TRX-4 Monster Truck?

[indybama]

Nice job! Looks awesome! Ive been workin on a monster truck build myself over in the misc section.

The traxxas bigfoot no 1. body is a shorter wheelbase, i think its 11 inch wb. Which sucks because thats where i was headed with mine. But in order to get 'bigfoot no 1' decals, u have to get the stampede clear body version.

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[MODC]

Nice job! Looks awesome! Ive been workin on a monster truck build myself over in the misc section.

The traxxas bigfoot no 1. body is a shorter wheelbase, i think its 11 inch wb. Which sucks because thats where i was headed with mine. But in order to get 'bigfoot no 1' decals, u have to get the stampede clear body version.

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That does suck. I JUST brought home a new trx-4 Blazer, but I'm leaving that mostly stock and on the shelf...the body is just too nice, and I have a defender, now bronco which is modified in a big way...lol.
Once into some spare funds I'm going to follow this build, but with a trx-4 sport. JConcepts will cover my body and wheel/tire needs I'm sure.

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[indybama]

That does suck. I JUST brought home a new trx-4 Blazer, but I'm leaving that mostly stock and on the shelf...the body is just too nice, and I have a defender, now bronco which is modified in a big way...lol.
Once into some spare funds I'm going to follow this build, but with a trx-4 sport. JConcepts will cover my body and wheel/tire needs I'm sure.

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The jconcepts 79 ford supercab body is a good choice lol

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[Dustrbd1]

Done! It's a military theme. Sharkmouth stickers from Ebay and some waterslide decals meant for a tank. Decided not to do any wet sanding but that silver paint is still under there, waiting to make future scratches look more realistic 8).



This project came together surprisingly easy. The biggest frustrations I had were with the stock radio, which had nothing to do with the monster truck conversion. If you're thinking about making your own TRX-4 monster, I have some tips:



1. It's pretty rad, DO IT.

2. Ditch the inner fenders. Almost all of the clearance issues I had to solve were due to those fenders. You'll also be able to mount the body higher without them, and more higher is more better.

3. You might not even need the axle extensions. I didn't try it without them so I don't know.

4. Try a narrower body meant specifically for a monster truck like one of the ones from Jconcepts or Proline. The proportions would look even more monster-trucky.

This looks awesome.

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[durok]

Absolutely astounding final results!

This demands submittal to RCCarAction or wherever, needs to be shown off...

I am quite envious of your abilities, sir!

 

[high plains drifter]

The two-tone paint and wheel choice was perfect. Not only was this a great build idea, but SO well executed. I don't think I'm the only one that wants to see a video of this one crawling!

 

[TooOldForThis]

Wow guys, thanks. I'm blushing over here

I got a little carried away with the paintjob so the next "mod" is probably gonna be to whip up a basher body. Maybe give that one a name, all the cool monster trucks have names. A couple of my favorites from Trigger King:

 

[pattyt]

Done! It's a military theme. Sharkmouth stickers from Ebay and some waterslide decals meant for a tank. Decided not to do any wet sanding but that silver paint is still under there, waiting to make future scratches look more realistic 8).



This project came together surprisingly easy. The biggest frustrations I had were with the stock radio, which had nothing to do with the monster truck conversion. If you're thinking about making your own TRX-4 monster, I have some tips:



1. It's pretty rad, DO IT.

2. Ditch the inner fenders. Almost all of the clearance issues I had to solve were due to those fenders. You'll also be able to mount the body higher without them, and more higher is more better.

3. You might not even need the axle extensions. I didn't try it without them so I don't know.

4. Try a narrower body meant specifically for a monster truck like one of the ones from Jconcepts or Proline. The proportions would look even more monster-trucky.

Must......build......one hahaha. Now I'm thinking of taking the lift out of my bronco, getting a trx4 sport, throw the lift in that, and going mt with brushless 2850 or lower. My questions are how do you think the sport would do with those massive tires? Would the axles/lockers hold up to bopping around? (Gotta stampede for 1ft and higher air) thinking single speed would be just fine. Thoughts?

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[TooOldForThis]

Must......build......one hahaha. Now I'm thinking of taking the lift out of my bronco, getting a trx4 sport, throw the lift in that, and going mt with brushless 2850 or lower. My questions are how do you think the sport would do with those massive tires? Would the axles/lockers hold up to bopping around? (Gotta stampede for 1ft and higher air) thinking single speed would be just fine. Thoughts?

I haven't given mine much of a serious test yet but i expect it to be pretty durable if you're just "bopping around". :ror: I would say a metal servo horn is a must and the next weak point after that is probably the servo itself or the axles. There's only one way to find out. 8) If you plan to do more bashing than crawling you may want to consider an open diff for the front at least. It turns a lot nicer that way.

As for gearing, I don't know how the single speed ratio in the Sport compares with the 2 speed, but with a stock motor on 2S in high gear it has enough speed to do little jumps but is still pretty slow. Brushless is the obvious solution there, and I agree 2850 KV would be a safe bet.

Update: It turns out 3S on the stock motor is plenty fast in high gear! Any faster and it wouldn't really be scale. Tons of fun, but with all the rolling weight the motor heats up quickly so a brushless setup would still be better.

 

[TooOldForThis]

Damn, more proof that Jconcepts really knows what they're doing. I've wondered if it would be possible to bolt up two Fling King wheels together to make duallys, but then they go ahead and make it idiot-proof with these new wheels. Too cool.

Meanwhile new solid-axle CEN monster trucks are almost in stores and there's strong SMT10 re-release rumors. It seems like monster trucks are having a comeback!

 

[pattyt]

I haven't given mine much of a serious test yet but i expect it to be pretty durable if you're just "bopping around". :ror: I would say a metal servo horn is a must and the next weak point after that is probably the servo itself or the axles. There's only one way to find out. 8) If you plan to do more bashing than crawling you may want to consider an open diff for the front at least. It turns a lot nicer that way.

As for gearing, I don't know how the single speed ratio in the Sport compares with the 2 speed, but with a stock motor on 2S in high gear it has enough speed to do little jumps but is still pretty slow. Brushless is the obvious solution there, and I agree 2850 KV would be a safe bet.

Update: It turns out 3S on the stock motor is plenty fast in high gear! Any faster and it wouldn't really be scale. Tons of fun, but with all the rolling weight the motor heats up quickly so a brushless setup would still be better.

Thanks for the info, the single speed is in between gearing of hi/low on the 2 speed. How has the long term been? Already got a good savox servo and horn, so good there. Keep thinking about.getting the Jconcepts wheels and putting em on the lifted bronco, but not sure how it would actually trail/ crawl as I just got the gf the blazer for us to go out and do some trailing.

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[TooOldForThis]

How has the long term been?

No issues yet, but it hasn't seen a lot of use. It's currently boxed up in preparation for a move :sad:

 

[TooOldForThis]

It's the spontaneous 4 year update absolutely no one asked for!

It hasn't seen heavy use but it's held up great to crawling, trail running and light bashing. No breakages to report.

The main "problem" with this truck was that it didn't have a name, because every proper monster truck really needs one. I wanted something military themed that was over-the-top, and settled on maybe the most offensive reference possible? I don't know, it was either this or something like "Sarge" and that just wasn't doing it for me, and the fact that all of my scale monster trucks have ended up with themes about brutal death is something I'll leave for my therapist to sort out :mrgreen:

I also went around sanding and chipping the paint off around the edges to add to the weathering effect and help blend in various scrapes from roll-overs.

But the most interesting thing (and my reason for posting) is the experience I've had with different power systems:

1. It started out with the stock 550 motor on 3S, which worked well enough but got a little too hot at times and didn't have the best top speed.

2. Then went in a Hobbywing AXE 2100Kv system. This had plenty of power and speed on 3S and obviously crawled well, but there was a weird delay with fast throttle inputs that I wasn't able to tune out in the ESC settings. So this was the best for crawling but the worst for bashing.

3. Next I tried a Hobbywing 1080 ESC with a brushed 775 motor similar to what comes in a Traxxas Summit. This had incredible torque but the top speed wasn't great. On 4S with the tallest possible gearing this might have been the winner, but before going that far I wanted to try something else.

4. Drumroll please...
​

:lmao::lmao::lmao:
That there is the brushed 570 motor out of an Arrma Infraction Mega. I'm running it on 3S with stock gearing and it's FANTASTIC. Great torque, great speed, no heat issues. It doesn't have the best startup/low-speed control but you can still crawl with it well enough and for a monster truck it's a reasonable trade-off. And it's cheap! The blasphemy of powering a Traxxas with an Arrma motor is just the cherry on top.

In summary, TRX-4 monster trucks are awesome jack-of-all-trades R/C's and everyone on this forum needs one! Many trucks have come and gone from my small collection over the last few years but this one is a permanent fixture.

 

[Ross413]

Thanks for updating this.

My local shop has been having a few Monster Truck comps and I have a spare set of TRX4 axles... May have to see what can be done with that.

 

[tigris99]

I'd have never seen this without the update, that's cool!!! Not big on monster trucks myself but that are badass and seeing a nice, custom scale looking version makes it even sweeter. Used to always be the known based off the 1:1s mostly. Something with person touches and uncommon body, heck ya great work!!!

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[Ross413]

How did the axle widening kit work out? Are there any other ways to widen the TRX4 axles?

 

[TooOldForThis]

How did the axle widening kit work out? Are there any other ways to widen the TRX4 axles?

They worked out good, I thought the longer axles might bend but the metal must be decent quality because they're still straight. There's no other widening options I'm aware of, except for those long generic hex extensions but I don't have a lot of faith in them.

 

[TooOldForThis]

Like all good trucks, this one keeps me wanting to try out new ideas. Lets give these +17mm hex extension kits by GPM a shot.

They only measure out a couple millimeters wider per side than the extension kit I already had on there, so it probably wasn't worth doing. I didn't need clearance or anything, I just wanted "more big" :mrgreen:. If you're wondering how the scrub radius on the steering is doing with all this extra width, it is, uh... not good. But that's life when you try to go as wide as possible on stock axles.

Next up, tires. During the holiday sales last year I picked up this set of JConcepts 2.6" dually Fling Kings, which were on my bucket list since they came out.

It's a cool look but the smaller size is actually pretty noticeable compared to the original Firestorms, and because the theme of this truck is bigger=better, they probably won't stay on.

So no major wins to report this time (unlike the 570 Arrma motor from earlier, which continues to be really good) but I have at least one more idea in the works for this guy.

 

[350TacoZilla]

Just a question but have you bashed on the truck at all with the clod diameter tires on it? Just wondering about the dependability of the TRX axles and such with bigger tires and I presume some speed & air time lol. I'm really tempted to build one using a K10 or F150 high trail as starting point but the cost to get into it would mean selling pretty much all my current RC trucks (and few projects) so I don't want to end up with something that can't take some bashing here and there but I don't do outright abusive stuff (skate park jumps\ hit curbs and that BS).

You and other have touched on widening the axles, I think it would be neat to see a axle housing that took 2 front long side shafts to widen it while allowing use of stock parts along with easy conversion to 4 wheel steer.

 

[TooOldForThis]

Just a question but have you bashed on the truck at all with the clod diameter tires on it? Just wondering about the dependability of the TRX axles and such with bigger tires and I presume some speed & air time lol. I'm really tempted to build one using a K10 or F150 high trail as starting point but the cost to get into it would mean selling pretty much all my current RC trucks (and few projects) so I don't want to end up with something that can't take some bashing here and there but I don't do outright abusive stuff (skate park jumps\ hit curbs and that BS).

I've scale bashed it, basically the kind of jumps and crashes you see during a Trigger King race. Note that I said "race" and not "freestyle", because some of them go really big in Trigger King freestyle and that's not what I do.

It all depends what you want to do with it. From crawling to medium speeds and medium jumps, the TRX-4 should be very reliable. But if you're not going to crawl and want to do higher speeds and bigger jumps, it would be better to start with a more purpose-built platform like the LMT.

On a related note, the driving experience between the two is very different so that should factor into your decision as well. The monster TRX-4 still mostly feels like a trail truck (bouncy and awkward at speed), but an LMT feels completely different with lots of weight transfer and better handling.