New MT410 - 'stock', second kit build

[pache]

The postie dropped off my ESC/Motor combo, pinions & servo horn today so that's all the parts except for a bodyshell & paint. Which might take a while because apparently standard Tamiya PS paint is an endangered species in Oz - hazardous materials shipping rules make it awkward to import spray cans... so unless I crack & buy an airbrush - or decide to paint it pink & mustard - the shell will have to wait for a few weeks.

Thankfully I should have plenty to keep myself occupied with the chassis & electrics.

This'll be my second build & second car since I was a juniorburger (had a Turbo Ultima as a kid - refreshing that will be a project for the future). Over lockdown I got back into the hobby with a TRX-4 Sport Kit which has been a lot of fun & is a great vehicle... but a logical next step seemed like something with a little more grunt & bounce - enter the MT410.

So now I've turned the new shed's bench into RC space & got all the gear to get round 2 rolling... first tho, I'll need to finish Step Zero:

...work out how to fit the kit on the workbench with all the other stuff


PS. Aiming to take my time & enjoy the process while going pretty "safe" and stock initially:
Tekin RX8 Gen 3 ESC with Tekin Redline T8 Gen 3 Truggy 2000kV motor
PowerHD Storm S35 servo (capable of 8.4v but running it via the ESC at 7.4v, so at that it claims 30kg/cm (416.6oz/in) and 0.075 sec speed)
Arrma Backflip LP 4s
4s LiPo (5000mA 50c)
FlySky FS-GT5 radio & matching receiver
Tekno's aluminium servo horn & I've got Tekno 15, 17 and 19 pinions to experiment with for now..

Other than some Associated Green Slime for shocks, I'll start off with the kit's own grease & oils.

Currently no motor fan/cooling but that's likely to be my first upgrade.
I find modern truck looks boring so I'm considering saving my experimentation for a non-standard bodyshell when I get that far (tho there is that HPI '67 Pontiac GTO...)

 

[Cheez]

I’m also going strictly stock to start with ( even servo arm) I’m curious to see how it holds up. If something breaks that’s when it’ll get upgraded. I want to start out light as possible.

 

[pache]

I've been contemplating a bit how I do this build thread considering most of the folks on this forum are vastly more familiar with these kits & the build process than I am. Plus obviously there's the question of what I find interesting as well as just the audience.

So I'm currently planning on aiming this more towards other first-ish time (Tekno) builders, or potential builders, and I might be a bit too painstaking for those with experience. Or you might enjoy seeing it with fresh eyes again, whatever.

Considering the manual is freely available on the product page, the company probably regards it as fair use so I might do a few compare & contrasts of reality-vs-diagram too.

Speaking of which.. Bag A unpacked (plus grease ):

Which also provided the first lesson - the parts numbers are actually package numbers, not individual parts.. note that the metal bevel gears marked TKR5150 are two different sizes of gear. So it is pretty clear what's what, but you're not going to want to zone out & go into autopilot at any point.

Didn't get photos of sticking the outdrive (5114XB) into the case/rings (greasy fingers), but I did learn you're better off greasing the O-ring's groove first... and that it's fortunate I had toothpicks lying around cos the threadless fixing bolt under the gear is very precisely sized:

Which then led to my first time filling an oil filled differential case. Hello Bubbles:

At this time the advice from assorted youtube videos about "it's a good idea to wait 24 hours" was starting to seem very appropriate... so rather than try to finish off Step A, I figured I was better off getting Step B rolling and getting the front & rear differential cases filled with oil too, cos they're close to the same thing all over again:

I stuck with the stock oils as suggested - 100k in the centre and front, and 50k for the rear.. all the materials in Bag B seem identical so the diff I did last got to be the rear. There's enough 100k oil for two differential cases but you wouldn't want to spill any... there was very little excess. That said it floooooows soooooo slooooooooowly that it'd probably take 5 minutes to spill it. When pouring you need to aim at un-filled bits of the case & I started leaving the bottles (sealed) upside down when I was checking the overall fill level, so they'd flow out a bit quicker when I continued... and my second & third attempts at pouring oil were decidedly less bubbly

With all three cases filled, and the front & rear cases marked on the outside with chalk so I know which is which, they all got plastic cups to shelter them from dust & a 24 hour holiday to settle while I get to continue hurry-up-and-waiting

PS. The things they're sitting in are sprinkler system fittings & the tray's an old icecube tray I use for holding screws... the advantages of hoarding junk

 

[pache]

Falling a bit behind on the writeup - strangely enough I've been using spare time to build instead of write about building (crazy talk, I know).

I've definitely come to the conclusion that the kit has a certain level of assumed familiarity, however I think it probably would be doable for a complete first timer. It definitely seems a lot less crawler-truck and a lot more racing-buggy-in-disguise. Haven't got up to shocks yet, but the oil filled diff has been the biggest problem (albeit not the thing that's slowed me the most).

At the start of day two, my three oil filled diff casings were all nice & bubble free.

At which point I remembered the assorted youtube videos I'd watched on diff maintenance - including a great one on tekno's own channel (

) - and it became clear that the manual's instructions on how to close the diff weren't actually as useful as random internet videos...

So I started by dumping.. err.. carefully placing... the final gear into the oil (with only a coffee break for bubble reduction this time...)

What happened next with the centre diff (left most in the pic above - they're centre, front & rear) pretty nicely summarises why Step A4 is a technically accurate but not very useful description...

I'd thought to deal with the gear in advance, but hadn't bothered thinking about the paper(?) washer, which promptly fell off the moment I went to get a mesh... not really a problem but another good reminder not to just follow the manual uncritically. However that was the last hurdle before I ended up with a nice, functional & only slightly overfilled centre diff:

But don't worry there's still plenty of room to stuff up the front & rear diffs

Because the large casing/gear piece on the front & rear diffs is both smaller & more solid, the paper washer fits extremely tightly so just tamping it down tends to end up with the holes out of position. However a couple of allen keys lets you twist them back into perfect alignment:

The fit of the oil-filled-casing and the gear/casing is also vastly tighter which makes snapping them into position together a bit awkward.

I got both on & locked down, spun the gears aaaand...

... one side of the front diff didn't cause the other to spin. Spinning all the other ends would cause their counterpart to turn, but the front diff only worked in one direction. Manual doesn't specify check-your-work type processes at the end of each step, but even I know enough about diffs to know that's not right.

So front diff got reopened. Diff oil got everywhere. And diff oil of the variety that we were barely given enough of in the first place... and the problem was revealed:

Like I said, the gear/casing segment on the front/rear diffs is a tight fit.. so in the process of wriggling it into place, and given that I carefully didn't over-grease the thing, the locking bolt must've slid out of position... slightly surprised it was still rotating in one direction, but presumably it was off angle but still with a bit of mesh.

Got the bolt back into position, topped back up with nearly the last of my 100k oil, got it down with a properly even seal this time (oil everywhere at least helped getting the case back together...), and one moderately slimy front diff resulted:

Nothing that isopropyl alcohol couldn't solve. Love that stuff.

Unfortunately from here out we get back to more boring same process as a basic tamiya kit type stuff for a while, so there's less opportunity for entertaining screwups.

Although I did enjoy the way, after puzzling through dealing with viscous planetary diffs (i think?) for the first time, the next step promptly had me applying threadlock to a tiny grub that's right next to ball bearings. Gotta make sure we're still paying attention

Starting to wonder if they've given us enough grease for everything either, but I'm potentially over-applying it and it's not like it's difficult to get more grease...

I will say, I love the quality of the parts in this kit. The whole thing is beautifully engineered. This is just one damn gorgeous looking gearbox:

That's not to say that everything is "perfect" - this is results oriented precision. For example on the gearbox itself, the moulding remnants on the outside are trimmed but there would be room for (purely cosmetic) improvement... but on the edge where it actually matters to the seal/function of the gearbox the finish is absolutely perfect, and I actually like this more than if it were all "perfect":

I will also say that I think Tekno probably knows their standard clientbase.

I could absolutely have gone for a little more hand-holding on the liquid diffs... but in Steps C and D there are big warning panels highlighting the differences between the front & rear bulkheads.

The two bulkheads are in completely different packets. The only way you get them confused is if you open multiple packets at once & get the pieces mixed up. Or if you get them mixed up post-construction & changed the default oils so you can't feel the difference between gearboxes by just spinning the exposed diff ends.

But I'm guessing they figure most of their customers are more familiar with these style of cars, and more inclined to rush in without reading the instructions anyway... probably a fair assumption tbh

For reference, here're my completed front & rear gearboxes...

OK, did do a bit more my second day... but honestly I could be continuing to build the truck rather than going through this in painstaking detail. So while I do find this sorta meta (over) analysis interesting, I think I'll leave the rest of it for later & go back to building for now...

Really loving this kit already. Been just what I was hoping for.