Tamiya eTNX

[Janezki]

Since I have always been a big fan of monstertrucks, I wanted to get one again after my earlier XRay project was finished.
From the start it was clear that it was going to be a conversion project and somehow I got my mind stuck on HPI Savage, either the X SS or the new XL.
(un?)Fortunately I stumbled upon a Tamiya TNX 3.0 roller at local bidding site. The car pleased my eye and I started to gather information from it. From what I read from different sites and looked all the pics I could find, I came to the conclusion that this could be pretty good base for my project. So I made the winning bet and the deal was done.
I ordered TeknoRC motor mount and started to plan the general layout.



At first I was little excited and unsure from where I'd get spares for my new purchase, but when I got the car into my hands I instantly noticed the similarities with the a-arms & suspension between E-Maxx & TNX. I read that someone had used Maxx's a-arms on TNX so I ordered a full Maxx suspension setup, 3.3 driveshafts and got a very nice deal from a set of Traxxas Big Bores from liquidRC.
I also needed new internals for both diffs, new center driveshafts & joint cups (had a lot of wear) and new brake disc as I was going to keep the mechanical brake. Earlier owner had modded a Revo spur to the 2-speed tranny, so I let that stay for the time being. If it doesn't hold up with the original slipper, I'll just drop in a Revo slipper & axle.
It became soon obvious that I needed to flip the tranny to make space for lipo at the rear, since there wasn't enough room elsewhere to put it.
As the transmission has two gears with hook style (centrifugal) clutch and one way bearing, it meant that I had to flip the diffs too or else I'd have a two speed reversing truck...
Flipping the tranny & diffs was a piece of cake, so the motor mount found it's place too. Motor is the HobbyCity cheapo B36-74-09XL with 1900kv. Battery tray is made from 2mm aluminium plate and bolted to the chassis with four 3mm countersunk screws. I also got excellent deal from 5pcs of slightly used Losi Aftershock wheels & tires, which are really huge!



Installing of the Maxx suspension was pretty straightforward, only the lower a-arms & mounting point to bulkhead had to be modified.
Lower a-arm bulkhead mount needed to be widened by 7mm to make the a-arm fit and the a-arm itself needed to be shortened from outer end by 3mm, pivot ball mounting hole drilled a bit deeper to get the camber angles correct and the holes from which the bulkhead pin goes through drilled to 3.5mm.
Traxxas 3.3 driveshafts were a straight fit to diffs, so no mods there.



I was planning to use Lutach's LT-6S-150A controller on this project, but did't find reasonable place to put it. Could fix a mounting plate to the rollbar maybe. So for the time being this will run with Mamba Max sitting on a plate attached to the motor mount.



Now the car is ready, but I haven't had a chance to drive it yet, because of the constant raining for two days. Today seems to be turning sunny, so maybe if the ground gets dry enough I can have a try...



More project pictures can be found from here

[DRIFT_BUGGY]

Well done, one of the first brushless TNX's ive seen. I haven't been able to drive my buggy for 1 month now from all this rain

[BL_RV0]

Looks great. You should add some colour to the wheels though.

[Janezki]

Thanks. I had those Velocitys with Big Joes about a year ago in my E-Maxx and they've been in storage for this whole year. Chrome from the wheels was in bad shape so I "washed" them in 80°C (176F) for 4 hours which removed chrome and old glue nicely.
The Losi Aftershock wheels & tires give the real Monster Truck-look



Managed to do the first drive today and I'm quite pleased with the results.
Cheapo motor works allright, might even gear up a bit and change the shift point to later.
Temps measured were better than I expected, motor was 59°C (138F), esc & lipos (emptied two 4S 4000mAh packs) were hardly lukewarm.


Short clip with poor quality can be seen here:

[BL_RV0]

Is that the HobbyCity XL motor?

[Janezki]

Yup, B36-74-09XL - 1900kv

[DRIFT_BUGGY]

Looks sweet with the Losi Wheels, vid pretty good aswell

[ICUBoy]

Great pics and posts Janezki- does your B36 get very hot??

[Takedown]

First E-TNX Ive ever seen. Looks great!

[trev3813]

Originally Posted by Takedown

First E-TNX Ive ever seen. Looks great!

Same, Great job

[Janezki]

Thank you guys! This really isn't the most converted truck around even though the process is quite easy. Very easy actually if you keep the original a-arms & suspension.

Forgot to mention that I'm using Kimbrough servo saver. Tried the Traxxas' E-Maxx saver but it was way too loose.

I must say that I'm surprised by the performance of this cheap 1900kv XL motor, it flips the truck on it's lid with full throttle start even though I have mild settings on Mamba. Temps are more than satisfactory with low timing, after full 4S 4000mAh pack the hottest I've measured was 60°C (140F), esc & lipo were hardly warm - and some of you might know that I'm not the gentle driver...

I know that some people have had bad experiences with this same motor, but I guess the chinese quality control might have something to do with that matter...
Seems to be at it's best with 4S setup, more cells and temps will definetely rise.

[rchippie]

You did a nice job on conveting your truck . It looks very clean .

[blueb8llz]

yes, nice job and well done converting the truck. seems to have decent power as well with those bigo tires. and those are very good temps on the motor.

[Janezki]

As I suspected, the stock slipper didn't last for long. Found good instructions from Tamiya Trucks on how to install Revo slipper to the tranny. Had the parts already available so the operation was quite quickly done.
Had to move motor mount 12mm forward too.



Now that should take the beating...

[Thunderbruiser]

looks very very clean