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kwrek

Blackfoot Brushed motor Overheating

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Hello.  I am about out of troubleshooting ideas and need some advice.  I have a Vintage Blackfoot that is ball raced and running a Thorp Diff, Counter Gear, Telescoping universals and wheel hubs.  I was running a Sport Tuned motor and noticed my temps were getting into the low 150s before I shut it off.  This was after aggressive throttle on grass.  I removed the motor and cleaned it and lubed the bushings.  I then rebuilt the Ball Diff with new grease.  There is no binding anywhere in the truck including the gearbox.  I am running the stock 10t pinion.  2s lipos are the power source.  I had an Arrma ESC and switched it to a Tamiya brushless ESC.  No difference in temps.

Tried another Sport Tuned that was new and used the Water Break in method.  No resolution .  Put in my trusty Dirt Tuned motor which does not have as high of RPMs as the Sport Tuned and I am getting lower temps in the 120s. Finally I threw a new silver can in it after the water break in and am seeing temps on the 120s.

Tires are Proline mashers which are similar in size to the stock tire size.  No screws are protruding into the motor.

Can a ball diff that is adjusted too tight or too loose cause overheating?  I have it adjusted to where there is just a tiny bit of slip under heavy load.

My primary driving environment is grass.  My Lunchbox and Pumpkin run sport tuned motors and run about 100 degrees max in the same environment.

Any help is appreciated 

Cheers

 

 

 

 

 

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Sounds like you have the basics covered.  Maybe the extra weight and bigger tire diameter of the Blackfoot are too much for that motor.  The Torque Tuned might be a better choice.  You could throw a set of your Lunchbox wheels on it to see if it helps.  Now I’m curious what the gearbox ratio difference is between the two..

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Perhaps the grass is too long. I don't think a tight ball diff would cause overheating. Grass actually provides quite a lot of extra resistance to  an RC. Think of the scale height of it. if it's 3 or 4cm long that's like driving through a field of corn to scale. Try running on tarmac or concrete and see if you get the same issue

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Just shot in the dark but are they the smaller Proline Mashers or the later and slightly larger Masher 2000s? The Masher 2Ks being larger than the stock tires plus the high load of grass might do it. Is the rear tire touching the protruding motor can? The Lunch Box's smaller tires plus its very low resistance drivetrain probably attribute to its lower temps. 

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4 hours ago, Saito2 said:

Just shot in the dark but are they the smaller Proline Mashers or the later and slightly larger Masher 2000s? The Masher 2Ks being larger than the stock tires plus the high load of grass might do it. Is the rear tire touching the protruding motor can? The Lunch Box's smaller tires plus its very low resistance drivetrain probably attribute to its lower temps. 

The tires are the Masher 2000s. #1074. The tires clear the motor. I will try the Lunchbox tires and monitor the temps.  Great suggestion!  If the temps are reasonable I may switch to Monster Beetle spikes tires.  I will report back.

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I appreciate everyone’s input.  This one is frustrating.  

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A tight ball diff definitely makes a difference, especially since you put tyres on it with actual grip. The original setup was not only open and very light, the tyres themselves allow for a lot of slippage. Now add the weight of the new driveline, the weight of the new tyres which are also larger in diameter, and you have made significant changes to the load the motor sees. Lastly you added a lipo which can deliver a lot more current than a nimh pack. Get the Monster Beetle boots on it and loosen up that diff. It will unload the motor quite a bit. Add a heatsink with a fan. That will pull some heat from the can if changing the tyres and loosening the diff won't help enough. 

If I was in your shoes, I'd shop around for a 550 mjll. A Kyosho Mega 360 would be a great choice.  If you want a cheaper alternative to the 360, I'd get this. Awesome workhorse and 21k rpm. https://www.hobmamodelbouw.nl/product/speed-600-bb-sp-72v/

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9 hours ago, DK308 said:

Add a heatsink with a fan.

Consider using thermal tape/paste if using a heatsink, it works! 

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Appreciate all of the tips folks.  I removed the Proline Mashers.  I decided to go with a set of standard Blackfoot tires.  I will loosen the diff.  I installed a heat sink with a thermal pad.  Once I get the new tires mounted I will check the temps and report back.  
Also I found that acetone on a q-tip works great for de-bonding CA glue!

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Update.  Installed stock Blackfoot tires.  Loosened up the Diff.  Installed heat sink with thermal pads.  Running silver can.  Ran on a mix of concrete and grass.  Temps not exceeding 100f on the motor.  The heat sink reads 140 max after a hard run.  I can accept that.  Thanks for all the input.  Note to self:  I have to be more cautious on these stock BF tires as the truck is easier to roll on the narrow tires compared to the Prolines.  My vintage Ford body ended the run with scratches.  Oh well I only keep runners so that is part of the fun.  

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