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Old June 18th, 2013, 4:12 PM   #1
nascarkeith
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Default Losi XXX-SCT Oval Gearing

I am having trouble getting my Losi XXX-SCT geared for oval racing.

The ESC temps are fine but the motor gets to hot and I don't have the power I need.

With a 24/88 gear the temps run around 200.

With a 19/88 gear the temps are about 170 but it is slow.

The fast guys at the track are running a 22/76 gear. The track has a 150 foot run line.

I thought that I was over geared but it has been suggested that I might be under geared causing the motor to wind out and work too hard.

Advice would be appreciated. Thanks.
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Old June 18th, 2013, 4:48 PM   #2
DolphinsFan
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What I can tell you is this the "fast guys" are running a 3.45 gear ratio (22/76)

You are running a 3.66 ratio (24/88) which I'm sure you already know this. So you can be under geared.


hot motor + cool ESC = under geared

There does come a point if you can gear down enough that you always have your throttle pinned just to keep moving that gearing down too much can put excess stress on any motor. if you never have to let off the throttle, the motor never gets a time without constant current flowing through it... so it's always gaining heat. Not sure if this is the case with you.
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Old June 19th, 2013, 9:36 AM   #3
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What motor/esc are you running? Are you running as a SCT,Modified or Late Model? Also what is the track surface. Just curious as I also run a Losi XXX-SCT.

Jim(Jolly)Rodgers
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Old June 19th, 2013, 7:56 PM   #4
nascarkeith
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SC Dirt Late Model Class. Loamy track surface not clay. Hobbywing 60 amp ESC and a 4379kv 4 pole motor.

When I raced the truck offroad 16/88 was a good gear ratio. Is oval really that different?
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Old June 20th, 2013, 5:26 AM   #5
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I am running one of mine as a Barts bodied Big Block Modified which is currently powered by an EZ Run 60a/4000kv combo geared at 16/87(AE spur) SCT tires,on a banked clay mix oval of about the same size.The other is setup as a SCT using a Castle Sidewinder SCT esc/Orion Experience 2 Pro 3750 kv 4 pole geared the same.
As i learn more about dialing these two XXX-SCT's in this may change but this is how they are geared for now. My temps are in the 120/140 range after several hot lap's followed shortly by a 4 min. main.


Jim
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Old July 13th, 2013, 10:51 AM   #6
Brian F
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Also... there could be a different problem.

1) If the drivetrain (Tranny, tight gear mesh, seized wheel bearing...) is binding somewhere it could heat the motor from it being overworked.

2) If you have you have an extremely tight race car (pushing in the turns) you can overwork the motor also.

3) Remember, tire size changes your gear ratio.

It all works together, don't just think of each problem on a separate basis.

Last edited by Brian F; July 13th, 2013 at 10:53 AM. Reason: spelling
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