Foell.org

One of the bandit arms is modified. To get the bandit arms to fit in the Slash 4×4 front caster blocks (6832) and retain full suspension travel, I had to cut and trim some things. If you’ve got the aluminum 6832X caster blocks you may not need to trim as much – as always, your mileage may vary.

I trimmed off much of the bridging near the wheel side of the suspension arm using a cut-off wheel, leaving just a small amount. I also used a sanding drum to remove some material from the top of the forward arm link so it wouldn’t rub inside the caster block.

Removing the forward arm link material allowed the suspension to droop much further without binding. You can see here how it dips below the caster block support:

I used a Dremel and two attachments to make these changes: a 409 Cut-Off wheel and a 430 Sanding Drum.

Axles

I planned on switching to Bandit axles, but it turns out the cross pins on the Bandit universal joints are smaller diameter than what comes on a Slash. RC Driver explains and shows it very nicely here:

This would mean also switching to Bandit diff output yokes and stub axles – the latter of which I wasn’t sure was going to fit in the Slash 4×4 bearing carriers. Not to worry – there’s a cheaper and easier solution: cut the stock Slash 4×4 telescoping driveshafts.

I cut 20mm from both halves, using a pipe cutter worked nice and kept a clean edge.

Here you can see before & after:

Turnbuckles

For the camber links, I used Bandit turnbuckles (2443), two sets for front and rear. You’ll also want to buy some extra hardware to mount them as the screws for the Brushed Slash 4×4’s non-adjustable, plastic camber links are different. A bag of 3x15mm button-head screws (2579) should cover you, or you can pick some up at the hardware store.

The steering turnbuckles are thinner than the suspension camber links – 3mm instead of 4mm. Also the rod ends are specific to the Slash steering bell crank and steering blocks. So I opted to retain the stock rod ends and install them on a shorter (3x45mm) turnbuckle. I reinstalled them into the forward most hole on the steering blocks for maximum turning angle.

I used a turnbuckle from TLR that I found at my local track, but any 3mm x 45-48mm turnbuckle will do. These ones are from popular models, so there’s a good chance your local hobby shop will have one:

• Team Associated 3x45mm Turnbuckles (4404)
• Team Associated 3x48mm Turnbuckles (91723)
• Arrma 3x48mm Turnbuckles (330013)

Keeping the front wheels/tires from rubbing the shocks at full lock was tricky. Crawlers need maximum steering angle for tight turns and I didn’t want to lose even one degree – especially considering the Slash wasn’t built with crawling in mind.

Using Pro-Trac wheels like on the Ultimate RC Chimera-B were not going to work with the short Bandit arms. They rubbed on the suspension and limited steering angle. Luckily I have a 2wd Slash on hand to facilitate some testing. The next level of wheel offset was the 4×4/2wd rear wheels. These also rubbed the shocks at full lock. Switching the wheel hex to the wider 2wd Slash front wheel hex (3654) helped, but it was still touching the shock (barely). In the end I used 4×4 Slash wheel hexes with 2wd Slash front wheels on all for corners.

The result is 254mm of overall width with tires on. Close enough to the 249mm I was going for to call it good.

The post Slash 4×4 Crawler (Part 2) Width appeared first on Meatball Racing.

To start this hair-brained experiment I started with two main ingredients:

1. Brushed Slash 4×4 (high center of gravity chassis)
2. Pro-Line Jeep Rubicon Unlimited Body

I understand that the thought of an independent suspension Jeep Wrangler gives many people an uneasy feeling. Somehow, it’s just wrong. But this is a thought experiment, and if you need help suspending disbelief, this does in fact exist in the real world.

I’m enamored by the Slash (both 2wd and 4×4) – it is the best selling RC platform in the world. With excellent parts compatibility between other Traxxas models, why not see if it’s possible? That’s what this hobby is all about anyway, making something custom from your own ideas.

I also love Jeeps. The Pro-Line Wrangler Rubicon Unlimited body, while made for the TRX-4, should be a perfect fit for this build. It just happens that the long wheelbase configuration of the TRX-4, at 324mm is exactly the same as the Slash 4×4

But could the Slash 4×4 be narrowed enough to look convincing? And could it still maintain good suspension articulation? Let’s try to remove some width and find out! Stay tuned for the rest of this build series.

The post Slash 4×4 Crawler (Part 1) Introduction appeared first on Meatball Racing.

At the front end is a Renogy 100 watt portable solar panel and a MPPT controller. This model is more expensive (at $275) than the normal $1-per-watt deals you can get on just panels. But it folds nicely, comes in a carrying case, and includes a waterproof controller and all necessary wiring.

The panel turns sunlight into power, and the MPPT controller decides how much power goes to the battery. It has several settings for different 12-volt battery chemistries (Lithium Polymer, Lead Acid, AGM, etc.).

For my “energy sink” battery, I went with a tried-and-true Interstate group 27 deep cycle battery that I got from Costco for about $100. It’s got 160 minutes of reserve capacity, so figure about 67Ah at 12v. Pro-tip: the deep cycle batteries aren’t available at Costco in the winter here. You gotta get them in the spring when Minnesotans are bringing out their boats.

I call it a sink, and I drew it to look like one in the illustration because I like to think of the stored energy like water in a sink. Energy in the sink can be emptied to charge another battery, it can be refilled by the solar panel, and it can be refilled from another battery. I’ll show you how…

Regenerative charging

My favorite part about this setup is with the right charger, I can do regenerative discharging. I did my research and found a couple of chargers that can do fast discharging by reversing power flow and putting energy back into the input – the energy sink. The two chargers I’ve found that will work are the Turnigy Reactor and most Junsi iCharger models. I went with the iCharger X6 because it’s extremely portable and packs a powerful 30-amp punch.

Why do I want to do regenerative discharging? When I go racing I usually bring two batteries for every vehicle we’re going to race. I’ll use one during practice and charge the other for qualifying and racing. At the end of the day, usually a 5-8 minute practice, qualifying session, or race isn’t even close to getting the battery to its most stable resting (storage) voltage – 3.8v per cell.

A quick way I had been discharging was to use a AOKoda Cellmeter 8 to bring their voltage down to 3.8v per cell. It works incredibly fast because I can draw up to 150 watts of power by running three 50 watt incandescent bulbs. The power turns quickly into heat and light.

But why not recapture that energy instead? Regenerative charging allows you to put that energy back into an energy sink battery just as quickly.

X6 regenerative discharging setup

The X6 has 4 “input source profiles” that you can use to tell it whether it’s being powered from a normal power supply or a battery. You can give it parameters for how much power these sources can deliver and whether or not they are regenerative.

To set up the input sources, first get to the system menu by pushing and holding the nav wheel down from the home screen. Then you can go to the “Input & Power Limit” section.

You then select one of the four available profiles you want to edit.

This is my setup when connected to the deep cycle battery. My Costco/Interstate battery has a reserve capacity of 160 minutes (at 25 amps). I set the max current to 20A so even if there’s no solar power input, I should get over 3 hours of charge time at 20 amps – but I’m never charging at that rate anyway.

Check the regenerative enable box to get those options. Here you need to know what the fully charged voltage you want to stop at and what the max charge rate is. This will vary whether you’re using lead acid, LiPo, LiFE and how many cells it has. Maybe you want to use something like my 6S lawn mower battery as the energy sink. Regardless of what you use, you need to know the max charge rate and voltage.

Based on my 67Ah deep cycle battery, charging it at 10 amps is a 0.15C charge, or 15% of its capacity. That’s between the recommended 10-30% of capacity rates. Best to be conservative here.

Discharge vs. Storage Programs

Once regenerative charging is enabled on the input source, we need to also enable it on the discharge setting for your charging profile(s).

Why Discharge and not Storage? Because storage is a smart mode that will either charge or discharge cells based on whether or not they’re above or below your target voltage of 3.8v. As long as all of your cells are above 3.8v, you can use discharge mode and set the discharge voltage to 3.8v instead of the default 3.5v. The charger can still do some balancing of the cells on the way down to the target voltage – enable it in the “Advanced” section of this screen.

There are several safety measures built in to make sure you don’t send power back to something that can’t accept it. The iCharger will warn you here with a yellow exclamation.

Once you’ve enabled Regenerative Mode, when you go to run the program, Discharge will have “REG IN” in red next to it.

One last safety feature – when you select discharge it will give you another confirmation on whether or not you want to do a regenerative or normal discharge.

Now you’re taking energy out of your RC battery and putting it back into the source energy sink! In the lower left you’ll see RE in yellow & red with the voltage and current. No wasted energy to light or heat – just put it back where it came from

Wireless Charging in Action

Here’s my setup at the track. On a sunny day I’ve seen the MPPT controller send out 6.0 amps to the battery. At 14v that’s about 85 watts. Not bad. Without taking away any battery charge from the energy sink, I can charge a 2S battery at 10A, and my 6S lawn mower battery at 3A.

Do you have any other green charging ideas? Let us know about setups you’ve built or seen in the comments.

The post Solar Charging Setup appeared first on Meatball Racing.

The Arrma ATX-300 transmitter & receiver I switched to for left handed use is a 3-channel unit. The 3rd channel is operated by the yellow triangle button at the top of the handle. This would be perfect for the firing mechanism. The button is even on both sides for right or left handed drivers.

With the parts gathered, I just needed to make things fit. The Dromida truck has a large firing mechanism in back, so the possibility of simply adjusting the LaTrax body post height was out.

3D Printed Solution

So I decided to design and 3D print a set of body posts that would fasten into the LaTrax chassis, but were purposely designed to fit the Dromida body without the need to drill any new holes.

Here’s the design: https://www.thingiverse.com/thing:3641857

Result

After a few revisions I got the fit just right:

I designed the posts to align the body with the front bumper right behind the grille. I did have to do some fender trimming with a body scissors on both the front and the rear fenders to avoid any rubbing during steering or suspension compression.

It’s like I’ve combined the best of both worlds. This thing shoots far! It frankly caught me by surprise the first time I fired it. Guaranteed to put a smile on you and your kids faces. Just don’t shoot anyone’s eye out!

I’m still experimenting with materials. My first 3D prints were from PLA filament but we’ve already broken a couple sets. I’m going to try PETG filament as I’ve heard good things about its durability, specifically for RC. I’ll update the notes at thingiverse as I improve them. If you’ve got any tips to increase strength through design or materials, let me know in the comments below.

The post LaTrax Wasteland Mashup appeared first on Meatball Racing.

I think it is spot on!

Because some of you might have 3D printers already, I’ll link my products to the STL files so you can print them yourselves. I’ll offer them for sale (with low shipping costs) for those who do not.

Keep in mind that sometimes it will be cheaper to order through MeatballRacing than to print it yourself. In the case of this Traxxas fan mount for most 2wd vehicles (Slash, Rustler, Stampede, Bandit) – the cost of the hardware alone would be more than ordering it from meatballracing.com direct.

Do you have any ideas for 3D printed parts? I’ve got some ideas in the hopper, especially for the venerable Traxxas Slash – maybe you have some as well? Let us know in the comments!

The post MeatballRacing 3D printed products appeared first on Meatball Racing.

MeatballRacing is going to debut a patriotic-themed Slash product in May, so I wanted to church-up my jump to go along with the theme.

I got an American Flag Distressed Stencil in 24″x18″ from Stencil Revolution. While I could have easily do a single-color paint job with it, I figured I could creatively reposition the stencil to get a full-color, red-white-and-blue, star spangled banner!

To make sure the paint would stick, I sanded the surface of my jump with some 220 grit sandpaper. I went in one direction, then another to create a crosshatch pattern.

For all of the paints I used Rustoleum 2X Ultra Cover spray paint – based on recommendations that it works well on plastic.

• Gray Primer
• Gloss White
• Gloss Apple Red
• Gloss Deep Blue

I started with the primer. I masked off some edges, which isn’t strictly necessary, but they’re useful as guidelines when removing & replacing the stencil.

Then it was time for the red stripes. I put some paper behind the stars as a mask. Then painted red in the striped cut-outs.

After the red dried, I repositioned the stencil slightly to the left and slightly up. I did this to cover the red I already painted and also so the angle on the top-most stripes would match up with the red and the white.

The last part is putting the stencil on for the last time to paint the stars. I went a little too thick on many of my coats, and the stars were no exception. I should have done multiple lighter sprays, but the few stars that bled don’t bother me – it adds to the distressed look.

Once your jump is done, it’s time to give it a go.

If anyone out there has done some artwork beyond adding a ton of stickers to their jump, let’s see a pic. Post up in the comments below.

The post Send It, ‘Merica! appeared first on Meatball Racing.

To pre-empt any bashing that would take place during the first track session, I removed most of the scale details:

• Windshield wipers
• Antennae
• Side-view mirrors

I left the scoop on since it’s low-profile, and also the wing since it might actually help on jumps.

Despite these efforts to keep the body in usable condition, I found out very quickly that the shell itself is not very durable.

First Laps

It did well on its first time out:

The S1 compound tires gripped nicely. I didn’t even add traction compound. My gut tells me that if there was a big SC Rally scene, the more commonplace stock Traxxas rally tires would also do just fine with some traction additive.

Traction Roll & Wing Durability

Once the tires warmed up they had enough grip to (inevitably) traction roll the vehicle. The general shape of hatchback rally car bodies is good because odds are the car will land back on its wheels. On my first roll-over where I landed upside down, I got hit by another Slash and the wing exploded.

Thankfully it was my nephew who crunched it, so I can’t really harbor any remorse.

Body Durability

Also, at one point I grazed the outside of the back straight and it almost completely tore off the front fender.

Needless to say the Basher/BSR 1/8 Rally Body is not up to the task of a full season of door-to-door racing. If I go all-in on this rig, I will instead get a thick (1.5 or 2mm) Deltaplastik lexan body.

Otherwise everything else performed nicely. Besides losing the wing and the fender, there was only a small nick along the body’s front edge, so the bumper did its job well. The tires gripped well. It drove and jumped predictably. It was great seeing a full-bodied rally car out on the track – mixing it up with other buggies and trucks like it was the Baja 1000.

More Power?

I got to trade transmitters with a fellow rally driver who had a 4WD Traxxas Rally. It had a brushless system on 3S power with insane speed. It was actually too fast for most of the course, but it made one jump very easy. It made me wish my brushed rally car had just a little more power to make the first jump in the turf series right in front of the drivers stand.

The brushless rally car could jump right onto the 2nd platform, making this obstacle more smooth and fun. But I wanted to stay true to the low-cost vision of a Spec Slash based rally car. One jump didn’t detract from the smile I had on the other 99% of the track.

The post SC Rally Testing appeared first on Meatball Racing.