3906 EMAXX - Couple Questions

Although not considered a traditional monster truck, they still have monster coolness.
Want to see your truck featured on the home page? Enter our monthly contest in the general discussion section!
Forum rules
Want to see your truck featured on the home page? Enter our monthly contest in the general discussion section!
Post Reply
User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

3906 EMAXX - Couple Questions

Post by matt1ptkn » Tue May 22, 2018 12:37 pm

Darn things are multiplying on me. :lol: I now have 2 of the 3906 Emaxxes with the wide maxx suspension. Still tweaking both of them in an attempt to make them more controllable. My 1st one with the Novak brushless is almost there. I changed out the original Traxxas steering servo for a Hitec, so I will see how it goes. But I have some general questions.
1. What is a good servo saver (SS)? I have one with the original Traxxas SS that seems ok, but on the other I have tried HD versions of Vaterra, Associated and Tamiya with little luck. They have been either not strong enough or just have too much slop. Is a SS even still recommended on the servo or does the stock steering system have one built in?
2. The EVX-2. I'm using an older version of this ESC with twin Titan 12T motors in one truck. In order to get everything to work properly, I have to wire the motors backwards. Otherwise, the brake works when going from reverse to forward, and not when going from forward to reverse like it should. I've calibrated the ESC with the channel polarity switch in both positions numerous times and tried reversing the switch after calibration, always with the exact same result. Do the 12T motors have the timing reversed from the stock Titans that were used in the truck? This is just weird to me.
3. Gearing - I am currently running 14 tooth, 32 pitch pinions with a 66 tooth spur and the motors seem to be heating up too fast. I planned to try out 13 tooth gears, but I may try just running it in low gear more often first (I still use the 2 speed transmission shifting). Anyone have suggestions for the optimum gearing for this configuration?

P.S. Why does the spell check tell me that I spelled Traxxas wrong? And when I click for suggestions, it suggests "Trash"? :roll:
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

ratpower396
Approved Member
Posts: 132
Joined: Mon Feb 13, 2017 6:14 pm

Re: 3906 EMAXX - Couple Questions

Post by ratpower396 » Thu May 24, 2018 1:12 am

kimborough heavy duty servo saver is the ticket for your servo saver issues. The gearing depends on how and where you are driving. deep sand or tall grass is going to heat things up. The 12t motors are different than the stock emaxx motors so the heat could be because of them being 12t motors as well the factory motors were 23t 550 sized motors. A pair of rc4wd 20t motors would be a nice replacement motor for the truck even though they are 540 sized. Ebay is a good place to find your pieces the motors are about $10 each and the servo saver about $10.

https://www.ebay.com/itm/Kimbrough-Larg ... 8882!US!-1

https://www.ebay.com/itm/RC4WD-540-Craw ... SwLF1X7BZY

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Thu May 24, 2018 11:11 am

Thanks for the links! That servo saver does seem to fit the bill. It will likely be my next purchase. I'm running the 12T motors simply because I had them already. Same with the pinions. Figured it would all make for a good starting point.

Edit: Just found this on Traxxas' website:
"NOTE: Titan 12T motors are intended for use in single motor and single battery pack applications, up to 8.4 volts. Traxxas does not recommend the use of Titan 12T motors in dual motor vehicles, such as the E-Maxx, Villain, or Villain EX." #-o
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Thu May 31, 2018 10:35 pm

I'm going to have to swap out to different motors. The Titan 12Ts just get too hot. I think I'll try a pair of 27T brushed motors next. I also recently noticed that the front of this Maxx is actually toed out a few degrees. I'm hoping once I reverse it to toe in, it may be more stable. Anyway, here's a couple photos of the twins. 8)
Attachments
IMG_0471.JPG
IMG_0469.JPG
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Mon Jun 04, 2018 5:24 pm

I swapped out the 12T Titans over the weekend for a set of 27T vintage brushed motors. Just holding it in the air and running it for a minute caused one of the motors to get hot. But only one. I assumed that motor had a problem. Cut the comm and added new brushes, still gets hot fast, while the other motor does not. Both motors work, exact same make/model motor and the drivetrain is free and spins smoothly, though there is some heavy fluid in the diffs. Swapped to another set of 27T brushed motors. Both motors work, both are the exact same motor. But the motor in the same position as the previous hot motor is also getting hot, while the other stays relatively cool. Is this a typical trend with a dual, brushed EMaxx with an EVX-2 or am I overlooking/doing something wrong? Note: I'm running dual 3000 mah, 6 cell NiMhs.
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Tue Jun 05, 2018 11:36 am

I think this used EVX-2 is crap. Bench tested for 2 mins., after double checking the wiring with the manual and checking the gear mesh and both motors went up in smoke. Went from cold to warm in about 1.5 min, then both smoking within another 30 sec. :( I prefer to keep this one brushed, so I think its time to break out the Super Rooster.
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Wed Jun 06, 2018 11:28 am

Just in case anyone is following with interest, I tried something yesterday. I put new 27T motors in the EMaxx but only put a pinion on one. Bench tested and ran both motors still, but only one powering the truck. Obviously the one powering the truck got hot and the other not. Swapped motors and same result. Double/Triple checked mesh and drivetrain, all perfect. Tested the voltage going to one motor: 15.7 volts, the other motor was the same. Checked the voltage to the motor on other brushed systems with one battery/motor. 7.6 volts. Hmmmm... So the EVX-2 combines the batteries in series and puts all that power to each motor. From reading on Google, this is normal. So my questions is, what kind of motors can last with this kind of power? I know about the 775, DeWalt and KO motors, but that seems like too much of a hassle. I'm a simple man, :lol: . Anyway, now I'm considering just wiring it up to run off a single battery and see how it goes.
I've tried reading on the Traxxas forums, but that's like a rabbit hole. Simple questions get asked, then everyone and his brother chime in talking about big expensive motors and 4s batteries then brushless, blah blah blah. Just answer the simple question! :mrgreen: So anyone got any advice/recommendations/etc. or just stay the course? "You can't change horses mid-stream." Right?
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
andymac0035
Administrator
Posts: 11241
Joined: Mon Mar 29, 2010 9:54 pm
Location: Canaan, NH

Re: 3906 EMAXX - Couple Questions

Post by andymac0035 » Wed Jun 06, 2018 10:20 pm

You could run the pair of 27t motors off of a single 3 cell and they might be okay, but a single 2 cell would be safer. I run my clod on a pair of 27t and 3-cell, but my gearing is a lot lower... 30:1 for a stock clod vs 20:1 for an e-maxx.

Your best bet is to run the "monster" traxxas titan motors (21T), or if you can find them, the HPI 550 motors are nice.

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Thu Jun 07, 2018 7:36 pm

Thanks for the suggestion. Horizon has the Traxxas motors, and I just read that the Traxxas Monster 21T motors are rated for 14.4 volts, so I can see now that they *should hold up with 2 x 2s or 2 x 6 cell. However, I've read a lot of topics over several forums where most, if not all, people say those motors don't last very long. I *think I'm going to try running 2 x 6 cell in parallel (so still 7.2 v) and jumper the one plug. I'll have plenty of run time and a balanced chassis, just 1/2 the power. :?
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
andymac0035
Administrator
Posts: 11241
Joined: Mon Mar 29, 2010 9:54 pm
Location: Canaan, NH

Re: 3906 EMAXX - Couple Questions

Post by andymac0035 » Fri Jun 08, 2018 2:01 am

I had good luck with mine, I think some people just abuse motors and complain when they go up in smoke.
The way you want to run it, I'd put the 12T 's back in there and use low gear. :)

User avatar
matt1ptkn
Regular Member
Posts: 91
Joined: Tue Jan 24, 2017 3:13 pm
Location: Moundsville, WV

Re: 3906 EMAXX - Couple Questions

Post by matt1ptkn » Wed Jun 13, 2018 11:23 am

So, 1st attempt running in parallel was a bust. Not for reasons you might think, but because one of the motors was apparently already past the point of no return. So I was running off the power of one motor, which was fighting to turn the other motor into a generator. So, I'm now in the process of cutting more comms while I wait for my bags of brushes to be delivered. For a few dollars more, I probably should have just bought the Traxxas motors. #-o
-Matt

My Trucks

"I wish there was a way to tell you're in the good old days, before you've actually left them."

User avatar
R Cane
Approved Member
Posts: 116
Joined: Wed Apr 27, 2016 9:54 pm
Location: north central Ohio

Re: 3906 EMAXX - Couple Questions

Post by R Cane » Mon Jun 18, 2018 4:26 pm

Interested to see where you end up with this, Matt.
I ran my 3906 a lot, until racing around my brother-in law's pond, I got clipped by another truck and did a barrel roll right into the water. Fried my 'lectronics.
Still trying to decide which ESC/motor combo to go with...
Please keep this updated with your results!
:)

Post Reply
Users browsing this forum: No registered users and 4 guests