TRX4 Tow Rig advice needed

[high plains drifter]

Time once again to pick the brains of those experienced with this topic-

I've recently gotten a trailer and will be using my TRX4 Defender to tow it.

TRX4 has the original XL5 ESC with a HH Trailmaster 550 21t and running a HH shv500 v2 if that matters. This rig will be pulling IMO a lot of weight... Trailer is little over 4 lbs and with a 6+ lb Capra on board, that's approx 10 lbs for the TRX4 to pull.

So... What should I do to insure that the TRX4 tow rig will perform at it's best and/ or what should I be concerned about? The stock ESC has been surprisingly reliable in this rig but wondering if it might have issues pulling this much weight around? Also wondering if the Trailmaster 21t should be sufficient and if not... what advice is there regarding a motor upgrade? Lastly I'm wondering about the gearing. Running the stock 32r/ 11p gearing right now. Not sure if there's a better motor and/ or pinion combo out there that would be better. The TRX4 is pretty heavy already fwiw.

Thanks very much in advance. I want to make sure that any potential weak points or sure fire failure points are addressed before heading out to the trails with this Defender tow rig.

[OnTheTrail]

Do you plan to just trail drive this set up till you get somewhere to unload the Capra? If so, then I'd just go down to a 9T pinion gear (smallest you can go with if I'm not mistaken....maybe 10T???) then just trail tow in low gear on the Defender.

If you plan to try to muscle the trailer and Capra up some serious hills, then you may need to do more. Frankly, I'd just do the 9T and run it and see what happens.

Think about the recent flatbed hauler they just came out with. Very large heavy and designed to haul an RC car on the bed. Don't think they modified the drive train and it seems to be holding up just fine.

Either way, share some photos!

[high plains drifter]

Thanks for the quick reply.

My intentions are to only use the Defender to tow along mild terrain... like you said, trail-drive to the rocks to unload the Capra. may encounter some mild hills and small obstacles along the way but I'm def not looking for the Defender to try to pull around the loaded trailer on any serious uphill climbs and absolutely not going to hit the rocks with it.

My main concern has been with the ESC heating up although not sure my concerns are valid. If I did replace the ESC it would be with a HW 1080wp but as usual, I'd rather not just throw money at this set-up if it can be avoided.

I've got a thread ongoing here on RCC where people are discussing 9t and 10t pinions ( although for a Capra) and I'm wondering if some of the concerns that I've read about on there as well as in some other threads might present issues. I'm not doubting your advice but I guess for example, I've read that to get good gear mesh with a 9t pinion, that it may need the teeth filed down. No idea if that's true but my understanding is that a pinion that small could present problems in certain applications. I hope you're right though... Swapping out pinions would be the cheapest mod for sure!

I laughed when reading your suggestion of the flatbed... I showed that to my wife before purchasing the trailer and wow... I've never seen her change the subject so quickly haha! It's just too much money to throw at the hobby at this time although I appreciate the suggestion... I'd love to have one. But I look forward to using the trailer too... to add another dimension to the handling, challenges, etc of trailing.

I love taking pics so I'll definitely do so. Thank you again.

[AK KRAWLER]

Originally Posted by OnTheTrail

Think about the recent flatbed hauler they just came out with. Very large heavy and designed to haul an RC car on the bed. Don't think they modified the drive train and it seems to be holding up just fine.

Originally Posted by high plains drifter

I laughed when reading your suggestion of the flatbed... I showed that to my wife before purchasing the trailer and wow... I've never seen her change the subject so quickly haha! It's just too much money to throw at the hobby at this time although I appreciate the suggestion... I'd love to have one. But I look forward to using the trailer too... to add another dimension to the handling, challenges, etc of trailing.

I believe he was saying to look at the Traxxas TRX6 Hauler from a design, build and functionality standpoint, not necessarily for you to look at buying one.

[DrIsotope]

The mechanicals of the TRX-4 shouldn't care about pulling 10lbs. As you're concerned about here, the weak link will be the XL5. Could be fine. Might just one day let the pixies out.

So as others have said, throw a nonagon in there, and don't try tackling any hills in 2nd with the trailer attached.

[ScaleLifeNewbie]

Originally Posted by high plains drifter

I've got a thread ongoing here on RCC where people are discussing 9t and 10t pinions ( although for a Capra) and I'm wondering if some of the concerns that I've read about on there as well as in some other threads might present issues. I'm not doubting your advice but I guess for example, I've read that to get good gear mesh with a 9t pinion, that it may need the teeth filed down. No idea if that's true but my understanding is that a pinion that small could present problems in certain applications. I hope you're right though... Swapping out pinions would be the cheapest mod for sure!

I have no experience with the Capra, but I had 9/45 gearing I my TRX4 for a solid 5-6months of hard abuse and it was no problem at all. Bound up so tight I thought something would explode. So I’d say as long as you swap to their 45T Spur you’ll be golden.

You seen the abuse the truck got lol.

[high plains drifter]

Originally Posted by AK KRAWLER

I believe he was saying to look at the Traxxas TRX6 Hauler from a design, build and functionality standpoint, not necessarily for you to look at buying one.

Oh... lol. Gotcha. But I did try to see if the hauler idea combined with puppy-dog eyes might bring a resounding "Oooh! Buy it! It's so cool and it's just the thing that you need!". Man, was I barking up the wrong tree.

Originally Posted by DrIsotope

The mechanicals of the TRX-4 shouldn't care about pulling 10lbs. As you're concerned about here, the weak link will be the XL5. Could be fine. Might just one day let the pixies out.

So as others have said, throw a nonagon in there, and don't try tackling any hills in 2nd with the trailer attached.

I appreciate the advice. I may throw a 1080 in there just to be on the safe side. The thought of trying to carry a 4 lb trailer plus a Capra and a TRX4 back to the trail-head does NOT appeal to me lol.

[high plains drifter]

Originally Posted by ScaleLifeNewbie

I have no experience with the Capra, but I had 9/45 gearing I my TRX4 for a solid 5-6months of hard abuse and it was no problem at all. Bound up so tight I thought something would explode. So I’d say as long as you swap to their 45T Spur you’ll be golden.

You seen the abuse the truck got lol.

I'm good on my Capra right now. But yeah with me using the TRX4 as a tow rig it's good to know that a 9t pinion worked well. If I keep the stock spur which I'm planning on, then that would be a 9t pinion, 32t spur, and a Trailmaster Sport 550 21t.

Yeah... You definitely beat the crap out of your TRX4 haha.

[ScaleLifeNewbie]

Originally Posted by high plains drifter

I'm good on my Capra right now. But yeah with me using the TRX4 as a tow rig it's good to know that a 9t pinion worked well. If I keep the stock spur which I'm planning on, then that would be a 9t pinion, 32t spur, and a Trailmaster Sport 550 21t.

Yeah... You definitely beat the crap out of your TRX4 haha.

I don’t have a trx4 on the bench anymore to look at, but I don’t think a 9T will work with a 32T Spur. IIRC, the smallest you can go with is an 13T, maybe a 12T. I ran 13/39 for a little while before swapping to 9/45. It was a little slow on the Fusion 1800kv, so if you do swap to 9/45 maybe something in the 2300kv range would be best. I’m not exactly sure what that comes out to in turns so I don’t want to spew out random info.

[high plains drifter]

Originally Posted by ScaleLifeNewbie

I don’t have a trx4 on the bench anymore to look at, but I don’t think a 9T will work with a 32T Spur. IIRC, the smallest you can go with is an 13T, maybe a 12T. I ran 13/39 for a little while before swapping to 9/45. It was a little slow on the Fusion 1800kv, so if you do swap to 9/45 maybe something in the 2300kv range would be best. I’m not exactly sure what that comes out to in turns so I don’t want to spew out random info.

Okay... Thanks for that. I'm not going to change out the spur so for now it looks like I'll just stick with the 11t, stock spur, and Trailmaster 21t and maybe upgrade the ESC.

Appreciate the help, SLN.

[DrIsotope]

The stock spur in the Defender is the 45T. Well, the stock spur in any TRX-4 with a 2-speed. The 39T is for the Sport. And when you get a Sport, the very first thing anyone should do is put in a 45T and throw the 39T away.

[high plains drifter]

Originally Posted by DrIsotope

The stock spur in the Defender is the 45T. Well, the stock spur in any TRX-4 with a 2-speed. The 39T is for the Sport. And when you get a Sport, the very first thing anyone should do is put in a 45T and throw the 39T away.

Dunno why I was thinking otherwise. I'll be sticking with the stock 45t spur and 11t pinion.

[austin-92]

I pull 15-30 pounds worth of kids around the house with with my scx10 lol. I’m sure a trx4 will do just fine with 10lbs


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[OSRC]

Right there with you bud:



Mods:
Heavier springs in the rear to support the weight
Reinforced rear bumper/toe hook
Holmes outrunner (for torque) and 9/45 gearing
Incision metal driveshafts to replace the plastic

That's about it...not overly worried about the mechanicals, they should hold up fine.

I'd run your stock stuff until it fails. Just keep an eye on temps if you can, motor and ESC are going to be working pretty hard.

[high plains drifter]

Originally Posted by austin-92

I pull 15-30 pounds worth of kids around the house with with my scx10 lol. I’m sure a trx4 will do just fine with 10lbs
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Oh man... lol. I wasn't expecting that kind of testimonial. That's awesome!

Originally Posted by OSRC

Right there with you bud:

Mods:
Heavier springs in the rear to support the weight
Reinforced rear bumper/toe hook
Holmes outrunner (for torque) and 9/45 gearing
Incision metal driveshafts to replace the plastic

That's about it...not overly worried about the mechanicals, they should hold up fine.

I'd run your stock stuff until it fails. Just keep an eye on temps if you can, motor and ESC are going to be working pretty hard.

I appreciate reading what you've done. Sounds like you turned it into a real workhorse.

I considered heavier springs and I think I'll do that.

I'll make any mods that I can to reinforce everything around the trailer and tow rig hitches/ mounting points. I also want to make sure that any frame twist is minimized.

I won't be able to afford an outrunner so I'll just keep my fingers crossed with the Trailmaster that I'm already running.

I've already replaced the plastic driveshafts with steel. They're seemingly very strong although I don't remember what brand they are.

[OnTheTrail]

Originally Posted by AK KRAWLER

I believe he was saying to look at the Traxxas TRX6 Hauler from a design, build and functionality standpoint, not necessarily for you to look at buying one.

Yes, sorry for the confusion. I was just referencing the robustness of the drive train that's the same with the TRX-6 and the TRX-4.

[HumboldtEF]

That longer wheelbase should work to your advantage but the rear weight bias will hurt you a little (if its stock). Some extra weight up front (knuckles/portal covers) would be helpful to keep th efront end on the ground.

I did some towing a few years ago and on anything but flat ground it was a challenge (big trailer towing a Gom or 2.2 Wraith). On anything too steep the rig would want to wheelie.
I kind of gave up on towing and just strap the extra rig to a backpack now.

I had one video with some towing if you were interested to see it struggle a bit (at the beginning and end of the video). https://www.youtube.com/watch?v=nVy5p5Qhijk

[high plains drifter]

Originally Posted by OnTheTrail

Yes, sorry for the confusion. I was just referencing the robustness of the drive train that's the same with the TRX-6 and the TRX-4.

Naw... my bad. I'm not the best at comprehension sometimes. But like I said, I really was looking at a flatbed before landing on the trailer idea despite buying one wasn't what you were suggesting.

Originally Posted by HumboldtEF

That longer wheelbase should work to your advantage but the rear weight bias will hurt you a little (if its stock). Some extra weight up front (knuckles/portal covers) would be helpful to keep th efront end on the ground.

I did some towing a few years ago and on anything but flat ground it was a challenge (big trailer towing a Gom or 2.2 Wraith). On anything too steep the rig would want to wheelie.
I kind of gave up on towing and just strap the extra rig to a backpack now.

I had one video with some towing if you were interested to see it struggle a bit (at the beginning and end of the video). https://www.youtube.com/watch?v=nVy5p5Qhijk

I opted to use the Defender for towing rather than my Bronco simply due to the longer wheelbase. Plus my Defender has plenty of added weight. Front end is pretty heavy and if necessary, I can always add a little more weight to keep the wheelies in check.

I'll be running .61/ blue springs on the rear along with a 1080 esc, a TM Sport 21t, shv500v2, 3S, steel driveshafts, f/r chassis braces, portal covers, c-hubs, and a few other things that'll hopefully equate to reliability as a tow rig. I'm actually looking forward to some challenging driving as long as I don't run into any major issues.

I appreciate hearing your thoughts and experience on this, so thanks for that. The wheelie thing has been a concern of mine from the get go. We'll just have to see how it goes.

BTW- That video was a lot of fun to watch... breathtaking views, endless lines... rock crawling paradise. As far as the hauling part of the video, I'm not planning to tackle anything that gnarly but it's good to see scenarios like that to keep my expectations realistic.

[austin-92]

Originally Posted by high plains drifter

Oh man... lol. I wasn't expecting that kind of testimonial. That's awesome!

It pulls the front left wheel on carpet with the 6 year old. Rear is under driven, HH crawl master 13 turn and HW1080. Think I’m running a 8t pinion though, only does like 6mph wot. Everything has held up ok though, gotten warm but not extreme.


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[OSRC]

Originally Posted by high plains drifter

I opted to use the Defender for towing rather than my Bronco simply due to the longer wheelbase. Plus my Defender has plenty of added weight. Front end is pretty heavy and if necessary, I can always add a little more weight to keep the wheelies in check.

Exact reason I chose mine too...I started outfitting a sport, but the WB convinced me to switch. Glad I did, my truck so far doesn't show any wheeling tendencies. I think it's also the tongue load as well, if your trailer puts a lot of weight on the hitch, you'll pull the front wheels. My trailer sits level w/o being hooked up when loaded, so I think that helps.