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Old 04-08-2008, 04:27 PM   #1
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Default Brushless Modified Cogging/Drag Brake Effect per different brands...

Hey guys,

I dipped into Mod Sedan this past weekend, racing on two different tracks/events. I had borrowed an LRP 4.5 from a friend to try, as I have yet to purchase a dedicated Mod motor for myself.

The motor bolted in fine into my TRF 416, I geared it at 8.4. Plenty of top end and punch, but I did have one gripe - the motor felt like it had waaaay too much drag brake, even after I turned it all of from the ESC (LRP TC Spec).

Are all mod motors like this? I usually run 13.5/10.5 and this thing felt like it had so much resistance under coasting. I'm wondering if any of the other brand mod brushless motors (Speedpassion, Orion, Novak, etc) share this similar feeling, or if it varies by brand. I'm looking to get a 3.5, but want to get one that feels "free", if that makes any sense.

Any help would be great!
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Old 04-08-2008, 04:54 PM   #2
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Originally Posted by StickyFingaz View Post
Hey guys,

I dipped into Mod Sedan this past weekend, racing on two different tracks/events. I had borrowed an LRP 4.5 from a friend to try, as I have yet to purchase a dedicated Mod motor for myself.

The motor bolted in fine into my TRF 416, I geared it at 8.4. Plenty of top end and punch, but I did have one gripe - the motor felt like it had waaaay too much drag brake, even after I turned it all of from the ESC (LRP TC Spec).

Are all mod motors like this? I usually run 13.5/10.5 and this thing felt like it had so much resistance under coasting. I'm wondering if any of the other brand mod brushless motors (Speedpassion, Orion, Novak, etc) share this similar feeling, or if it varies by brand. I'm looking to get a 3.5, but want to get one that feels "free", if that makes any sense.

Any help would be great!
The rotor diameter will change the drag brake feel. SInce you did not mention which rotor you were using, I will assume you were using a 14mm. Most if not all the LRP team drivers (including myself) use a 12.5mm rotor. This will not only give you less drag brake, it will give you better feel under power.

The tightness of the belts will also change the drag brake effect. Even with a 14mm rotor, the car should coast pretty well.
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Old 04-08-2008, 05:00 PM   #3
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My 2c is that you're just not used to it. In mod you need more drag brake because you're coming to the corners much faster. The LRP with the default setting is just right. What you felt wasn't speedo induced drag brake but the difference in gearing, running a much higher gear ratio means the car will feel like it's got a lot more drag brake.

Just drive the thing with the speedo's standard drag brake setting and get used to it, you're not driving a slow 10.5 anymore...
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Old 04-08-2008, 05:31 PM   #4
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The rotor diameter will change the drag brake feel. SInce you did not mention which rotor you were using, I will assume you were using a 14mm. Most if not all the LRP team drivers (including myself) use a 12.5mm rotor. This will not only give you less drag brake, it will give you better feel under power.

The tightness of the belts will also change the drag brake effect. Even with a 14mm rotor, the car should coast pretty well.
I'm not really sure which rotor was in it - I believe it was the standard rotor that comes with the motor. Is that the 14mm rotor?
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Old 04-08-2008, 06:22 PM   #5
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The reason for the dragbrake feel, is the design of the motor. The Novak/LRP motors use a slot design, as some other motors, Neu designs and Plettenberg. Think of a brushed motor built inside outthe cast iron arm is the case with windings in the slots and the magnet is on the axle and reacting with the slots (where the windings are wound, That reaction is causing a mild drag. If using the bigger rotor, you might have too strong an attraction between the magnet and case/slot. The motors like the mambamax, fegaio's, some hackers and all lehners use a pressed winding method, that winds the wires and press them in the can without an iron core don't have that reaction and can free wheel
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Old 04-09-2008, 08:37 AM   #6
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I'm not really sure which rotor was in it - I believe it was the standard rotor that comes with the motor. Is that the 14mm rotor?
Yes.

You want the motor to have some drag brake. If it free wheels with no drag you have to depend entirely upon the ESC drag brake settings.

With the zero drag brake setting, the motor should coast no less easily than a 10.4 or 13.5 brushless motor or brushed modified motor. If the drag brake is greater than this (like a brushed stock motor's drag brake or greater), there might be something wrong with the ESC, motor, or the car's drivetrain.
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Old 04-09-2008, 04:28 PM   #7
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Yes.

You want the motor to have some drag brake. If it free wheels with no drag you have to depend entirely upon the ESC drag brake settings.

With the zero drag brake setting, the motor should coast no less easily than a 10.4 or 13.5 brushless motor or brushed modified motor. If the drag brake is greater than this (like a brushed stock motor's drag brake or greater), there might be something wrong with the ESC, motor, or the car's drivetrain.
I'm pretty sure my drivetrain is pretty free. I'm very meticulous when it comes to that aspect. With a 10.5/13.5, this car still has drag brake, but not an overwhelming amount to where it hurts my rolling speed in those low hp classes.

With the mod I ran, the thing feels very bound. And it's definitely the motor imposing an "engine brake" type feel. It slows down so much it affect the weight transfer of the car (front to rear). I'll try and see if I can locate a 12.5mm rotor and throw that thing in. I have a feeling it'll be what I'm looking for...

Thx
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Old 04-10-2008, 07:54 PM   #8
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Quote:
Originally Posted by Rick Hohwart View Post
The rotor diameter will change the drag brake feel. SInce you did not mention which rotor you were using, I will assume you were using a 14mm. Most if not all the LRP team drivers (including myself) use a 12.5mm rotor. This will not only give you less drag brake, it will give you better feel under power.

The tightness of the belts will also change the drag brake effect. Even with a 14mm rotor, the car should coast pretty well.
I use a novak SS4300 (the old version of 10.5), the rotor is non sintered, which have less magnet force. the feel of drag brake is quite mininal with 7.44 final drive on my 415.

my ta05ms with novak 3.5 has a sintered rotor. which has much stronger magnet force, I can feel it just by turning the spur gear. the drag brake is also much stronger with 9.09 on it.

I agree the size of the rotor diameter does play important in drag brake and initial torque, but also the kind magnet which it uses.

The new novak "Light" bushless motor, I beleive they have a smaller diameter rotor in it. but also the sintered rotor for better heat resistance.

also I heard some of the guys say, the trf416's upper deck needs a little trim to reduce tension, hope this would slove your problem too. ya, it may or may not be about your drive train.
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Old 04-10-2008, 08:07 PM   #9
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Default drag brake effect

I felt like I had the same problem in oval at the snowbirds.
Where can you get the 12.5 rotor?
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