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Why did I upgrade my Wltoys A979b?
Click here for a YouTube video on A979b.
After the initial run of my RC truck, I found that it spun a lot. Whenever I gave it full throttle, it would spin.
This truck uses a plastic steering system, and its wheels can swing without moving the servo arm. Thus, the truck cannot run straight.
During the run, I could never drive this truck at its full potential – 70 km/h. For this reason, I examined if it was a good idea to use aluminum parts to overcome these problems. Usually, with aluminum parts, you can make a lot more adjustments on an RC truck, not to mention that the truck can become more durable. This is the reason why upgrading with aluminum parts is almost the requirement for using a brushless power system.
This is a post for RC car beginners as upgrading a Wltoys 1/18 buggy is quite a challenge.
Here were the things I purchased for upgrading my a979b to full metal
The upper deck for a979b is different from the one for a979. The one for a979b has enough space for the big reduction spur gear.
Enlarging the Battery Holder
This RC truck comes with a small LIPO (1500 MAH), so the running time is only about 10 minutes. At the time of upgrading this RC car, I had 3 LIPOs with 4200 MAH, each sitting idle, thus, I wanted to find a way to use all these LIPOs without investing any more money on buying any new LIPO.
Later, I found out that after I replaced the plastic upper desk with a metal one, instead of placing the ESC next to the LIPO, I could put the ESC on the top of the upper deck. By doing so, I could increase the size of the battery holder by 30%. It was enough for holding each of my old LIPOs. You can check out the result after the modification in the first picture of this post.
In the process I was upgrading the RC car, I encountered a problem with the steering knuckles shown above. I found that the area was too small for inserting a bearing. So, from then on, I have realized that not all option parts were created equal. Some option parts have less quality, especially the ones made in China.
Do not expect that aluminum parts are perfect. While you do not get stripped screw too often if you use aluminum parts, some aluminum parts might not have a perfect fit while you install them. To fix this, you can go to a hardware store and buy some aluminum oxide abrasive papers. You can use them to sand away the extra layer of your parts.
Moreover, I found out that while the aluminum connection rods had too much slack, the original plastic rods were good options. In fact, I tried both and found out that the original plastic rods could make the car run more steadily.
You can download the A979 manual here. Here is a copy of the manual you can take a look. Without the proper instruction, you cannot upgrade this RC truck. If you are as careless as I am, you might find yourself installing your optional parts in the wrong direction. This suggestion is valid and important if you buy this truck second hand.
Screws and Glue
I found that building/upgrading this RC car requires you to have some extra m2, m2.5, and m3 screws as some sellers of option parts might forget to give you enough. You should check if you can find those screws on eBay before you start your project. Besides, you will need some screw glue as you will need to tighten the screws once you make sure that you have installed all the optional in the correct positions/directions. The glue is essential! However, if you use too much glue on your parts, you might need to use an air blower to soften the glue, in order to get the screws out when it is necessary.
Body Poles and Shock Stands
While you are using aluminum poles and shock stands, you might find that you need to re-drill holes for the body as the position of the poles might move a little. In my case, I needed to redrill the hole a little bigger.
The Electronic System
As the ESC and the receiver are in one unit, it is a good idea to replace the whole electronic system if you want a stable one. If you replace the ESC/Receiver unit, you will also need to get a new servo.
The original servo has five wires and with plastic gears. It is not a servo of the standard size. If you plan to replace it with a 3 wired servo with metal gears, you have to make sure that you can get the right size of it. Never buy a servo that is too big or too small. With a wrong size servo, you will fail to install an appropriate servo in the car to make the car run straight.
Check out one of the servos that are designed for the 1/18 Wltoys RC car. The size of the original servo is 28mmX13X27mm.
I also used an aluminum servo stabilizer as I could secure the servo much easily.
The servo I used is Emax ES3004 (an upgraded version is ES3104) and it was 23T; it is hard to find a servo saver for it as most of these in the market are 25T. In my case, I finally found a metal saver arm of 23T in Taobao.com. If you are not in China, you can search this on Aliexpress.
The above image shows the shocks you should get if you want to replace the original plastic shocks. These shocks have enough power to support the chassis and can be adjusted. Once you use more aluminum parts, the chassis would become heavier, so a set of capable shocks is essential.
There is another type of shocks in the market for Wltoys 1/18 buggies. For the above shocks to work properly, you need to open them and add oil. I used Tamiya shock oil for this purpose. They work perfectly if your chassis is not very heavy.
As I tried to upgrade to metal gears, I found out that I just wasted my money as a979b included a full set of metal gears for the cars. I was too careless. One of the sellers on Taoboa.com confirmed that the newest release of a979b included a full set of metal gears and the central shaft. At the time of my writing this post, there were still some old versions of a979b in the market. Thus, if you have an a979b, and you want to upgrade to full metal gears, you need to open the gearbox to check it out first before you place an order.
While upgrading my a979b, I found that I needed to decide whether I should replace a small part for the truck. Look at the image below. The part number is A979-03. Later, I found out that it fits the front and rear end of the truck. While this part is made of plastic, it is an important component holding the a-arms. There is an aluminum alternative in the market, but it is relatively expensive. ($4.99 vs $12.90 online). As I am using metal bumpers, I think using these plastic arm holders should be enough.
Radio Link – RG4GS is very useful in making this RC car run straight as it has a gyro. For more information about what gyro is, read this post.
As my skill level grows up, I might get a brushless system. Anyway, it really depends on where I run my truck. If I mainly do bashing, the brushless system should bring up the excitement. On the other hand, if I run it on a small track, I will stay with the brushed system as running on a track does not require high speed but accurate handling. In fact, this RC truck is overpowered already with its original brushed motor.
If you are an absolute beginner and hate driving a car that cannot run straight, do not buy this little truck. With plastic or aluminum parts, it still has much slack. It really takes a professional / or semi-professional to have this little truck set up correctly so that it can run straight and be competitive on a track. Even I have spent about $300 for all the upgrade parts, I still found some slack in the car.
Now, it is running straight finally
After several attempts to make this car run straight, I finally made it a reality. I first made the front wheels toe in, and then put in screw glue in the connection rods so that there is not so much slack in them. I also make sure that all rods have equal length. It is without a gyro in the car.
A979b is a great little RC truck at a cheap price. For such a small size, it is equipped with a 540 brushed motor. While it has a lot of weaknesses, its potential for upgrading is wonderful. I have seen a lot of people run these Wltoys RC cars on the track such as the YMT in Hong Kong. It is so competitive in the track. In fact, it is the main reason why I got this RC truck. It is a challenge to set up this truck right.
By the way, this car should be on-road only as the gears are not protected by a cover.
Will you buy this RC truck? If you have this RC truck already, will you, just like me, upgrade it to full metal? Just leave any idea you have about this truck and its potential for upgrading. Also you can join my forum to exchange ideas about this RC truck.
Thanks for reading this post.
Written and Edited by Carlos Santos, your webmaster.