NEOTRX-1

[Dirtburner]

Back in 92' when I started racing at Harewood RC Car Club in Christchurch, New Zealand, the most popular 2WD was the TRX-1. This car competed with Cougar 2 Works cars and a sprinkling of RC10's and Losi's. The two main model shops were Moore Models which sold the Traxxas buggy and Acorn Models which sold the Schumacher's. We raced in the summer on a loess track which was quite dusty and loose, changing to a grooved line as the day wore on. As a poor boy I could only dream of owning a TRX-1, or a purple chassised, quiet and smooth Works Schumacher. I preferred the Schumacher's at the time.

Fast forward to 2022. I took up the hobby again and found a nice example of a TRX-1 which was raced at the 92' ROAR Nationals in Texas. I raced the buggy for a while then sold it last year as I took a break from the hobby.

This project will use the Bezerk carbon chassis modified for a "Stealth" transmission. Having recently finished rebuilding a Team Car, I took some measurements and tested a few things to see if it would work. An overlay of the RC10 Graphite chassis was used to check all the hole positions.

The Stealth holes were moved back 4.5mm to get the outdrives inline over the centre of the arm mounts and to not foul the bulkhead. It looks to be in roughly the same position as the pro transmission in terms of weight distribution. On the original tranny, the casing slots into the bulkhead. I'll need a longer trans brace to the bulkhead.

The motor guard holes were also moved back. With the standard bloody gap between the guard and motor plate I thought this wouldn't be necessary. With hindsight...yes.

I mocked the rear end up.

Look's like I'll need to tap some holes. Scr8p mentioned somewhere that Cliff went around bending up the back of the tubs at the 93' World's for extra clearance. I was a bit worried with the longer arse on the thing.

Of course, there's also the right side inner camber link mount fouling on the spur cover. I was planning on using Yokomo rod ends - well, not here.

Next, I'll build the diff, shocks etc to see which drive shafts will work. Will try Yokomo ZC-422 first?. I do like the look of the Yokomo hub and wheel.

[Chewbacca]

Nice build.

I don’t quite get what you’re building here. A TRX1 with a stealth transmission? Or an RC10 with Traxxas rear arms?

I’m guessing the last picture is not your vehicle?

[TRX-1-3]

Duh, I was gonna post about the trans brace addition (and did), then actually READ your entire post. Carry on. This will be an interesting build.

The long dogbones for TRX-1 (for Lethal Weapon applications) from Factory Works may be an option, if they are still available. They fit the Stealth outdrives, but are intended for a Lethal Weapon diff gear, running 1/8" diff balls.

[Dirtburner]

I’m guessing the last picture is not your vehicle?

That's my Team Car.

Duh, I was gonna post about the trans brace addition (and did), then actually READ your entire post.

Hey, no worries. Should have a custom top brace soon. 41mm centre-centre for the RC10 Stealth brace, extended to 48mm here.

The long dogbones for TRX-1 (for Lethal Weapon applications) from Factory Works may be an option, if they are still available. They fit the Stealth outdrives, but are intended for a Lethal Weapon diff gear, running 1/8" diff balls.

Thanks for the tip. Certainly a nice bit of kit.

I went with the 870c universals. I read on here that Tamiya DB01 universals fitted the 870c. I have some TRF201 universals, so tried those for fit in the TRX. These were in the ballpark. I wanted to use Yokomo uni's not only for the look of the hub/wheel, but also the design of the hub and axle allows for some lateral adjustment to get everything in the correct place.

Now, the FR-005 "Stealth" Transmission assembly...Not good.

The diff when built as standard was not smooth, or gritty, I'm talking gravel. In the FR-01 thread I read all about the diff issues. Gone are the balls, for ASC6581, the caged thrust washer for ASC6574. I couldn't get rings locally. I sanded the outdrives and rings with 800 grit. When built it's now acceptable.

Sigh...now the rest of the transmission. Spent a few hours trying different things and running it in, but couldn't get it even close. Very rough, with binding. More reading, and a ASC6565 case and ASC7812 gear set, which I believe has the ASC6570 idler, are on the way. Seems like a hangover from the World's Transmission.

[GoMachV]

So, bad news on the rerere 6565, AE decided to narrow up the trans just a few thou, just enough to where a vintage diff (or the FanRC) won't fit. To use the rerere 6565 you also need the AE outdrives. It sucks for sure but they are nice and smooth.

I fought the fan diff in my kit as well, notchy and gritty. My diffs assembled from parts were smooth. Not sure what's up with that but the rings do seem to be the majority of the gritty feel. I was unable to get my fan transmission to spin smooth, I ran it for 2 hours on my drill press and it was better but still not good. Frustrating for sure

[Dirtburner]

So, bad news on the rerere 6565.

I was waiting for you to chime in with some compatibility issue...thanks

I was unable to get my fan transmission to spin smooth, I ran it for 2 hours on my drill press and it was better but still not good. Frustrating for sure

With the above news, I had another crack with the FR-005 tranny. Thinking back to Jim Halsey's "Tranny Tips" article, I spent some time filing the gears and opening up the case internals. The filing didn't really do much, but when I dremeled the case around the idler gear this improved the binding dramatically. It now spins quite free, and I'm satisfied with it.

[GoMachV]

Interesting to hear that about the idler clearance. On mine it is tight all the way around both with only the idler and diff and with only the idler and top shaft, but with the diff in I get a noticable notch at one point that is repeatable and clearly on the diff itself. I can't see anything wrong with the teeth, but I did run the knife around the tooth a bit and still has that notch. I hope to take a little more time with it over the weekend. I'll grind away at the case a bit too, I hadn't expected to hear that might be one of the issues.

[GoMachV]

Okay, I spent a little bit more time tonight with the fan transmission. First off I wanted to try and get the diff smoother. Our diff rings on the lethal weapons were not glass smooth like an associated ring- they were scuffed like you would do a brake rotor- but the diffs were smooth. I decided to try something similar by just roughing up the surface with a red scuff pad. After doing both rings and reassembling the diff was actually quite a bit smoother. It still has some roughness to it but it's definitely an improvement. I'm happy with it at least. Then I moved on to the gears. I tried taking away a little bit more material from the gear and nothing helped. I put all of the gears into a rere World's case and it got incredibly tight. I found an old world's rere idler gear and installed that in the fan transmission. That actually worked quite well, it was quite a bit smoother. Unfortunately that doesn't help because those are pretty hard to find. I went back to the fan idler gear. The notch is mostly gone and really it's just a little tight at this point. I'm sure it would wear in more after some use.

[Dirtburner]

Back end's done.

Quite a bit of fettling with the printed parts. The hinge pin holes were 3mm instead of 1/8" (3.18mm), so I had to ream those. The 5x11x4mm bearings wouldn't fit without some work. Traxxas rear arm mounts needed minor dremeling for outdrive clearance.

Best to use a good-fitting alloy screwdriver for installing the 4mm aircraft screws. Extra points for collimated screws.

Shocks are much darker than the originals, closer to black than gunmetal. Caps are the more modern dark blue. More hideous in my opinion. I have the GP3D white shock clips for any ride height adjustments. These look good.

Thanks to Retro rc for the tip on the Kyosho springs.

A few months back, I built an egress with some alloy hubs. I picked up some "Loctite" from a local hobby shop which I used on the build. I then proceeded to shear off 3 screws doing work on this buggy. Something was up with the threadlocker?. Yesterday I noticed the name on the bottle. Don't use this stuff, it's nasty.

[carloco8]

Very neat build! Had me doin' a double take on that LOOLIFL..... LOL

[Dirtburner]

Front clip done.

Mostly standard stuff. Some dremeling needed on the castor blocks.

[Dirtburner]

Orange and purple stuff.

Novak ESC with cans. Not enough orange!

All this wiring for damn brushless?

Front width with the DT02 wheels is around 254mm. I have some BMAX2 wheels that take a 5x10mm bearing that I'll try. Rear width is 245mm with the Yokomo setup. Seeing one of these pink TRX bumpers was the impetus for this build. It does look somewhat incongruent. I tried to use white parts wherever I could. I don't like black parts on the TRX-1. Maybe I'll give the RPM gear cover a dunk in pink?

Bellcranks from Jeff, cheers!

Cut down battery cups for LCG pack.

Onwards. Finish off the build and let-it-loose on a real track.

[Dirtburner]

With the B-MAX2 front wheels, the front width is now 245mm, same as the rear. Just enough clearance from the Yokomo rod ends and arms throughout steering movement.

[Retro rc]

Are you gunna run that at MRC? Would love to see it in person. Also gomach5 has a lipo holder on file that works for the trx-1 and blue eagle that he made up for me

[Lavigna]

Cool idea of integrating the Stealth. That should make this car a real weapon on the track. Great build.