1:10 or 1:12 scale project wanted...

[riceman]

This is interesting. I haven't had any issues with my 4600 running 2S with 12t/46t. I'm going to kick it up a notch and put in a 13t pinion.

[BrianG]

What temps are you getting? I'm right around 160*F on the motor and around 150*F on the ESC, which is WAYYY too hot for my liking. Some people think this is OK, but I don't. Batteries are at about 120*F.

I'm using a 16T pinion, but that only creates a FDR of 9.5, while the Jato (running larger tires) is running a FDR of 9.638. The Jato, which is bigger and heavier, runs forever without getting anywhere near as warm as what the CRT.5 is getting.

The temps lead me to think it's overgeared, but then I compare the Jato and I just don't see it. The only other thing I could think of is that it's not loaded enough...

[hyperasus]

Could not being loaded enough make that much difference? I kind of doubt it but I'm certainly open for some education on the matter.

[BrianG]

lol, I don't know. Oddly enough, this is the hottest conversion I have and the lightest. Like I said, the temperature rise feels just like if I were to put my truck on a stand and run it near WOT.

[hyperasus]

Well adding load seams easy enough. Give it taller gearing and see what it does. I'm betting it will run even hotter.

[BrianG]

Well, I don't have anything higher than 16T. Nor do I have anything smaller. Plus, I'm currently running the hardened steel pinion so my options are limited.

[hyperasus]

How you manage to run a MM motor on your Jato without melting it is a mystery to me. Too me this looks like another epidemic classic case of running too high kv motor on a 10th scale truck.

[BrianG]

Well, the Jato is 1/10th scale, which is what the MM is designed for, and everything runs cool. Don't know why, but it does. I'm lucky if the temps get to 140*F on a really hot day after two battery packs (~90 minutes) and doing constant high speed runs or track use.

Since the CRT.5 is 1/12 scale, it should be fine, especially since I chose the lowest KV motor in the MM series. Plus, I'm running only 2s.

I can see having issues trying to run the 7700 motor on 3s geared high, but I'm not. Gearing is a little high, but not too bad IMO.

[IBJAMMIN]

The Jato probably runs cooler because it's 2wd vers 4wd with the crt.5 your running the power through 2 more diff's and 2 more tires. :)

FYI my crt.5 with the 5700kv Mamba and 3s lipo runs around 150deg with a 13/46 Kyosho gear.

[Dafni]

Brian, it wouldn't surprise me when your temps come down once you get the chance to try a higher gearing.

BTW, this 160/150 temps, how long does it take to get there?

[BrianG]

Yeah, higher gearing would load the motor more, but then it's too fast. That's why I was thinking about going with a smaller motor, like the Feigao 380c/9. Then, I could get the same speed with the proper gearing. This is for a small track, I wanna keep it under 40.

I haven't checked at various times throughout the run, just at the end of the 5Ah pack, which takes about 30 minutes, maybe a little more. So, the temps could rise quick and stay there, or they could gradually increase, I don't know.

[squeeforever]

Instead of getting another motor, I would simply set the throttle EPA down some...

[BrianG]

I thought of that, but that doesn't change the load. I like the speed I'm at now, the temps just get too high. I figured a faster motor would be loaded correctly and then I could use the EPA to dial down the speed.

[RC-Monster Mike]

150F after 30 minutes doesn't seem terribly hot to me. Not cool, mind you, but not too hot, either. I have 20 tooth hardened gears if you want to try getting more speed and dialing back the epa. Typically, if the controller temps at 150 and you feel this is hot, less load would be appropriate. The motor could go either way, though(too much or too little load can cause heat in the cheaper motors). You could always use the dreaded $10 fix as well("f" word), though I know this is against your religion or something. :)

[RC-Monster Mike]

I spent a few hours last night working on a delrin spur for this little gem. I got the file worked out perfectly and proceeded to cut 5 spurs(40 tooth delrin). I was using a molded spur gear and machining both sides to replace the stock spur directly. After the first operation, all the spurs seemed fine. The second operation, however, revealed the flaw of a molded spur gear....air pockets from the molding process. Not a single usable spur after hours of work(though the file and cutting program are perfect, the air bubbles are all in the middle-right where I need the strength)). I will spend the early part of this week sourcing a suitable spur(hopefully) so I can complete the conversion. I did modify a kyosho spur to work as well. It will require an 8x14 bearing(which I happen to have) - not a big deal, as I can make this into the motor mount, but I prefer a custom spur rather than modifying the Kyosho and requiring a special bearing). I ended up with around 6.5mm toothwidth vs 5mm on the Kyosho - the Kyosho spurs also rubbed the diff mount a little. The Kyosho gears themselves are pretty cheap, though.

Any thoughts on plan B(modifying Kyosho spur and including the bearing into the motor mount)?