# Brushed Stock Motors



## dhiracing (Jul 19, 2005)

Hi Guys,

At our local racing track, we use sealed 21 turn stock motors for 10 mins races in the beginners class. Anyone can confirm what will be the effect of using hard springs, horizontal or diagonal slots in brushes? Need to get more revs and runtime, what will you suggest? Thanks ...


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## MARTIN (Feb 26, 2004)

Heavy Springs Increase Rpm,but Also Amp Draw At The Same Time So In Turn Would Lower Run Time.the Reedy 728 Brush Might Be A Good Choice For Your Application.


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## Z-Main Loser (Nov 17, 2004)

Lighter springs increase RPM and reduce amp draw. Using a harder spring on the - and softer on the + will also increase RPMs and lower amp draw. Drill a small hole in the brush.


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## Mayhem (May 5, 2002)

Heavy Spgs increase RPM under load, lighter will give the illusion of more RPM on the bench because of reduced drag, IMHO. Full brush = more torque and amp draw, holes or slots lower ampdraw and increase RPM under load. I prefer heavy springs with a hole or slot and a little lower gear....try it you'll like it.


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## dhiracing (Jul 19, 2005)

Thanks for the suggestions, will try at the track and let you know ;-)


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## erock1331 (Apr 1, 2002)

I've always had best output on the dyno using soft springs (greens).
Higher watts, rpm and Torque with greens over reds and pruples. My guess is on a flywheel dyno the motor spins up free-er with lighter springs.

Whether that relates on the track is the hard [email protected]#$%^ LOL
But a lighter sprung motor always seems to finish better for me, maybe due to a little less amp draw.

I always heard light springs reduce the amount of friction/force on the com letting it spin faster = higher rpm. Which is probably referring to what Mayhem said (looks good on the bench).

Probably the only way to know for sure is to put the car on a chassis dyno, but really that isnt under the load (gravity and g-froce) like a track pulls. Does that Eagle Tree data recorder measure RPM? I would be curious to see if a motor spring change really make a difference on the track.

I'd like to hear Putnam or some or the other motor tuners comment.

Another question: why do On-road guys always run purple springs? I would think Torque would be what they were after.


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## bsracing8 (Dec 14, 2004)

Another question: why do On-road guys always run purple springs? I would think Torque would be what they were after.[/QUOTE]

Eric i think jason schreffler can answer that for you?

Brandon


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## MIKE VALENTINE (Mar 12, 2002)

I would think brush bounce, the heavier spring will keep the brush in contact with comm better under breaking.


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## MARTIN (Feb 26, 2004)

looks like it is mayhem and martin vs.erock and bsr in the motor spring debate

lets get it on!!!!!


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## erock1331 (Apr 1, 2002)

bring it...lol


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## MARTIN (Feb 26, 2004)

hahaha


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## Todd Putnam (Mar 4, 1999)

Erock is correct: Lighter springs actually increase torque, contrary to popular belief. The reason that heavier springs are used in On-Road/Sedans in to eliminate brush glaze due to heat. If you are burning brushes or suffer from the motor fading late in the run due to heat, increasing spring tension will help cure this.
Remember, watts, ("electrical horsepower") is the force that physically moves mass (our cars in this case). Watts is the product of RPM and Torque...:thumbsup:


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## MARTIN (Feb 26, 2004)

Looks Like Martin-mayhem Wins...erock Said Heavy Purples Were What Produced Torque...

Congrats To Team Dream,and Through God All Things Are Possible.peace Love And Santa!!!


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## Todd Putnam (Mar 4, 1999)

erock1331 said:


> I've always had best output on the dyno using soft springs (greens).
> Higher watts, rpm and Torque with greens over reds and pruples. My guess is on a flywheel dyno the motor spins up free-er with lighter springs.
> 
> Whether that relates on the track is the hard [email protected]#$%^ LOL
> ...


 
...I think Erock stated higher RPM,Torque and Watts w/ green springs vs. reds or purples in paragraph 1...:thumbsup:

-TP


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## dhiracing (Jul 19, 2005)

So I guess no straight forward answer ey! Some people think that lighter springs generate more revs and other heavier springs. Hehe ... confused ;-)

The wider the brush (laydown) more revs? The thinner (upright) more torque?


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## RPM (Dec 20, 2004)

dhiracing said:


> So I guess no straight forward answer ey! Some people think that lighter springs generate more revs and other heavier springs. Hehe ... confused ;-)
> 
> The wider the brush (laydown) more revs? The thinner (upright) more torque?


Also, depends on the brushes you use.

Reedy 767 or Putman greens for stock (timed)
Trinity 4383 or Putman x brushes for 19 turn (hole in center)

Peace


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## MARTIN (Feb 26, 2004)

All i said was that increasing spring rate increased rpms and amp draw,which in fact it does.does not mean that it would put out more power,that would depend on the type of motor and power band you were tuning for.

Regardless of the power output at the end of the change harder springs increase rpm over a softer spring....if you do not agree well..i guess our dynos read differently.


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## dhiracing (Jul 19, 2005)

So ...

Making a heavier spring on positive or negative, what will be the difference?

Thanks,
Mark


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