Increase your Mini-Z MR-03/MR-03EVO Performance with PN Racing PNR2.5W Chassis Kit

Today, we are looking at the PN Racing 2.5 Chassis (900100). This is going to feel old school because it is. This chassis has been out for at least 8 years now.

What is it? It replaces the chassis housing of Kyosho's MR-03 while maintaining compatibility with basically all MR-03 parts. What is it good for? It increases the car's corner speed of lowering the center of gravity.

Here's my Mini-Z LM build with the PNR2.5W chassis, plus standard MR-03 frontend and R246-1202 LM motor pod and damper. Batteries are loaded from the bottom with minimum covers. This puts the primary mass of the car as low as possible. The main board, which came from an MR-03VE donor, is placed also as low as possible. The idea is quite simple really, but PN really perfected this. Aside from tires, the PNR2.5W chassis is arguably the next most important performance upgrade for an MR-03.

For comparison, here's a standard MR-03 with RM motor pod. From this angle, it becomes clearer to see how the PN chassis achieves lowering the center of gravity. A stock MR-03 like this with the right tires actually runs decently on a track. It's not super fast around corners, but it generally handles well enough with its brushed motor power. I keep a stock MR-03 around because it's a lot of fun at 90mm.

Another comparison we can make is with the MR-03EVO. The chassis itself is no different from a standard MR-03. This MR-03EVO with its MM2 pod sits quite tall. That's not great for performance but it makes up for having a lot more power. I would say most PNR2.5W chassis is built with EVO electronics as it's the best Mini-Z electronics available today.

One thing to keep in mind: PNR2.5W does not support a narrow front track configuration. In addition, the upgrade is not a straightforward one either as it requires some soldering and handling very tiny fragile wires. In my case, I started with an MR-03VE. Others build their PN 2.5 cars from scratch using Kyosho/PN parts.

Let's see how I did this.

This is the donor MR-03VE. It's an older ASF brushless chassis with an 102mm wheelbase. I decided to do the PN 2.5 chassis upgrade to mix things up a bit in my fleet of MR-03. The VE main board is actually perfect for this conversion. The PNR2.5W kit came in a box like this. It's $29 and I think that's a good deal.

Inside the box, we have the chassis itself, a bag of parts, detailed instruction manual, silicone wires, and some screws. The chassis is constructed using nylon with fiberglass and ABS material. It's lightweight and strong. It's quite well made. All the lines are sharp. I didn't see any excess plastic anywhere. Here are the other parts we will need later in the build.

Let's begin disassembling the MR-03VE. We can see the main board and the exposed servo here. Transplanting them to the new chassis requires some patience and care. There are 7 wires attached to the back side of the board. Both the servo motor and power switch are secured by separate screwed down covers. Watch out for tiny wires. The board, power switch, servo motor, and the whole servo assembly finally came out. The motor also came along because I didn't want to desolder it.

Prepare the PNR2.5W chassis by tinning the 4 battery terminals. Drop the servo assembly into new chassis. Servo wires should be routed along the groove to its right side. The servo motor and power switch are also located in the same locations as stock MR-03.

To fit the longer VE or EVO board, the screw hole nub on the servo motor cover must be trimmed off.

Got all the electronics installed after fiddling for placement for some time. It's all about managing the wires underneath. It's time to solder the red and black wires to the battery terminals in the middle. The servo cover can go on now. Watch out that it doesn't clamp down on any servo wires. Do the last bit of soldering by connecting the two far side battery terminals. For me this was a good day of soldering.

Only now can I test whether I messed up the main board or wires. Steering and throttle are still good.

PNR2.5W uses its own t-plate holder. Everything else is standard. Some people would be going for an upgraded frontend like the PN Double A-Arm. I'm going to keep using the stock MR-03 frontend.

It's done! I needed a few hours to get this done, but I'm happy with the result. Everything fits well. Wiring looks clean. It feels like a proper upgrade. I can already feel the chassis being faster. If you have an extra MR-03, I think this is a fun upgrade to do. It's worth doing even without going for fancy suspension hopups.

This is Sammy and thanks for watching!

Music: "Instructions for Living a Life", Savfk (   • Instructions for Living a Life by Savfk  )