OS's comp(ish) fun trucks.

[OSRC]

Something a little different from my usual builds. But first, a little backstory. I learn more to the scale and trail runner side and I don't compete in comps or anything, but I do like tinkering around to get better results. Over the past few years at my local crawler spot, mother nature has washed out a lot of the dirt and smaller rocks along the creek leaving a fairly large raw boulder field. We used to have a few lines up here for the scale trucks, but they really can't get through here anymore since it's so washed out. Some do, but it's much more suited for more capable rigs without bumper overhangs, big tires, and with good clearance.

So I've been working on some trucks just to get through this section. Always had some comp-ish style rigs around, I just never drive them much since I prefer to trail run. Having a nice big technical section now to play on made it a much more interesting proposition. I've got a nice out and back course that's about 30-45 minutes of wheeling - perfect for a quick test session on Sunday mornings. Instead of creating threads for each truck, I thought I'd put them all in one thread. I'm driving them all over the same areas on the same lines so I can directly compare them to each other which is kinda fun in nerdy way.

So let's meet the trucks. In a sea of VRD's and TGH trucks, they're not anything special, but as far as my fleet goes they are the top of the ladder.


First is the TRX4 Carbon. I had a set of decked out TRX Sport axles with some serious brass, OD/UD, and a bunch of other goodies sitting here collecting dust. I took a chance and ordered an Injora carbon chassis for them and a take off sport transmission and it pretty much all fell together. The Ecto body fits it perfectly and overall it's a pretty nice setup. At this time I was running an outrunner to try and keep the overall chassis weight down.

I felt it did pretty good on the shakedown run, though first time out it had some issues. The GTS shocks are great, but don't have a ton of travel and were a bit stiff with the stock springs. After some head scratching and ebay surfing of shocks and spring options, I realized my SCX10 III has too much travel and way too soft springs. So in a fit of Wile E. Coyote Super Genius I killed 2 birds with one stone and just swapped them between trucks. This was it's first time out on the new shocks and overall I think they are a much better fit - spring rates are better and I get just a bit more flex. Jato was running his VRD for a nice comparison. The Carbon TRX absolutely held it's own.

Even sidehilled pretty good for a portal truck. The only issue was the noise. The Outrunner on a Castle ESC is just loud. I really like how it drives, but the constant whining in otherwise silent woods was getting to me. Plus the pinion and spur were a noisy combo for whatever reason so overall it needed a bit of tuning.

 

[OSRC]

Aluminator: I figured if an old Integy aluminum chassis would do that good, a more modern carbon chassis would be better. I settled on a Power Hobby carbon chassis and tore the old girl down for a rebuild.

Definitely a lighter setup! 50 grams right off the bat.

However, the sunshine and rainbows ended pretty quickly when setting up the links. Clearly, they were not meant for Capra axles and it was either make some new ones or swap axles. I hate making links, so I started digging around.

In my SCX box, I had more than enough parts to build some nice AR44 axles. Also found an SOA mount I completely forgot about. So pretty much it was meant to be and I swapped everything over. Links fit perfectly and it all fell together.

Figured this would give me a nice straight axle rig to compare to the 2 portal trucks I had been running. I stole the skid, electronics, shocks and transmission from the Aluminator and almost have myself a roller. COG is ridiculous, it's stable at over 90 degrees.

However, I built the chassis 78mm wide and I've got a lot of rubbing. Way too much, not sure what I want to do here. Wider wheels? rebuild as 70mm and fab a new skid? Not sure.

 

[OSRC]

So now I've got 2.5 trucks... what to do? Order some parts to get the Aluminator running again! And just like that, 2 trucks become 3 trucks. Well, almost, 2 of them are in parts...

So after a little dent in the old RC account, parts started rolling in for the Aluminator rebirth. New trans and skid arrived, along with a belt drive conversion. Thought I'd give it a try since I like a nice quiet truck. The steel gears were fine, just sounded like a blender going down the trail. I robbed the Holmes motor (so much for the noise!) out the TRX and moved it over here to lose some weight up top and paired it with the belt drive.

Robbed some electronics from another truck and got the old girl running. Lots of question marks about the belt drive. We'll see.

So I took it back to my crawl spot last weekend and had at it. I didn't take any more pics per-se, but it did fantastic as always. Belt drive was a non-issue all day - quiet and smooth. However, I flipped off the test rock which is about 4 feet in the air. I half-assed caught it, but it did smack the ground pretty hard. Looked ok at a glance, so I kept on wheeling. I wanted to swap some tires around when I got home - which I did, and while admiring the nice new KM3's I realized the rear axle was off to the side by an inch. I started playing with the links thinking I had ripped one out during the fall, but after a while I clued in that the chassis was bent.

New shoes look great

That's not good.

That's really not good.

And that's pretty much the end of the line for the Trail runner chassis. It was flimsy to begin with, I'm not surprised it bent. I am surprised that I got years and years of use out of it before it gave up the ghost.

I didn't want to buy a new chassis again, so I started digging around for a replacement. Settled on this home cut SCX chassis I ran a while ago. Did some mods to it and everything bolded over fairly smoothly.

BUT it would have moved the body mounts, needed new bumpers and sliders.... kinda wasn't feeling up to all that, so I tore down another truck and stole the stock steel Axial chassis and just bolted everything back on. Swapped over to brushed motor w/belt drive so it should be super quiet now. Also changed out the rear shock towers for a set with a little more adjustment so I could lean the shocks more. It's noticeably heavier, but wow - what an increase in chassis stiffness. The other one was like a wet noodle. Maybe that was the secret sauce that made it work? Time will tell.

Shaved the body about 1/2 inch and lowered it. I like it, it just has a mean stance to it. Cut through some of the decals so I removed them for now.

And that's up to current on this little adventure. As of right now:

Aluminator- needs some decals, and ready to go
TRX Carbon - Stole the electronics out, waiting on a new HH motor which is en-route.
Spare parts - Almost a roller. Need to figure out this 70/78mm chassis issue. Wasn't a problem with the wide Capra axles, but doesn't quite work with the AR44's.

 

[hnoroian]

That’s a ton of work in 35 minutes! Too bad about the trail runner chassis, but I like where this is going…

 

[high plains drifter]

I love content like this... comparisons, fails/ solutions, etc. Will be following.

 

[SpareParts]

Cool builds as always! I like the belt drive for less noise. I currently have belts in my traxxas Villain boat and they seem to be holding up.

 

[OSRC]

Got the TRX Carbon all back together. Actually, I had it back together last week and took it for a test drive, I'm just way behind on pics. I was not a fan of the Hobbywing system in my IFS Element, but I do REALLY like it in the TRX. Slow, precise and very smooth. When I went to the Holmes outrunner, the power was fine but I threw off the weight balance of the chassis and it was very noticeable, especially on steep climbs. Having a large can hanging off the front of transmission really makes a difference. It's back to it's old ways.

I went belt drive on this one too. 32p gears were very noisy for some reason, it's pretty much silent now. No issues with skipping or anything so far.

Swapping over to the SCX10 v3 shocks made a nice difference. It's just over 2 tires of flex, and that's good enough for me!

------------

Also worked on the straight axle rig, hereby named Spare Parts (Since I've been digging in all my bins to find stuff to finish it.)

Really like the stance on this one. Still needs some front suspension tweaks, but overall I like it.

I shaved a few mm off both sides the plastic skid and used the 70mm chassis spacers. The tires no longer rub the front of the chassis at all.

At the shock...well, it's another story. I think I can clear it, just needs some tweaking of the shock position.

Started looking at bodies... I really like the Coyote body, but not for this chassis. Didn't want to slant cut the bottom to match the chassis. so....

Another Ecto body to the rescue! Love these bodies....for under $60 for the entire body kit and bumper, it's a great option. Lots of clearance and easy to fit.

I have some new tires coming as well - the Showdowns are pretty dang good actually, they just suffer a bit on the rocks since they don't have a lot of contact patch, and sicne these trucks are going to be on the rocks a lot I thought it was time for a change. I think I ordered some PL Trenchers since they were on sale... I don't even remember. I like being surprised when random parts show up at the house.

 

[89Industries]

I'm curious about the belt drive durability. Not so much about the belt but the bearings in the motor and spot gear shaft.

When bicycles first started using some Gates belt drives they wore out bottom bracket (crank) and rear hub bearings because you had to put so much tension on the belt to keep it from slipping. Things have improved though.

My vs4-10 vfd twin is so loud I don't like driving it, especially on some of the trails with more hikers.

 

[OSRC]

I don't have mine adjusted super tight - there's just a little bit of give in the belt. I figured I could always pull it super tight if I need to. Time will tell!

 

[89Industries]

I think I have to try the belt drive out. What brand/where did you get your belt drive?

Looking at the injora one for the scx10ii (which would likely fit the VFD twin transmission I have) it seems geared a bit too high. They say 13:36 gearing. I'm currently running 15t pinion with the stock straight axle 56t spur, which is already higher than the straight axle kit comes with (13t pinion).

 

[OSRC]

I found them on amazon. I agree the gearing is a bit high, I wouldn't use it for a straight axle rig. It's right in the butter zone for a portal ring though

 

[JatoTheRipper]

The Power Hobby chassis looks like the Injora chassis. Are they the same?

The Carbon TRX-4 has me wanting to build another truck.

Ecto body looks much better.

 

[89Industries]

I found them on amazon. I agree the gearing is a bit high, I wouldn't use it for a straight axle rig. It's right in the butter zone for a portal ring though

Thanks. I order one of Amazon since it was cheap.

I'll try it just to see if that's the noise culprit.

I did a little research last night am taking a guess that the belt and pulleys are MXL toothed timing pulleys. You can find down to 10t pulley with 1/8" bore on places like McMaster-Carr. So I could achieve a 3.6 ratio which is pretty close to the 3.73 I'm running now. Finding a bigger spur is trickier and more expensive but not impossible.

If the belt makes the vfd twin quiet it would be worth it. Really the only thing I don't like about that truck is the noise.

Thanks for the info.

 

[OSRC]

The Power Hobby chassis looks like the Injora chassis. Are they the same?

Yes, I just looked at the Injora and they look identical. Pretty nice kit for the price honestly.

 

[OSRC]

Got the solid axle truck all finished up. I call it Spare Parts since most of the driveline was scavenged out of my parts bin and other builds.

Chassis finished, sorted out some bumpers and mounted up a new set of Trenchers I just picked up on sale. I think they fit the truck well.

Found this cool cut-to-length driveshaft on Amazon. It's cheap so I'm not expecting a lot of longevity here, but it's a cool idea.

Body mounted, trimmed and painted. First painting I've done in forever. Came out ok, I'm definitely a bit rusty. Not sold on the colors, but overall I think it came out decent. Good enough to bash off the rocks anyway... I left off all the details on the side so nothing gets hung up.

Still mounted the roll bar. Dumb to put additional weight up there, but I like it.

Love the Ecto body for these builds. Fits the sliders perfectly and is easily trimmed up.

 

[Gula]

Those cut to length shafts had me intrigued a while back. I picked up some for my 2 winnebago projects. "if i ever get to them" Good to know you have a set and can report on longevity

 

[Col_Sanders]

I like the Ecto bodies. Just wish they were about a half inch or so shorter in length.

 

[JatoTheRipper]

The chassis sits bad ass when complete. And I like the truck as a whole. Nice build.

I wonder if that cut-to-length driveshaft is hardened. Doesn't appear to be which could cause issues in no time. But you are already aware of this.

 

[OSRC]

I like the Ecto bodies. Just wish they were about a half inch or so shorter in length.

I took about 1 inch out of this one. Pretty easy to do, and I'm not a bodywork guy.

 

[Col_Sanders]

Ive shortened a few lexan bodies. Sometimes though i just want to give them a quick single color paint job and move on.