Schumacher Atom GT12 Pro build and Review

The GT12 scene really came alive when Schumacher first released their SupaStox as a rival for the Mardave V12 back in 2012. Like any racing class, competition always accelerates progress and the class has gone from strength to strength since that date. It has seen a many improved chassis released over that time as the manufacturers compete to ensure they have the class leader.

The latest chassis to enter this arena is the Schumacher Atom. It is billed as the ‘latest innovation in the exciting world of GT12 racing', so let's take a closer look!

Two Specifications which one to choose?

The Atom come in both Pro and Sport versions. The sport has fixed rear axle, no side dampers and old style SupaStox wheels, the Pro kit comes with Carbon Pro diff, side dampers, left wheel clamp and the new Atom wheels.

Cannot wait to look inside

I went for the Atom Pro Spec GT12 as my local club has open rules that allow me to run all of the the options it provides. The box is relatively small as there is no bodyshell included, but it looks very cool and it hints of what is to come.

Clear instructions and labelled bags

On getting home and opening the box you instantly see many separate bags all labelled up for each step of the build along with a well presented and clear instruction book. It also has several Schumacher RC related catalogues, a roll of fibre reinforced tape and a decal sheet.

Ready for the build!

I felt it would be easiest first to arrange the bags into step order rather than having to route through each time for right bag. Only a few tools are needed to build the kit:

• 1.5 and 2mm hex drivers (although Schumacher handily include basic Allen keys in some of the bags), 
• 3mm nut driver
• Pliers
• Small file (This will become clearer later)

The instruction manual is as you would expect from Schumacher very clear and shows what screws you need and how many for each step.

The manual is clear and easy to follow

Each step has a diagram showing where the parts go and what fastenings you use, the second diagram shows how it should look once step finished

Step one – Here we see one of the big changes from all the other recent GT12 cars. Gone is the composite material, instead we have an aluminium chassis that is anodised in black with some stylish looking machined edges. The goal here is to lower the centre of gravity, and you cannot put weight any lower than the chassis itself.

The aluminium chassis is really well finished

First up we need to fit some fibre pieces that form part of the battery housing and suspension mounting.  These are made from Schumacher's S1 composite material, which has a built up a good reputation over the last few years as it's proven to be strong.

The parts are all joined together on a sprue

These parts will require a little filing where they have come off the sprue (this is not essential but it improves the look of the finish).

Take time to file the parts to make them smooth

At this point you also add the front body post mounts which are plastic and a tip here is to first run through the holes with a M3 tap.

Step 2 – More parts to add to the chassis, first up is the front pivot for the rear pod which is pre bonded into an S1 composite plate.

The main chassis is taking shape

This is followed by a few black anodised aluminium spacers and bolts for the upcoming suspension.

Step 3 – Now we get to the rear pod, using anodised and machined aluminium for the sides and the S1 composite for the braces (one having a plastic piece pre-bonded into one piece) It is important to follow the instructions carefully here as the pod is asymmetrical.

Excellent machining allows this pod to be precise and square

Now I must say that unlike my previous car and as you would expect from a Pro kit I was pleased that the the Atom's pod screws together really easily. The fit is excellent and when giving it the once over it proved it to be precisely square.

Step 4 – This is split into 2 parts A and B, A is fitting a long grub screw and in the manual shows a precise measurement that this needs to be screwed in by – 2.75mm so I recommend a digital Vernier.

Take your time assembling the rear pod or you will have tweak!

Section B involves adding a few more parts to the rear pod including ball ends for the suspension link.

Step 5– We now come to attaching the already completed pod to the chassis, screwing it to the pivot that was bolted to the chassis in step 2. Also the first of the 5 springs, what appeared unusual was a conical spring that clipped to the nut and again a precise measurement for screwing nut down.

2 plastic moulded links then clip the side of the pod to ball ends attached to the S1 composite plates that were attached in Step 1.

Step 6 – Another multi-section build step. The mounting of the the rear body post mounts to an S1 composite plate (again with plastic pieces pre bonded to them by Schumacher which is a nice touch). Like the front mounts they are plastic and I strongly advise running a 3mm tap through the holes.

B. Attaching the rear springs which are very similar to that used on L.M.P cars and again the springs clip onto moulded nuts (I hope these will stay in position when running, but I guess Schumacher's R&D will have tested this) These are screwed onto grub screws that were fitted to the brace.

C. This part is the attaching of the plate onto the Anodised spacers fitted at step 2.

Step 7 – Another multi-step section but just covering the centre damper which is made up of 3 parts and 2 ball ends.

Oiled up my stiff rod.

The damping is provided by little ridges in the piston which you coat with the included 12000 weight silicone oil which is very gloopy stuff.

Clipped on and ready for action

B. Is clipping the completed damper to the pod and chassis.

Now onto the front of the car.

Step 8 – More composite parts comprising of an upper and lower beam. Starting off buy bolting a steel king pin to attach side of the lower beam, the king pin has a small hole to allow it to be held securely whilst tightening up bolt.

Once those are on the steering knuckles are slid over the pin paying attention to the manual as though they are the same as the ones on the earlier Schumacher GT kit, this time they are mounted other way up., (they are a satisfying fit, not loose so there is slop but slide smoothly on the pin).

Above the knuckles are small springs on each side and then the top brace is then bolted to the king pins to sandwich it all together. Damping can be added to front suspension by coating the king pins with the 12000 wt silicone oil but I decided against this.


Step 9 – Fitting of the front axles which are much smaller in diameter than the SupaStox and GT items but are secured the same way with a nut at back of knuckle (don’t over-tighten or it effects the rotation of the knuckle).

The tolerances of the parts is great!

Ball ends are bolted to small spacers which is then attached to the steering knuckle. There are 2 options for this and I followed the kit instructions of inner hole. A pair of grub screws are mounted to the lower beam again with a very precise measurement of 4.4mm (Schumacher don’t mess around do they)

Step 10 – Fitting of the front beam to the chassis. Starting off with the front bumper plate a spacer and then the beam screws from under chassis screw into more pre glued pivots in lower beam.

The front end is taking shape now

The whole beam assembly is now fitted.

Step 11 – We move onto fitting of the servo, now this is where you need to provide your own servo. Various different ones can be fitted however the recommended one (which is the one I went for) is the Core RC CR194. It is a small servo that sits nicely in the chassis putting the output on centre line of chassis. There is instructions later in the manual for fitting other servos. A servo saver is included in the kit (Kimbrough type) 2 ball ends are bolted to this along with a small brace to strengthen the servo saver. Most who have run GT12 cars in past will have experience the saver breaking where ball ends mount, this should alleviate this.

I added an additional brace, but removed it as it changed the ackerman and made the steering too aggressive.

B. Good quality Turnbuckles are included and for this part of step just need the ball cups screwing on to the recommended gap 14.7mm (vital to use the Vernier again). C. Once the servo is bolted in the turnbuckles can be clipped to the servo saver and the steering knuckles, Schumacher advise starting with adjusting these so that 0 degree toe in is achieved.

Step 12 – This step is fitting of the body posts (although I decided to leave this until I was ready to mount shell).

Also the fitting of the bumper which is held in place by 2 posts. It is made of foam and may need to be trimmed to fit different shells.

Step 13 – This step shows the advised positioning of the electronics I.e. esc, receiver, personal transponder (all of which are not included in kit. At this point the aerial mount screws to the chassis, a grub screw will hold the aerial tube into mount securely.

There are instructions on how to mount the motor as per other GT12 chassis the opposing screw mounts are done away with. This allows the motor to be mounted much lower and it is seriously low in the Atom, slots in aluminium motor mount allow easy adjustment.

The battery (1s lipo shown in manual not included) is secured in place with fibre reinforced tape of which a roll has been included in the kit. A lipo strap is going to be a hop up item but by looks of it a SupaStox GT strap should fit.


I decided to go for all new electrics in this car and chose the Fleta 1s esc, Fleta 13.5 motor and the core rc servo. It was easy enough even for me to get quite a neat install. I struggled with setting up the ESC but a quick call to Keith at Much More (a great guy who happily chatted with me to sort my issues which turned out to be a setting on my transmitter – fixed by resetting the memory)

Going Pro!

As I have the Pro spec version of the Atom, you need to move to the right part of the manual to carry on with the build.

Step 14 and 15– The differential build. This is the first of Schumacher's GT12 cars to have a carbon axle (like the Zen and Mardave). It is important to follow the instructions closely in order to build the diff accurately. Do not worry though as this stage has some very clear diagrams in the manual to follow.

Very smooth and light

The build is very straightforward and using the included silicone lube the diff built up into a very smooth unit and light (although it is a touch heavier than the Mardave)

Step 16 – this covers fitting of the rear axle into the pod, Schumacher have included several eccentric axle bearing holders/ride height adjusters. Each bearing holder allows for the ride height to be kept but using different diameter tyres.

Check you have the correct settings on both sides of the pod

The included bearings feel very free running and smooth and fit well within the bearing holders.

The axle spins freely

The axle is then slid through the right side bearing through the left and then a spacer is slid over the shaft before the left side clamp/wheel mount is tightened up – it is important here to allow for a very small amount of end float.

Step 17 – Now the new wheels, these look great, the rears are a very deep dish design moulded in white plastic. The fronts are ball raced and a lock nut holds them on shaft again allowing a little end-float to ensure the wheels spin freely.

Carlos Fandango super wide wheels?

The rear wheels (like the Zen and Mardave) are secured with 3 small bolts – Ensure that the wheel is sitting flush otherwise it may not run true.

Step 18 – Pinion mesh, again pinion is not included in the kit and is a 48dp item (to suit the spur). The manual shows very clearly how to adjust the motor position to get the optimum mesh (a small amount of backlash is important)

Side Dampers
That is most of the kit built it is just a case of flicking a few pages to come to the side damper section which is included as a hop-up item. Building the pair of side dampers is exactly like building the centre one (section 7).

Side dampers installed

The dampers clip to ball studs that need bolting to the front brace on rear pod. This means taking the brace off and although only a quick job (2 bolts) It might have been an idea for Schumacher to put a note in section 5 that if building the Pro version to refer to this and do it all in one go. However saying that it was a 2 minute job and went together well.

For me it was now back to the bodyposts which slide into the mounts and a small grub screw is used to hold it in place. Here is the final chassis, it looks 100% a race car and I hope it runs as good as it looks.

Installed and ready to race!

Rear end shot

Low and fast (post race scars on show)

Top shot

Fitting the body

Once change on the Atom is that the rear posts are now just forward of the rear wheels(which I believe is akin to LMP cars) this may cause a problem with some shells as it requires a shoulder on the shell alongside rear windows. (not all shells have this)

I used vinyl wrap on the shell

I will be running my Protoform McClaren which mounted nicely to the Atom. I could then set the bodyshell height and trim the posts.

Lightweight

Even with all electronic in and a battery the car is super light (surprised me considering the aluminium chassis).

Need to add weight to make this car legal!

Running well below the BRCA weight limit, without the body shell but with all electrics mine weighed in at 780g and BRCA minimum weight is 950g, Schumacher have brass balance weights available that can be bolted front and/or rear.

At the Track

After what seemed like an age I was able to take the Atom to my local club (Wirral Model Car Club), the club runs a fairly small track but is always challenging and just lately I had found myself in the B final with my previous cars. So I was keen to see how the Atom would perform on the track!

I ran the Atom as per the kit settings, putting additive on rear wheels and just a 1/3rd of inside of front wheels. Onto the track and straight away it felt great, very forgiving and nicely balanced with plenty of steering.

Wirral doesn't actually race on grass ;)

The first thing I noticed is how much easier it was to drive than my previous GT12's. With my first run I was 3rd fastest overall. I did improve through the next 2 rounds and qualified 4th in the A final a testament to the car and its out of the box performance.

Unfortunately in the warm up the car took a huge impact in the rear when lining up for the race and when I went to move to the line after the collision I the Atom just squealed! No final for me :(
I looked over the car and despite the impact of another car hitting the back of the stationary Atom at full speed nothing had broken. It had just tweaked the pod out of true so the axle wouldn't spin freely (hence the squealing).

Back to the track the following week after it was rebuilt was more of the same and again I qualified in A final. However during the evening I finished one round with a very deformed wheel caused by a cracked spoke.

The new Atom wheels don’t have much support to them unlike the old contact wheels, and I found out that many others had the same issue– however Schumacher are aware of this issue and have since reissued new strengthened wheels with more nylon in them and more webbing. They have also replaced my broken wheel for free, which is great customer service.

Currently I find that running the following works well

• Kit tyres 44mm at the rear and 42mm for the fronts
• 0.75mm rear droop and 0.5mm (ish) front 
• 3.6mm ride height

Overall

I have been really impressed with the Schumacher Atom. The build is very straight forward and the quality of the components is great. Importantly for a race car, the chassis is fast straight from the box!

In my opinion it is a big jump from the previous model, and it has raised the bar again for Schumacher in the GT12 class.

Yes it has had a few teething problems mainly the fragility of the wheels but Schumacher were quick to listen to racers input and have sorted the issue by adding more nylon into the mix and adding webbing. They have also replaced broken wheels, what better customer service could you ask for.

Importantly this car has been rewarding to drive from the moment it went on the track, I've improved my times and I look forward to getting more track time.

The Atom is available from your local Schumacher stockist (Click Here for more info)

Review and Pictures by Richard Armstrong.