Micro Racer's 6x6 Build

[micro racer]

Well, I must unfortunately declare that this build is dead. After starting college, I have found that I can put in neither the time nor effort to finish the suspension work within an acceptable tolerance. The hand made parts were cut to fit, which means that any part I CAD will have to be slightly different, and I simply cannot convince myself to do that much trial and error with printing parts. In addition to this, I would have to rework ALL of the suspension links, which is another several hours that I don't really have to spare.

On a more positive note, the core concept of this build will live on, albeit in 4x4 form. I will have to go to a more bolt-together chassis (SCX10) to simplify the suspension building, but it will retain the Knight Hauler cab and will get a new rear bed and roll cage. It will still have some fancy lights and two winches, and will keep a class 1 legal tire size.

Thanks for all the comments and support throughout the build! I hope you all enjoyed it while it lasted!

 

[micro racer]

IT'S BACK, Y'ALL!!

The stripped chassis of this truck has been quietly living behind the side-door to my garage for almost four years (oh geez I'm OLD now). But I have since taken a ride around the hobby/life merry-go-round to finally wind up rebuilding this beautiful bastard.

Before I can get to work on Flatbed 2.0 and the rest of the bodywork improvements, I need to fix the original problems of this chassis. Well actually, I need to fix the broken parts *before* I can even get to work on solving problems.

If I can go back and edit some earlier posts to fix the Photobucket shenanigans, y'all will see I pretty much destroyed the front axle shortly before retiring this truck. Basically, the pin pressed into the dogbone axle slipped out and the cast axle housing, stub axle, and steering knuckle were no match for a granny-gear 3s brushless system with nice pin-shaped lever arm.

Anyway, I needed a new front axle. BUT BETTER. Maybe not much better, as the RC4WD CVDs are kinda meh, but they give more steering throw.

Mmmm... Shiny. Note the BTA toe link that I am going to use for no other reason than it surprisingly does fit.

After building a TRX-4 chassis kit for another project, I've decided to switch over to TRX-4 rod ends instead of Revo ends(Jato ends are still helpful in specific cases), mostly due to the angled and longer options that have more tolerance for building suspension with mismatched links.

I understand the utility of all-thread and brakeline links, but they get flimsy at the longer lengths required on a truck like this, and I always have a hard time getting a nicely finished thread on the ends. So I'm sticking to original link kits (for off the shelf builds) or picking approximate lengths from either Traxxas or Axial M4 threaded links.

The chassis is currently a bit farther along than I have pictures of; I'll try and get a few pics for an update tomorrow-ish.

 

[micro racer]

"Tomorrow-ish".... *doesn't post until a month and a half later* At least I actually got something done this time...

And by "got something done," I mean "wow it runs already!".

Check this out, ladies and germs:

Sorry for the choppy video; my phone camera has excellent resolution but the auto-focus sometimes has a seizure while shooting video... https://i.imgur.com/E7ELPmr.mp4

This truck has no problem wrapping tires around the wheel. I may need to put some dual stage foams or closed cell single stage if this seems to be an issue.

Showing off all 11.5mm of flex from the middle axle...

Yeah, yeah . Just ignore the battery velcro-strapped to the rear crossbrace; I'M WORKING ON IT.

(Hmm, hopefully that video works fo y'all) If it does, you can see that this big pig has a surprising amount of power. I can't believe I disgraced this build with a Trashass motor either... (it was a spare from a TRX-4 kit)

Again, I'm rather impressed with the amount of power this motor seems to have in this truck, although I'm sure that 3s and a huge gear-down help it tremendously. And holy spur-gears, there's barely enough room on the transmission to fit this 7.11:1 ratio.

Like, I had to shove in a Supershafty extended Wraith output (in 6mm flavor), and then cut down the topshaft spacer in order to clear the 64 tooth spur gear. Even with that done, the motor screw slots are only long enough to perfectly mesh a 9 tooth pinion (a 10t will crash).

(The gap is bigger on camera than in person)

Powered by spaghetti.

Does this *need* that 20 Amp, 12s-rated Castle BEC. Well, noooo... But I've always wanted to try one of these (even though it doesn't do anything special that a more normal BEC wouldn't do), and a BIG TRUCK seemed like a good excuse for a BIG BEC. To be fair, it does directly power a Hitec D956WP (at 6.0V), along with the rest of my electronics, including a few LED strings, light bar, and eventually a servo winch (or two), so it has a good amount of overhead to keep temperatures low. But all of that still won't pull anything close to 20A regardless.

The Hitec D956WP replaced this crappy TowerPro that I keep forgetting to throw away but always ends up as a test servo...

Also in that pic, you can see a turnbuckle for a panhard bar, and a piece of bent steel strip functioning as a panhard mount. I have since replaced the strip with a Locked Up RC steel panhard mount for a Gelande, and that necessitated some trimming of the turnbuckle.

Cutting threads further down the right-handed threads (I don't have any left-hand dies, because who does that???)

Cut vs original

Much like the 20A BEC, I have also wanted to try turnbuckles in place of fixed-length panhard and drag-links for a while. For a custom truck like this, with strange mounting positions and dimensions, their adjustability was a huge help in getting the axle and steering lined up with the chassis.

Here's a few more random pics of the chassis:

Transmission sideplates, cut from ~1/8" aluminum sheet. My original build had much shorter (lengthwise) sideplates, and I found that the lack of overall material made them a bit flexible, and the whole transmission, skidplate, and link mounts would wobble and shift side-to-side between the chassis rails. These still flex just a little, and I think I will put a couple more screws into the rails, but these are much more sturdy.

Skidplate, the motor overhangs a little more than normal because the motor plate is pulled closer to the trans to allow the modifications for more spur gear clearance. It's still protected by the lower link, and I will likely switch back to a 540 can when the Titan inevitably burns out (though it would be some sort of Torquemaster or Puller motor to make up for the lost length).

Middle and rear links. I'll have to get a better picture for the next post, but I had to reinforce the shark-fin link mounts with a titanium threaded post to prevent them from flexing. The shark fins are cut from the same sheet as the transmission mounts, but they're much smaller and can't quite support themselves without the brace.

That's about it for now! I'm currently drawing up a rear bed in CAD, but I just started and it's only a layout and a box (to represent the battery) so I figure it wouldn't be the most interesting to post...