Cosmo's TRX-4M Bronco Project

[CosmoM3]

As I feel my TRX-4M Defender is setup the way I wanted (Overlander/Crawler) and taking on the challenges of a heavy body, I think I've been successful in making it the best possible 1/18 scale Defender in the most practical way. I'm still waiting on a decent all-in-one brushless motor from Hobbywing or a plug-and-play setup from Holmes while retaining the stock ECM. The new Furitek looks rushed and the cable management just looks like a rat's nest to me.

That being said, I've started my Bronco project to make it into a pseudo Baja style Bronco where speed and handling take priority, which is on the opposite end of the spectrum compared to my Defender.

To start, the Bronco comes stock with the following spring rates from the factory:

Fronts: 0.095 Rate [TRA9758]
Rears: 0.095 Rate [TRA9758]

What is amazing is that the Bronco comes with a near perfect 50/50 weight distribution out of the box, which make it a fantastic candidate for anything really, moreso than the Defender.

I've spent long hours and several days on tuning the car through piles of rocks, pebbles and jumping it off some ramps to high-grip, lateral turns to the point where the stock servo and shocks had died.

Based on running the stock model into the ground, I've come up with the following parts to improve/reinforce the Bronco to meet my goals.

Electronics

• Traxxas Pro Scale LED Lights [TRA9783]
• REEFS RC 99 Micro Servo x DSM Off Road TRX-4M Servo Mount
• REEFS RC SHORTY Micro Horn

Body

• Traxxas Lower Links (Steel) [TRA9749] [Swapped with the Defender]
• Traxxas Hardware kit (Stainless Steel) [TRA9746X]

Internals

• Traxxas Sealed Steel Bearings

Suspension

• Traxxas Shocks w/30wt OEM Shock Oil
• Traxxas Springs - 0.095 Front [Stock] + 1 Clip / 0.095 Rear [Stock] (w/2x Preload Clips)
• Traxxas Shocks, GTM, Orange [TRA9764-ORNG] [On Order]
• Traxxas Shocks w/50wt OEM Shock Oil [On Order]
• Injora Steering Blocks (Brass)
• Injora Caster Blocks (Brass)
• Injora Steering Link (Brass) [On Order]

Powertrain

• Traxxas Speed Gear Set [TRA9776X]
• Injora Axle Covers, Brass (Front + Rear)
• Injora 6mm Wheel Hub Extenders (Brass)

Wheels & Tires

• Traxxas Canyon Trail Tires [TRA9769]
• Traxxas Method 105 Beadlock Wheels [TRA9781-BLKBL]
• Traxxas Wheel Weights (Brass) Front and Rear [TRA9780]
• FubberStufferz V24 TRX SlymeBallz

Misc

• Jim's Bearings PTFE Coating for Axles Shafts, Stub Axles, Stub Axles, Transmission and Driveshafts
• Jim's Bearings Waterproof Grease for the Axle Gears and Transmission Gears

[CosmoM3]

Just a comparison between the Injora and Traxxas Brass Casters and Blocks:

Injora

• Injora supplies their own bolts and screws for their parts, but no instructions.
• More squared off edges and finishing marks

Traxxas

• Existing Traxxas hardware works with all their parts
• Clean and smooth finishing with no marring
• The brass looks like they're more gold. Not sure if this reflects the quality of the brass.

[CosmoM3]

The new Injora 6mm brass wheel hubs extended the stance out to an additional 2mm from stock, however this finally led to the death of my stock servo as the additional width and weight of the steering knuckles, wheel weights, grippy tires and additional weight on the chassis was just too much for the servo to steer.

However, adding weight to both front and rear wheels with additional weight on the front axle helped get rid of all instances of rolling over during high speed cornering (on stock motor + speed gears) on the Canyon Trails. They're definitely the grippier tire compared to the stock BFG.

Food for thought.

I actually burned through two stock Traxxas servos within 24 hours, but no worries as I knew this was going to happen so I had another REEFS 99 Micro on standby:




Also picked this up for my TRX-4 Bronco project that I'm planning to work on for 2023:

[2471:24]

Nice! Interesting to see how it runs with that brushless setup.

[CosmoM3]

Originally Posted by 2471:24

Nice! Interesting to see how it runs with that brushless setup.

That brushless motor wasn’t meant for the Bronco (not this one anyways). I’m going to patiently sit on my hands for a better than Furitek setup.

[CosmoM3]

Hope everyone enjoys their new TRX-4Ms today:

[B-MOW71]

Following along! Nice upgrades so far! I need to check out all of these new Injora brass parts for mine. Looks like there are many options now.

[CosmoM3]

The leaking shocks are becoming tiresome and I just rebuilt them for the 4th (and last time). I even coated the shafts with PTFE coating to remove any friction between the o-rings (covered with grease) and the shaft itself under load.

The TRX-4M's biggest weak points are the shocks and the rear axle gears (due to the rear axle being bowed in, the gear teeth aren't grabbing completely under stress).

[Ynad]

Even though traxxas build shocks with the double seal they leak like all others in small scale.

Sent from my LG-V521 using Tapatalk

[Runnin2live]

Good stuff right here. Following along while I wait on my parts I just ordered

[2471:24]

Originally Posted by Ynad

Even though traxxas build shocks with the double seal they leak like all others in small scale.

Sent from my LG-V521 using Tapatalk

My injora shocks don’t leak. But I gotta say that they haven’t been on the truck that long. I’ll keep you updated on this. I’m gonna put them on my furitek cayman when it arrives.

[JimK]

Great looking Bronco. I have the same white one that I've fully modified. These are very capable and fun little trucks for sure!