The rc track has been relatively consistent lately which allowed me to run a suspension setup test. I started out with testing the extremes, such as super soft suspension in the front and hard in the rear and vice versa. Funny enough it turns out that the Tamiya suggested setup (the stock setup) produces the best car handling and smoothest ride on my particular track. A hard rear suspension and medium to soft front makes the car prone to oversteer, but can produce very fast laps. The lap times are Continue Reading »
It is absolutely amazing how the RC cars handling and riving characteristics change when switching from All Wheel Drive to Front Wheel Drive or Rear Wheel Drive.
I did a Front Wheel drive test a while back, impressions and lap timing results are available here. Now I finally had the time and most importantly consistent track conditions to run the Tamiya Subaru in AWD and RWD on the same day back to back.
In order to change the rc car to rear wheel drive only I simply removed the front drive shafts as shown in the picture below.
Granted that this does not produce the optimum performance compared to removing the main drive shaft and therefore eliminating the Continue Reading »
I have been running a Brushless Novak Motor ever since I build my backyard RC track. However during the last rain session I fried the Speed Controller (water and wet mud got in it) which forced me to switch to Tamiya’s stock 540 motor. The lack of response, torque and top end speed was immediately apparent, but and that should be a bold yelling “BUT” – the Tamiya Motor has a higher resistance when turning over, which essentially acts as breaks when easing of the throttle in or before corners.
After several laps of getting used to the new handling I was actually able to turn faster lap times compared to the Brushless motor thanks to the new found “breaks” that allow me to get of the throttle later.
I have to investigate if there are Electronic Speed Controllers for Brushless motors that would allow me to adjust the coasting (breaking) resistance when letting off the throttle.
Just out of curiosity I removed the rear drive shafts going to the wheel on my Tamiya df03ra and ran it on the rally track that I set up in the backyard.
The car is much to light in the front (which was clearly visible right from the start) for making it a serious front wheel drive contender. I did not have the chance to run the front wheel drive configuration on tarmac, things might look different there.
One of the positive aspects of having the Continue Reading »
Now that the track is build and the racing line is measured I of course want to know how fast my car is. Unfortunately my current webcam based lap counter software does not have a function where it calculates the average speed based on track length.
I posted earlier how to calculate gear ratios and top speed. I also compared the RPM’s and MPH of Tamiya’s stock motor with a Brushless motor.
Here is the math to figure out the average speed:
Average Miles Per Hour
Average Speed = Total Distance divided by Total Time
D = distance (length of the track) in feet = 130 feet
T = time in seconds = 14.716 seconds (based on 4 test days and 3 race days)
S = speed in miles per hour
To convert seconds to hours use 3600 (because there are 60 seconds in a minute and 60 minutes in an hour)
To convert feet to miles use 5280 (because there are 5280 feet in one mile)
S = 130 feet / 14.716 seconds = 8.83 feet per seconds
8.83 feet per seconds x 3600 = 31788 feet per hour
31788 feet per hour / 5280 = 6.02 miles per hour
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Average Kilometers Per Hour
Average Speed = Total Distance divided by Total Time
D = distance (length of the track) in feet = 39.62 meter
T = time in seconds = 14.716 seconds (based on 4 test days and 3 race days)
S = speed in kilometer per hour
To convert seconds to hours use 3600 (because there are 60 seconds in a minute and 60 minutes in an hour)
To convert meter to kilometer use 1000 (because there are 1000 meter in one kilometer)
S = 39.62 meter / 14.716 seconds = 2.69 meter per second
2.69 meter per second x 3600 = 9692.3 meter per hour
9692.3 meter per hour / 1000 = 9.69 kilometer per hour
Finally the wait is over!
Today was the first day the car went on the backyard track.
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Good News:
- Car handles like a champ
- Surprising off-road capabilities even in soft gravel
- Plenty torque and still enough speed using a 7:1 ratio and Brushless Novak motor
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Bad News:
- Track is too narrow in some areas
- My lower chicane is too tight for the steering radius of the Subaru
- Track is a bit short
- Speed Controller and Receiver dust cover still let’s to much dirt in
Unfortunately Tamiya’s DF03 RA Rally Cars feature an open tub chassis that easily collects dirt, gravel, mud and water.
In order to make the chassis a little more “Rally friendly” – which means running in wet and/or dusty conditions I decided to build a plastic cover.
I am using a thick-monofilm available in most arts and crafts stores. When designing your own cover make sure that your ESC (Electronic Speed Controller) still gets proper cooling or you are running the risk of overheating your ESC.
Detailed images below.
Tamiya Rally Car RC Dirt Cover Side View
Continue Reading »
Without a doubt one of the most widely and frequently used RC car motors is Tamiya’s stock 540 Motor.
The motor is produced by Mabuchi Motor Co. LTD, based in Japan. If you would like to know Voltage, Speed, Efficiency, Watt etc. to calculate your R/C cars speed and performance then this official 540 Motor product spec PDF might just what you Continue Reading »
Here is a side-by-side comparison of the theoretical top speed using Tamiya’s Stock Motor, the Mabuchi 540 and the Brushless Novak SS4300 with different gear ratios. If you would like to calculate the top speed of your own RC car take a look at my Step-by-Step Guide on how to figure out RPM’s, Internal Gear Ratios, Tire Circumference and all the other data you need to know.
Here is the Continue Reading »
Here are step-by-step examples on how to calculate the most common specs, such as Gear ratios, Motor and Wheel RPM’s and the calculated Top Speed of the Car.
Gearing Ratios
Driver Ratio (aka Spur/Pinion Ratio) [-Equals-] Spur Gear [-Divided by-] Pinion Gear
Example: Spur Gear 75T / Pinion Gear 32T (T stands for Teeth – if you are not sure how many teeth your gear has, just count them).
75 / 32 = 2.34 | The Driver Ratio is 2.34, which means that the Spur Gear will turn 2.34 times, while the Pinion Gear turns 1 time.
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Internal Gear Ratio (aka Transmission Ratio) [-Equals-] Final Drive Ratio (found at the wheels) [-Divided by-] Driver Continue Reading »
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