Talk 1520 - your experiences

[Jahay]

do you think this motor would be suited for a savage flux geared at 25tpinion/44t spur and 39t High speed idler? That should bring me to a 60mph top speed on 6s right?

[bruce750i]

This might help with finding mphs check it out. http://www.scriptasylum.com/rc_speed/index.html

[Jahay]

with high gearing, would temps stay in check? Has anyone run similar high gearing on their truck without temp problems?

[ANGRY-ALIEN]

What are your objectives with that setup? just speed runs or bashing?... the truck's weight and tyre sizes should be factored in also...
did you try your number in the calculator? If you post the results from the calculator here, we can look at it a little closer and
see how best to approach your setup.

Alien

[Jahay]

Alien, i only bash but i have plenty of space to run and love my high speed runs... But i dont do repeated high speed runs like some do. My truck is around 13lbs and im running strapped HPI dirt claw tires on SPI Rims.

these are the results i got from the speed calc

Differential Ratio: 3.3076923076923075
Transmission Ratio: 2.215277777777778
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 25
Total Voltage: 22.2
Motor KV: 1800
Tire Diameter (inches): 5.91
Tire Ballooning (inches): 0.5
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 1.76 : 1
Total Ratio: 12.89632 : 1
Tire Circumference (inches): 21.71 inches (551.39 mm)
Rollout: 1.68:1
Total Motor Speed: 39960 RPM
Vehicle Speed: 63.7 mph (102.32 km/h)
Effective KV Value: 1800
KT constant: 0.75 oz-in/A

As you can see on a 6s running 44/25 and accounting for tire ballooning at 0.5" i can hit 63mph supposedly... This setup doesnt include the 39t Idler which would probably give me up to 10mph more.

If i really am capable of these speeds then i would def gear down as i would never reach those speeds anyway.

[ANGRY-ALIEN]

hmmm... Interesting... but i'm a little confused... Do you want to run 1520 or a 1518? the 1520's KV is 1600 (you have 1800 which is the 1518's KV)...
I am pretty sure the 1520 can push that truck to the 60s, but if you are going to bash with it geared that high (accelerating hard and braking hard), the motor
might start getting warm a little faster... I have geared my truck for the high 40's to 50's and the motor handle it well... but I don't think during bashing
I have ever gone past the lower 40's... So now I am geared for the high 30's and the motor seems to like it temp wise and the acceleration never gets old.

Your setup with some changes:

Differential Ratio: 3.3076923076923075
Transmission Ratio: 2.215277777777778
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 25
Total Voltage: 25 <------------- 6s on peak charge
Motor KV: 1600 <-------------- 1520
Tire Diameter (inches): 5.91
Tire Ballooning (inches): .5
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 1.76 : 1
Total Ratio: 12.89632 : 1
Tire Circumference (inches): 21.71 inches (551.39 mm)
Rollout: 1.68:1
Total Motor Speed: 40000 RPM
Vehicle Speed: 63.76 mph (102.42 km/h)
Effective KV Value: 1600
KT constant: 0.85 oz-in/A

I recommend you gear down for bashing (it should make your Batts happier too):
Differential Ratio: 3.3076923076923075
Transmission Ratio: 2.215277777777778
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 18
Total Voltage: 25
Motor KV: 1600
Tire Diameter (inches): 5.91
Tire Ballooning (inches): .5
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 2.44 : 1
Total Ratio: 17.91156 : 1
Tire Circumference (inches): 21.71 inches (551.39 mm)
Rollout: 1.21:1
Total Motor Speed: 40000 RPM
Vehicle Speed: 45.91 mph (73.74 km/h)
Effective KV Value: 1600

Differential Ratio: 3.3076923076923075
Transmission Ratio: 2.215277777777778
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 16
Total Voltage: 25
Motor KV: 1600
Tire Diameter (inches): 5.91
Tire Ballooning (inches): .5
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 2.75 : 1
Total Ratio: 20.15051 : 1
Tire Circumference (inches): 21.71 inches (551.39 mm)
Rollout: 1.08:1
Total Motor Speed: 40000 RPM
Vehicle Speed: 40.81 mph (65.55 km/h)
Effective KV Value: 1600

[Jahay]

although i think the torque of the 1520 would be ideal... i think the 1518 would be more suitable for me. My truck isnt too overweight compared to other savages...
I think i would run an assortment of pinions depending on what surface or what sort of running i would be doing that day (asphalt, grass, dirt, or pure jumping) I am just making sure that if i do run on asphalt and run high gearing, that i do not cause any damage to my motor or esc. I would probably no run 25T most of the time... But i would like the assurance that i could if i want to and get away with it.

[nuz69]

Hello Jahay.
Anyway, the 1520 would be the best choice for your application, because it can handle more power than the 1518 and had always an higher efficiency.
Where the 1518 works good, the 1520 works just better in truck and truggy. You have all to gain by choosing this one, and the cons are insignificants : +30gramms and maybe +10-15$ with the insurance to keep the motor cold even by pushing it hard.
The 1518 should be the right choice for buggies geared in 5 or 6S for high speed tracks but it just can't match with a torque monster 1520 in heavier vehicle like truck or truggy/muggy...

[Jahay]

Thanks nuz for your opinion... The difference in price between the two motors really isnt a factor when you are spending this sort of cash. neither is the weight i guess. But i guess i am worried that i will not be able to gear high enough to reach my desired speeds. but according to this gearing, it looks like i can just about considering the high speed idler gear will be installed.

Differential Ratio: 3.2222222222222223
Transmission Ratio: 2.215277777777778
Other Ratio: 1 + high speed idler gear should add around 8-10mph
Spur Tooth Count: 44 stock spur
Pinion Tooth Count: 25 largest pinion
Total Voltage: 22.2 ideal average voltage
Motor KV: 1600 neu 1520
Tire Diameter (inches): 5.5
Tire Ballooning (inches): 0.5 Hpi dirt claws on spi rims
Motor Current Draw: 0 not sure how many amps the motor would draw on stated gearing. would esc overheat????
Motor Coil Resistance: 0
Spur/Pinion Ratio: 1.76 : 1
Total Ratio: 12.56309 : 1
Tire Circumference (inches): 20.42 inches (518.68 mm)
Rollout: 1.63:1
Total Motor Speed: 35520 RPM
Vehicle Speed: 54.67 mph (87.82 km/h)
Effective KV Value: 1600
KT constant: 0.85 oz-in/A


if this speed calc is accurate then i would get the 1520 immediately. i need a motor asap... starting to get savage withdraw symptoms haha.

[RC-Monster Mike]

IMO, the 1518 is waaay more motor than a buggy needs and plenty for all but the porkiest trucks. The 1520 is plain overkill unless you have a 15lb truck with big aluminum rims or something.
Jahay -an idler gear doesn't add any speed or take any away - it is simply there to create space(usually to allow proper gear mesh with a larger diameter motor or small spur gear) and it reverses the direction or rotation(as far as the gear ratio goes...it is "idle"). :)

[Jahay]

i thought 1520 would be completely un necessary, considering i thought my torq2200 was pretty adequate already.
So i may just get the 1518 and can also gear a couple of teeth lower on the pinion considering it spins a little faster than the 1520.

Nice1 Mike. I think they are in stock in the rc monster store...

[Jahay]

i would love to get that 1520... but for the speeds i want to reach i think it spins too low... 1518 will be better for me. I bet the 1520 just has way to much torq!

[ANGRY-ALIEN]

Originally Posted by Jahay

i would love to get that 1520... but for the speeds i want to reach i think it spins too low... 1518 will be better for me. I bet the 1520 just has way to much torq!

No one is saying you can't reach 'those speeds' with a 1518... all we are saying is that the 1520 will get there with a little efficiency... 1600kv is not that low... as said before, if you gear it appropriately it will still do the job.

From Wikipedia: 'Torque, also called moment or moment of force, is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist.'

So, the higher 'moment of force', the faster motor will achieve it's "twist'... which translates to greater acceleration and getting to 'top speeds' quicker...

See the comments below:

Originally Posted by RC-Monster Mike

"The 1520 is plain overkill unless you have a 15lb truck with big aluminum rims or something.")

Originally Posted by nuz69

"Hello Jahay.
Anyway, the 1520 would be the best choice for your application, because it can handle more power than the 1518 and had always an higher efficiency.
Where the 1518 works good, the 1520 works just better in truck and truggy."

As the thread name says, '1520 - your experiences'... I can only really speak to the 1520... but I am sure the numbers also speak for themselves... I too believe that the 1520 is overkill,
but that's what i love about it.

Alien

[Jahay]

angry alien... looks like i will go with the 1520...
The 1518 is out of stock everywhere.... I will just gear it a little higher when i want to do speed runs... and im sure ill enjoy the torq when gearing lower for bashing...

Thanks for the advice... really appreciate it

[ANGRY-ALIEN]

No worries man...