Mamba competition pack and Mini Quake

[MikeyLikesItSI]

I've had this setup for several months now just as a little beat around the drive way machine. The reviews i've read mentioned that it cogged a bit so i was expecting that (which it does). I've got the smallest size pinion gear (12T) and largest spur gear (49T) i could find. I'm running this all with a 2s lipo 1400mah.

Well if i start with a fresh battery and run it until its dead, the battery AND the motor are smoking hot. So hot you can't even touch under the chassis where either are positioned. The speed controller is just warm enough to comfortabley keep your finger on it. From what i've read, the gearing needs to be altered if one or the other is getting hot, or did i not understand?

Either way, where is a good place to start to try to get this to run lower temperatures.

I can't find a lower tooth metric pinion to fit this setup. Any suggestions are welcome (even critical ones that tell me the small mamba motors are garbage :027: )

[BrianG]

A hot motor usually means it is undergeared. If it was overgeared, it makes no sense that the ESC wasn't hot as well.

Also, running the motor to those temperatures might have reduced the magnetic capability of the magnets (intense heat does that), so you might be dumping more power into the motor than you would need with a good motor. Not saying the motor is for sure bad, just a possibility.

[MikeyLikesItSI]

Brian thanks for the quick response and insight. I must say the reason for my gear ratio was to try to over come the cogging issue. I figured larger pinions (which if i read your response correctly, would help reduce heat from the motor) would make it cog worse since it required more torque to turn the driveline

[silentbob343]

Most of us MQ owners agree that the mamba motors are a tad small for the Quake. I would suggest a 28mm motor; the popular motors at the moment are the Ammo 3900, 5100, and the Permax 5200. Robinson sells 1/8 48P metric pinions that most 28mm motors use. Neu has some 28mm motors as well if you want high quality motor. If you really want to run the mamba motor you can use part of a two piece MQ alloy spur and Mini-T spur to get better ratios for the mamba motors.

I run an AON 3000kv motor and it runs pretty cool at 16/45 stock gearing, unless hill climbing for an entire pack. Good thing about the AON motors are the closed endbells and they can be taken apart for maintenance, but the downside is they only go up to 3500kv. I know most here would prefer the lower kv motor with more cells, but the stock battery location can really only hold a 2s pack. I modified mine with longer post and can fit a 3s and maybe a 4s would fit, but I think that would be pushing it.

I’m looking at going with a 6 pole motor, but need to email Quark and see what they say about that idea. If they tell me that 6 pole motors aren't a good idea I'll probably go with the Ammo 3900 since it can be taken apart for cleaning and maintenance. Currently have two pinions 13 and 16, will have to wait and see how the motors hold up with these larger wheels.

Currently the Quake is in pieces awaiting a new controller, motor, and some shims. Here it is mocked up with the body:

[BrianG]

Originally Posted by MikeyLikesItSI

Brian thanks for the quick response and insight. I must say the reason for my gear ratio was to try to over come the cogging issue. I figured larger pinions (which if i read your response correctly, would help reduce heat from the motor) would make it cog worse since it required more torque to turn the driveline

Well, you are right. If geared too high, the motor doesn't turn enough from a stop so the ESC can get feedback pulses from the motor. However, you have it geared low enough that it ends up spinning too fast at high speed. IMO, it sounds like the motor doesn't have the start torque it needs (and cogs) but then spins too fast once it gets going. You could have weakened the magnet with the heat which would also affect both cogging and heat.

[JOHN01374]

Hi guys. I've heard a little bit about the mamba motors (380 size) being a little small for the Mini Quakes. Here's an idea. I've seen kits that allow the use of 540 size motors. Anyone ever tried the larger MM 5700 motors in one of these things? I've considered buying one of these trucks for a while but the only one i ever ran was seriously under powered. Well compared to my MM5700 Rusty :)

[jnev]

I think a 5700 will make the mini quake way over powered. However, a 4600 combo may do the trick.

[silentbob343]

Originally Posted by ***RC***

I think a 5700 will make the mini quake way over powered. However, a 4600 combo may do the trick.

540 BL motors will kill the drivetrain. Even with ball diffs the plastic driveshaft pinions and main diff gear are not able to handle that kind of power. Heck guys using 28mm BL motors have a hard time keeping it together with the gear diffs. It can be done with a mini servo and the 540 motor mount, but runtimes would be pretty short and balance would be upset. So far the longest mAh lipo I found, and own, is the max amps 2200 2S2P, but you need to modify the battery post and hold down to use it.

Now, if somebody like Mike made some Delrin or metal gears.....

Originally Posted by JOHN01374

Hi guys. I've heard a little bit about the mamba motors (380 size) being a little small for the Mini Quakes. Here's an idea. I've seen kits that allow the use of 540 size motors. Anyone ever tried the larger MM 5700 motors in one of these things? I've considered buying one of these trucks for a while but the only one i ever ran was seriously under powered. Well compared to my MM5700 Rusty :)

Mamba motors are not 380 sized motors they are 20mm/280/300.

380/28mm motors are what you want:
Great Planes Ammo-28-XX series
Permax-400 series
Neu
Mega-15 series
Golden Horizon-3600 or 4700
Ebay-Cool Red 3500 and there is a 5100kv ebay motor that has received a decent review.
Align and align clone from ebay

[MikeyLikesItSI]

OK i'm trying to make a choice on a new BL motor for my mini quake

1st runner up: http://www2.towerhobbies.com/cgi-bin...7&I=LXLWY2&P=K

2nd runner up: http://www.flydma.com/catalog/produc...roducts_id=137

Any feedback/suggestions/criticism?

[wallot]

i use GH4700 with mamba25 and 3S lipo works great and has 2.3mm shaft to use mq pinions.
2S lipo would have been enough :)

[MikeyLikesItSI]

I'll check that one out.

Also, the second part of my original question was never answer. The hot motor we figured is from numerically too high pinion/spur ratio.

But what about the battery? the lipo gets way to hot for its own good (it must be damaged by now)

[silentbob343]

Originally Posted by MikeyLikesItSI

OK i'm trying to make a choice on a new BL motor for my mini quake

1st runner up: http://www2.towerhobbies.com/cgi-bin...7&I=LXLWY2&P=K

2nd runner up: http://www.flydma.com/catalog/produc...roducts_id=137

Any feedback/suggestions/criticism?

Can't really go wrong with either one. I would love to get a neu, but just can't get myself to spend twice the price of the ammo or permax motors. Heck the ebay $20-$30 motors tempt me.

[wallot]

i use some quite cheap 3S 1700mAh 12C (15C peak) packs - motor takes 11-18A (25Apeak)so they can handle it with ease. Had to modiefy the chassis a bit as the pack is bit taler :)

[silentbob343]

Here is how I did my batt hold down mod:

ORIGINAL: Silentbob343

Here is my setup to hold the 25mm tall batt


Two 6-32 threaded 1" tall spacers .25" OD
Two 30mm long pieces of 6-32 rod secured via red loctite
Two 6-32 coutersunk screws
Two 6-32 Wingnuts-I like the nylon ones, but they are a bit big and hit the antenna post when it gets close to being snug.

To get the spacers in the post holes you will need to get a .25" drill bit to enlarge them. I recommend you grind the end off the bit to allow it to travel to the bottom of the post hole. The chassis screw holes will also need to be made slightly larger to take the 6-32 screws. The previous owner of my MQ had already screwed holes in the chassis so I had no problem making a few more changes.

I also ordered some 4-40 hardware from servocity, the 4-40 screw should fit in the stock holes. Enlarging the post holes to .25" isn't a big deal as the stock posts have a tab that fits in to a slot on the post hole and prevent the stock post from turning.

I cracked the front post hole because I didn’t enlarge it, I tried to force the spacer in. The spacer is holding firm though and I figure if it ever does let go I can get a new chassis without holes drilled all over it and use the 4-40 hardware. I'm not sure that was my fault either. When I received the MQ there were washers jammed in the front post hole and the spacer slid in fairly easily without out enlarging it like I had to do with the rear post hole.

I switched to the 4-40 hardware I bought from Servo city and redid the holes in a new chassis by sanding/grinding the tip off a drill bit so it would enlarge the entire post hole without making the screw hole in the bottom of the chassis any larger. Worked perfectly; no cracked post hole, 4-40 hex screws sit flush with the bottom of the chassis.