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Old 03-10-2005, 07:02 AM   #1
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Post Gearing issues - HOT motor (reeddy 19t spec.)

Hi,

I'm running a reedy 19t spec (pro model) motor in my Tamiya TT-01 Chasis, using a Super rooster esc. It has all bbs.

At the moment I'm running a 19t pinion gear and a 61t spur gear (wich gives me a ratio of 8.53) and the motor is getting really hot!

Would it be worth trying to get hold of a larger spur gear to make a larger gear ratio???

Also, would attaching a heatsink to the motor do anything? I've read somewhere that all it does is trap heat between the motor and the heatsink!?

Is it worth cutting some air flow holes in the body to get more air flowing through the car?

Any help and suggestions would be greatly appreciated!!!
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Old 03-10-2005, 07:04 AM   #2
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opps!!!!!

That's Reedy...not Reeddy!
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Old 03-10-2005, 08:56 AM   #3
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Capt,
8.53 is way to low of a ratio to run with the Reedy Qmag motor. Most racers choosing to run this motor that i know are running a much higher ratio. Try 6.00 as a start and work your way up or down depending on track conditions, tire size, ect. Hope this helps.
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Old 03-10-2005, 11:11 AM   #4
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I am not sure what you run on in your country, but if your running a 36x70 foot carpet track you got about the right ratio . if you run on a 110x50 foot pavment track your way under geared.
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Old 03-10-2005, 03:12 PM   #5
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Undergeared motors can get just as hot as an over geared motor because it'll be at full RPM far too long. I usually run a Reedy QM between 6.1 and 5.8.
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Old 03-10-2005, 05:35 PM   #6
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thanx heaps for the help...I'll go out and get a new spur gear to get the new ratios...

Thanx again!
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Old 03-31-2005, 08:57 PM   #7
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Quote:
Originally posted by Jon Kerr
Undergeared motors can get just as hot as an over geared motor because it'll be at full RPM far too long. I usually run a Reedy QM between 6.1 and 5.8.
I never know that undergearing a motor would also cause it to overheat. I always play safe with motors so i dont go too high on the gear raios and use 5.6 to 6.5 for stock motors and 7-8 for modifieds. Haven't gone below 5.6 for any motor.


Captjono- hows the tt-01 holding up with the 19t motor? i might buy this kit and use it for rally. are the suspensions durable? I heard the dogbones are plastic and outdrives break easily. Still its so cheap and includes an esc.
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Old 03-31-2005, 11:10 PM   #8
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That's actually geared pretty high. The lower the number (ratio) the higher you're geared. A 6.0 is a higher gear than a 7.0. I know it's confusing. Think of it like being in your car. High gear is as close to 1:1 as the transmission gets. But 1st gear or low gear is going to be more like 6.0:1. (Don't know exact ratios on full size tranny's) But you get the idea. The higher the gear, the smaller the number on the ratio. That's why we say to gear up when you go to a bigger pinion, giving a smaller ratio.

I haven't run stock in a couple years so I'm not too sure how to gear them any more. Mods, depending on the wind and track, I try and stick in the 8.3 to 9.0 range. 19 turn really depends on the motors. Reedy quad mag I gear to the moon, around 5.7-6.1, again depending on layout. I'd be at least two teeth on the pinion smaller with a Trinity C2 19 turn.
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Old 04-01-2005, 12:51 AM   #9
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Yeah like i said. I wouldn't go very high on the gear ratios. for mods I use 7-8 and nothing below 7 that would be too hot for the motor. Same goes for stock nothing higher than 5.6. But I honestly didnt know that gearing a 19 turn on a low gear like 8.53, which seems too low, could cause a motor to be very hot.
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Old 04-01-2005, 09:03 AM   #10
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I was recently running a QM 19T at 7.50 (24/72) in a TC4 the car would top out before the end of the straight. After a couple of runs I noticed the comm had gone bright red. I was advised by the locals to go to a 27/72 or 28/72 (forget the ratio offhand) this made the car of course much faster, and after a run or two the comm was back to its normal colour.
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Old 04-01-2005, 09:34 AM   #11
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That's exactly what I was talking about. Under gearing can be worse than overgearing because the motor will be spinning at max RPM far too long and doing nothing but generating more heat.
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Old 04-01-2005, 10:45 AM   #12
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guys running at SO CAL sedan what's the recommended gearing ( FDR) for:

8x2 V2 Modified:
19 t Chameleon:
27 T Monster:


TNX

Assasin
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Old 04-01-2005, 11:09 AM   #13
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I can help with stock -

Depending on layout, between 7.0 and 7.5 with a Monster.

I haven't run a C2 there yet, but my Reedy Quad Mag likes 5.8 to 6.1. I would imagine the C2 might like to be geared a little lower, somewhere around 6.2/6.5 maybe.

Mike
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Old 04-01-2005, 05:42 PM   #14
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how bout a 19t v2 dynasty, any recomendations for gearing in a trf414
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Old 04-01-2005, 06:08 PM   #15
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Default Re: Gearing issues - HOT motor (reeddy 19t spec.)

Quote:
Originally posted by Captjono
Hi,




Also, would attaching a heatsink to the motor do anything? I've read somewhere that all it does is trap heat between the motor and the heatsink!?
Forget about what you read. Aluminium has a low heat capacity. That means that it will absorb heat much faster than other common metals. This will draw heat off the motor, and the heatsink will get hot. This redistribution of heat reduces the motors temperature. The end result, is long run times and less comm-brush damage. Also, you can freeze the heatsink before the race. Heat always flows from hot metals to cold metals. So the motors heat will flow to the heatsink much faster.
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