Atomic BZ5 1:28 Competition Chassis Review Build Tips Micro-Z
The 1/28th scale class has always been an enigma in the world of RC racing. Kyosho started the trend in the early 2000's with the Mini-Z. A small scale car that didn't take up a lot of room
(Note Tamiya had actually started the micro revolution with the 1:24 Tamtech series in 1996, but Kyosho were first to make 1:28 scale).
They started becoming popular with their wide range of shells and ease of use. A simple car that used AA batteries, nothing really specialized about it. However, people started seeing the potential it started to spread across the globe
This has lead to other manufacturers entering the class with their own high end race chassis. This cars are even faster and it has created a variety of classes in the 1:28 scale race scene. Nowadays you can race something as simple as a stock Kyosho Mini-Z, 2wd pan cars all the way up to 4wd modified!
A good friend of mine runs a club very local to me and has been nagging me to have a go. I was at a loose end one Friday evening and decided to go down and have a look. Suffice to say, these cars proved to be a lot of fun and certainly a challenge to master
I started doing some research and seeking advice where possible. I decided to have a go with a 4wd car. I liked the look of the Atomic range of cars and settled on the newest variant, the BZ5. It's a brand I'm not too familiar with as they are only involved in the 1/28th scale class. I started sourcing all the parts needed and got to work building the chassis
It's a very small car which arrives in a very small metal tin. Opening the box reveals the kit is laid out in bags fifteen individual bags. Hoping there isn't much back and forth between bags but we shall see
I was ready to have a good look at the manual and see if there were any particular areas of interest or if I needed to buy something specific. However, no manual was provided! Looking on the underside of the lid revealed a QR code which lead me to the online manual. Something to watch out for.
Laying all the bags out seems there isn't a lot to this kit. I also bought a set of roll bars which are an upgrade which I will fit as I build the kit
Bag 1 is a tool kit. There are a range of Allen keys, a drill bit, some sandpaper and even a 4.5mm 1/4" socket. I have worried that my 1/10th car tool kit would be too big, so it's nice that some tools are provided. I had a look and found 0.050" is very close to 1.3mm so I have a Allen driver from an American car I used to own.
The screws are in bag 2 and are separated in M1.5 & M2. I'll be keeping them separate as they are tiny!
The build starts with fitting the front lower arms to the bulkheads and then to the chassis. The lower chassis is aluminium with gold edges, looks great quality. The arms needed a little fettling with the supplied 1000grit paper and they dropped under their own weight
The rear arms bolt directly to the chassis. It's a mixture of new/old technology in the 10th world. Ball ends to hold the front of the arms and a pivot block right at the back. I know there are optional blocks to adjust rear toe, so this makes sense. Zero issues with fitment and dropped under their own weight.
Next the rear bulkheads and motor mounts attach to the chassis. There are keyways in the bulkheads so zero issues with alignment
Now we get to the Differnentials
I wasn't sure what I was expecting, but the car is equipped with ball differentials front and rear. Whilst I wouldn't consider myself a pro at building a ball diff, I like to feel I can build to a good standard. Some 2000grit paper is supplied to scuff the D plates and thrust bearing plates.
You need to glue the pulley guides on before you build. Mine kept popping out, but a touch more glue and they eventually sat in where they need to
They build very similar to a conventional ball diff. No greases are supplied, but I use Schumacher ball diff grease for the plates and balls and Associated black grease for the thrust bearing
The only real difference is that it uses a firm o ring to act as the spring to retain force. We'll see how this holds up. The main of the diffs are plastic, but there are aluminium ball diffs available as an upgrade. I may fit those later on
The car has a servo saver arrangement within the assembly, not a conventional servo saver on the servo itself. No preload adjustment, so it will be as tight/loose as kit
The process says to flip it over, compress the unit to fit the e clip. Quite tricky to push, hold everything in place and then try to fit the clip. I put the assembly in a vise to act as me holding it down, but not too tight in case it breaks anything. This freed up my hands to fit the small e clip
The servo assembly is built up next. I went on a recommendation and used a GL racing 0162-TG. Utilising a floating system that 10th touring cars use these days. I fitted the servo with no issues, but realised that no servo horn was included so had to source the correct one for this servo.
The diff pulleys are moulded onto the spur gear as 1 complete unit. There are different pulley sizes front/rear, so make sure you note which side is which.
The driveshafts are CVD units front and rear. They are prebuilt, no directional clips to worry about. I just added a couple of drops of CVD oil and worked it in
The steering turnbuckles have a hole that you slide an allen key in to adjust the lengths. The threads are handed so just keep an eye out on these
The upper arms use a threaded rod for camber adjustment. I know there are turnbuckles available as an option part, so this may be the next upgrade. I found to thread them in the arm before the ball end was a easier process
No oil filled dampers here. Just a rod and housing unit. I feel this is good as I didn't fancy bleeding shocks this small! Instead you use damper grease on the rod to give different tuning, similar to some 1/12th LMP side dampers. A few drops, push it in a few times and wipe off the excess. I was recommended to have 15000 & 30000 greases to start.
The bodies are threaded so ride height adjustment is easy
I chose to fit the optional roll bars front/rear. As you can see in the pics, I fitted the bulk of the parts early on and attached the rest when the suspension as fully assembled. Nothing really fancy here, but a little work to get everything aligned and operating as designed
The car has a brace/cage unit that has adjustments for different battery sizes. I'm using a reflex racing 340A 2s lipo to start. To change the battery, you need to unscrew the entire holder from the car from the underside. It might seem tedious, but it's a very sturdy way to hold it on place and prevent the lipo moving
Electrics
With the modern era on these cars, people have made micro receivers for different brands so you are no longer restricted to KO Propo handsets. Nothing wrong with KO Propo but I use a Sanwa M17, I didn't wanna buy a handset just for 1 car!
Team Powers were able to supply me with their latest Radon V3BT 30A esc. It has Bluetooth integration, so tuning should be a breeze. You download an app and everything is there for you to adjust as required. I did find connection was an issue to start. However, I recommend visiting the app store again after the initial download and you are given the option to update it. Once done, it works perfectly!
I fitted a 5500kv motor to start with a 7000kv to go in when I gain confidence.
Fitting the electrics in the car was certainly a challenge.
The goal was to try to make everything fit, yet not making the wiring a complete rats nest! A little bit of tucking and repositioning and we got everything to fit
Bodyshell time!!
This chassis is open to a lot of different body choices. You can run a hard body or a lexan body, but you will need optional body post and bumper fitting kits. This kit includes side mounting points for hard bodies
Kyosho produce a massive range of hard bodies that all have different wheelbases and offsets. You will require a 98mm wheelbase shell for this chassis
My local club mainly use GT3 style bodies, so wanted something along those lines. I've always been a fan of Super GT racing and the Kunimitsu team so ordered a 2014 Raybrig Honda NSX- GT 2014 concept.
When you buy a hard body from Kyosho, they are mounted on a mock up frame to display the car if you wish. A couple of screws and it's removed. The nose piece is always unique and allows the shell to fit correctly on a Kyosho chassis. The Atomic has mounting points for this so shows that have taken the idea of a more universal body fitment. The nose piece also acts as a stop for the lower arm hinge pins to prevent them falling out
However, once the plate was fitted and shell clipped on, the nose sits way too low. The tyres rub and no suspension movement is possible. I thought about having something 3D printed, but it turns out I'm not the only one to have this issue
A little bit of research showed this is a common issue with loads of bodies so there are aftermarket fitting kits that actually allow you to adjust the height. You buy a base plate then, carbon or plastic shims can adjust the height to suit an individual car. Result! The rear sits a touch high, but I will track test it and make a decision from there. A little bit of rake should help with rear grip. The front did still sit a little low, so I added a couple of shims to allow it to sit higher.
Once everything was fitted on the chassis, I fitted the shell and the lipo/motor/esc fouled against each other in places. Some gentle use of a Dremel on the side supports and chassis body mounts and the body now fits. Hopefully the side supports still hold up on track
Wheel fitment is also crucial to the shell. I did source some wheels off some recommendations, but they all sit a little proud. I ended up using the kit supplied wheels which are actually the perfect offset for this shell. I asked what tyres the locals use and bought those. The spare wheels won't go to waste as I suspect I will be buying other shells at some point. I also changed to some alloy wheel nuts as the supplied plastic nuts weren't to my liking, plus blue is always faster!
The finished chassis looks fantastic.. the Gold reminds me of the Durango DETC410
Track test
I did a couple of test laps at the last round of the winter iconic cup hosted by Chippenham model car club. Just to shakedown the car and see if it worked. Suffice to say, it worked very well!
The track utilities foam squares that slot together like a big jigsaw puzzle. Once we got the track laid out, I got a battery charged and was ready to hit the track.
The club mainly runs an open practice race format. Should race numbers be present, they will operate a race night. However, an open practice night allows everyone to try their cars with minimal pressure. It also allows novice drivers to get used to driving. There are also hire cars available, ideal of you just want to try but not ready to commit to buying a car just yet
Once everything was ready, I got the car onto the track and started getting a feeling for the car and level of grip. The car was really good from the start. Plenty of grip and drove really nice. Although you want to take it steady, race cars work best when driven hard so I started pushing and seeing what was capable. The car was locked in and wouldn't break traction which gave my confidence to push
I ran for a few minutes and decided to pull off to have a look over the car. Although the motor was very warm, nothing was loose or broken. On my first run, I managed to break the lap record!
Over the course of the evening, I was just driving the car and getting used to it. My lap time was improving but still on the 6.2 second time.
I did have a couple of crashes, mainly hitting the soft barriers. As there was always a mix of abilities on the track, so car to car contact was always gonna happen. The car held up but the shell has taken some damage. All the front canards have broken off, front splitter is cracked and I managed to break the rear wing support on the last run of the evening. A bit of glue and it will be fighting fit again!
The only car damage was that when I had a bit of a high speed crash which caused a corner to come apart. I only needed to clip the ball ends back on and refit the driveshaft. I did lose a shock spring, but one of the younger drivers had better eyes than mine and managed to find it! I was concerned the plastics weren't up to the task but that has been proven wrong
The good news was that in my final run, I managed to get a 6.1 second lap time, a new track record!
Summary
Delving into the 1/28 scale micro racing is proving to be great fun!
You don't need a top spec car to race in this class to enjoy yourself. However, if you want to go faster then a full race spec car would be the way to go. Very much like racing 1/10th Touring car
There were a couple of small issues in the build, but nothing I would consider negative or would be a problem. If you aren't a novice to the hobby, you will have no problem building this car
In terms of upgrades, I plan to fit aluminium ball diffs and the optional rear toe blocks to see how the car changes. I also plan to fit a shell with less details to break off!
Thanks to the following people
Rick Cheng for the car, additional parts and running Bristol micro R/C raceway
Andy Bird at Team Powers UK for the motor/ esc
Chippenham model car club for the track test and taking pics on the track
Kieran Hyde for the video footage
