Technical Trail... Honcho

[zane!]

I'm getting back into crawling after a long break. Ten years ago I had a built AX10 that was a lot of fun, and I later regretted selling it, so after playing around with an ECX kit for a while I dove back in to an Axial.

The goal was a scale-ish 1.9 truck that behaves similar to a 1:1 wheeler. I have a built flatbed Toyota on 37s so the Trail Honcho was a natural choice. I've been driving it for a few months, starting from stock, and this is what I've ended up with. The mods aren't too crazy, just enough to improve the weak spots and increase crawling capability.

SCX10ii Trail Honcho RTR
Bobbed flatbed 30mm, added fuel cell, trimmed fenders
DIY aluminum bumper and sliders
Pitbull Rock Beasts, Pitbull 2 stage foams with an extra stage added to the rears
SSD Steel Beadlocks
Axial U-Joint front axle shafts
JX 30kg Coreless Waterproof Servo, Axial aluminum servo horn (enough steering angle to rub the lower links)
Vanquish stainless steel link set
Traxxas TRX-4 GTS shocks, black "heavy" pistons, 20wt oil
Axial white 1.13 lb/in springs front, green 1.70 lb/in springs rear
Common Sense RC 5200 2s LiPo
Stock Axial motor/ESC
Axial 12t pinion for a bit more gear reduction

It's a pretty fun little truck now! I've done a bunch of trimming/adjusting/shimming to get everything set up well and I think it's pretty dialled in for now. I'll definitely upgrade the motor and ESC in the future, but the compact TTX200 transmitter works well and is pretty lightweight for hiking around with the truck so I don't see a need to swap that yet.

 

[zane!]

Crawling at our local spot:

 

[zane!]

I also brought the truck up to Lake Chelan, WA, during a camping trip and found some rocks:

 

[zane!]

That's about it for the way it sits now! I'll continue to post as things evolve, and I usually get a few pics each time I take the truck out.

 

[OSRC]

Beautiful terrain you've got there!

Welcome back to the addiction...

 

[zane!]

Beautiful terrain you've got there!

Welcome back to the addiction...

Thanks! It's a bit of a drive to the good spots but it's always worth it for a few hours of fun.

 

[malvesjpx]

Beautiful shots!


Nice and simple setup (that is how I like it too). Can you please tell me how are the TRX4 shocks behaving on the Honcho.


Thanks in advanced and regards from Brazil


Marcelo

 

[zane!]

Beautiful shots!


Nice and simple setup (that is how I like it too). Can you please tell me how are the TRX4 shocks behaving on the Honcho.


Thanks in advanced and regards from Brazil


Marcelo

Thanks!

The TRX-4 shocks are great, very smooth movement though they seem to stick in place a tiny bit if the truck has been sitting for a few days. Once you cycle them by hand the sticking is gone. I'm sure a bit more Green Slime would solve that but I don't really want to take them apart. Lol

One thing to note is that the shock pistons in them are the heavier damped Black pistons, which are meant for the heavier hard-body TRX-4 trucks and the generic Traxxas shock oil (which is comparable to 30wt). On a lighter rig like my 5.8lb Axial that damping is too much so you would either need to switch to the Traxxas Red pistons from a TRX-4 Sport, or just run 20wt shock oil.

Otherwise they're a bolt-on affair. Even the Axial springs fit well on them.

 

[zane!]

Last time the truck was out it yeeted itself off the top of a rock, landing 3ft down onto another rock which bent the heck out of my bumper. I managed to work it straight-ish with some mallets/wood blocks so it'll work for now. I really don't want to build another... Lol.

But the bigger update is that I reconfigured my shock towers and mounting for better uptravel and motion ratios.

On the front, I moved the upper mount locations and added an aluminum brace. I couldn't do much else as the steering would bind with any additional uptravel (hey, kind of like a real truck).

For the rear... The towers are now swapped left to right which gives better angles. This also required changing the body post setup and new holes in the body. The shocks are now mounted to the lower link mounts which places the axle in a good spot for good uptravel while not hitting the frame/body. Add another aluminum brace and that's a wrap.

I think this setup will add some stability under flex, at the expense of a slightly lower belly.

 

[zane!]

I've looked. Is there a source to buy those red pistons separately?

Is the difference three holes versus two?

I'm running very thin oil which is working, but I fear it will seep out faster than the thick.

Thanks

The TRX-4 shocks have different pistons, they don't have holes but instead have slots on the edges. These are the black pistons (in a rebuild kit):

And these are the red pistons, Part # TRA8261. They have larger slots to allow more oil to flow through:

https://www.amainhobbies.com/traxxas-trx4-damper-piston-red-4-tra8261/p893676

 

[zane!]

Got some crawling in today at the usual spot. I like testing changes in the same location as I know how the truck has performed on certain lines recently.

These changes were... Awesome. The rear end is a lot more stable under flex while climbing, resulting in more traction. One side effect: more torque twist than the truck has ever had before. I did notice the lower belly and sliders as I was sliding on them more than usual. Still worth it!

 

[zane!]

Beautiful. Thanks. Ordering them today.

Awesome, I'm curious how the damping compares to the black pistons. It will definitely be lighter. How heavy is your truck?

 

[zane!]

Minor update, with a couple recent crawling pics.

The TRX-4 shocks have nice preload collars that spin smoothly... Too smoothly apparently. They loosened up after a couple runs causing less preload on the springs.

I gave each one a blob of RTV sealant to hold them in place. It seems to work so far, and will be easy to remove if I want to change the preload.

And some pics when I got out on the rocks this week. I gotta say it was a good day.

 

[zane!]

UPDATE

The red plungers having arrived, I expected to see bigger holes/gaps, but they appear to be smaller in diameter is all, allowing fluid to flow more freely around them. I would have thought smaller pistons was not an option, since the plunger sliding along the inner wall supports the rod, but if Traxxas say it's okay...

Anyway, red plungers at all four corners now and 15wt 104 cst Losi oil. Green Axial springs up front and white out back. I didn't have to do the trick where you back off the lower cap, add spacers, secure with tape, etc.

Bottom line, I dunno if Traxxas makes good crawler shocks, but I have an awesome Baja truck now. My Comanche floats over rough ground at top speed (3S) like a big ol' Cadillac.

And I'm kidding, it crawls beautifully with the new suspension. Lastly, the plastic Axials in the obsolete parts bin look gross by comparison.

Nice!

Next time I tear mine down for a rebuild I'll swap in the red pistons.

 

[zane!]

It's been a while, summer and fall have been a bit crazy and I took a break from the crawler. I eventually wasn't feeling the way it was driving, specifically the power delivery of the drivetrain. Something wasn't right about it. I figured it was just the stock ESC/motor/gearing combination on 2S batteries and I would just need to upgrade it all to my liking. So on the shelf the truck sat.

With sales this week I ordered some goodies that will be here soon. 3S batteries, Hobbywing 1080 ESC, Crawlmaster Sport 550 12t, and 9/60 steel gearing. This will be a rad and powerful setup so I'm excited to upgrade!

However, after I tore my truck apart in preparation, and did more motor/ESC research, I found an issue with these RTR trucks that would potentially explain my dislike of the power delivery...

The RTR SCX10ii, with the silver LCX trans, is a Reverse Rotation motor configuration. From the factory, the motors are wired to the ESC in a Forward Rotation configuration. To "fix" this the transmitter throttle direction is reversed. Which means that to move the truck forward the ESC is putting out reverse power, and vice-versa for reverse.

The tech specs for the AE-5L ESC are lacking, but from what I can tell most decent ESCs have different power delivery curves and current limits for forward and reverse directions with forward being more aggressive and faster. So if the reverse power from the ESC is weaker, and that is what's being used to drive the truck forward, it would definitely perform worse than it should.

My truck is now torn apart and I don't really want to reassemble it with the stock drivetrain to test this, but in theory if the motor leads are swapped to Reverse Rotation and the transmitter is put back to normal throttle there might be a noticable difference in power delivery. Or it might do nothing. If the ESC has identical forward and reverse throttle curves it wouldn't matter. But it's definitely a Reverse Rotation application and I'll need to wire the new motor and ESC correctly to account for this.

 

[zane!]

And after sitting for 4 months, the Traxxas shocks haven't leaked a drop. I was half expecting them to be a total mess like Axial shocks would be. :mrgreen:

 

[zane!]

I got the crawler back on the rocks!

I'm really happy with this powertrain setup. There is more power than I know what to do with and the low-speed control is better than I've ever driven, including a very strong drag brake. There is also a bit more wheelspeed than stock (35t 3slot, 2S, 56/13 gears) which was my goal too. The ESC has a 7.4V 3A BEC which makes the steering servo even snappier.

Crawlmaster Sport 550 12T
Hobbywing 1080 ESC
Turnigy 2200mah 3S 60C batteries
60t Axial metal spur gear
9t hardened Robinson pinion gear

I broke in the motor DRY (for the love of all things RC, never break in a motor with water) on my charger in power supply mode. Turns out 4mm Castle bullet connectors plug right into female banana plugs.

I had to trim the battery tray, trim the lump off the receiver box, and relocate the upper front suspension link to the right side of the chassis to make room for the longer 550 motor.

One of our new neighborhood parks was designed well enough that it has a rc crawler rock sculpture! But really, every time we've brought the kiddo here I wished for an opportunity to bring the crawler at a time when it's not swarming with children. Schedules aligned and I made it happen!

There's also a nice slab on the backside, but I couldn't make it up more than this... my new goal is to climb this thing.

 

[zane!]

Anybody left around here? Not sure if I should post updates if they're not being viewed...

 

[lonleycreeper]

They are definitely getting viewed.

 

[LincolnofDeath]

Yeah, this banana plug idea rocks. And how about that 12T 550? Just started using that in an Enduro and it’s just sooo good. Not sure if cause of the size of the can over 540 I was using but it’s in a total sweet spot for tractable power. Still stock gearing for me and it’s so manageable.
Fun pics you have there, too.