sert rc
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- Arrma RC's
- Limitless
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- Vorteks
Here's my Typhon Grom GT build. I hit 70mph on 4S on its maiden run which is promising. I cannibalized most of the parts from a Granite Grom I had built, I just had to buy the motor, body and wheels. I thought up the idea when Arrma accidentally leaked this chassis as a spare part during the Granite launch. The carbon undertray is full length and hold two CNHL 2200mah batteries very well.
Parts List:
Fun to build and came together quickly and easily. The car in general is easy to work on. It can be disassembled in about three minutes which is nice for a plastic car. A car this small allows me to go a 1/4 mile down the street from my house to run which is much more accessible then the 1.5 hours I drive one way just to be able to run my Limitless.
The car is very easy to drive with the gyro. You can see the gyro in action as the car runs past you. I'm running the gyro mainly to avoid crashing into the cement curbs on either side of the street I run on. I think aluminum arms would add stability and consistency to the suspension which would make the car more predictable to run without the gyro. I might run them, I might not. Unsure at the moment.
After the gyro, the biggest benefit came from removing the servo saver. I actually don't hate the stock Spektrum servo, it's got enough power to get the job done on such a light car. But the servo saver adds a level of unpredictability to the steering that is just unacceptable for speed runs. Sometimes the car would dart across the road with small input on the transmitter and other times you'd get the right amount of steering you are looking for. The Shift Nano M is plenty strong. I've got the speed turned way down as well as the dual rate to keep the car going straight while remaining predictable.
The biggest drawback to this platform is definitely the pinion/spur setup. 0.5mod is just not a very popular pitch, less so when you are running a 3.175 motor shaft. LC Racing makes pinions up to 24T in 0.5mod and 3.175 bore. I did find a 26T/28T/30T 0.5mod 5mm bore pinion on Amazon and I'm using a Robinson Racing reducer sleeve (RRP1200) and so far so good.
The Hot Racing adjustable motor mount is advertised as allowing up to a 30T pinion but I don't see it. I hit 70mph with a 26T pinion and 57T spur (vs. stock 59T spur). I had to use a file to expand the adjustment slot and the mesh is still tight. I don't know if there is enough room to grind the mount some more to get a 28T to fit. I highly doubt the 30T is going to work. The spur itself has a hexagonal bore and I don't know of any other spurs that would fit. A 48P 50T spur would be a great addition.
And herein lies the problem with this car as a speed runner: without good gearing options, its Limited. McCoy posted a 79mph run, but he's McCoy, he could make a tortoise run fast if he tried. I could fit a Mamba X in it, but the Castle motor is rated for 4S max, not 6S. At the moment the best I could hope for is to match a 79mph run on 4S and a 28T pinion.
All that being said, this build did turn me on to small scale speed running and I love the fact that I can do it so close to home. I loved it so much that I just picked up a 256mm 4-tec chassis from Ram Jam. I can run mod 1 gears, which I have plenty of thanks to my Limitless, thus solving the gearing issues of the Grom. But its still small enough in scale for me to run it on my local road. Looking forward to pushing both cars to their limits.
Parts List:
- Handcut carbon fiber undertray
- Deltaplastiks WLT3003 body
- Castle 1010-4400kv motor
- Castle Copperhead 10 ESC with XT-90S connector
- Hot Racing 57T spur
- Shift RCS Nano M servo
- Vitavon steering bellcrank
- NSDRV Min B servo horn
- Futaba GYC441 gyro
- Futaba R334SBS receiver
- BSR 1:10 35 shore foams
- Hot Racing adjustable motor mount
- Arrma option part axles and wheel hubs
- Arrma option part toe links
- Arrma option part differentials with 2MM weight oil
- Arrma option part shocks
- Firm springs from McMaster-Carr (part #94125K114)
- X-Ray body posts
Fun to build and came together quickly and easily. The car in general is easy to work on. It can be disassembled in about three minutes which is nice for a plastic car. A car this small allows me to go a 1/4 mile down the street from my house to run which is much more accessible then the 1.5 hours I drive one way just to be able to run my Limitless.
The car is very easy to drive with the gyro. You can see the gyro in action as the car runs past you. I'm running the gyro mainly to avoid crashing into the cement curbs on either side of the street I run on. I think aluminum arms would add stability and consistency to the suspension which would make the car more predictable to run without the gyro. I might run them, I might not. Unsure at the moment.
After the gyro, the biggest benefit came from removing the servo saver. I actually don't hate the stock Spektrum servo, it's got enough power to get the job done on such a light car. But the servo saver adds a level of unpredictability to the steering that is just unacceptable for speed runs. Sometimes the car would dart across the road with small input on the transmitter and other times you'd get the right amount of steering you are looking for. The Shift Nano M is plenty strong. I've got the speed turned way down as well as the dual rate to keep the car going straight while remaining predictable.
The biggest drawback to this platform is definitely the pinion/spur setup. 0.5mod is just not a very popular pitch, less so when you are running a 3.175 motor shaft. LC Racing makes pinions up to 24T in 0.5mod and 3.175 bore. I did find a 26T/28T/30T 0.5mod 5mm bore pinion on Amazon and I'm using a Robinson Racing reducer sleeve (RRP1200) and so far so good.
The Hot Racing adjustable motor mount is advertised as allowing up to a 30T pinion but I don't see it. I hit 70mph with a 26T pinion and 57T spur (vs. stock 59T spur). I had to use a file to expand the adjustment slot and the mesh is still tight. I don't know if there is enough room to grind the mount some more to get a 28T to fit. I highly doubt the 30T is going to work. The spur itself has a hexagonal bore and I don't know of any other spurs that would fit. A 48P 50T spur would be a great addition.
And herein lies the problem with this car as a speed runner: without good gearing options, its Limited. McCoy posted a 79mph run, but he's McCoy, he could make a tortoise run fast if he tried. I could fit a Mamba X in it, but the Castle motor is rated for 4S max, not 6S. At the moment the best I could hope for is to match a 79mph run on 4S and a 28T pinion.
All that being said, this build did turn me on to small scale speed running and I love the fact that I can do it so close to home. I loved it so much that I just picked up a 256mm 4-tec chassis from Ram Jam. I can run mod 1 gears, which I have plenty of thanks to my Limitless, thus solving the gearing issues of the Grom. But its still small enough in scale for me to run it on my local road. Looking forward to pushing both cars to their limits.
