2991Likes1/12 forum
10-18-2015 | 08:46 AM
1/12th 21.5 2s in action.
Can you guess who is the hack in this race? Lol
https://m.youtube.com/watch?v=4BtOV0Zkhsc
Can you guess who is the hack in this race? Lol
https://m.youtube.com/watch?v=4BtOV0Zkhsc
10-18-2015 | 09:06 AM
Joined: Oct 2004
Posts: 3,360
From: Michigan
1/12th 21.5 2s in action.
Can you guess who is the hack in this race? Lol
https://m.youtube.com/watch?v=4BtOV0Zkhsc
Can you guess who is the hack in this race? Lol
https://m.youtube.com/watch?v=4BtOV0Zkhsc
Had an amazing race yesterday. 41 clean laps nose to tail with a guy that ended up getting me by 2/10's of a second at the line. It was a qualifier, so I was in front the entire run, but it was a nail biter trying to gain time as well as not lose time. So cool to see where you are faster than somebody and pull away, and where you are slower and they close back up.
When I decided to get into 1/12 again, I changed my outdoor track at my house to be tight, with a center section that was really technical and at one point like 3' wide. I try to run at least one twenty minute run every day with laptimes broadcast over a bluetooth speaker, and I really believe that has helped immensely with being able to jump in to 1/12 and being able to focus for that amount of quick laps. Wish I could get that kind of track time with the little car every day to figure out the finer points of the car itself along with the fast lines around the track.
10-18-2015 | 05:50 PM
10-18-2015 | 05:53 PM
Lovely track facility. Sadly, it's an one hour bullet train ride to get there. I've been there a couple times for TC and 1/12th. However, I am in desperate need for more track time. I've finally got the car hooked up, I just need to practice more with it. Going 8 minutes can really work the concentration.
10-18-2015 | 05:55 PM
Edward, the man of the situation! I was waiting for your answer as I remembered you told us drivers in Japan had an "outlaw" class to run 1/12th scale chassis and 2S LiPo 
In the meantime, I checked some motor specs to determine which 2S combo would have quite the same performance as the classic 10.5t 1S combo (this is the specs from Team Orion VST2 Pro Stock website; because I currently use a 17.5t Orion motor):
10.5t (385W - 4570kv) @ 1S = 16909kv
17.5t (295W - 2600kv) @ 2S = 19240kv
21.5t (250W - 2350kv) @ 2S = 17390kv
(FYI, as it seems to become the new regulation for the 12th stock class:
13.5t (330W - 3650kv) @ 1S = 13505kv)
So, the 21.5t motor seems to be the most relevant option to use 2S LiPo and compared to the classic 10.5t 1S combo.
But in the fact, here in Europe, people who run in the GT12 class can use a 17.5t 2S combo, so why not with a normal 12th car? And I remember some times ago, when you ran in WGT, you could choose between a 1S 10.5t combo or a 2S 17.5t combo (of course at this time, the slightly more powerfull motor for the 2S combo helped to deal with the increased weigth of the 2S battery).
I also would like to have your opinion about this measure: do you think guys 12th scale will move from 1S to 2S batteries in the near future? (with adaptation of the motor of course).
For me, I think it could be a very good solution: no more 1 cell specific ESC, less charging programs, no more booster or receiver pack,...
This could make people coming back in the class I think.
Regards,
G-rem
PS: thank you for the video Edward!
In the meantime, I checked some motor specs to determine which 2S combo would have quite the same performance as the classic 10.5t 1S combo (this is the specs from Team Orion VST2 Pro Stock website; because I currently use a 17.5t Orion motor):
10.5t (385W - 4570kv) @ 1S = 16909kv
17.5t (295W - 2600kv) @ 2S = 19240kv
21.5t (250W - 2350kv) @ 2S = 17390kv
(FYI, as it seems to become the new regulation for the 12th stock class:
13.5t (330W - 3650kv) @ 1S = 13505kv)
So, the 21.5t motor seems to be the most relevant option to use 2S LiPo and compared to the classic 10.5t 1S combo.
But in the fact, here in Europe, people who run in the GT12 class can use a 17.5t 2S combo, so why not with a normal 12th car? And I remember some times ago, when you ran in WGT, you could choose between a 1S 10.5t combo or a 2S 17.5t combo (of course at this time, the slightly more powerfull motor for the 2S combo helped to deal with the increased weigth of the 2S battery).
I also would like to have your opinion about this measure: do you think guys 12th scale will move from 1S to 2S batteries in the near future? (with adaptation of the motor of course).
For me, I think it could be a very good solution: no more 1 cell specific ESC, less charging programs, no more booster or receiver pack,...
This could make people coming back in the class I think.
Regards,
G-rem
PS: thank you for the video Edward!
10-19-2015 | 04:42 AM
What about the weight of the car too Edward. We have a guy from Japan racing here and his car was about 100 grams less than ours, running 2s and 25.5. We were using our 1s 13.5 and the pull that thing had coming out of the corners was insane compared to ours. We run ROAR rules @ 730grams. His 2s battery was lighter than our 7000mah 1S and his car was all milled out to get it even lighter. He now is on a ROAR legal RSD chassis, battery and motor. But I was really surprised at the pull that 2S adds coming out of the turns. It wasn't noticeably faster down the straight but that's the shortest part of the track, its the turns that make the times drop.
10-19-2015 | 05:03 AM
What about the weight of the car too Edward. We have a guy from Japan racing here and his car was about 100 grams less than ours, running 2s and 25.5. We were using our 1s 13.5 and the pull that thing had coming out of the corners was insane compared to ours. We run ROAR rules @ 730grams. His 2s battery was lighter than our 7000mah 1S and his car was all milled out to get it even lighter. He now is on a ROAR legal RSD chassis, battery and motor. But I was really surprised at the pull that 2S adds coming out of the turns. It wasn't noticeably faster down the straight but that's the shortest part of the track, its the turns that make the times drop.
With all that milling to the chassis it sounds like he's some sort of mechanical engineer...
2s and 1s batteries only vary by 10~15 grams. I have a 3500mAh 2s and it weighs 155 grams a Trinity 7100 1s which is only 140 grams.
As for weight the Japanese rules are the same - 730 grams
The extra rip out of the corners is due to the extra voltage. Those extra volts will give you that extra rip out of the corners. Are you sure he was running a 25.5 motor or a 21.5? 21.5 is the standard motor class in Japan.
10-19-2015 | 06:49 AM
Sounds like he's cheating.
With all that milling to the chassis it sounds like he's some sort of mechanical engineer...
2s and 1s batteries only vary by 10~15 grams. I have a 3500mAh 2s and it weighs 155 grams a Trinity 7100 1s which is only 140 grams.
As for weight the Japanese rules are the same - 730 grams
The extra rip out of the corners is due to the extra voltage. Those extra volts will give you that extra rip out of the corners. Are you sure he was running a 25.5 motor or a 21.5? 21.5 is the standard motor class in Japan.
With all that milling to the chassis it sounds like he's some sort of mechanical engineer...
2s and 1s batteries only vary by 10~15 grams. I have a 3500mAh 2s and it weighs 155 grams a Trinity 7100 1s which is only 140 grams.
As for weight the Japanese rules are the same - 730 grams
The extra rip out of the corners is due to the extra voltage. Those extra volts will give you that extra rip out of the corners. Are you sure he was running a 25.5 motor or a 21.5? 21.5 is the standard motor class in Japan.
10-19-2015 | 07:50 AM
10-19-2015 | 06:19 PM
Joined: Oct 2004
Posts: 3,360
From: Michigan
Couple questions..
So on my carpet knife the left side of the axle sticks out almost 11mm past the hub.. seems to me I should just cut it off rather than have the motor spin something the car doesn't actually use. Sooooo, should I?
What is considered a big jump in rollout? Say I'm running a 3, and jump all the way to a 4, I'm guessing that would be a big jump. Would going to a 2.75 or a 3.5 be a big change?
I'm used to offroad vehicles where you just try pinions until you get the feel you want and then basically leave it alone until you switch from a long track to a big track.
I read from one of the links earlier than a 2mm change of tire diameter can be like a one tooth change on the pinion. I guess if that is true, than I can just calculate two rollouts with one tooth pinion change and see how significant the number difference is..then try it on the track and see how significant it feels to me.
Thanks for baby-sitting the offroad guy
So on my carpet knife the left side of the axle sticks out almost 11mm past the hub.. seems to me I should just cut it off rather than have the motor spin something the car doesn't actually use. Sooooo, should I?
What is considered a big jump in rollout? Say I'm running a 3, and jump all the way to a 4, I'm guessing that would be a big jump. Would going to a 2.75 or a 3.5 be a big change?
I'm used to offroad vehicles where you just try pinions until you get the feel you want and then basically leave it alone until you switch from a long track to a big track.
I read from one of the links earlier than a 2mm change of tire diameter can be like a one tooth change on the pinion. I guess if that is true, than I can just calculate two rollouts with one tooth pinion change and see how significant the number difference is..then try it on the track and see how significant it feels to me.
Thanks for baby-sitting the offroad guy
10-20-2015 | 02:01 AM
Tech Elite
Joined: Feb 2006
Posts: 4,951
From: Windsor, UK
Couple questions..
So on my carpet knife the left side of the axle sticks out almost 11mm past the hub.. seems to me I should just cut it off rather than have the motor spin something the car doesn't actually use. Sooooo, should I?
No, as you can adjust trackwidth, some of that may get used up when you add the axle shims
What is considered a big jump in rollout? Say I'm running a 3, and jump all the way to a 4, I'm guessing that would be a big jump. Would going to a 2.75 or a 3.5 be a big change?
I'm used to offroad vehicles where you just try pinions until you get the feel you want and then basically leave it alone until you switch from a long track to a big track.
I read from one of the links earlier than a 2mm change of tire diameter can be like a one tooth change on the pinion. I guess if that is true, than I can just calculate two rollouts with one tooth pinion change and see how significant the number difference is..then try it on the track and see how significant it feels to me.
Thanks for baby-sitting the offroad guy
So on my carpet knife the left side of the axle sticks out almost 11mm past the hub.. seems to me I should just cut it off rather than have the motor spin something the car doesn't actually use. Sooooo, should I?
No, as you can adjust trackwidth, some of that may get used up when you add the axle shims
What is considered a big jump in rollout? Say I'm running a 3, and jump all the way to a 4, I'm guessing that would be a big jump. Would going to a 2.75 or a 3.5 be a big change?
I'm used to offroad vehicles where you just try pinions until you get the feel you want and then basically leave it alone until you switch from a long track to a big track.
I read from one of the links earlier than a 2mm change of tire diameter can be like a one tooth change on the pinion. I guess if that is true, than I can just calculate two rollouts with one tooth pinion change and see how significant the number difference is..then try it on the track and see how significant it feels to me.
Thanks for baby-sitting the offroad guy
Pinion x tyre diameter (mm) x 3.14, then divide that result by the spur.
76t spur, 40t pinion and 42mm rear tyres would give 69mmpr etc.
We need to know what motor etc, which would get you in the ball park, then up or down a pinion could be used to fine tune.
If you're too far out to begin with you might overheat your motor.
10-20-2015 | 04:58 AM
Joined: Oct 2004
Posts: 3,360
From: Michigan
As we use rollout for 1/12 cars, due to the fact that the tyre diameter changes as they are used, you really need to use that for calculating gearing.
Pinion x tyre diameter (mm) x 3.14, then divide that result by the spur.
76t spur, 40t pinion and 42mm rear tyres would give 69mmpr etc.
We need to know what motor etc, which would get you in the ball park, then up or down a pinion could be used to fine tune.
If you're too far out to begin with you might overheat your motor.
Pinion x tyre diameter (mm) x 3.14, then divide that result by the spur.
76t spur, 40t pinion and 42mm rear tyres would give 69mmpr etc.
We need to know what motor etc, which would get you in the ball park, then up or down a pinion could be used to fine tune.
If you're too far out to begin with you might overheat your motor.
43mm tires, 60T pinion, 76T spur. Trackstar 17.5 two timing marks towards +, with a trackstar genII one cell esc, not in blinky mode. She's a good runner and I plan on trying to fit a 61T pinion this week.
I was just wondering what was considered a big jump in rollout. Would shaving 2mm off the tires be a big jump? Or fine tuning? Would 1 tooth pinion change be a big jump or fine tuning? I'm just curious.
And should I cut the extra length of my axle off that sticks out 11mm past the left wheel hub?
10-20-2015 | 09:06 AM
Tech Master
iTrader: (20)
Joined: Oct 2011
Posts: 1,879
From: Fort Collins, CO
Thanks for the information. My rollout right now is 4.2 using a 17.5 motor and one cell battery. That leads me to another question, do most state the rollout in metric or standard? I've had people talk to me about it in both.
43mm tires, 60T pinion, 76T spur. Trackstar 17.5 two timing marks towards +, with a trackstar genII one cell esc, not in blinky mode. She's a good runner and I plan on trying to fit a 61T pinion this week.
I was just wondering what was considered a big jump in rollout. Would shaving 2mm off the tires be a big jump? Or fine tuning? Would 1 tooth pinion change be a big jump or fine tuning? I'm just curious.
And should I cut the extra length of my axle off that sticks out 11mm past the left wheel hub?
43mm tires, 60T pinion, 76T spur. Trackstar 17.5 two timing marks towards +, with a trackstar genII one cell esc, not in blinky mode. She's a good runner and I plan on trying to fit a 61T pinion this week.
I was just wondering what was considered a big jump in rollout. Would shaving 2mm off the tires be a big jump? Or fine tuning? Would 1 tooth pinion change be a big jump or fine tuning? I'm just curious.
And should I cut the extra length of my axle off that sticks out 11mm past the left wheel hub?
I would recommend starting at 96-98 mm and then look at fade over eight minutes to dictate where you go from there.
I personally wouldn't recommend cutting down tires to adjust rollout. I would consider a change of 2 mmpr to be 'big', but I am not entirely sure I follow what you are trying to figure out, here.
It sounds like you have bigger things to figure out than worrying about a couple grams of extra carbon axle. Also, are you sure you aren't running the rear crazy narrow? Max width is 172 mm and nearly everyone will be within 4 mm of that.
10-20-2015 | 09:55 AM
Joined: Oct 2004
Posts: 3,360
From: Michigan
I don't plan on cutting tires to reach a rollout, it was just a question trying to figure out what's a drastic change or a small un-noticeable change in rollout numbers. Thanks for taking the time to write, I can drive the cars decent, great with offroad setup, just trying to lean the carpet ways now too The trackstar motors.. they aren't the fastest things in the world but they can take heat and keep on turning lap after lap after lap. I've got a spreadsheet with 2000 timed laps from this summer, the majority ran with the same 6.5 motor. It's on it's third set of avid bearings, and that thing has been phenomenal for a budget racer.
10-20-2015 | 10:27 AM
Tech Master
iTrader: (20)
Joined: Oct 2011
Posts: 1,879
From: Fort Collins, CO
Thanks for the reply. I guess I'm more bench racing than asking anything. I like the technical side of things I get into, so using roll out and things interest me. So I was just curious what is viewed as a drastic change. 2mm in the rollout, or is 10mm in the rollout drastic. Doesn't matter, I know I don't make sense a lot. So I'd say with my 106 rollout I'm right next door to the ballpark you stated. I ran a 104 the week before and felt my car didn't have the speed compared to the others. Wasn't the case when I bumped up a pinion, (104 to 106). I will go measure my axle right now. It shouldn't be crazy narrow, it's built as per the crc manual. I downloaded that and found the guy I bought it from had the left hub on backwards so it was 3mm wider on the left side than the right. Handled much better after fixing that I don't plan on cutting tires to reach a rollout, it was just a question trying to figure out what's a drastic change or a small un-noticeable change in rollout numbers. Thanks for taking the time to write, I can drive the cars decent, great with offroad setup, just trying to lean the carpet ways now too
The trackstar motors.. they aren't the fastest things in the world but they can take heat and keep on turning lap after lap after lap. I've got a spreadsheet with 2000 timed laps from this summer, the majority ran with the same 6.5 motor. It's on it's third set of avid bearings, and that thing has been phenomenal for a budget racer.
I don't plan on cutting tires to reach a rollout, it was just a question trying to figure out what's a drastic change or a small un-noticeable change in rollout numbers. Thanks for taking the time to write, I can drive the cars decent, great with offroad setup, just trying to lean the carpet ways now too The trackstar motors.. they aren't the fastest things in the world but they can take heat and keep on turning lap after lap after lap. I've got a spreadsheet with 2000 timed laps from this summer, the majority ran with the same 6.5 motor. It's on it's third set of avid bearings, and that thing has been phenomenal for a budget racer.