Tekno RC EB48 Thread
#497
Tech Addict
iTrader: (23)
Joined: Jan 2010
Posts: 616
This is straight from Austin's father.
Austin has been using a mamba max pro speed controller and a 2400kv Castle short course motor with a 5mm rotor. He's tried 2 shorty 3800 ProTek batteries-4s, which has resulted in about 8 1/2 minutes of runtime outdoors and about 11 minutes indoor. Not bad considering this combination is still as fast as a 1/8th scale Castle 2200kv motor. If we need more run time we just drop in a ProTek 6400 4s battery.
We're able to run this combination because the car is at minimal weight and we dont need the bigger motor and speed controller. At the end of races the speed controller fan isn't turning on so heat isnt an issue. We're running this weekend at Delta, so its going to be a little warmer out so we will see what happens.
Steve
Austin has been using a mamba max pro speed controller and a 2400kv Castle short course motor with a 5mm rotor. He's tried 2 shorty 3800 ProTek batteries-4s, which has resulted in about 8 1/2 minutes of runtime outdoors and about 11 minutes indoor. Not bad considering this combination is still as fast as a 1/8th scale Castle 2200kv motor. If we need more run time we just drop in a ProTek 6400 4s battery.
We're able to run this combination because the car is at minimal weight and we dont need the bigger motor and speed controller. At the end of races the speed controller fan isn't turning on so heat isnt an issue. We're running this weekend at Delta, so its going to be a little warmer out so we will see what happens.
Steve
#498
If you go back in this thread, I posted a vid of a race before it was announced, there is another video with some racing, and then a trade show interview and up close look.
I usually video races with my wife, but make no promises on having one. If I do though, I'll be sure to post it up for you all.
I usually video races with my wife, but make no promises on having one. If I do though, I'll be sure to post it up for you all.

I will have Austin take some photos of the buggy with his current equipment. That way you can see the layout. Just in case you missed it he's currently running a Castle 1/10th scale 4x4 short course motor and Mamba Max Pro speed controller, which is smaller than the Mamba Monster.

I use a standard MMP and an external castle BEC on my converted DNX408 and had no issue with the heat at all
#499
Tech Regular
iTrader: (8)
Joined: Dec 2004
Posts: 313
From: PA
This is straight from Austin's father.
Austin has been using a mamba max pro speed controller and a 2400kv Castle short course motor with a 5mm rotor. He's tried 2 shorty 3800 ProTek batteries-4s, which has resulted in about 8 1/2 minutes of runtime outdoors and about 11 minutes indoor. Not bad considering this combination is still as fast as a 1/8th scale Castle 2200kv motor. If we need more run time we just drop in a ProTek 6400 4s battery.
We're able to run this combination because the car is at minimal weight and we dont need the bigger motor and speed controller. At the end of races the speed controller fan isn't turning on so heat isnt an issue. We're running this weekend at Delta, so its going to be a little warmer out so we will see what happens.
Steve
Austin has been using a mamba max pro speed controller and a 2400kv Castle short course motor with a 5mm rotor. He's tried 2 shorty 3800 ProTek batteries-4s, which has resulted in about 8 1/2 minutes of runtime outdoors and about 11 minutes indoor. Not bad considering this combination is still as fast as a 1/8th scale Castle 2200kv motor. If we need more run time we just drop in a ProTek 6400 4s battery.
We're able to run this combination because the car is at minimal weight and we dont need the bigger motor and speed controller. At the end of races the speed controller fan isn't turning on so heat isnt an issue. We're running this weekend at Delta, so its going to be a little warmer out so we will see what happens.
Steve
#502
@teknorc: why do you choose a clutch system rather than a slipper?
#504
The downside of a 2s or 3s setup is that it will indeed have less torque and more heat compared to a 4 to 6S setup. I would stick with a real 1/8 motor for a long term and go for a SCT on tight or indoor tracks only. The EB48 is already very light and having a car that is just too light could make it harder to drive especially on a rough track. I see it myself with my JQ when I go from a 2200mah lipo to a 3700 in 5S between the quals and finals, the weight can be an help to have a car that feels more planted. It will be a bit slower in the corners of course but it's just a compromise to find. I try to have the lightest car I can, but there is a limit where I do too many mistakes to make it worth it. That said an experienced driver will handle a very light car much easier, so its up to the driver
#505
We've heard this question a lot. We know it seems weird, but you have to try it to really see and feel the benefits. Here is a response from another forum (edited for context):
------------
I'd like to take this opportunity and address the many questions about the clutch and clutch bell setup being used in our conversion.
We were intent on building the fastest 1/8th scale brushless vehicles around. Believing that if it's fast at the track, it'll be fast most everywhere. After looking at some current direct drive setups and having been into 1/10 scale electric truck racing back in the day, we saw a need for better traction. Add brushless motors and lipo battery packs to the mix and you have a considerable issue.
Drawing on years of nitro racing and tuning, we noticed the gas cars didn't want to spin around as much. The clutch system didn't only keep the engine from stalling, it aided in the traction and power delivery. We decided a clutch system like that would also benefit an electric vehicle in exactly the same way. The only difference is the motor can't stall.
A centrifugal clutch is different than a 'slipper' or friction clutch. Slippers only slip when the input power exceeds the friction force being applied between the plates. So, a slipper doesn't slip at low RPM, but rather only at high RPM or high power input. Contrast that with a clutch bell setup where it slips at low RPM and engages at higher RPM and higher power input. The systems are nearly complete opposites in how they deliver power. As a result, the driving profile and characteristics are different and the centrifugal clutch system is better suited for larger vehicles as proven by the absence of slipper clutches on 1/8 scale vehicles. Through testing we found that the clutch works best when the shoes are flipped over in the leading position. This is because with an electric motor that doesn't stall, we don't need to wait until we build 1-3000 RPM to build power. When set up like this, the clutch engages quickly, but still provides all of the benefits of a centrifugal clutch. The obvious benefits are easing the stress between the drivetrain and motor and of course better traction.
A lot of ESC's have power limiting features, why not just use that?
Yes, this is true. However, the ESC has no physical connection to the vehicle whereas a clutch can still respond to the driving conditions. This is handy say, when you are on throttle trying to land a jump. It will subtly respond to bumps and ruts as the loads on the tires change.
What about the added weight and rotational mass? This is a valid question. While the difference could be measured with equipment, it simply hasn't been an issue. Again, there is so much power and torque in these motors that the added rotational mass is negligible. We've never been in the situation where we needed more power than what the system could deliver. On the flip side, one could argue that mid-range punch may be enhanced with the addition of the extra weight. Nitro clutches are even heavier and nitro cars don't have trouble getting around the track.
What about clutch wear and clutch bearings?
Great question. Our clutch shoes have lasted well over 8 months of hard running. As long as you are running them in the leading position, there should be no issues. Bearings will fail eventually and should be replaced every 2 to 3 months or as necessary, but we can assure you it's absolutely nothing like if you were running a nitro. There is no fuel and oil for the dirt to stick to and foul things up. Additionally, the clutch isn't 'dragging' like it is on a nitro, which is evident in how long the clutch shoes and bearings are lasting.
What about wasted power due to slippage?
This is an issue whether you run a 'slipper' clutch or a centrifugal clutch. Any clutch system will have some wasted power. Which one wastes more under normal use would be hard to measure. Of course you could run the centrifugal clutch below it's engagement point for a whole pack and say it wastes more power and generates more heat, but how much fun would that be
Why not use motor brakes, they're just as powerful or more powerful than mechanical brakes?
Putting the front/rear brake bias ability aside, mechanical brakes are easier on the motor and ESC resulting in less heat. Subsequently, they are easier on the drivetrain as well. Mechanical brakes are just as reliable and some say more predictable than motor braking. Adding the front/rear bias back in and you have a cool operating system that can out-handle motor brakes alone.
So the clutch system is actually quite a difference compared to direct drive. We realize it's new and people are comfortable with how it's been done for all these years. The results were so good that we have basically staked the future of our company and our reputation on using a clutch and clutch bell in an electric car. How it goes from here is anyone's guess, but the race results don't lie. We hope it becomes the new norm.
Thanks for reading and please let us know if there are any questions.
--------------
To sum up - cooler operating temps, smoother power delivery, true front/rear brake bias, better jumping and handling (no drag brake), less wear on drivetrain and motor bearings.
Recently we've discovered another benefit. We have yet to wear out a clutch bell. We have hundreds, maybe close to a thousand test hours on our systems now and still have not had to replace a clutch bell. We are running the stock steel gears, no need to switch to plastic and risk stripping a gear during a race. Contrast that with the wear that some people have experienced using pinion gears.
All that aside, you can still use our kits with pinion gears if you have absolutely no interest in the clutch system.
__________________
Tekno RC
www.teknorc.com
------------
I'd like to take this opportunity and address the many questions about the clutch and clutch bell setup being used in our conversion.
We were intent on building the fastest 1/8th scale brushless vehicles around. Believing that if it's fast at the track, it'll be fast most everywhere. After looking at some current direct drive setups and having been into 1/10 scale electric truck racing back in the day, we saw a need for better traction. Add brushless motors and lipo battery packs to the mix and you have a considerable issue.
Drawing on years of nitro racing and tuning, we noticed the gas cars didn't want to spin around as much. The clutch system didn't only keep the engine from stalling, it aided in the traction and power delivery. We decided a clutch system like that would also benefit an electric vehicle in exactly the same way. The only difference is the motor can't stall.
A centrifugal clutch is different than a 'slipper' or friction clutch. Slippers only slip when the input power exceeds the friction force being applied between the plates. So, a slipper doesn't slip at low RPM, but rather only at high RPM or high power input. Contrast that with a clutch bell setup where it slips at low RPM and engages at higher RPM and higher power input. The systems are nearly complete opposites in how they deliver power. As a result, the driving profile and characteristics are different and the centrifugal clutch system is better suited for larger vehicles as proven by the absence of slipper clutches on 1/8 scale vehicles. Through testing we found that the clutch works best when the shoes are flipped over in the leading position. This is because with an electric motor that doesn't stall, we don't need to wait until we build 1-3000 RPM to build power. When set up like this, the clutch engages quickly, but still provides all of the benefits of a centrifugal clutch. The obvious benefits are easing the stress between the drivetrain and motor and of course better traction.
A lot of ESC's have power limiting features, why not just use that?
Yes, this is true. However, the ESC has no physical connection to the vehicle whereas a clutch can still respond to the driving conditions. This is handy say, when you are on throttle trying to land a jump. It will subtly respond to bumps and ruts as the loads on the tires change.
What about the added weight and rotational mass? This is a valid question. While the difference could be measured with equipment, it simply hasn't been an issue. Again, there is so much power and torque in these motors that the added rotational mass is negligible. We've never been in the situation where we needed more power than what the system could deliver. On the flip side, one could argue that mid-range punch may be enhanced with the addition of the extra weight. Nitro clutches are even heavier and nitro cars don't have trouble getting around the track.
What about clutch wear and clutch bearings?
Great question. Our clutch shoes have lasted well over 8 months of hard running. As long as you are running them in the leading position, there should be no issues. Bearings will fail eventually and should be replaced every 2 to 3 months or as necessary, but we can assure you it's absolutely nothing like if you were running a nitro. There is no fuel and oil for the dirt to stick to and foul things up. Additionally, the clutch isn't 'dragging' like it is on a nitro, which is evident in how long the clutch shoes and bearings are lasting.
What about wasted power due to slippage?
This is an issue whether you run a 'slipper' clutch or a centrifugal clutch. Any clutch system will have some wasted power. Which one wastes more under normal use would be hard to measure. Of course you could run the centrifugal clutch below it's engagement point for a whole pack and say it wastes more power and generates more heat, but how much fun would that be
Why not use motor brakes, they're just as powerful or more powerful than mechanical brakes?
Putting the front/rear brake bias ability aside, mechanical brakes are easier on the motor and ESC resulting in less heat. Subsequently, they are easier on the drivetrain as well. Mechanical brakes are just as reliable and some say more predictable than motor braking. Adding the front/rear bias back in and you have a cool operating system that can out-handle motor brakes alone.
So the clutch system is actually quite a difference compared to direct drive. We realize it's new and people are comfortable with how it's been done for all these years. The results were so good that we have basically staked the future of our company and our reputation on using a clutch and clutch bell in an electric car. How it goes from here is anyone's guess, but the race results don't lie. We hope it becomes the new norm.
Thanks for reading and please let us know if there are any questions.
--------------
To sum up - cooler operating temps, smoother power delivery, true front/rear brake bias, better jumping and handling (no drag brake), less wear on drivetrain and motor bearings.
Recently we've discovered another benefit. We have yet to wear out a clutch bell. We have hundreds, maybe close to a thousand test hours on our systems now and still have not had to replace a clutch bell. We are running the stock steel gears, no need to switch to plastic and risk stripping a gear during a race. Contrast that with the wear that some people have experienced using pinion gears.
All that aside, you can still use our kits with pinion gears if you have absolutely no interest in the clutch system.
__________________
Tekno RC
www.teknorc.com
#507
The 1700 and a 1900 Tekin T8 with either a MMP, MMM or RX8 on 4s seem be the most popular electric 1/8 race setups. Since this buggy is significantly lighter than any other stock 1/8 electric buggy, I can imagine having to use some throttle limiting and punch control to keep things under control.
#508
Tech Fanatic
iTrader: (6)
Joined: Jan 2008
Posts: 977
From: Tamarac
What is the weight of this roller? What is the weight of this car ready to run with a typical 4S setup and an 8 scale motor/esc.. i.e Tekin T8 1900 KV motor and RX8? I am interested in this car, but don't want too light of a setup as the car may not be as planted compared to a 3S setup for large outdoor tracks.



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