brushless MBX5T Prospec

[cart213]

Here are some pics of my newly converted Mugen MBX5T Prospec. I bought it used from someone on another forum. It was filthy with nitro crud when I got it, so I spent several days cleaning it and replacing worn out parts.

The truggy has the following brushless equipment:
Mamba Max (with fan and two 330uF caps added)
Mega ACn 20/45/1E motor (2100kV)
Polyquest 25C 4S 5000mah lipo
RCM motor mount
RCM battery mount

The only noteworthy thing about the conversion is the old-style TMaxx receiver box that I used. It has the Spektrum receiver and CCBEC stuffed in it, which cleans up the wiring nicely.

I've run through one pack so far, and everything works well, but I was surprised how loud the steel spur is. My gearing right now is 46/18, btw, which should be good for about 40mph.

The motor got pretty hot, so I'll probably order an RCM motor heatsink soon. Also, I'm going to make an aluminum center diff top plate to secure the MM better.

[tom255]

What temps you have and what runtime you have?
BTW pretty clean work!
I am also think to buy MEGA motor, how it performs?
I see that motor have open front, i think it can be issue on dust/dirt track, maybe need somehow cover it?

[lutach]

That is nice. I can just imagine how that beast runs as my ACn22/30/2 lifts up the front end without breaking a sweet and the batteries are in the front of my truck.

[cart213]

lutach, what is your gearing and batteries with that motor? How hot does it get, and does it have any cooling or a heatsink?

[lutach]

Originally Posted by cart213

lutach, what is your gearing and batteries with that motor? How hot does it get, and does it have any cooling or a heatsink?

The spur is 49T, pinion 14T and internal diffs are 3.30 for a nice 11.55 final ratio. I'm currently using my batteries which are 3S 2200mAh (Wired in series). I'm testing them with something not really made for them to see how well they take it. The motor never gets hot and I have a Schulze 18.61K in the truck now and it doesn't get hot at all. No fans on the ESC, just the heatsink and no heatsink on the motor.

[tom255]

As I understood Mega motors have 6 poles? Interesting how MambaMax run it with new firmware

[lutach]

Originally Posted by tom255

As I understood Mega motors have 6 poles? Interesting how MambaMax run it with new firmware

I tried my MM after the update and when I went to try it again, sparks came out of it. Now it's dead. Before the update it was impossible to even get the truck going.

[tom255]

Originally Posted by lutach

I tried my MM after the update and when I went to try it again, sparks came out of it. Now it's dead. Before the update it was impossible to even get the truck going.

And How to understand this? That possibly I will fry my MM ESC with this motor?

[cart213]

My MM runs this mega motor just fine. No cogging or any other issues with the esc. I'm running the latest firmware on the MM.

[lutach]

Originally Posted by tom255

And How to understand this? That possibly I will fry my MM ESC with this motor?

I think it wasn't my day when that happened.

[Patrick]

Mugens seem like nice cars. I know you have a different layout and setup to what you were running in your ST-1, but how do you think the 2 cars compare.

[cart213]

I haven't driven the mbx5t enough yet to compare the driving characteristics of the two.

But just looking at them, you can tell the mugen is a better truck. Wherever the ST-1 has stamped aluminum, the mbx5t has machined aluminum or carbon fiber. And the mbx5t has much longer suspension arms and is therefore a lot wider than the ST-1, which should make it a more stable racer. The only thing I prefer about the ST-1 design is the front bumper. It's really strong and helps protect the truck in crashes.

With all that said, the ST-1 is an excellent truck for the money. It is an RTR that is half the cost of the mbx5t, which is a roller. For someone with a tight budget looking for a new truggy, you can't beat the value of the ST-1. If you've got the extra cash, though, the mbx5t seems worth the money.

[Patrick]

Yeah the ST-1's aren't very wide, but for the tight tacks that I mostly race at it doesn't bother me too much. The pro version which I have does come with carbon fibre parts instead on stamped aluminum.
If I was going to get rid of the ST-1, the mugen would be near the top of the list for cars I'd look at.
Are the mugen diffs the usual 43/10 ratio? Because if they are I thought you'd be geared for more like mid to high 40's, which could be why the motor gets hot.

[cart213]

The mugen diffs are 4.6:1 instead of the usual 4.3:1, so that's why I say I'm geared for about 40mph.

[cart213]

I raced at the track for the first time today. Unfortunately, I had to race on worn-out tires, so I was plowing around the whole track. Plus, the suspension setup is not how I like it yet. I still need to do some tinkering to reduce the understeer.

I finished 4th out of six truggies in my class. No one at the track had ever seen a brushless conversion before, so it got a lot of interest. Lots of people asked if it was the new Novak conversion kit! I set them straight and told them it was from RC-Monster, though.

After ten minutes of racing, the motor was 180F, the MM was 120F, and the batteries were 110F.

I need to reduce the motor temp, so I'm going to order a RC Monster heatsink. Has anybody done testing to see how much the heatsink will drop the temperature? I'd like to reduce the motor to about 160F, if possible.