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Hi guys,

Just sharing a project I recently worked on, my simple take on a mid-motor RC10.

The history...

Like most of you, I was excited when AE re-released the Worlds car and a couple of buddies and I bought them with the intention to race them at our local races. The buggies were awesome and performed really well and even made the A-main on good days. Loved the performance but our track has some pretty big jumps and when we cased the jump there was a good chance we might land on the rear of the car and the rear cage would bend and often take the motor plate along with it. That would mess up the gear meshing and ruin spur gears and kill runs. After a bit I put the car aside with the intention of selling it. As it sometimes goes... procrastination pays off and I recently purchased a 3D printer... so I decided to see if I could revive my RC10 Worlds car as a mid-motor. With the huge amount of rear-grip the car generates, the hope is that a mid-motor version would not only improve the car's agility but still have a good measure of rear traction to make it shine.

I looked at the many wonderful projects here and decided that what I wanted to achieve was :
- retain as many stock parts as possible to keep the project simple - intention is to flip the gearbox around and re-use the rear bulkhead, arms, shock tower, etc. and not to have to cut a new chassis.
- design and 3D print a minimum number of parts to do this conversion.
- try to make it look clean, functional and factory where possible.
- maintain or improve the performance for track racing.

I'll post more info on the build process if anyone's interested, but here's just a quick picture of how version 1 turned out.



I printed 3 main parts for this project - a motor plate spacer to properly position the motor plate on the flip side of the gearbox, a waterfall brace to support the gearbox by connecting it to stock chassis holes, and finally the part I'm most proud of - a reverse gear cover to fit the stock motor plate.

More to come.

Looks good! Nice job on the printed parts!

mk-Zero wrote: ↑Mon Aug 14, 2017 1:52 am Looks good! Nice job on the printed parts!

Thanks man! I've seen many of your posts while doing my "research".

Snapped a pic with the bodyshell.



Glued a piece of lexan where the original rear shock cut-outs were. It's not great but it'll do till I get a new shell done.

And while I was wrenching I took a pic of the gear cover I was talking about. I was always stuck when it came to stuff like this in the past but a a download of Fusion360 and a week of youtube tutorials later I am happy with the results! I specifically wanted this cover to work with the stock motor plate and also have a lip to wrap over the edge of the motor plate for better dust protection because our track is quite dusty.



Thinking of maybe getting shapeways to do a print of this so I could have a different finish from this but I'm happy that this fits amazingly well.

Fantastic job!

Fantastic project! I'm really digging your gear cover, love to have one

Oops, went back and read earlier post and it's a reverse style cover

You ran into the same issue I did when making my mid motor RC10, the body no longer lines up with the shock tower. STILL looks way better than the cab-forward crap.

NomadRacer wrote: ↑Mon Aug 14, 2017 9:08 am Fantastic project! I'm really digging your gear cover, love to have one

Oops, went back and read earlier post and it's a reverse style cover

lol... I'm curious... Why would you need a non-reverse one? Wouldn't that be the stock great cover?

This cover allows me to run the 3-gear mid motor transmission by simply flipping the gearbox.

Snuck in a run at the track today and the car was very promising! Jumps very well and has great forward traction but I need to play around with the shocks and camber links as I'm getting a bit too much steering off power. Little tuning to work out but for a first run everything worked and survived so I'm very happy!

Revised the design of the waterfall to be stronger and also integrate the shorty pack retainer into it. This version has a more functional look to it and the plan was to try to maintain the design aesthetic of the other car parts.




Here it is installed on the buggy. The wires route nicely around it with ample space. Just for fun I added the initials of my handle "BC" onto the part as well.
The brace also uses existing holes in the chassis so there is no need to drill new ones to fit it on.




A quick pic of the car at the track. Will make some tweaks to the setup and do more running this weekend. Hopefully will get someone to shoot a vid so you guys can see this thing run.

very nice design. love when one part of an assembly can serve more than one function.

BloodClod wrote: ↑Mon Aug 14, 2017 10:24 am

NomadRacer wrote: ↑Mon Aug 14, 2017 9:08 am Fantastic project! I'm really digging your gear cover, love to have one

Oops, went back and read earlier post and it's a reverse style cover

lol... I'm curious... Why would you need a non-reverse one? Wouldn't that be the stock great cover?

The stock (Worlds re-release) gear cover is pretty much "unobtanium" and I need one
I picked up one of RPM's white covers but just not digging it.

NomadRacer wrote: ↑Mon Aug 14, 2017 6:10 pm

BloodClod wrote: ↑Mon Aug 14, 2017 10:24 am

NomadRacer wrote: ↑Mon Aug 14, 2017 9:08 am Fantastic project! I'm really digging your gear cover, love to have one

Oops, went back and read earlier post and it's a reverse style cover

lol... I'm curious... Why would you need a non-reverse one? Wouldn't that be the stock great cover?

The stock (Worlds re-release) gear cover is pretty much "unobtanium" and I need one
I picked up one of RPM's white covers but just not digging it.

Ah I see. The good news is that with the CAD files it's a simple operation to flip the design around and print one in normal orientation.

On a related note, it's been a while since I've been fiddling with my RC10 and while I know the car has been discontinued, what's the situation on parts? I see a number on backorder on some popular online stores, are they still available or are we going to have to find them in the resale market from now on?

toying with some ideas...

after a quick first run, my thoughts are that the car could generate a bit more forward traction and also that the rear has a bit too much roll so after direction changes the rear seems to take a while to settle. These are probably a result of the suspension being catered more for the rear-motor setup. So there were 2 things on my mind that I wanted to tweak if possible - anti-squat and roll-center.

For anti-squat, I'm not sure what the standard anti-squat on the RC10 is but I'm guessing it's probably about 3 degrees or thereabouts? Typically for rear motor cars with the weight hanging out back we run more anti-squat to control that weight on power. With mid-motor cars, too much anti-squat reduces rear weight transfer and can affect forward grip on med-low grip... so I wanted to reduce the anti-squat. A couple of washers sandwiched between the rear suspension blocks and the chassis would do this.

Roll-center was a little more challenging as there aren't any good options for mounting the upper camber link in different positions unless new holes are drilled on the rear bulkhead but then I might have clearance issues with the gear cover. So I thought I'd try a different route and adjust the lower hingepin heights instead - raising them up should raise the roll center and reduce rear roll for a more reactive rear end.

So I combined both ideas into 1 and made these little spacers to mount under the rear suspension blocks. They raise the hingepins by 1mm and have a 1 degree angle to them so depending on their orientation I can add or remove anti-squat.

All just theory at the moment. It's fun trying to see if it pans out in reality. lol!

Here's a pic of the spacers.

Great idea on the anti squat spacers, I found the same problem on my yz2 lay down RC10, be interested to see what your findings are

RC10 Worlds re-release parts are drying up on ebay. I look nearly every day.

Yeah.... I thought the parts availability would have lasted a bit longer than it has.

Oh well, back the old days of pre 2014.