warm motor

You running it in the stock configuration (36V)? What sort of terrain you on? Lots of stop-and-go? Hills? Need input!

What I could hold on to all day, most people would drop and say it burnt my hand, so depending on if you are blue collar or white, too hot to touch could be pretty cool to me. But yes after a 30 minuite ride in warm weather, a BD36 will be quite warm. I'm riding in 100f plus weather and am now carrying a squirt bottle just to hose down my hub after a big hill climb. It wasn't an issue till it got so hot the motor slowed noticeably. Under 95 degrees it seems to be no problem at all for rides over an hour.

At your temps, you may never need it. I just do it when the motor gets so hot it really slows down, feeling like good ol sla voltage sag when I'm running a lifpo4 battery. If I can't do 20 mph, I know the motor is hot enough to fry an egg. I just wet down the part between the spokes, so water won't get in the axles. It's more to save my watts than help the motor.

Seems that I read somewhere that brushless motors don't get as hot as brushed. Anyone know if that's true?

I don't own a BL-36. But like I suggested to Dogman, if there are alot of steel parts in the motor, they retain heat longer than aluminum. Aluminum "wicks" away the heat. I work in a hydraulics company and learned this. Brushes might make it a little hotter, but the side opposite of the brushes is just as hot. My guess is that BL VS BD temp differences are about the same. The windings get hot etc.
But that's a guess.

I'd agree on that one. What seems to get motors too hot is hills, The motor is getting power to go 25mph, but since it can't go more than 15 up the hill, more of the power gets made into heat instead of motion. Pretty soon its not a motor, its a heating element. The part of the motor that I fried, the magnets, is on the inner hub, stuck to steel, and water on the hub only cooled the windings. Still, cooling the windings did get the speed back in the motor.

Seems that there would be little point in going brushless then.

No, brushless is better for many many people, if not most. But if 15-20mph is too slow and you still want to run 36v, or if you need to climb a monster of a hill, or if your ride is just going to be less than 5 miles, then brushed may be better.

Brushless is better for longer rides since it is more efficient by a large margin. Riding 15 mph on brushless will take you at least twice as far as brushed so if you need to ride 10 miles per charge, brushless will allow you to do it without buying expensive lithium batteries. Brushless would still get me up the hill, just slower. It's kinda like buying a truck, v8 or 6 cylinder. Both will haul a half ton, but one will go up the hill faster, the other will get better mileage. The decision is based on whether you will be hauling that kind of weight every day, or twice a year.

When I bought the first brushed motor, it was a full $100 cheaper and I bought just on price. Later it made sense to get the same thing again so I could interchange parts. I would like, at some point, to put a brushless on the trike so I can go a bit farther without buying a second lithium battery. The trike doesn't usually go down the big hill.

WE has a 600 watt brushless for the 2008 model. I bought my BD-36
used and the ebayer said it was brushless. Though he was well intentioned, my bike has a brushed motor. Sometimes people can't tell them apart. But if you can find a good deal, buy the brushless 600 Watt. The drawbacks, in my opinion, with a brushless 600 watt vs a brushed 600 watt is that there is more complication in the controller and motor. More parts mean more potential problems and it might be harder to troubleshoot. Brushless and brushed are hard to visually tell apart. Look
at the controller on a brushless, it is "electronic" and bigger.
The brushed has a smaller "electric" controller. Whether a 400 watt brushless is less warm than a 600 w brushed is debateable.
I'm not an expert JL

The old model brusless controller was a 20 amp, and the brushed, a 35, so the old brushless may have run cooler since it was much slower.

Good point dogman. I've read that the 600 watt brushless has a 50 amp controller. If the 400 BL has a 20 amp controller maybe the motor is cooler, but perhaps that 20 amp controller can get too hot! I've read many stories about lower amp controllers overheating/frying. You can put 40 or 45 amp on a 600 BL to save juice, but some say it will heat/stress the controller more. If I had a brushless, a cool controller would be paramount. They are expensive to replace. For a 400 BL try a slightly higher amp controller, if possible. Maybe 25 amp.

How to tell the difference Brushless all have 3 wires coming out the motor.
I have had a lot of experience with small brush and brushless motors. I have used both in flying r/c models.
Brushless always out preformed the brush motors. These hub motors are what I would call an outrunner because the can moves not the shaft. Not good to get them hotter than 200f. 100 to 130 was ideal. Had to change prop size to smaller if they got too hot. or put in a bigger motor
pn controller you need to match amp draw to controller.
There is no way a 20a controller going to take 30A
Heat depends on the load you supply. Put a big load on a small motor and it going to over heat. For most people a 600 to 750W motor going to do just fine.
As for the reliability of controllers for brushless motors. They work for many hours as long as you have one that is rated for or higher than what you are doing.