It looks like there are a lot new folks picking up HG P407 (especially considering the world situation right now), and most of them are asking the same questions. What upgrades and/or modifications should be done? I wanted to share some information that I was keeping for myself in the hopes that this helps the new folks.
Here’s the current stock specifications for HG P407:
HG P407 Specifications
Car size: 524×273×259mm(L*W*H)
Wheel diameter: 123mm
Wheel width: 60mm
ESC: 320A esc
Motor: 540 brushed motor
Servo: 2*6kg S3003 Standard Simulation Plastic Teeth Servo
Stock bearings and sizes:
7 unique sizes and total of 45 bearings:
Upgrades & Modifications LIst
#1 Front Steering Servo Mod - relocate the steering servo to front and upgrade to high torque servo with metal 25T horn. You can download the 3d file from Files section, or order Ampro’s from Shapeways. Few cheap, but effective servo options:
#3 If you plan to take it offroad, you will need to lock the front and rear differential with pins included. There is a small hole that you can install the locking pin, but there is actually 2 different sides on the transmission, one side is threaded and the other side isn’t. I recommend opening the axles (especially when you are opening it up to replace the bearings) to ensure that you are installing it from the correct side and tightening it down accordingly.
Battery relocation and removal of Electronics box. This isn't for everyone, but my experience has shown that it makes a huge difference in climbing capabilities. Much more involved as you have to fab the battery holding plate, and electronics tray.
(FREE) Remove 1 leaf springs - front and back. Most folks recommend removing the smallest leaf from each corner. I ended up removing the middle leaf.
Remove springs on shocks and add washers. Stock shocks are not very good and they leak. You can make modification to improve it. A good video from Dennis Dempsey Radio out of Control - https://www.youtube.com/watch?v=Iin6AAnf4gI
(FREE) (rear only) turn rear shackle mounts around. It lets the back flex a little more than current setup, and lessens the chance of snapping the leaf springs as it will have enough compression to not over work the leafs.
(FREE) chino mod
(FREE) break in those leafs
Install LED lights. I am using the following light kit. Ampro Engineering did reviews on few different sets, and this one was recommended. The only downside is that for the brake light, you will need to solder in 3mm red LEDs instead of the 5mm red LEDs that comes with it - LED Light Kit - https://ebay.to/34EyqPP
Replace transmitter & receiver with Fly Sky FS-GT3B, hack firmware (key benefit is ability to convert it into 6 channel system) and mod to Lipo battery. Not necessary, but it is so nice have an upgraded transmitter. If you do go this route, here’s a video that I put together to mod it to use Lipo battery - https://youtu.be/pYCW6VbDgMo
12mm Hex Conversion. Best way is to either get the RC4WD 12mm hex conversion kit or replace the axles to Yota 1 or 2 axles (it's easy conversion on front, but for rear you will need to look for Bruiseraptor axle which is discontinued and difficult to find). Additionally there are 3D printed mod options, but they tend to stick out the wheels too much.