Eagle Racing "M"31-16"RM"

I've started a project converting my Eagle R31-16fm into a rear-motor M chassis.....just because 

"M" = m-chassis
"RM" = rear motor

First off, the R31-16fm is a front motor chassis, which isn't really that ideal for RWD drifting since there ends up being less weight over the rear wheels causing the chassis to struggle to get up to speed and drift with others, unless you put grippier rear tires.....and front motor chassis are more suited for CS drifting (from my experience). I also want more variety during drift sessions so drifting an M-chassis would at least provide that.

Now, Tamiya's M-chassis in particular have adjustable wheelbases since they make bodies of different wheelbases (210, 225 and 239mm). I will also make the wheelbase adjustable. It will pretty much be a 2-piece chassis where the upper and lower decks overlap and mount using hardware. This way it will maintain rigidity. The front half will mount below the rear half to prevent snagging on track curbs and debris. And making it rear motor putting all the drivetrain in the rear makes this possible since there's no long any drivetrain parts that span the length of the chassis.

Ok, enough babbling. Here's some pics.


Comparing the chassis to a Tamiya MX-5 body to get an idea of how much I need to shrink the chassis.




Checking clearance with motor assembly. Clears the spur gear and the rest just fine.




Here's a pic of the motor assembly separate. I'm using the stock 18t center pulley with a TA05 36t diff pulley, and the belt is a 50t with a tensioner. 


I thought I was gonna have to custom fab my own lower control arms, but after digging around my spare parts and looking at parts online, I discovered I can use some existing parts and modify them. The rear arms are Tamiya TA04/05 front arms. I plan on using Sakura D4 front arms for the fronts.


The C-hub area is where I can mount a rear upright. There was already a tiny hole right where I needed it to be to insert the pin so I used it to drill out. 

Shaved the rest of the arm for clearance for upright.

Test fitted the Eagle upright. Will be using Tamiya 2 degree uprights.

Assembled on chassis.



I just so happened to have 30mm cvds in my parts bin (lucky). I know the diff cups are damaged. Might grind them out so I can use cushions.

I'm using the stock deck just for mock-up. I will be making a custom adjustable deck. And if you're wondering about the O-rings for the turnbuckles, they're simply there just to reduce wiggling since they do move quite a bit.

Both arms done and mounted.

Test fitting body. 






Nice and flush. I actually lucked out on the arm length. Those are HPI Cup Racer MX60 6mm wheels.



In short, this proves that it's very doable to reverse this chassis into a rear-motor layout. I'm just taking it further with doing an M conversion.

More updates to come