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Old 05-20-2008, 01:39 AM   #1
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Default Electronic heat in 4wd buggy

So, I've finally been able to run my B44, which is my first real foray into 4wd buggy, for about 10 packs or so now on a real offroad track. I'm seeing my electronics build up some massive heat, way more than what my 2wd cars would, but I guess that should be obvious. I'm running a Orion revolution 10t, IB4200 unmatched packs, and a Hara Twister 2.2 esc. Once my pack dumps at 8 minutes my motor has hit 215F. The ESC is at about 130F and the battery is about 130F as well. I am running an over sized cooling vent hole in the stock body and a fan that is hooked up to the motor wires currently (going to switch to an rx connection soon). Gearing is 19/84. I tried 17/84 as well and I got the same temp, just with less top speed and no extra torque.

The question I've got is: Are 4wd buggies just destined to make their motors run super hot(200F+)? Or do I just need to provide more cooling to the motor?

Options I'm going to explore to get the temps lower: Run a lipo saddle pack to reduce stress on the motor, fan that runs full time, and a lower turn motor with conservative gearing.
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Old 05-20-2008, 05:48 AM   #2
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Maybe the brushed motor? 8 minutes on a dirty comm could build up lots of heat.
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Old 05-20-2008, 07:48 AM   #3
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Have you checked to make certain the entire drive train is free. You may have had a bearing fail or something may have shifted and be putting a strain on the drive line. Friction will make a 4 wheeler unhappy. I never had that much of a problem running a BJ4 with 11 turn. Hot yes but not that much. I ran with chassis protector and one small cooling hole in front of ESC. Used NIMH and GTX just for comparison. Same combon in XX4 never got too hot either. This was running 6 min quals and mains in Indiana in summer (80-90 degree average).
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Old 05-20-2008, 08:27 AM   #4
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Personally, I have noticed that 4wd's can make motors very hot due to the work they must produce from the 4wd. I would experiment with smaller pinions until I found something that worked reasonably well. Other than that, you could try placing a fan on the motor.
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Old 05-20-2008, 10:33 AM   #5
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Brad I'm experiencing the same temps in my B44. 130 esc and 230 on the motor. Given I'm using it on the street with alot of flatout running. GTB esc, reedy 1 star, and matched ib4200's. 19/84 gearing. I'll see what happens at the track when this rain stops. On a good note the gtb hasn't thermalled.
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Old 05-20-2008, 10:51 AM   #6
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wfd is right, 4WD has alot more strain on the motor than any 2WD will. Mount a fan near it or go brushless.
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Old 05-20-2008, 11:10 AM   #7
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On my BJ4WE Im using a heatsink for my brushed motor (12x2) and a novak Atom. I cut a couple of scoops on my body to help direct air over my motor and electronics.

Everything mentioned are def. causes for heat
-Drivetrain bind
-improper cooling
-Gearing
-motor condition

I don't think brushless is that much different. Im working on picking up a unit here soon, but I still think its all about the environment.


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Old 05-20-2008, 11:55 AM   #8
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Quote:
Originally Posted by MOmo View Post
On my BJ4WE Im using a heatsink for my brushed motor (12x2) and a novak Atom. I cut a couple of scoops on my body to help direct air over my motor and electronics.

Everything mentioned are def. causes for heat
-Drivetrain bind
-improper cooling
-Gearing
-motor condition

I don't think brushless is that much different. Im working on picking up a unit here soon, but I still think its all about the environment.


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Brushless runs alot cooler then brushed until you gear it o the moon.
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Old 05-20-2008, 02:05 PM   #9
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Well, the comm is clean, the brushes are fresh, and the drivetrain is free. I'm going to build a double fan mount and put a huge heat sink on the motor. That should solve the problem. Thanks for the input guys.
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Old 05-21-2008, 03:43 AM   #10
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I'd run the car for 5 mins(same as a normal race) and then take it off, allow everything to cool. 8 mins is pushing it well past what would be normal conditions
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Old 05-21-2008, 03:49 AM   #11
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Quote:
Originally Posted by RB FIVE View Post
Brushless runs alot cooler then brushed until you gear it o the moon.
brushed: 64% efficiency
brushless: 92% efficiency

most of the energy lost is lost to heat, so brushless runs cooler.
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Old 05-21-2008, 12:15 PM   #12
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Don't use the undertray! That alone will help it all get cooler. I've used 3m clear vinyl for years instead of an undertray for this very reason.

A fan will help but that isn't a rediculous temp for an 8 minute run. I agree that 8 minutes on a mod brushed motor is asking for it. That is simply too long and the motor is telling you this. My other though is that you really need to make sure that you have that motor sprung right. Medium springs will not get it done on that motor in that chassis. You should be running med/firms or firms.

Your gearing is good so just make sure you don't have any bad bearings in the rear hubs,etc.

A heat sink can help as can the fan. However the heat needs to get out of the body/chassis as well. So just blowing warm air over everything won't get it done...
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Old 05-21-2008, 01:09 PM   #13
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I case you're curious i have a AE TC 3 motor heatsink that fits realy well in the B44. I did grind the fins a little bit to fit under the top deck. It's huge, and it's tapered in a way to use maximum fins in the useable space.

I use a Novak 6.5 with a GTB and lipos for 20 minutes straight almost every time i drive. I'm getting 130 at the esc and 150 at the motor.
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Old 05-21-2008, 06:24 PM   #14
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The undertray is a big issue. I have a Kyosho ZX-5 that I run with no undertray and only small vents in the body. I do run a standard size Novak fan blowing right on the endbell of an Insanity Motors Cobalt II 10x2. I run full 4600 packs through the car and the motor comes of cool enough that you can just grab ahold of it.

I also have a Yokomo MR-4BX and I have large cooling holes cut in the body, but I run the undertray, and no fan, so the same motor will come off around 190* after a full pack.

So Like Randy says, you may want to ditch the undertray.

In my experience the Orion V2 motors seem to be harder to keep cool, and 10 turn motors and lower seem to require a LOT more maintenance than 11 turns and higher, even with Checkpoints and V2 motors. I've had better luck with Cobalt II motors.

Good luck sorting things out.
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Old 05-21-2008, 09:54 PM   #15
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The temps you are experiencing are pretty much normal for a brushed motor setup and not really that bad/anything to worry about. You should only really worry about the motor as the heat can make the motor fade/get soft at the end of a run even though you can have a good amount of runtime left and will wear the comm/brushes out faster. The best thing is to get the Novak black fan and wire it up to cool the motor. On a modified truck by putting the fan on it made my brushed motor run 40* cooler. You shouldn't need to change the motor to make it run cooler unless if your power setup (gearing, timing, etc...) is way off. Brushless is the other way around, the motors run pretty cool, but you have a fan on the speedo to keep it cool.
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