|Feb 08, 2012, 05:49 PM|
Here's what i have done so far:
Pulled the engine, gas tank, throttle/brake servo, and flipped the top bracket over to the opposite side. I moved the top plate over so I could mount the motor down on an area that didn't already have holes drilled everywhere.
I'm looking to fabricate or buy a motor mount. I'm getting the angled aluminum for free, but I don't know if my dad's old drill press still works. If i could find a nice motor mount for less than $30, i'd go that route. The mount needs to allow for mesh adjustment so i'd have one static screw hole and the other will be curved. the opening for the shaft bearing will need to be oblong.
Scrap aluminum example:
I can order replacement spur gears but only a 42T.
I don't know what motor/esc I should get, but im not limited to a 540 size, i have the space for a larger motor diameter. I've been trying to look it up but it's hard since i'm working with a 42T spur. i'm finding alot of nitro stuff and the Backdraft 8E but thats a 20lb 1/8 scale buggy so that motor wont be too great on this 1/10 touring sedan.
AS far as the ESC, HobbyKing has a HK-60A ESC for $25. It's OOS so might as well move up to the $40 HK-1-8-80A sensored ESC.
A TP540-11.5T 3350kv Brushless R/C Car Motor w/sensor is only $25 but i don't think that will get me to the speed i want. I'm looking to reach about 50MPH so I'm about to pull the trigger on that ESC and a XK3650-10500KV Sensored Brushless Inrunner
Will a HK-1-8-80A ESC and a XK3650-10500KV Sensored Brushless Inrunner get me goin about 50MPH on this 42T spur? Those are $40 a piece so i'd be looking at $80 for the set.
80A sensored 3650-10500KV turnigy
80A Sensored ESC hobbyKing
I'm still learing how to calculate this, Thx
|Feb 09, 2012, 08:14 AM|
What size car is that? What's the final drive ratio? How many cells do you plan to run it on? 10500kv sounds like a 1s motor to me.
If you work out the circumference of the tire and know the final drive ratio you can figure out how many RPM you need at the motor, take the number of cells and then see the kv you need.
|Feb 09, 2012, 06:34 PM|
It'a a smartech 101420
Length--------------------------------- 385 mm
Width--------------------------------- 200 mm
Height ------------------------------- 150 mm
Wheelbase ------------------------255 mm
Tread(F/R) ------------------------ 200 mm
Wheel Dia ------------------------ 66*26 mm
Gear Rate----------------------- 8.4 : 1
Weight ........................... 1.64KG
Engine ............................ 15 CXP
I plan to run it on a 2s 30C 8200MaH from my truck. I have 2 of them. I don't know the formula, going to try and look that up now...
What pinions will i be limited to? how do i figure out what pitch i need, all i know is the pinion needs to be wider than the spur so it doesn't wear inconsistently.
|Feb 09, 2012, 09:57 PM|
i lost my patience and bought that motor. I bought a 120A ESC instead of the 80A
I tried to calculate the speed with a calculator online but i don't know what pinion to use. I'll be waiting for these to come in the mail and I will post my results. i need to get the mount, find a place for the battery and toss my gps in. I have no idea what pinion to use though guess i'll try a 19T and then a 28T. I hope i dont trash my spur trying the wrong pinion...
|Feb 10, 2012, 08:43 AM|
10500kv is way too high for 2s use, you'll need a small pinion to not burn things up.
Based on the stock gear ratio and rough math, you need about 5700kv to hit 50mph on 2s.
66mm diameter wheels roll 0.20724 meters per revolution, so 0.00020724km/revolution.
80km/h is 1.3333 km/minute
That's 4894 rpm at the wheel to hit 80km/h(50mph), add 15% because you'll need more RPM so that the loaded RPM gives you what you need, so 5628rpm at the wheels.
Stock gearing is 8.4:1, so 47275rpm at the motor. Divide by 8.4v (fully charged lipo) and you get 5628kv. If you want to base it off 7.4v, then you need 6388kv.
If you do run the 10500 kv motor on the same gearing, and nothing burns up you'll hit about 113km/h (~71mph). That'll be a lot of amperage and heat though, most people gunning for speeds like that run 3s and lower kv.
|Feb 10, 2012, 07:04 PM|
How small of a pinion do you think I can go? I understand there's pitch to consider to maximize spur life. I can order one of these for about $30. Is there anything to be aware of before chosing a motor mount? These look sturdy but would I want to secure the back of the motor also?
I'm assuming I can replace one side of the spur gear carrier with one of these. For $30 after shipping, I think its a great deal. I couldn't make something this nice with my drill press.
|Feb 10, 2012, 10:06 PM|
I just bought that blue one for $20 shipped NIP. When this mount, motor and ESC come in, ima toss it on there right away but i dont know about programming at all...
Guess I have a couple days to research...
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