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標題: Gearing for rc12r5 [打印本頁]

作者: xiang 時間: 2010-3-10 19:10
標題: Gearing for rc12r5
Can someone please advise on gear ratio for 9T/60A hobbywing with A123 at wan chai track.
thanks!

作者: hardmankam 時間: 2010-3-11 12:11
Are u running 1S A123 (3.3v) or 2S A123 (6.6v)? what is the diameter of the rear tires? (in 1/12, gearing is based on rollout and the tire diameter is a parameter to calculate rollout.)

作者: xiang 時間: 2010-3-11 12:41
I never knew you could play 1S A123. I expect you have to have a very faster motor for this.

I intend to play 2S A123. As far as the rear tire diameter... i cant answer this yet, depends on what Fatboy delivers! I'm really looking for a rough range to start out with and slowly fine tune.
thanks hardmankam.

作者: hardmankam 時間: 2010-3-11 13:43
typical rear tire diameter is from 44 to 46mm... so here i will assume 45mm.
from novak website for a 8.5R motor with 4cell NiMh (4.8v), the rollout is 40mm. In your case, if you use 2SA123, your rollout should be a little less, so maybe 37mm (just guessing).

here is the rollout formula:
(tire diameter) x (Pi) x Pinion / Spur = Rollout
or
Pinion = Rollout x Spur / (tire dia x Pi)

If you use 95 spur, pinion becomes: 40 x 95 / ( 45 x 3.14) = 27

作者: xiang 時間: 2010-4-8 21:06
thanks hardmankam.
I've ended up playing my r5 with 2s lipo from my 1/10 cars, as my old lipo's dont have enough punch anymore for 1/10, but more than enough for 1/12. Just did a little modify to fit the 1/10 lipo running 22/96 and 9T. Whats great is that the batteries last for a very long time 4,200mah, but the top speed too fast for me to play full throttle at wan chai track, therefore i set the forward throttle to 70%.

作者: hardmankam 時間: 2010-4-9 10:05
Show us a pic of how you modify 2S lipo into a R5.

作者: swswsw 時間: 2010-4-9 10:08
2s Lipo in Wanchai, 18/100 with 8.5turn brushless, rear wheel 44mm diameter
can be full throttle with good control

作者: xiang 時間: 2010-4-10 10:59
Initially i just used small cable ties through the battery mounting holes, but this limited the chassis clearance to the ground. so then i came up using a larger cable tie with a hole drilled through one end to clamp it to the chassis at the front, using the smaller screws/nuts that come with the r5 for the battery bracket. At the back I used some posts (i think come from L4 or RC10LS), this limit the battery movement and act to secure the cable tie with a screw through it. On the bottom I used some foam(sticky on one side), (easy/cheap to find from shops - wanchai got one near track) to raise the battery so it doesnt effect the links. Also needed to raise the shock a little...2mm is enough at front, back of shock doesnt actually need to be raised at all.

I'd be interested to see how other ppl modify their r5 for 2s lipo.

[attach]361395[/attach]
[attach]361396[/attach]

作者: xiang 時間: 2010-4-10 11:04
本帖最後由 xiang 於 2010-4-10 23:47 編輯

2s Lipo in Wanchai, 18/100 with 8.5turn brushless, rear wheel 44mm diameter
can be full throttle wi ...
swswsw 發表於 2010-4-9 10:08

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Hi swswsw,
thanks for the info. I was worried before about correct gearing/over heating etc before which is why i ran 22/96, but these 1/12 dont seem to be so fragile to run as 1/10 so I will try 19/96. because these 1/12 so light seems you can get away with pretty much any gearing you want. Will let you know how i get on. (will play Sunday at wanchai!)

作者: RC881 時間: 2010-4-10 13:06

Initially i just used small cable ties through the battery mounting holes, but this limited the chas ...
xiang 發表於 2010-4-10 10:59 AM

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又真係幾好方法wo , well done !

作者: lazer 時間: 2010-4-10 13:46

又真係幾好方法wo , well done !
RC881 發表於 2010-4-10 01:06 PM

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Very Good Design!! Well Done!!!

作者: hardmankam 時間: 2010-4-10 14:23
excellent design! good job.

作者: xiang 時間: 2010-4-10 14:37
thanks guys...
if it helps anyone else out... then great!
Definitely makes it a cheaper option if you already play 1/10 and want to play the 1/12(r5).
I was struggling for a while as I didnt want to have to fork out for 6 lipo batteries for the 1/12.
Now my old lipos dont go to waste, but i think, after these lipo's die, i will go A123 for all my rc cars. Then i suppose i can just remove the foam.

hardmankam... u gonna make it down to wanchai this sunday?

作者: swswsw 時間: 2010-4-10 22:55
as the track in Wanchai is so small, i found the control will be much better in overall track if full throttle can be given in the straight line.... finally with team power (short version) 8.5T, 18/100 is the best.

作者: swswsw 時間: 2010-4-10 22:57
[attach]361615[/attach]

作者: xiang 時間: 2010-4-10 23:48
swswsw - Am i right in thinking i recognise your car? u often play in wan chai?

作者: swswsw 時間: 2010-4-11 07:39
yes quite often previously, except these few months vocation period...

作者: xiang 時間: 2010-4-11 10:22

yes quite often previously, except these few months vocation period...
swswsw 發表於 2010-4-11 07:39

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swswsw - Haha! i know you! Do you know who i am?

作者: swswsw 時間: 2010-4-11 12:12
many friends down there in Wanchai, guessing u're one of them.....will come again very soon..

作者: xiang 時間: 2010-4-11 19:39
lucky u didnt play today... track very very wet! we all left early for some food!

作者: lky2000 時間: 2010-4-11 20:42
Haha! i know you you a mxxk

作者: xiang 時間: 2010-4-15 00:55
lky2000! better get ready for me at PYC. I take no prisoners!

作者: xiang 時間: 2010-6-18 20:35
My R5 setup is now
tire diameter: 47mm
pinion/spur: 20/96
motor/battery:9T/lipo2S

I can only play with the throttle set to 70% on the wanchai track.
I actually wanted to buy a 17T and 18T to try out, but the Spec-R brand 64P doesnt have these sizes, are there any similar pinions with these sizes. I like the Spec-R ones as they have 4 grub screw holes in the pinion... good if you strip the thread in the pinion.

作者: hardmankam 時間: 2010-6-18 23:38
Even if you reduce the pinion from 20 to 17, the speed would be similar. If you want 100% throttle, you will have to change to a slower motor, like a 11.5R or 13.5R with your 2S-Lipo setup.

作者: xiang 時間: 2010-6-19 00:44
Hi Hardmankam,
I don't get it. If i change the pinion to 17T from 20T, then my rollout will be 26 instead of 30. surely there would be a decrease in top speed if i left the throttle at 70%.
Are you saying that difference in top speed would be negligible?
As u guessed...i'd prefer to have the throttle at 100%, or at least closer to 100%.
I kinda based my theory from swswsw's post, where he is using 100%throttle,8.5Tmotor, 18/100 for the wanchai track.

作者: hardmankam 時間: 2010-6-23 18:48
本帖最後由 hardmankam 於 2010-6-23 18:50 編輯

The short 8.5R motor is a 3000kv motor, while the HW 9T is a 4300kv motor. So given the same gearing and same voltage, 8.5R is slower than 9T. Therefore, your's at 70%, his is at 100% throttle.

There are a few things u can do to try to achieve 100% throttle.
1) use the smallest pinion
2) use the largest spur
3) use smaller tires
4) use less voltage
5) use less kv motor

have you tried 2SA123 + 9T... this could be your answer to 100% throttle using the same gearing.

作者: xiang 時間: 2010-6-25 17:31
I broke the carbon fibre shock holder! Can't find it anywhere in KWS...

I'm gonna try a 18T instead of the 20T pinion to see how much i can increase the throttle once i find the part. Can't fit my 2S2P-A123 in my r5...

作者: hardmankam 時間: 2010-6-25 18:36
My CRC shock mounting is a little different from RC12R5. But i will post how to mount the A123 (2S1P) to my CRC for your reference later.

作者: chestertai 時間: 2010-6-25 19:16

I broke the carbon fibre shock holder! Can't find it anywhere in KWS...
I'm gonna try a 18T inste ...
xiang 發表於 2010-6-25 17:31

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R5 FT Upper Pod Plate can be found @ 友邦 or 1/F

作者: xiang 時間: 2010-6-26 01:19

R5 FT Upper Pod Plate can be found @ 友邦 or 1/F
chestertai 發表於 2010-6-25 19:16

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Not pod plate.... i broke the small carbon fiber part connect the front of the shock to the chassis... "Front Shock Holder". I checked in 1/F, 友邦, all the shops... no stock!

作者: swswsw 時間: 2010-6-26 07:16
go to World model in Kwun Tong, they have.

can call them to check before go.

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