here's a big pile of questions: need setup advice

[mk351e]

my quest for understanding continues............

so if a neu can safely spin to 60k, and I'm spending $255+ on it, then don't I want to be able to hit 60k rpm with it if i want? Not that I'm gonna run that speed all day long, but shouldn't I be able to hit that number or close to it sometimes? If not, why? If heat is the issue, will it really be? I can make some type of air intake, and it will be the finned can anyway. If so, then wouldn't a 1515 1.5D (2700kv) be the ticket on 6S?? Or the next 1515 down (2200kv)??

Reason is, I saw the 6s savage video (found that a while ago actually), and THAT was what made me decide to go BL! FAST on grass!! Also, I saw satheman's video, and while it was nice, it was geared real high (22T pinion) and STILL flipped like crazy (WAY too much for me) with a 1521 Neu 1577kv. That's why I'm thinking maybe I don't want a 1521; too much torque, AND it looks like the don't come with a finned can.

Feel free to correct all my mistakes!

[lincpimp]

Well, the faster you spin the motor, the less life you will get out of the bearings. Plus you do place more load on the rotor and the case. Power is not really an issue with a neu 1515. I would say that a 2000kv neu motor would be fine on 6s. Plus, you run into issues gearing a motor turning more than 40k rpm low enough to keep speeds around 40-45mph. I have a buggy that has a hacker c50 8l on 4s lipo. It spins around 45k rpm. I have to run an 11t pinion to get speeds around 40-43mph. That is the smallest pinion I can fit before the motor hits the center diff outdrive.

[MTBikerTim]

Originally Posted by mk351e

Like a Toyota or a Honda :)

If only Toyota and Honda made RC cars.

[mk351e]

ok, but why do I want to limit top speed with low gearing? Wouldn't I just limit throttle on my radio? Or just not pull the trigger as much? OR is there something weird that happens with BL that I'm missing?? I hope not, my auctions for all my nitro stuff end tomorrow afternoon!!!!

Or is this in the name of heat and keepin it cool?

As for motor bearings, I kinda hope they die soon, so I can put ceramics in there. I can change them myself on a Neu right?

[lincpimp]

Partial throttle causes more heat in the esc, as the fets are switching on/off very quickly to limit output voltage (simplified description). I gear my stuff so I am WOT most of the time, and do not have heat issues. Plus you will find that over 45mph a big truck it very difficult to control on anything other than a very smooth surface.

[mk351e]

ooooooooooohh. OK. SO, let's say I gear for 60mph with a 1515 neu. I run on a parking lot wot most of the time, and all is well. THEN, I leave everything except the wheels alone, I go to a track, and I'm not running wot, but on and off for a smallish track. Am I asking for problems here??

PS - thanx for all your help linpimp, and thanks for helping me find those pinions. Do you know what grade of steel is strongest there?

[lincpimp]

Originally Posted by mk351e

ooooooooooohh. OK. SO, let's say I gear for 60mph with a 1515 neu. I run on a parking lot wot most of the time, and all is well. THEN, I leave everything except the wheels alone, I go to a track, and I'm not running wot, but on and off for a smallish track. Am I asking for problems here??

PS - thanx for all your help lincpimp, and thanks for helping me find those pinions. Do you know what grade of steel is strongest there?

By pinions you mean the 8mm ones on spi huh? The only real choice is the carbon steel ISO8 , as the commercial quality do not have a hub. These are still not hardened so you will want to use them with a plastic spur. If you want to use a metal spur, the hardened gears that mike sells are the only option that will last.

Not sure if a 1515 will get that truck to 60 without getting hot. Someone with more experience than I will have to advise you on that. I would just gear the truck down to track/offroad speeds. Your runtime will be better and everything will run cooler that way. Plus you will have more throttle control.

[Patrick]

Don't know what savage your talking about, but the e-maxx on 6s that jzemaxx linked to is mine. It's only a 1700kv 1515 2.5d (no more than 37 000rpm on 6s) geared 51/20 with e-maxx diffs and old 2 speed trans (12.5:1 fdr). Theoretical top speed of ~50 mph, but the amount of tire ballooning I had can throw the calculator out a bit, and I don't have anything to test the actual speed, but it was fast enough for those old bow ties. Very hard to get to top speed without it trying to wheel stand. I don't know how it would go being geared for 60, but I'd be more worried about my esc and batteries
That setup has worked well for me with that type of driving, but in smaller areas where you can't get to top speed and your doing lots of stop starting (racing) I don't use that gearing, it just puts more load on everything.
Your real car will drive well on a highway in top gear, but you don't drive around the city in top gear.

[mk351e]

yeah, I figured out it was an emaxx after I posted. Not sure why I thought it was a savage, but it was fast nonetheless! Thanx for that info!