My DT-03 for fun driving and tinkering

[BuggyDad 6377]

DT-03 build, mildly hopped up for fun driving and resilience to future ill-treatment. 

This is, aside from a stock kit built with my son just the other week (same kit), a first return to rc for me since childhood (80s), so I'm clearly not blazing a trail here but I am making a few changes to stock, generally for functional (or perhaps pedantic and making no real life functional difference, depending on your outlook) rather than blingy reasons. And so I can learn from trying/changing stuff. I studied engineering at university but never worked in it, so I've a geeky interest and (rusty) basic principles but little practical experience. I hope to get a bit more fun and a bit more learning from the build and ongoing changes and to end up with a decent "first" car. 

I thought I'd pop a thread up to keep me focused on doing a nice job of it, and in the hope someone might pipe up with things I haven't thought of. And because I'm impatient for the last bits to arrive...

Broadly my plan is:

• stainless fixings where possible
• improved suspension pivots & shock mounting ball joints (all that play annoys me)
• my first experience of brushless motor and lipo
• add weights to the front end
• add camber adjustability mainly so I can play with it and learn
• driver figure
• wheel options
• different body shell(s)

 

[BuggyDad 6377]

So far, I've done the shell:

I probably won't add any more stickers, although there might be a temptation. 

I probably will run it with a different sacrificial wing. Just working out what to go for. It seems a reasonable thing to do with a few options out there, some for as little as £3, and it'll be interesting to see what they do to the look of it.

I also have another very different shell for it, but I won't sort that out til I've got it running. 

[BuggyDad 6377]

And some shopping:

[BuggyDad 6377]

Last bit of critical shopping arrived. 

These screws have a more aggressive thread than the Tamiya ones and a coarser pitch. Whether this is better or worse I'm not sure but something that is noticeable is that you would have to apply significantly more force to strip the plastic through over tightening. The end point is very defined. 

[BuggyDad 6377]

Washers and grease in an attempt to reduce play in the suspension

Did the same in the top ones just for completeness but it's pointless there because there's so much give in the attachment points. And anyway I'll be fitting turnbuckles when they arrive. I was looking at making up my own - left and right hand threaded aluminum ball ends are available but the right length shafts I couldn't find, and then I found the Tamiya turnbuckle set could be had for a good price anyway. 

[Nikko85 3951]

13 hours ago, BuggyDad said:

So far, I've done the shell:

I probably won't add any more stickers, although there might be a temptation. 

I probably will run it with a different sacrificial wing. Just working out what to go for. It seems a reasonable thing to do with a few options out there, some for as little as £3, and it'll be interesting to see what they do to the look of it.

I also have another very different shell for it, but I won't sort that out til I've got it running. 

Nice colour. Love a green car.

[BuggyDad 6377]

Didn't do much today and what I did do is largely straight out of the manual. Build so far is otherwise stock except the stainless screws (satisfying - torx engagement is so much better plus they're a strong fix and should resist rusting at the beach) and some shims to reduce play. And thick grease in the diff. Stainless pivots and steel drive shafts not arrived yet.

So I was thinking about switch placement and moving things around a driver figure. 

Likely to go for this switch location:

Someone on here flagged a YouTube video with this switch location idea in it. It looks a bit vulnerable but he had it on 3 pretty battered cars so I take that as a good indication it should be OK. I might get a balloon round it for a spot of water protection. 

Equally I could get it into the stock position I think, but I think I prefer the above for access and because I can fix it there quite easily. . 

[BuggyDad 6377]

I may be going mad. Went for that switch location and used the amputated pinkies of two surgical gloves to keep the crud out of the switch. And fashioned a rotating lexan plate by the servo which I stuck the receiver to with bathroom sealant. To make space for the driver I had to find somewhere else for it. It's tight though, hence gluing it rather than eg velcro, let's see how it holds.

Compared with our other one, which we built stock, there's a very pleasing lack of slop. However it serves to highlight just how much play there is in the front wheels, between bearings and wheels. Might apply a bit of ptfe tape or something there. Not that it'll have any practical impact, I know. Plus I don't intend to use these wheels that much. 

Anyway, it's built, although quite a lot of the other bits I ordered still haven't arrived, and the driver needs some love with a paintbrush. Looking forward to giving it a test run, 10.5t brushless will be a new experience for me... 

[BuggyDad 6377]

Ready to go but for the lack of a sensor cable and wing, which I haven't got with me. 12mm heat shrink round the cluster of motor wires is a cosmetic improvement I'm happy with. A ridiculous amount of time sorting cable routing has got me somewhere vaguely acceptable, and having realised I could use the rear shock shaft spacer as additional preload (duh) rear ride height/sag looks ok without stacking endless preload rings on top. In fact, I'll try the stock springs as well, because it might not have been spring rate I had wrong so much as the starting position. 

[BuggyDad 6377]

Driver paint to come, as well as suspension pivots, turnbuckles, front hex conversion, different wheel options etc. 

[BuggyDad 6377]

[BuggyDad 6377]

I've fitted the bottom spring collars above the 6mm spacers on the rear. It needs that extra bit of preload because the springs are short.

Will try these Core RC springs vs the CVA ones that came in the kit. With this extra bit of preload I think the CVA ones might be right actually. 

O ring on ball joint trick is neat and effective. All feels nice and slop free (except the front wheels, and that's all in the wheels) 

[BuggyDad 6377]

Wing, cables etc done. Ready to go. And replaced the big ugly zip ties with teeny tiny ones.

 

 

 

[BuggyDad 6377]

Then had a wee spin round the house, remembered how the front tyres don't work and went full truggy. For the doughnuts. 

Can't wait to get it outside. It'll be plenty quick enough for this novice. Already noticed it feels more controlled in adjusting the power in a slide on a smooth floor, compared with TBLE-02S and Torque Tuned. Is this the ESC? 

Understeer horrific with the buggy fronts, and transformed with the grippy compound truck fronts. At least I assume this is all in the front tyres. (accepted a polished floor is far from the intended surface!) Also noted the bearings seat relatively nicely in the aqroshot wheels where they're very sloppy in the Neo Fighter ones. 

 

Spec over stock so far:

- Speed Passion V3 Competition 10.5t

- Hobbywing Quicrun-10BL120

- 2S Lipo

- Schumacher Vee 4 blue rear, Stagger Rib yellow front on Aqroshot wheels

- so far added 25g sticky weights in the front

- Hours mulling over such critical matters as zip tie size, location and orientation. 

 

Concerns:

- it will never be (probably even remotely) clean again. 

- it's faster than my son's (17.5t and a TBLE-04, same kit and wheels).

 

Initial to do list:

- paint driver

- stainless pivots and turnbuckles when they arrive

- Schumacher Cougar KR front hex mod

- experiment with bodyshells and wheels

- learn about brushless timing

- improve my soldering skills then fit motor connectors at 90° on black wire with better heatshrink, just because.

[BuggyDad 6377]

Twins

 

[BuggyDad 6377]

And a bad soldering job (by the shop) makes itself known on the first run. 

[BuggyDad 6377]

But good god can this thing tear up the grass. The harder rear springs need to go back on. 

[BuggyDad 6377]

Turns out it wasn't just the soldered joint. Soldering the Deans back on was easier than I expected but now neither the ESC nor motor are working, so both have gone back to the shop . On the first battery!

Cracked the wing as well... 

[BuggyDad 6377]

I'd used threadlock in the motor screws which it turns out was a bad idea. Sheared both off removing the motor. Embarrassing - such a noob. Not too bothered because it's likely I'll get a replacement motor anyway and if I don't I can use other holes. It may be mostly weakness of the Tamiya screws (I've used this stuff plenty without this issue, including on similarly sized screws) but there's a lesson learned. 

I also used some on the servo screw, because this one threads into metal and the other one has come loose a couple of times. Other Neo has standard servo saver, this one a Kimbrough. There is a shed load of play in the Tamiya one, like absolutely masses. Zero in this one. However, dare I try ever to remove it? Not til I've another servo in stock. No matter for now - I don't need to. On that note, this car is showing me that it would be interesting to learn what a faster servo feels like. 

So a Kimbrough is on order for the lad.

Should probably update this thread title to something about a catalogue of rookie errors...

[Busdriver 6546]

On 11/17/2021 at 4:58 PM, BuggyDad said:

Should probably update this thread title to something about a catalogue of rookie errors...

To paraphrase a Paul Simon song 

“still a rookie after all these years” 

63 and still making them  and learning from them. 

[BuggyDad 6377]

I got a new motor and ESC. Exactly the same as before. Except bullet connectors soldered at 90 degrees and on slightly shorter cable, which is cosmetically nice and should be especially so when I have an hour to tinker with black heatshrink. 

Anyway, ref advice here:

I thought I'd experiment with running the original stock buggy wheels and tyres vs my truck ones back to back. 

My personal view is I just don't like the stock fronts. Understeer on either grass or a slightly rough rocky surface is just massive. It's well reported but I didn't think it'd be this bad. With the big wheels and Schumacher cut stagger fronts it's completely different. 

It takes, and especially lands, jumps more cleanly on buggy wheels though, even if you don't get it quite right. I suspect this is a combination of lower c of g because of smaller diameter and perhaps a bit about the much wider track of the truck wheels, especially the fronts, creating a correspondingly greater rotational force on any part of takeoff or landing you don't get quite right left to right. It also seems less nose-heavy in the air for some reason (NB I've added 25g weights to the front already, but that's true regardless of wheels). It's easier to drive with buggy wheels, less sensitive. And with all that understeer it's not going to flip in a corner, so assuming it can turn the corner it's at least less likely to break!

But it's 90% about the understeer for me; the car is far better with anything that deals with that. And it's just much more fun with the truck wheels. Lairy, aggressive, wants to lift the front, can turn on a sixpence but will flip if you get it wrong. I'm not racing, after all. 

So this all makes me more interested to try different wheels and tyres. I think the buggy version of the Schumacher fronts might be interesting. I wonder whether I can get a good compromise between the two options with treads and compounds like the truck ones on more buggy-like diamater and track.

The reason though for going back to buggy tyres was to reduce load on the motor/esc. I think it does run slightly cooler with the buggy tyres but I can't quantify it really. With either its not getting too hot. The hottest I've got the motor I can still comfortably hold my fingers pressed against it for 5 seconds, which I'm pretty sure makes it well under 60c/140F (I use feel to gauge the temperature of milk I'm steaming for coffee, so I know what that temp feels like). From what I read I'm not in troublesome territory there. It does however collect a lot more grass round the drive shaft area with buggy wheels. With the truck ones it stays pretty clear. 

[sosidge 717]

Yes you'll find that a spike tyre will give a lot more front end grip on grass, the ribbed tyres really only work on dirt.

Dry grass I'd be looking at Schumacher Minispikes all round in yellow as a starting point.

Wet grass, ballistic buggy green Minispikes are the way to go. Will also work in the dry but with a higher wear rate.

Cut staggers are more of a dry/worn grass/astro tyre, but will give a little less steering than a minispike.

These tyres should all fit on the modern Tamiya wheels.

[BuggyDad 6377]

Ah. Thanks. Lots to learn! Sounds like tyres are very conditions specific then. For our limited purposes I'll try not to own too many, something I have not achieved for mountain bikes! The Schumacher Vee 4 blues on the back really struggled on hard fine gravelly ground where we lost the back end constantly, but it was only a brief run. I think the fronts have functioned to our needs on all conditions we've encountered so far. I anticipate our uses to span grass, fine gravel forest tracks and packed hard rocky gravel which is often wet (our driveway). Dirt surfaces that suit a bash with an rc car feel like a hard to find thing round here. 

But then there's also the standard of driving.... 

I already ordered some cheap fastrax buggy spikes ("stub"), so will try them but I guess the Schumacher mini spikes would be much better because of their softer compounds. Also ordered some Fastrax "cuboid" ones as a more "all terrain" option, just as a cheap experiment, kind of thinking they're for mostly tarmac. 

I ought to curtail the spending though for a while, so more new tyres may have to wait.

But then I am oh so prone to being suckled down a rabbit hole.... 

[sosidge 717]

For bashing the tyres don't really matter that much but if you have a specific need (i.e. performance on a given surface) then the race tyres are proven.

The Fastrax tyres might be awesome. Or they might be dreadful. You just won't know until you put them on.

[BuggyDad 6377]

Took some knocks today. 

Going to have a crack at reinforcing mount holes and other vulnerable bits of shell, to see how much of a difference I can make.

And Drive's grazed his head. I feel bad about that. But I've got sandpaper, putty and paint so he'll soon be better than new, hopefully. Maybe he needs a roll cage? 

Front shock tower I'll replace like for like out of my spares kit but maybe I should consider ally. Comes the question that given there's more mechanical advantage on the bits below, might the break happen sooner if the tower is ally? Not sure. Clearly it'd pass the hit across to something else, as is well documented, but I wonder what selection of parts makes up the overall toughest version of a dt-03?