Ultra4-ish 4Runner

[12sad5]

Hi everyone! This thread will be where I document my build. I'm afraid it may take several months to complete as it is fairly involved and I have to balance it with work and life. I will do my best to make progress and document it here each week.

Overview of the project and my goals:
I have started working on an ultra4 car that is less for competing, and more "just for fun". I want to drive it a local Recon G6 and other just-for-fun events. My goals for the vehicle are a compromise between looks, performance at speed, and crawlability.

I'm going with a proline 4runner body (Ordered). While having IFS might be more "4runner appropriate", I don't feel that the element IFS really has the travel and clearance I am looking for, so I am going with a 4 link front and rear. I am using Proline TSL SX Super Swamper (non XL) sized tires. I have the XLs on another vehicle and they perform well where I live, and I think this size will fit the body well.

I have done A LOT of planning and thinking for this build already, and will try to sprinkle it into my posts, as I get through each part of the build.

With all this said, let's begin!

Axles and Shocks
The axles are of the diamond variety, and will be SLS printed when the vehicle gets closer to completion. I've designed them to use Vanquish AR44 underdrive gears (to help with torque twist and pumpkin clearance), with cutdown incision wraith drive axles. The front is getting vanquish wraith scale C-hubs with vanquish wraith knuckles (non-scale).

I am outboarding the shocks as much as possible, so that I can maximize suspension travel, without having too much articulation. This will be good for decreasing chassis roll when making turns at speed and side hilling, and decreasing torque twist. The shocks will be mounted on top of the C-hub mounts with custom brackets (the scale C-hubs have an extra clamping screw at the back that I am using to help with this). I am mounting the shocks on top of the axles, rather than behind, so that I can get more steering angle and have no issues with the tires rubbing on the springs at full steering lock.

Shocks will either be TRX4 longarm shocks with the limiter removed, or shortened front shocks from the ryft (most likely the former because the latter will likely still be too long for the ride height I am shooting for and I think they will require holes in the 4runner hood We'll see what I can manage when I actually have the body in front of me!).


I've designed the first prototype of the front axle:


I do not have the servo mount in the model yet. I am using one of the new HH SHV500 LP servos that sits perfectly behind the axle. The combination of the servo's low height and this placement, keeps the servo fairly hidden and COG lower and allows for more up-travel (and possibly a 3D engine bay):


Here it is FDM printed and mocked up with a non-functional printed skid and VFD (this is not the trans I will be using - more on that later). I've mocked it up to test for link/driveshaft clearance after roughly optimizing the link positions for roll center and antisquat. There are no issues with clearances at this point, but I will revisit the geometry as the vehicle gets closer to completion and the COG location is better understood.



That's it for this week! Let's hope for a productive week ahead (several of the previously mentioned components should be arriving this week).