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Old 06-19-2017, 09:41 AM   #1
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Default new2rocks Guide to the TRX-4

The much-anticipated Traxxas TRX-4 scale crawler is finally here, and it’s a good one. Traxxas clearly put lots of thought into the design and engineering of this all-new truck, and they have enhanced the platform since its initial release. I’ve started this guide to help you sort through the new features and components, and to help plan your inevitable mods and upgrades. Because this platform is still new, I’m intending this guide to be a work in progress as we learn from our collective experiences with the TRX-4.

Here’s what we’ll cover in the guide:
1. Overview of the TRX-4
2. Recommended performance upgrades
3. Transmission and driveline
4. Motor and ESC
5. Axles
6. Suspension
7. Electronics
8. Wheels and tires
9. Chassis
10. Body
11. Reserved for future

It's also worth having a good look at the Owner's Manual that Traxxas has posted on their website (but does not include in the box). The RTR version has some very helpful info:
https://traxxas.com/sites/default/fi...-OM-EN-R02.pdf

And the kit version is a great resource if you need to take anything part for maintenance, repairs, upgrades, or just morbid curiosity:
https://traxxas.com/sites/default/fi...Manual-WEB.pdf

If you have any questions, suggestions, or feedback, please let me know. Enjoy!

1. Overview of the TRX-4

The TRX-4 combines the familiar c-channel chassis architecture and linked suspension architecture with a host of features not typically found (some not previously found at all) in RTR scale crawlers. Some of the highlights include:
- 2-speed transmission
- Remote locking and unlocking front and rear differentials
- Portal axles for added ground clearance
- 45 degrees of steering
- Option to upgrade radio with Bluetooth programming capability
- Inner fenders included with stock body

The initial release of the TRX-4 included a licensed Land Rover Defender 110 polycarbonate body, with some great looking scale accessories bolted on (think roof rack, spare tire, jerry can, high lift, and faux winch):
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The only real letdown to the body is the use of stickers for “windows” instead of masking off inside the body before painting to leave the windows clear. From a functional perspective, the body feels very strong and should prove to be very durable out on the trails and rocks.

Traxxas followed this up with a licensed Ford Bronco that is simply stunning (and has clear windows!)...
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...along with a kit version. That's right...a KIT from Traxxas! I Roo has already started on his:
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The kit version takes a different approach from the other big players by including electronics (radio, receiver, ESC, motor and servos) while leaving out the body. Here's a sneak peak at the kit from Roo:
https://www.facebook.com/BowHouseRC/...0278995914018/

As Roo makes progress on his build, I'll be updating this guide with info on the kit.

Getting the RTR versions of the TRX-4 running is as simple as adding 4 AA batteries to the remote and a charged pack to the truck, turning it on, and heading off on the trails. But before you head out on any extended runs, we recommend taking a few preventative steps:
1. Check the pinion gear placement and pinion/spur mesh (see transmission section below)
2. Check the diff, tranny and transfer case gears for grease. Greasing from the factory in early production models has been hit or miss, which isn't uncommon with RTRs. Cases shouldn't be packed with grease, but there should be enough grease to give the gears a nice, full coating.
3. Check your steering endpoints. There have been a few early reports of snapped CVDs, most likely due to oversteering the axles.
So how does it drive? Box stock, the TRX-4 is well balanced with a very smooth drivetrain and highly capable suspension. Even with the diffs unlocked, the TRX-4 is capable of handling most trailing and light crawling duties. With diffs locked, the TRX-4 turns into a highly capable crawler whose only major let down in stock form is the weak stock servo. But that’s an easy fix (for more on that, see below). Here's a short video I put together that shows the TRX-4 in action in a variety of terrain:

https://youtu.be/2t_CQ70V7LQ

Here are a links to a few helpful video reviews:
Harley Designs (good overview followed by other videos with more details):

https://youtu.be/bUb9do5e_rU

John Holmes of Holmes Hobbies (excellent technical overview):

https://youtu.be/3ROIJ1E58jg

Matteo's RC (excellent demonstration of different features):

https://youtu.be/dj6KBFL2NKs

And here's a link to a very good write-up from Big Squid RC, which is known as a bashing site but has added a lot more scaler content over the past year or so:
Traxxas TRX-4 Scale & Trail Crawler Review « Big Squid RC – News, Reviews, Videos, and More!

2. Recommended performance upgrades

Box stock is all well and good for a little while, but tinkering will be necessary in some cases and, in others, a lot more than half the fun. When looking to improve the performance of your TRX-4, there are two areas where you will notice the biggest and most immediate differences:
1. Steering servo - The very first thing you should do is replace the stock steering servo, which is very underpowered (only 125 oz-inch / 9.0 kg-cm of torque). I recommend 250 oz-inch at a minimum, but 300-350 is even better. The Holmes Hobbies SHV500 is a great option because it can run directly off of 2S or 3S battery power using the auxiliary JST power plug that comes on the XL-5 ESC.

2. Lower the Center of Gravity - Straight out of the box, the TRX-4 has a relatively high center of gravity due to the combination of high battery placement relative to the chassis, portal axles, tall shocks, and top-heavy bodies (esp. the Defender 110 body). There are a variety of ways to lower the CG, including a low CG battery tray, adding brass portal components, running shorter shocks, choosing a body with a lower CG, and adding weight to the wheels. If you were going to choose two, I'd recommend lowering the battery and running shorter shocks. And I'd put adding weight to the wheels last on the list, in part because it can add stress to the driveline. But whatever you do, find a way to lower the CG. It will make a big difference.
As you’re starting to consider the options, there is one important limiting factor to keep in mind. If you’re planning to keep the stock axles, your body and wheel/tire choices will be limited by the width of the stock axles and size of the portal knuckles. Simply put, the TRX-4 axles wouldn’t look right under most narrow to medium-width bodies, which pretty much eliminates using this as a class 1 truck with the stock axles. But that still leaves tons of options for making the TRX-4 your own as a class 2 truck, so let’s get on with it…

Last edited by new2rocks; 03-12-2018 at 04:30 PM.
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Old 06-19-2017, 09:43 AM   #2
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Default Re: new2rocks Guide to the TRX-4

3. Transmission and driveline

All versions of the TRX-4 come standard with a 2-speed High/Low transmission with 32 pitch gears, mated to a 1:1 transfer case also utilizing three 27T 32P gears. The transmission is mated to a 45T spur with twin plate slipper clutch. There are two important things to note about this transmission:
1. The difference in final drive ratios between high gear and low gear is much greater than most (any?) other 2-speeds on the market. With the stock spur and pinion, the final drive ratio in low gear is 64.64:1 compared to 25.85:1 in high gear. That's a biiiiiig difference.

2. The 25.85:1 final drive ratio in high gear is very tall for a scaler/crawler, which explains why Traxxas recommends using a 550-can motor instead of a 540-can motor if you are going with a brushed motor (see motor and ESC below).
The first thing you should do before running your TRX-4 is check your spur/pinion mesh and pinion gear alignment. Proper gear mesh is important for prolonging the life of your spur and pinion gears and keeping temperatures down. The TRX-4 motor plate uses fixed motor mounting positions designed to take the guess-work out of adjusting gear mesh. The holes on one side of the plate are labeled with the letters A-H:
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The manual includes a table specifying which holes to use for different pinion and spur combinations:
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This is a nice idea for newcomers, but there is a problem in the execution. The recommended motor placement for the stock gearing (hole "C" in the motor plate) may leave spur/pinion mesh too tight, which can cause premature wear of the spur gear and undue strain on the motor (which can in turn cause overheating). This doesn't appear to be a universal issue, as some users have reported pinion mesh too tight and others just right with the "C" hole and stock gearing. So check your mesh, and if it's too tight in the C position with stock gearing, just move the motor one hole further out to hole "D":
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My testing of several other pinion sizes indicates a similar issue with the recommended motor placement for other spur/pinion combinations. So the best recommendation is to use the manual as a guide but not as a substitute for checking the mesh yourself regardless of what gearing you're running. Given these issues, I suspect it won't take long for the aftermarket to provide a motor plate with more adjustability for experienced builders.

While you have your spur gear cover off, you should also check your pinion/spur alignment. On some early production models (including mine), the pinion gear is installed too far out on the motor shaft, causing the pinion and spur teeth to be offset:
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This in turn can cause premature spur gear wear. The fix is simple...move the pinion closer to the motor so that the teeth align better with the spur gear:
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With respect to choosing a gear ratio for your setup, if you use the stock motor and ESC, Traxxas recommends no larger than a 12T pinion with the stock 45T spur, and that’s sound advice in my book. The stock Titan 21T 550-can motor running on 3S has plenty of juice in high gear, while low gear provides gobs of usable torque and excellent low-speed resolution.

If you need to service your transmission or transfer case, Harley posted an excellent video showing how to disassemble the tranny:


Stock driveshafts use hardened steel U-joints connected by plastic male and female shafts. If the durability of the Traxxas Maxx shafts is any indication, these driveshafts should hold up well.

4. Motor and ESC

The TRX-4 comes standard with the Traxxas XL-5 HV ESC and Titan 550 21T reverse direction motor. The XL5 supports up to 3S Lipo, and I definitely prefer 3S to 2S with the stock setup. Although a 21T motor on 3S might seem a bit fast and perhaps lacking in torque for a scaler, the 550 can size, combined gear reduction of the drivetrain and axles in low gear more than compensates. Low-speed resolution and torque are very good, particularly on 3S in low gear, and there is plenty of wheel speed in top gear when needed or for giggles when the trail flattens out.

Both Traxxas and resident motor guru John Holmes of Holmes Hobbies recommend NOT using 540-sized brushed motors in the TRX-4 due to the tall 25.85:1 final drive ratio in high gear. So when choosing a motor/ESC combo, keep in mind that you will want to stick with a 550-can brushed motor or a lower kv brushless setup than you would normally choose in other rigs to keep wear and motor temps under control. Holmes Hobbies offers the TorqueMaster Pro 550 in 21T and a limited edition 30T. They also offer the Crawlmaster Pro 550 (which is a 5-slot design) in 10T and 12T flavors, which would be comparable to a 21T and 27T 3-slot motor, respectively.

If you plan to go brushless, a 2200 kv 540-sized sensored brushless 4-pole motor should be a good baseline to get performance similar to the stock 21T motor. My current favorite 4-pole sensored brushless motors are the Puller Pro line (stubby or standard 540 size) and the new Castle 4-pole crawler motors. Matched with a good ESC like the Holmes Hobbies Trailmaster BLE or the Castle Mamba X, both offer very smooth startup and low speed resolution combined with lots of torque and plenty of top end (relative to the kv rating). My word of caution on brushless motors with the TRX-4 is not to overdo it either with kv selection or driving style this early in the game. The TRX-4 is a very new platform, too new for us to know its true weak points, much less for the aftermarket to have addressed them. The last two major releases (the SCX10 II and the Ascender) had weak points at initial launch (transfer case gears and pinion/driveshafts) that seemed fine with a stock RTR setup but didn't hold up so well to brushless power, especially when pushed hard. Eventually, the manufacturers and/or aftermarket developed more durable alternatives, but it took a little while.

I do have one quibble with the stock ESC setup. The XL-5 HV has 5 different driving profiles, including a crawl mode with a drag brake and immediate reverse. But it comes preset to trail mode, where the first application of reverse on the trigger applies brakes and a second application is required to go in reverse. Traxxas should be shipping these pre-programmed to crawl mode (it is a scale crawler, after all). It’s easy enough to change modes (just hold down the EZ-Set button on power-up and let the LED go through its blinking cycle until it blinks red 5 times in rapid succession, then release), so it’s a relatively minor quibble. But it’s also an easy fix for Traxxas, so hopefully they’ll make that change and save everyone the effort of switching the drive profile.

One neat feature of the stock ESC when used with the stock radio is the ability to program it through the optional Traxxas Link module. But as noted in the electronics section below, it would be nice to see Traxxas add more programming options through Traxxas Link.

Last edited by new2rocks; 03-12-2018 at 04:31 PM.
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Old 06-19-2017, 09:44 AM   #3
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5. Axles
The TRX-4 comes with trick new portal axles that feature steel gears and remote locking/unlocking differentials on the front and rear. The differentials use a 34T ring gear and an 11T pinion, producing gear reduction of 3.1:1. The portal gears use a 10T input gear with a 23T output gear to provide an additional 2.3:1 gear reduction, for a combined 7.1:1 gear reduction at the axle, which is over twice as much reduction as most of the existing scale axles on the market. With 45 degrees of steering on tap (which has become the new standard thanks to the Vaterra Ascender and Axial SCX10 II), steering is excellent with the diffs locked, and it gets even better with the diffs open.

Of course, the biggest benefit to portal axles is ground clearance, and the new TRX-4 axles don’t disappoint. Based on my bench measurements, the TRX-4 with stock tires has over 52mm of ground clearance at the pumpkin, which is approximately 12mm more than you get with an SCX10 II on stock tires. Here's the TRX-4:
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Here's an SCX10 II with stock tires:
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It makes enough of a difference that the pumpkin rarely comes into play out on the rocks. The center skid becomes the one to look out for.

With this setup, certain 1.9” wheels will not fit all the way onto the axle without modification. Options include adding a spacer between the wheel hex (this works if the hex slot on your wheel is deep enough to bite with a spacer between the wheel and hub), drilling out the inner hole of your wheels so they fit over the 6mm portion of the shaft, using wheels that take SLW hubs (which fit over the shaft with no problems), or using a wider wheel hex to cover the 6mm portion of the axle stub.

It should come as little surprise that, between the remote lockable diffs and portals, servicing the axles is a fair bit more involved that servicing a typical locked diff axle. Harley put together an excellent video showing how to disassemble the axles:

https://youtu.be/9aq0IusoAf8

As you can see from Harley's video, the axles are a fairly complex design, and with complexity comes opportunities for parts to fail, particularly when pushed to the limits. Thus far, the axles seem to be holding up just fine to typical trailing and crawling. But if you are one of the early adopters, I would recommend some discretion when setting up and running your TRX-4 until we have a better idea of where the points are and, perhaps more importantly, the aftermarket has kicked in with heavier duty upgrade options.

One other design feature to note is the diameter of the axle stubs. The stock wheel hexes leave a portion of the 6mm stub shaft exposed before the stub tapers to the 4mm threads:
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SSD has released a portal delete kit that allows you to convert the TRX-4 axles to a standard setup. The portal delete kit lowers ride height by 13mm and narrows the track width by 12mm, from 192mm to 180mm, which puts them essentially on par with the AR44 axles from the Axial SCX10 II. But keep in mind that deleting the portals has trade-offs, the biggest one being the loss of the 2.3:1 gear reduction in the portals. That means low gear with the portals deleted has only slightly more gear reduction than high gear with the portals.

6. Suspension

The TRX-4 utilizes fully linked suspension with 3 links and panhard in front and 4 links in the rear. Links are all metal and use a new rod end design. The TRX-4 also includes newly designed 90mm aluminum GTS coil-over shocks. These new shocks come pre-filled with 30W oil with staggered spring rates (.45 in front, .54 in the rear). The stock setup is silky smooth and provides excellent damping with the stock body and a typical sized battery pack. The shocks are also easily tunable to suit your preferences. I have a sneaking suspension these may become the go-to 90mm shocks for scalers. They are that good (at least so far).

That said, the stock shocks leave the truck riding fairly high. Together with the top-heavy body, that makes for a pretty tippy ride. Switching over to 80mm shocks lowers the CG enough to make the truck much more stable and capable over a wider variety of terrain. Here are a couple of pix, starting with the stock shocks:
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After installing the 80mm shocks:
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If you want to keep the stock shocks, another good option for lowering the ride height is to insert a spacer around the shock shaft below the piston. Either way, lowering the ride height is one of the best performance mods you can do, and it also helps in the looks department. Win win!

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Old 06-19-2017, 09:47 AM   #4
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7. Electronics
Making all of the gadgetry work requires more electronics than you typically find in an RTR scale off-roader, and time will tell whether this ends up being the Achilles heel of the TRX-4. Here’s a breakdown of what’s included:
-- Steering servo: The steering servo is an updated version of the 2075, called the 2075X. On the plus side, the 2075X is waterproof and uses all metal gears. As I mentioned at the beginning of the guide, the downside is that, with only 125 oz-in of torque on tap and a .17 second transit time, it is underpowered and slow for this application. When driving, it’s workable at least for a little while to get you out on the trails and for light crawling, but it didn’t take long for the initial wave of buyers to start seeing failures. So the servo should be at or near the top of your upgrade list. I recommend a waterproof servo with at least 275 oz-in of torque paired with an external BEC. But regardless of whether you are running the stock servo or an aftermarket upgrade, it's very important to set your endpoints so that the servo doesn't oversteer the front axle and put unnecessary stress on the CVDs.

-- Shift and locker servos: Shifting and locker duty is handled by three Traxxas 2065 servos, mated to servo savers. These servos are not known for being the most durable, so it will be interesting to see how well they hold up in the TRX-4.

-- The radio is a 4-channel, Traxxas Link-enabled TQi radio with a 2-position 3rd channel switch for the shift servo and a 3-position 4th channel switch for the lockers (both open, front locked with rear open, or both locked). Although very basic in appearance, the radio allows you to make a variety of adjustments, including exponential throttle curve, steering end points, etc. Without an LED display, you’ll need the manual to figure out how to make it all work. The optional Traxxas Link module allows you to adjust certain settings through the Traxxas smartphone app and a BT connection between your phone and the receiver. The app does make it easier to fine-tune some of your settings, but some basic adjustments (like putting the ESC into crawler reverse or other throttle modes) still require using the transmitter or ESC. All in all, the system is quite workable, but hard core enthusiasts are likely to upgrade their radios at some point to gain more control over their setups.
All in all, with the notable exception of the steering servo, the stock electronics provide a very workable starting point to enjoy the TRX-4. So my recommendation is to start by replacing the steering servo (adding a BEC unless your servo will run directly off 2S or 3S power from the battery) and then replace other components as needed when things break or you’re looking for feature upgrades.

8. Wheels and tires
The TRX-4 includes all-new 1.9 Canyon Trail tires glued to plastic wheels with 12mm hexes. The Canyon Trail tires have a 4.64” OD, and I must say they work very well with the stock foams for an RTR setup. Grip is good in a wide range of conditions, and the sidewalls hold up well to sidehilling loads. If you’re just looking to have fun out on the trails and rocks and aren’t planning on comping, these tires will be more than up to the task. But we know that most folks will want to try their own, so here are some things to keep in mind when choosing your wheel/tire combo.

Let’s start with wheels. As noted in the axle section above, you’ll need to take into account the stock axle stub design and size of the portal knuckles when choosing your wheel/tire combo. For wheels that use SLW hubs, you’ll want to take into account the inner diameter of the beadlock ring when choosing hubs. If the inner beadlock ring has an ID or 40mm or greater, you should be able to clear the portal knuckles with positive offset that tucks the wheels over the knuckles. If not, you’ll need to choose a negative offset that keeps the inner beadlock ring outside of the knuckle. svt_923 put together an excellent thread showing fitment of different wheel/hub combinations:
TRX4 wheel fitment info

One last word on wheels. I don’t recommend 1.55” wheels on these axles. The combination of already wide axles and bulky portal knuckles would require pushing 1.55 wheels way out on the stubs, which would look a bit silly. Stick with 1.9s (or even 2.2s with 1.9 tires stretched onto them).

Choosing a tire for your truck involves lots of variables, including what body you plan to use and how you plan to drive the truck. If you are keeping the stock body, you’ll be able to fit 4.75” OD tires without rubbing or modification, which opens the door to Pit Bull’s 1.9 Rock Beast XL and 1.9 Growler, RC4WD Baja Claws, Pro-Line Super Swamper XLs, and Voodoo KLRs. Anything less than 4.5” will look a bit small inside the large wheel openings on the stock body, but that will be different with other bodies.

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Old 06-19-2017, 09:49 AM   #5
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9. Chassis
The TRX-4 chassis is designed to support multiple wheelbases ranging from 11.8” (300mm) to 13.2” (336mm). Out of the box, the TRX-4 chassis is set to a 12.75” (324mm) wheelbase to fit the stock Defender 110 body. The stock configuration places the motor and transmission in front of the truck and battery tray in the middle between the chassis rails.

More info on different WB setups coming soon...

10. Body
As I mentioned in the intro, the stock D110 body is one of the nicest RTR bodies on the market. Although it seems quite large at first glance, it turns out to be dimensionally almost identical (excluding the bolt-on fender flares) compared to the RC4WD D110 and Team Raffee D110 bodies.

Here are a few comparison pix with an RC4WD Gelande 2 D110:
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And here are a few comparison pix with a Team Raffee D110 pickup sitting on top of a GCM CMAX chassis:
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The interior dimensions are also nearly identical to the RC4WD D110 body, which means that it should be fairly easy to install an RC4WD interior. It would take a little bit of cutting to make room for some of the extra stuff underneath the TRX-4, plus ditching the rear body post tower and modding (or replacing) the rear fender wells, but all of that would need to be done to run any interior.

More body-related info to come...

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Old 06-19-2017, 09:49 AM   #6
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11. Reserved
This section reserved for future updates

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Old 06-19-2017, 10:13 AM   #7
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A 550 is recommended because of the rollout in 2nd gear, it will kill 540 brushed motors really fast. The only way to keep a 540 brushed motor happy is to gear the rig down as much as possible, then 2nd gear is slow enough. With stock gearing, 2nd gear @25:1 requires a 550.
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Old 06-19-2017, 10:28 AM   #8
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Quote:
Originally Posted by JohnRobHolmes View Post
A 550 is recommended because of the rollout in 2nd gear, it will kill 540 brushed motors really fast. The only way to keep a 540 brushed motor happy is to gear the rig down as much as possible, then 2nd gear is slow enough. With stock gearing, 2nd gear @25:1 requires a 550.
Thanks for the quick input on motor selection. So with the disclaimer that I haven't yet had a chance to test out other powertrain combinations, wouldn't the added gear reduction in the axles (over twice as much as a the AR44 axles, for example) be enough to offset the relatively tall second gear and allow using a decent (i.e., not a silver can) 540 brushed?
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Old 06-19-2017, 11:14 AM   #9
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Nope. 25:1 is the same reduction whether in the axles or transmission. It's too tall for a 540 to survive unless running tiny wheels.
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Old 06-19-2017, 12:23 PM   #10
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If you can fit a 550, I'm not sure why you'd want to downgrade to a 540 anyway. That'd be like trying to test 380s in an SCX. If a 550 fits then stick with more torque and a cooler motor. There are plenty of great 550 options cheap and expensive. Maybe that's just my perspective. I always try to overbuild and/or underwork my electronics rather than constantly push everything to its limit. After my first big crawl and test yesterday, I personally feel like the stock 550 is underpowered on 3s and a 9t pinion. I'll be upgrading the motor on this truck for sure.
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Old 06-19-2017, 01:16 PM   #11
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Quote:
Originally Posted by JohnRobHolmes View Post
Nope. 25:1 is the same reduction whether in the axles or transmission. It's too tall for a 540 to survive unless running tiny wheels.
Thanks for the email exchange, JRH. Your info on gearing was better than mine, so I just updated the motor/ESC section.

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Originally Posted by SCREAMER View Post
If you can fit a 550, I'm not sure why you'd want to downgrade to a 540 anyway. That'd be like trying to test 380s in an SCX. If a 550 fits then stick with more torque and a cooler motor. There are plenty of great 550 options cheap and expensive. Maybe that's just my perspective. I always try to overbuild and/or underwork my electronics rather than constantly push everything to its limit. After my first big crawl and test yesterday, I personally feel like the stock 550 is underpowered on 3s and a 9t pinion. I'll be upgrading the motor on this truck for sure.
Lol...yes and no. One of the great things about the Puller Pro Stubby motors is the ability to get comparable performance out of a smaller, lighter motor, which brings down weight and makes more room for other stuff under the hood. But that said, with the final drive ratio in high gear being so much taller than typical scalers/crawlers, a 550 sized motor would be a must if you stay brushed. As for the stock motor, it feels pretty good to me compared to other stock RTR motors, but there are obviously plenty of options to improve on that (which I'll do soon enough).

Please keep the comments and feedback coming!
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Old 06-19-2017, 06:58 PM   #12
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This is a great thread! Looking forward to the different bodies / wheelbases that are possible. I think a lot of people, in my area at least, plan on ditching the body immediately. Knowing what's compatible will save lots of time.
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Old 06-19-2017, 08:14 PM   #13
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Was at my local hobby shop today [ ie 50 miles away ] He had 2 TRX-4 and a guy there matching up the wheel base of a PROLINE 2 piece 87 Toyota extra cab with bed ,,It looks real close just body mounts from what I have seen ,I bought a PROLINE 66 chevy c 10 cab bed version ,Looks killer On RichDog51 TRX-4 ,

Gonna do some servo winch mounting vids when my mount shows up ???
Really like my TRX-4 . For a out of the box rig all I can say is well done Traxxas ,,
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Old 06-19-2017, 08:48 PM   #14
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Originally Posted by robertjpjr View Post
This is a great thread! Looking forward to the different bodies / wheelbases that are possible. I think a lot of people, in my area at least, plan on ditching the body immediately. Knowing what's compatible will save lots of time.
Thanks! Just updated with some comparison pix showing this body vs. the RC4WD and Team Raffee D110 hard bodies. The biggest limiting factor with bodies will be width of the axles. Apart from that, the basic architecture allows for enough adjustments to fit a pretty wide range.

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Originally Posted by KMS View Post
Was at my local hobby shop today [ ie 50 miles away ] He had 2 TRX-4 and a guy there matching up the wheel base of a PROLINE 2 piece 87 Toyota extra cab with bed ,,It looks real close just body mounts from what I have seen ,I bought a PROLINE 66 chevy c 10 cab bed version ,Looks killer On RichDog51 TRX-4 ,

Gonna do some servo winch mounting vids when my mount shows up ???
Really like my TRX-4 . For a out of the box rig all I can say is well done Traxxas ,,
Good to know on the Pro-Line Toyota body and totally agree with the pat on the back to Traxxas. Look forward to seeing your servo winch mounting videos.
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Old 06-19-2017, 10:03 PM   #15
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Great wrote out information and kept to the point. Thank you! I enjoyed reading all of it (so far).
Reading through, I stopped in my tracks at the thought of these GTS coil overs in 90mm form being possibly the next go-to shock for scalers. I might have to agree with you on that as I had a similar thought of them and happy you mentioned it. My short time with a demo rig a couple weeks ago, proved these things are silky smooth. I guess time will tell if they are the go-to. I'm hopeful the price will be right to make that happen, and the oil actually stays inside of the body long enough to get some life out of a factory set up with a lot folks new and old just ditching them at the first signs of ONLY residual (I'm guilty of it). Also I hate to bring this to the table but, epic fail from axial with a chance to improve on the leak status with the release of the 10.2. The big bores and GTRs I have on other Traxxas trucks don't seem leak happy at all, maybe just some very small residual on 1 or 2 corners of the vehicles. I'll bend one of their TiN coated shafts on a shock with a way awkward landing before a leak problem starts. With that said I have a good feeling these Traxxas shocks won't need to be screwed apart to add oil and your typical greenslime/teflon with fingers crossed scenario.
I can't wait to get out and have fun with mine. I wish it was a kit but the release time was perfect for such an awesome tough RTR, with the nice weather, who wants to be inside putting a kit together letting it sit on the bench unfinished/and or waiting for parts? I leave the kit and major maintaince teardowns for the winter.
I wanted to also add that I'm a fan of the 2.2 wheel and 1.9 tire stretch, doing it myself on a rig, but it must be executed the right way. This truck offers a chance of some combos to try out and I'm positive the look will do wonders on this slightly larger rig.
Speaking of go-to, thanks again for this go-to thread for us on this rig now. I'll be sure to use it as quick reference especially since you have the numbers, ratios, counterparts all in one compact write up for easy skim-ability.

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Old 06-21-2017, 08:22 AM   #16
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Great wrote out information and kept to the point. Thank you! I enjoyed reading all of it (so far).
Thanks for the kind words (and I agree with you on the rest, lol).

I have updated the tranny section with info on pinions being installed out of alignment with the spur on some trucks and addressing pinion/spur mesh with the stock setting (per SCREAMER's thread). More updates to follow...
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Old 06-21-2017, 08:49 AM   #17
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I haven't seen this mentioned but I am wondering. Portals are not really used in trucks that are rock crawlers, they are used for overland vehicles. Their application is limited to added clearance on trail obstacles, mud and sand.

If you have never driven a portal axle vehicle you might not understand just how much difference the higher COG makes. Portal axles make most rigs very tippy, which is why they are not common and are application specific.

How does this translate with the TRX-4. I am looking at the d110 with the rack. My d90 with a rack is very top heavy, to the point that it is more of a trail truck now, add the portals to it and I couldn't imagine it being very good on side hill.

The added leverage on my d90 meant stiffer foams in the 4.19 inch tires to compensate on side hills, it noticeably affects my contact patch when crawling.

I could see the TRX-4 with portal as a good looking scale truck with a hard body(considering buying one just for trailing with a D110 body), but other then that I don't see a good hard body application.

Thoughts?
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Old 06-21-2017, 10:05 AM   #18
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I haven't seen this mentioned but I am wondering. Portals are not really used in trucks that are rock crawlers, they are used for overland vehicles. Their application is limited to added clearance on trail obstacles, mud and sand.

If you have never driven a portal axle vehicle you might not understand just how much difference the higher COG makes. Portal axles make most rigs very tippy, which is why they are not common and are application specific.

How does this translate with the TRX-4. I am looking at the d110 with the rack. My d90 with a rack is very top heavy, to the point that it is more of a trail truck now, add the portals to it and I couldn't imagine it being very good on side hill.

The added leverage on my d90 meant stiffer foams in the 4.19 inch tires to compensate on side hills, it noticeably affects my contact patch when crawling.

I could see the TRX-4 with portal as a good looking scale truck with a hard body(considering buying one just for trailing with a D110 body), but other then that I don't see a good hard body application.

Thoughts?
You raise interesting questions. Let's start with side-hilling. Overall, I was pleasantly surprised by the truck's performance out of the box. Without having had time to do a direct comparison yet, I'd say the stock TRX-4 is comparable to a kit-built SCX10 II in sidehilling performance. Here's a quick video showing my still box-stock TRX-4 with a few interesting side-hill and off-camber situations mixed in:


I have pushed the limits even further a couple of times, and it's pretty good. It's not as good on the sidehills as a low-slung rig like my GCM Skeleton or TF2 SWB, but it remains very predictable and therefore very manageable.

The point you raise about 1:1s with portals is interesting but doesn't apply as much to RC trucks. Though I don't have experience with portals in the 1:1 world (other than seeing a Mog in person once, lol), I'm guessing that top-heaviness of portal-based trucks has as much to do with other design choices to maximize ground clearance as it does with the portals themselves. In the RC world, there's no reason you couldn't have both portals and a low CG, as some of the Mad Moose-based builds have demonstrated.

On the TRX-4, I don't see any reason why you couldn't lower the truck with shorter shocks (80mm should be fine) and smaller tires (class 1 between 4-4.19") to get the benefits of both - good ground clearance and a low CG. The new Low CG Battery Tray that we (BowHouse) just released also helps by lowering the battery within the chassis, thus lowering the CG.

With all that said, I really don't mind (in fact I quite enjoy) top-heavy scale rigs. I find them much more challenging and, in most terrain, more enjoyable to drive than more capable trucks. Here's an example of my very top-heavy, 10.5-lb Gelande 2 D90 navigating a wide variety of terrain on RC4WD 1.9" Duratracs with the stock foams that come with the tire:


As far as hard bodies are concerned, I'm inclined to agree with your hunch that they won't work so well on the TRX-4, but for a completely different reason. The biggest limiting factor on body selection is going to be axle width, not weight distribution. Most of the popular hard bodies on the market currently are designed for much narrower axles than the TRX-4's. The RC4WD Cruiser body is one of the wider ones, and it looks perfect with Yota-width (i.e., 170mm pin-to-pin) axles. The RC4WD and Raffee D90 and D110 bodies also look just right with 170mm axles, and the Hilux/Mojave bodies need an even narrower axle to look right (which is why we came out with our 152mm NCYotas). If you continue down the list, you see a pattern (Killerbody LC70 is as narrow as a Hilux/Mojave, XJ hardbody looks best with 170-175mm axles, etc.).

All of this suggests to me that hard bodies won't be a popular choice until either (a) there are some good quality wider hardbodies on the market or (b) someone comes out with a narrowed TRX-4 based portal axle. My crystal ball is hazy at best, downright opaque at worst, but my guess is that (a) is very unlikely because there's unlikely to be much of a market for big, wide hard bodies), and (b) may happen but will take some time.

If you factor in that the TRX-4 is initially going to draw a higher percentage of first-time scalers (even first-time RCers) than other scale platforms, all signs point to not seeing too many hard bodies on TRX-4s any time soon. But that's just a guess, and it doesn't change the fact that the TRX-4 is a great addition to the scale market - a highly capable platform packed with innovation. That's my .02, for whatever they're worth.

Last edited by new2rocks; 06-21-2017 at 05:55 PM.
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Old 06-22-2017, 08:47 AM   #19
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What an awesome write up David...This will help the TRX-4 community to help us research on how things work, what's compatible, pool our ideas etc.

Looking forward for 'ahem'...more updates? lol.
Well done man, kudos!
Lol...thanks for the kind words. Ask and ye shall receive...

Latest round of updates includes links to some good video reviews, recommended maintenance/vehicle checks before driving, motor recommendations, and links to Harley's excellent videos showing tranny and axle disassembly.
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Old 06-22-2017, 09:59 AM   #20
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I agree with ViperCrawler, excellent write up and great job updating the info so far
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