# free rev's on brushless



## charger01 (Oct 17, 2006)

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## briano_72 (Jan 21, 2006)

well under no load, its actually spinning at the highest rpm it ever will. that should not really be bad for it, but i guess for some reason it is. even in a wide open area, it will never get to that rpm level while driving your car, its still pushing the weight of your car, so you will loose a few rpms there as compared to freewheeling.


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## Fred B (Sep 26, 2001)

I would bet that this is less of a problem with the 13.5 (and high wind motors). With the low wind motors 5.5 and below, they turn so much RPM that things can come apart. It's nothing different than frespinning a 6,7 or 8 turn brushed motor.


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## 98Ron (Jun 14, 2004)

please follow the link, it is to the Novak and explains why to not free run the BL motors.



http://www.teamnovak.com/tech_info/free_revving_warning/free_revving_warning.html


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## charger01 (Oct 17, 2006)

Thanks 98ron, the message is loud and clear!


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## swtour (Oct 8, 2001)

> I would bet that this is less of a problem with the 13.5 (and high wind motors). With the low wind motors 5.5 and below, they turn so much RPM that things can come apart. It's nothing different than frespinning a 6,7 or 8 turn brushed motor


Exactly! If a 3.5 motor is 10,500 Kv 'unloaded' on a 7.2 volt pack it would be expected that a FREE RUN on this motor would have it spinning over 75,000 RPM's

Where say a 17.5 motor is only 2,200 Kv so a free spin on those motors would only be around 16,000 RPMs, and I think the 21.5 free spinning would only be around 12,000 - 13,000 RPM's


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## jenzorace (Dec 23, 2005)

How is a sintered rotor going to "break apart"? Maybe this warning is for bonded rotors. And the ones with the string rapped around them.


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## kevinm (Jan 16, 2002)

Anything will fly apart if you spin it fast enough. The picture in the link above is a sintered rotor.


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## NovakTwo (Feb 8, 2006)

jenzorace said:


> How is a sintered rotor going to "break apart"? Maybe this warning is for bonded rotors. And the ones with the string rapped around them.


The warning covers all rotors. The rotor in the photo is sintered.


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## jenzorace (Dec 23, 2005)

Ooops i didnt scroll down that far. Holy ca rap. How long was that rotor freereved?? When the sintered rotors first came out, i had one come apart from the shaft. I glued it back together. It still runs today.


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## harringBONE (Oct 15, 2001)

what happens if your pinnion falls off??


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## briano_72 (Jan 21, 2006)

your not going to sit there for 2 minutes with your motor freewheeling untill you figure that out, are you ? :freak:


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## oscaryu1 (Mar 25, 2007)

It might burn out something faster. Think of running a engine wide open. It doesn't end well...


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## NastyButler (Dec 27, 2005)

harringBONE said:


> what happens if your pinnion falls off??


Good question, I don't see why the esc has not got a rev limiter.

If you are running a 3.5t with lipo and you kill the motor just because the pinion fell of whos fault is it?


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## Loopedout (Mar 3, 2008)

jenzorace said:


> How is a sintered rotor going to "break apart"? Maybe this warning is for bonded rotors. And the ones with the string rapped around them.


Trust me I've seen two sintered rotors blow up inside the can on a 3.5, not mine though


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## DIRTsportsman (Oct 1, 2006)

What difference does it make? You have no reason to ever spin your motor without the car on the ground anyway. 

PS If you cant keep your pionion gear on you shouldnt be running 3.5. Try stock untill you build up the strenght to tighten your pinion setscrew.


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## Loopedout (Mar 3, 2008)

The ones I saw blew on the track, was running a 13-1FDR when everyone else was running around 12 to 12.5-1.
Heres a pic of a blown up sintered rotor.


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## NastyButler (Dec 27, 2005)

DIRTsportsman said:


> What difference does it make? You have no reason to ever spin your motor without the car on the ground anyway.
> 
> PS If you cant keep your pionion gear on you shouldnt be running 3.5. Try stock untill you build up the strenght to tighten your pinion setscrew.


what a jerk


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