the body to sit. The only slight issues I’ve spotted so far are  that the front body mount posts sits a little too far forward and I’m not sure that I’ll be able to fit the stock rock sliders or rear bumper.
 

I will probably need to see what I can do to move the front body posts back a little, so that these clear the front window and allow the body to centre properly on the axels,  but I suspect I can live without the rear bumper and rock sliders for now. Hopefully I can find some aftermarket post mounts that have different offset to the standard ones for this. 

Edited December 9, 2021 by BigGinge

[Lone-wolf]

coming on well, if you get stuck with front mounts look at magnetic mounts on body

[Redback]

17 hours ago, BigGinge said:

I will probably need to see what I can do to move the front body posts back a little, so that these clear the front window and allow the body to centre properly on the axels

Did you get this with your body post set, if its on the front it should offset it enough to just clear?
 

[BigGinge]

1 hour ago, Redback said:

Did you get this with your body post set, if its on the front it should offset it enough to just clear?
 

Oddly I probably put this onto the chassis about half an hour before you posted this after having rummage through the left over bits while the kids were eating dinner. I think it just gets me enough clearance on the front but I don’t have my motor in yet so will need to check it doesn’t crash with that when it’s mounted as I have a horrible feeling the two and going to go in at the same time. 
 

If there is a clash I can potentially print some sort of support to go on the motor and then butcher the bracket to mate with that. 

[Buggy Malone]

That's a very smart project!  I'll certainly learn a few things from your work.

 

Keep the pics coming 

[BigGinge]

Today I’ve temporarily mounted up the kit motor so I can see if the offset body post mount does clash when used in the front of the van. Unfortunately it does, so I will still need to work out a solution to the mounting for the front of the body shell. 
 

 

 

 

I suspect what I will do with this is to 3D print a bracket that clips onto the motor and engages with the upper sections of the offset body post mount. I can then trim off the bits that clash with the motor and hopefully keep something that is structurally sound when it's all fixed together.  It is a bit of a shame though as this will slow the build down a fair bit as I still don’t have the final motor I’m intending to use so might take a while to get a new bracket designed (unless I put a variant together for the traxxas motor too?)

 

The alternative would be to try and design a new body post mount that attaches in the same way as the official part but sits nicely with the motor, I'm not 100% sure if a purely 3D printed part would be strong enough for this though. If anyone has any experience of making crawler parts like this it would be good to hear of your experience (both good and bad) 

Edited December 9, 2021 by BigGinge

[BigGinge]

Have also put the rock sliders, diff lock servos, battery tray and rx box onto the chassis now. 
 

 

It’s looking a lot like I should be able to use the mounting slots in the stock rock sliders to capture the side panels of the prairie wolf body if I trim it in the right place. This is a nice surprise as, so far, it looks like it is going to fit on much better than I ever thought it would. Just need to get some quality time with the scissors now to properly trim it and do final fit checks. 
 

The diff lock servos went onto the chassis fine but it looks like their home position isn’t in a brilliant place for the provided actuation cable lengths. I think this would put a lot of stress on the servos if left like this (as the springs in the servo savers would be applying a constant force to the motor) which isn’t brilliant for their expected longevity.  Hopefully I can sort this out by adjusting their end point settings once I have my receiver in and FS-GT5 transmitter paired. 
 

At this point I’ve gone with putting the RX box in back to front so that I can avoid having to extend the wires from my steering servo. I haven’t found any issues with doing this yet but I haven’t finished the wiring or build; will report back in if I do find any issues with doing this. It may only be possible to put this in backwards because I’ve pushed the rock sliders as far out in their mounts as possible to fit with my body. 
 

I’ve put the standard battery tray and catch in for now but I think I will need to make some changes here soon as the main battery pack I’ll be running in this (a 3S 5200mah Goldbat hard-case pack from Amazon) too tall for this at 38mm. Will probably just take the catch off and use some Velcro straps for now but may look at new 3D printed battery tray options further down the line 

 

I also seem to be short a few m3 x 8 mm button head screws, haven’t worked out if these have been swapped for something else or if they are just missing (as I’ve not been following the build instructions in the proper order) but have ordered a few more just in case. 

Edited December 9, 2021 by BigGinge

[BigGinge]

I'd forgotten how nice it is to work with pre-cut body shells. 

 

Shame the Carisma Prarie Wolf one isn't pre-cut.

[BigGinge]

 

I’ll need to give the front fenders a little trim so I can slide the body back a few mm to properly line up the wheel arches but it’s pretty much there in terms of fit. 

[Lone-wolf]

Not knocking, it looks good but to me wheelbase looks a tiny bit off, like if you slide body back a couple of mm the rear tyre may be very close to leading edge of wheel arch, maybe if you have adjustable links you could gain a couple of mm 

[BigGinge]

I think the flared wheel arches and perspective make it look worse in the photo than it does in the flesh. This is a picture I took after trimming the fenders and getting the shell centred as best I could over the two axles. It still looks a bit off, especially with the shadow on the wheels,  but I’m person it all seems nicely lined up. 
 

[Lone-wolf]

Actually i take it back, that looks pretty darn right mate

[BigGinge]

So, I’ve been faffing about with paint samples and think I’ve settled on a new colour scheme for the body shell. Now that I’ve confirmed none of the paints I can find will give me a match for the colour in the pictures of the original inspiration for the build I can hopefully start making some progress towards getting the body prepared and painted before Christmas. Wheelspin have been quite helpful with this by getting the paints I put on order in for, at around 16:00, yesterday to me before 10 today. 
 

I’ve also been spending some time modelling a body post mount that will fit onto the front of the chassis to let me get some body posts into a suitable position. Before I make a start on the near six hour print of the final mount I figured I would do a couple of quick samples to check the fit on the contact points and I’m glad I did. Turns out I’d added 1cm to the measurement if taken between the front light pockets which would have been a painful thing to learn if I’d gone straight into building the “final” part. 
 

 

I’ve now fixed the body post mount model and will see if I can get a copy printed out tomorrow, once I’ve set the printer up to use some new reinforced filament I picked up. 

[Buggy Malone]

Some great work there - I think we're all looking forward to seeing the body painted and complete. Very smart indeed 

 

 

[.AJ.]

Nice build 👍 

[BigGinge]

Been a bit quiet on the build front for the last couple of weeks with Christmas, a birthday and trying to get a new bedroom decorated for the lad (so we can finally kick his little sister out of our room) but finally had a chance to sit down with it again tonight. 
 

Managed to build and install the drive shafts, install the esc and receiver, connect all the wiring, set the end points for all four servos and cut a few holes in the body shell for a few of the bits of trim. 

 

 

 

As of about 15 minutes ago it’s been quite happily driven around the house and seems to all be working well. 
 

The current list of things to get done for it to be finished (for now) is:

⚫️Print out the front body post mount so that  the shell can be fixed in at both ends

⚫️Print out a mount for the ESC and power switch

⚫️Drill out a couple of new holes in the right mounting plate to move the backwards receiver box back a bit (the wiring is fouling the rock slider mount at the moment) 

⚫️Get the shell painted and taped. 

Edited December 30, 2021 by BigGinge

[Lone-wolf]

Looking good, looking like a van that can

[mch87]

Looks a good build and really liking the van body... shame I have the shorter wheelbase TRX4

[BigGinge]

9 hours ago, mch87 said:

Looks a good build and really liking the van body... shame I have the shorter wheelbase TRX4

 
@mch87 It isn’t that difficult to expand the wheelbase on the TRX4 if you want to run a longer body shell. In fact I had to extend the kit wheelbase from 12.3” to 12.8” for this build.  
 

I used the rear suspension links and longer drive shaft section from the 8057 long conversion kit form my build but stuck with the fenders from the chassis kit as these already had the mounting holes required for all the different wheelbase lengths. I just used the ones furthest back on the fenders rather than the one with the arrow pointing to it in the image below. 
 

 

[mch87]

4 hours ago, BigGinge said:

 
@mch87 It isn’t that difficult to expand the wheelbase on the TRX4 if you want to run a longer body shell. In fact I had to extend the kit wheelbase from 12.3” to 12.8” for this build.  
 

I used the rear suspension links and longer drive shaft section from the 8057 long conversion kit form my build but stuck with the fenders from the chassis kit as these already had the mounting holes required for all the different wheelbase lengths. I just used the ones furthest back on the fenders rather than the one with the arrow pointing to it in the image below. 
 

 

Thanks, I'll keep that in mind....

 

I did just buy a new body and was hoping not to cut the fenders but no such luck... (the spec for the shell listed the widest point which would have worked but that's not what the arches are 😞 )

 

Will just have to keep an eye out for a cheap set of fenders to cut or bite the bullet and buy new narrow ones... but it just seems that everyone wants to add £4-5 minimum to post them and I know it would only cost like £2 to post. (yes I'm tight but I've become a poor student again)

 

I had wondered about using the longer links from the defender as a cheap small lift kit... as the Traxxas long arm kit is just mind blowingly expensive for what it is

Edited January 8, 2022 by mch87