Gearing an L can motor

I have a buggy conversion that I did and am usually running a 7XL with 14/46 gearing. This runs great. I'm relatively new to the larger brushless motors, but got an 8L motor as my parking lot/go fast on concrete motor. I didn't have any extra pinions, so I just ran it with the 14T pinion that I had. I got caught up in racing and didn't pay attention to the temps. The battery got so hot that it melted the shrink wrap and puffed two of the cells. Must have been pulling some serious current. Oddly enough, the motor didn't over heat, and the esc never thermalled. By the way, I was running a Maxamps 3S 4Ah pack. It's rated for 80 amps constant. I'm now running 4S Lipo, but haven't tried the 8L on 4S.

What would be the usual gearing (pinion size) range for an 8L in an 1/8 scale buggy?

[MetalMan]

A 12t pinion should work to give you about 40mph (theoretical).

Well, that sucks. I'm getting better than that with my 7XL. I guess the theory behind gettng the 8L was all out of whack. I suppose I'll sell it. Any takers?

Thanks MetalMan.

[MetalMan]

I would if I didn't already have one :p.

[glassdoctor]

I haven't run any #'s but I think an 8L at 12/46 should be closer to 50mph than 40.

A 1900kv motor at 12/46 will do just over 30. The 8L is around 3000kv. I had an 8L in my first bl buggy but it burned a coil before I ever got lipos. One of my old vids I posted had the 8L and 9 GP3300 cells. I don't know haw fast it was.... probably in hte 25-30 range? It was prety fast on 12 cells... but again I don't know exactly how fast. No GPS back then....

glassdoctor,

Do you think that I was running it overgeared at 14/46? Like I said, it was odd that the MM didn't thermal, which I would have thought it would have done, if I was overgeared. Really, the only problem that I had was the fact that the battery melted the shrink and puffed. Perhaps I wouldn't have had that problem if I was running a battery with more guts. I was, after all, running a 4Ah 3S lipo. I have 4S2P 6Ah lipos now. Perhaps I should try it again. This motor is only for running on concrete, so rolling resistance should be at a minimum.

[glassdoctor]

Well I don't think 14/46 is a too tall to run. Something like 10-11T is more in it's wheel house for racing, but 14 is good for a high speed street setup.

I ran mine with 13/46 and 11/46 I think, with 9-12 cells. I don't recall a lot of details about temps or anything. Back then I didn't have temp gun, gps, lipos, or data recorder. ;)

Do you think that I was running it overgeared at 14/46? Like I said, it was odd that the MM didn't thermal, which I would have thought it would have done, if I was overgeared.

Like a said before and everyone else disagreed......never trust an ESC to thermal. I rarely have one thermal, mine usually smoke....but your batteries were your weak link instead. So that stinks, at least it didnt catch fire.

Now see my point Serum? :p
That was the point I was tryin to stress before. :dft012:

[neweuser]

Maybe the MM did not get hot enough to thermal? Just an idea...

yea, hard to say. I wouldnt expect a constant load over 80 amps not thermalling it, but who knows. Most likely the packs werent quite up to what they were suposed to be.

Oh, the MM didn't get hot. Neither did the motor. It was just the batteries. I was running 3S. I'm going to try it with 4S this time and see what happens.

According to the guys at Castle, the MM will run to about 200F (sometimes a bit over) before thermalling. I was told that the MM does a good job of protecting itself in over temp situations. I believe that the Mamba Max is good for 100A constant and up to 300A bursts.

Mine hit 260F without a thermal.

OK, it hit 260. Did it fry or is it still running?

fried. :036:

It took probably 4 minutes to get up to that temp, so it wasnt a fast process. I have only had 1 or 2 controllers thermal, I would say 90% of mine fry before thermal. Gearing was perfect, but was just goofing around with it and not really running it hard....they dont like that. It would still be kickin if I had been running it full throttle. Motor 102F esc 260F, batt 60F. It happens.