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Old 07-28-2011, 11:10 PM   #1
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Cool TC5 with mamba max 7700 running 200+ degrees

Having trouble gearing my TC5. I have a mamba max pro with the 7700KV motor. I am currently using an 18t 48 pitch pinion and 87t spur.
My ESC is running fine at 140 degrees all day long. However i cant seem to get my motor temps down. Do i need to go lower than 18T? Can someone please point me in the right direction.
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Old 07-29-2011, 03:24 AM   #2
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Quote:
Originally Posted by Zeus426 View Post
Having trouble gearing my TC5. I have a mamba max pro with the 7700KV motor. I am currently using an 18t 48 pitch pinion and 87t spur.
My ESC is running fine at 140 degrees all day long. However i cant seem to get my motor temps down. Do i need to go lower than 18T? Can someone please point me in the right direction.



Im not up with mamba's specs in what temp they can handle but if you want any brushless motor to last you wanna keep it under 180*f max hey....
Even then the motor will last but not a long time like intended.
I know you can go up in spur size more. So yes you need to gear down if going on temps alone.

But is your car free of binding and so on??? Take ur pinion off and roll the car and make sure everything is free. Next would to make sure all your timing and throttle curves are to what you need to be running. Also hard on and off with brake throttling will have a massive part to. So driving style YES does play a big part

More info would help everyone to help u
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Old 07-29-2011, 05:15 AM   #3
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As it is mentionned, check that everything is free.

a 7700 must equal to 4.5t approx, this is hot!

9.67 fdr is maybe a little high, but you could also have the motor turning too much with this gearing.

It does happen sometimes that instead of going down to cool your motor you need to go up instead.

I would recommend that you run your car with a 17t/87t for a couple of minutes and check temp, then after cooling down, run a 19t/87t for again 2 minutes and check, you should be able to see if your car is faster during these trials and decide what is best. Maybe running a fan on motor will help too if you have none.

An important point here with hot modified is that your batteries can take the amp draw, and run 5/6 minutes top at the time.
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Old 07-29-2011, 05:51 AM   #4
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Possible tho that you have already cooked the motor thus weakening the magnets and even if you have the gearing spot on, a dead motor will always run hot (if at all)
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Old 07-29-2011, 09:45 AM   #5
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Cool,

Thanks everyone for this good information. I made sure I was free from binding and everything was flowing smoothly. I am going to try the 17t and see what I get. Originally i started with a 25t pinion and worked my way down to the 18t. Boy it ripped down the road with a 25t! I had also tried the cooling fan that castle makes and a heat sink to no avail?!

- whom ever posted about having already burned the motor up. Interesting concept. I had not thought of that as a possibility. Certainly hope thats not the case.

Also...could it be that my belt tension is too much?

Last edited by Zeus426; 07-29-2011 at 10:13 AM.
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Old 07-29-2011, 10:48 AM   #6
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you should have some play on both belts, the front one needs to be able to lift gently by 5mm in middle of top brace, the rear one to push down by 3mm between gears, this should be a good start.
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Old 07-29-2011, 01:51 PM   #7
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checked my belts. all is good thier.

So i called Castle. They said i most likely burned it up. They told me as soon as motor temps go above 200 degrees that there is damage that will be done. More importantly, It will still run fine, But over time the motor will continue to get hotter and hotter and less efficient. Once you cause damage it also raises the KV of the motor, so you dont know where its really rated. So they told me to use my castle link to test the motor. Apparently there is a hidden function for this that they explained to me. Given of course you have the right firmware revisions etc.

SO I am going to test the motor. In the mean time i ordered a new 1406 5700KV setup. They say that these 1406 motors with the 4 pole magnets run generally less hot. They also explained that the 7700KV and the 9000KV are really meant for short stints for top speed/drag racing. And that the 5700 is the better choice for bashing and top speed when paired with a three cell.

I will probably end up sending back the 7700KV if i find it really damaged and have them upgrade it to a 1406 4 pole for 80 bucks. Then use it for top speed drag runs only.

Thanks all.
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