Mid Motor Rustler - V2

[rc10nick]

It's been a while but I'm back to working on my MM Rustler project. I've decided to design a new version which is why I've started this new thread. It's been a long time since I started my original mid motor conversion and in that time I've gotten way better at 3D design, bought myself a 3D printer, and tried a bunch new designs that I want to implement into this car now. There were some things about the old car I never liked that I want to fix, and with my 3D printer I can make parts I couldn't before. I also want a standup transmission I can use to run this car on outdoor dirt.

I plan on being able to swap between a laydown and a standup config, but I've started working on the standup because I know it's going to take me until the start outdoor racing season for me to get this project ready to race - I'm realistic about how long it takes me to complete projects, lol.

Anyway, today I finished the CAD work and I've started the first batch of parts on my 3D printer. Here's what the design looks like now:



The design is based on the same idea I've used on my DEX210 and my TLR 22 5.0 in the past. It's a double deck design that pushes the battery all the way back to the motor in order to get as much rear weight bias as possible. The design also has a separate rear camber link plate that will be easier to adjust and has an integrated sway bar mount. And while it's not something you can see, I can now make changes to the design of one part without breaking a whole bunch of other parts (my old design files are horrendous to work on, part of the reason for a clean break, lol).

[rc10nick]

The printed parts went together pretty nicely! I've got some very minor corrections and a few tweaks to make, but for the first time ever I've printed a prototype that didn't have massive glaring issues that needed multiple iterations to fix. Feels nice. I'm pretty much ready to move on to making final parts.




The rear arms are something I didn't mention in my original post, but I redesigned my long rear arms from my last build. Instead of machining them out of delrin I want to experiment with rigid polyurethane resin casting. My old arms were a major pain in the rear end to make, but resin casting is pretty fast and easy. And unlike my previous arms, these arms have 3° of toe-in added in at the hub. I wanted to be able to use the Nitro Rustler suspension mounts (available in 0° and +/- 1° for tuning) and I also wanted them to work with the stock Traxxas transmission case, too.

[RCveteran]

Impressive work! MX Acres on youtube right not is proving a regular old Bandit can compete so this version you should have an IFMAR contender

[rc10nick]

Impressive work! MX Acres on youtube right not is proving a regular old Bandit can compete so this version you should have an IFMAR contender

Thanks!

You know, I just recently stumbled on those videos a few days ago looking for other examples of people racing Traxxas cars. There are dozens of us! DOZENS!

[76jimmy]

I've been working on a mid motor bandit as a kit bash with a nitro rustler transmission. I would much rather have a transmission that uses the stock bandit gears. Are the internals of the trans all stock traxxas parts? Great work BTW i loves the V1 thread so ill be checking in here too.

[rc10nick]

I've been working on a mid motor bandit as a kit bash with a nitro rustler transmission. I would much rather have a transmission that uses the stock bandit gears. Are the internals of the trans all stock traxxas parts? Great work BTW i loves the V1 thread so ill be checking in here too.

I saw your thread and your build is really cool, too! I'm excited to see you get that Factory Works chassis put together.

And yeah, my transmission case is designed to use the stock 272 internals. I waffled a little bit between going with the 272 which is what I have, or getting my hands on the new 272R internals. I just went with the 272 because it's what I had, it's worked well enough, and I didn't' feel like dropping the money on the 272R parts. Maybe in the future I'll do a 272R version if I feel I really need that gear diff. Although if Traxxas had upgraded the slipper on the 272R to something modern it would have been a lot more tempting.

[76jimmy]

I have the factory works chassis almost done need a few pieces of hardware to finish it up. Any chance you would print me a trans case to play with? Send me a PM if that's something you could do. I'd pay for the print and shipping of course. If you and machv Collab on the mid project you guys almost have a bolt on mid kit for the bandit/rustler.

[rc10nick]

I have the factory works chassis almost done need a few pieces of hardware to finish it up. Any chance you would print me a trans case to play with? Send me a PM if that's something you could do. I'd pay for the print and shipping of course. If you and machv Collab on the mid project you guys almost have a bolt on mid kit for the bandit/rustler.

At this point none of what I've designed is tested or final. When I'm done I might put files online but since I design everything to what I want and specifically for my car it might not be universally compatible.

Machv does great work and I bet that FW chassis will be amazing without my parts on it anyway. Can't wait to see your build with it!

[rc10nick]

It's been a while, but I finally have an update for this project.

As stated in my initial post, one of my goals with the project was to have a design that allowed me to easily swap between a laydown transmission and a standup transmission. I finally got around to designing and prototyping the laydown config. Here it is next to my standup prototype. I'm pretty pleased with how it turned out, though I do need to adjust the shape of the chassis slightly due to some minor Bandit body fitment issues.



My next step is to make a car I can actually drive, and for that I think I'm going to try 6061 aluminum for the chassis instead of my usual G10/FR4. Like usual, though, I have no timeline for when I'll get around to that other than "whenever I feel like it." I do vaguely have a "goal" of driving it at the indoor carpet track at some point this winter, so maybe I'll have this done sometime before next summer.

[tmaxx51]

Just came back to check and progress and it's looking good! I've been in the process of building a mid-motor Rustler for a couple of years and your builds have been gold. I am currently trying to cast my transmission cases so I will have to come back and let you know how it goes to see if that's any help to you.

What diff are you using again? I had no idea there was a 272R until this thread. Awesome to finally see a sealed diff, but it looks really heavy. I have a plastic geared diff right now to reduce weight.

[rc10nick]

Just came back to check and progress and it's looking good! I've been in the process of building a mid-motor Rustler for a couple of years and your builds have been gold. I am currently trying to cast my transmission cases so I will have to come back and let you know how it goes to see if that's any help to you.

What diff are you using again? I had no idea there was a 272R until this thread. Awesome to finally see a sealed diff, but it looks really heavy. I have a plastic geared diff right now to reduce weight.

Thanks! Your design looks really nice, too. I like the quick access diff. I bet the casting turns out great, too. I'd love to see your results when you get the pieces made.

On dirt I've used the old SRT ball diff which fits into the old 272 internals. I've tried the hot racing sealed gear diff before and honestly that's junk - it leaks just as much as the stock straight cut gear diff. I'll probably go back to the stock 272 gear diff even though it can't be filled with oil. I've been using a gear diff on my carpet buggy with only grease on the gears and no oil and I've been liking that so I'll do the same on my Rustler whenever I get to making it.

[rc10nick]

I was recently hit with the urge to get back to work on this project and decided to make some changes.

First - I wanted to narrow up the chassis. The original shape is a flat projection of the stock chassis but the more I thought about it, the more I realized there was no good reason to keep that shape. It's too big and the only thing it does is make the car heavier. The chassis is now about as narrow as other current 2wd cars. I think it looks much better this way, too.

Second - I dropped my dual deck chassis design for the standup version of the car. I had another summer to race on my TLR 22 5.0 with an identical layout and there were just some things about it I never liked. At the end of the summer I switched back to the factory standup layout and was just as fast and my car had just as much grip. Since there's no noticeable performance gain that justifies the extra complexity/parts and other inconveniences of that design I designed a more standard standup configuration. Again, I think it looks much better this way.

Third - I added a fan mount to the laydown transmission. A fan is 100% required for stock racing on carpet so I made sure I had a way to mount one.

Below are the updated designs in Fusion360:



I think I'm ready to make parts now. Like for real this time. I don't know if I'll get the car running and everything, but I at least want to get a roller put together next so that will probably be the next update I post.

[rc10nick]

Hope everyone else here in the states had a good Thanksgiving yesterday!

I've made a few more tweaks to my design and also printed out a prototype to test fit all the pieces. I'm over the top happy with how great it looks and this 100% confirms I want to make a working car. The chassis itself is at least an entire inch narrower and the entire thing truly looks like a modern racer now. I've got a sheet of carbon fiber on the way and I bought one big enough to make at least 4 or 5 cars. The only thing left to decide is what kind of car I want to make... I've actually been leaning towards taking this project back to its origins and making it a Slash again - I've still got the stock RTR pink body sitting around and it would be a hoot to race that again!

Anyway, enough blabbering, here are the pics of the new design with some comparisons to the previous one. (Yeah, I know, that Novak receiver has seen some better days)

[rc10nick]

The CF panel I ordered finally showed up yesterday! Today was the first day of my Christmas vacation so I managed to get this done today.




The panel was a bit of a gamble - I bought it on AliExpress and it was nearly half the price of most other similarly sized panels. As far as I can tell it's 100% CF - plenty stiff and plenty light. Speaking of light, this new chassis design is about 15g lighter than my previous chassis so it was definitely the right call making it narrower.

I'm still waffling back and forth between buggy or stadium truck, but at this point I'm thinking stadium truck. Regardless of what I decide, I still need to make a motor plate, rear shock tower, and battery hold down. And if I do go stadium truck I'll either need to make more of my custom arms or just switch back to stock rustler arms. Then once I get that figured out I'll need to make sway bars. So it's still a long road ahead before I get this out on the track again, but it's really nice to see it this far.

[rc10nick]

I've got another update. I've been working on designing and prototyping the final details. The most critical update is the battery hold down. I went with rotating tabs like the TLR 22x-4 has. The tabs stay in place pretty well and make it really easy to get the battery in and out of the car.

The next set of design updates were related to using the TLR 22 shocks I had sitting around. Even though they're meant for the 22 buggy and have an overall shorter length, they have a longer stroke than the stock traxxas shocks. In order to use them I designed shock bushings (the front and rear bushings had to be different due to reasons) and I had to redesign the shock towers to accommodate the shorter length.




Now that I've got all this figured out, I can CNC the rest of the parts - motor mount, new towers, and battery hold down tabs.