Mamba X 1406 1900kv weak drag brake

[vvv850]

Hello everyone,

I'm looking for some help with a new power system on my TRX-4.

I recently installed a Castle Creations Mamba X with a 1900kv 1406 motor and I noticed that the drag brake is a bit weak on its maximum setting. The truck rolls slowly on a 45 incline.

The batteries I'm using are 3S 4000 mAh. I calibrated the esc correctly, maximised drag brake, maximised brake, maximised reverse throttle and even set up the aux wire on a separate channel to be able to customise the drag brake on the fly.

This is my first dip in the crawler territory and maybe this is normal, but I think the stock power system was holding a bit better.

Should I use 4S batteries? Or am I missing something?

Thanks

 

[tuanies]

Is it a green or gray motor?

I'm running a Mamba X with a 1900kv Slate motor on 3S and 4S with zero drag brake issues.

 

[vvv850]

The grey motor.

I have some questions if you are running the same power system:
- what setting are you using for start power?
- on level ground, how much pushing force does your model need to get rolling, or does it even roll?
- do you feel a difference between 3s and 4s regarding the drag brake?

Thanks a lot.

 

[tuanies]

The grey motor.

I have some questions if you are running the same power system:
- what setting are you using for start power?
- on level ground, how much pushing force does your model need to get rolling, or does it even roll?
- do you feel a difference between 3s and 4s regarding the drag brake?

Thanks a lot.

I don't remember TBH, its been a while since I programmed it. Maybe something like 50% or so?

If I push it, it will roll, but it stays still otherwise.

No difference in drag brake between 3S and 4S.

 

[robert@castle]

Drag brake force is highly dependent on gearing. High gear in the transmission may be too high of a ratio for effective drag brakes.

If you are in 'Crawler Reverse' 'Reverse Type' then 'Brake Amount' setting does nothing.

It is possible the the AUX wire is overriding the drag brake setting and setting it to a lower value than you are expecting. You can see the aux wire value in the datalogs, or unplug the AUX wire and it will use whatever value you selected in Castle Link.

 

[vvv850]

Drag brake force is highly dependent on gearing. High gear in the transmission may be too high of a ratio for effective drag brakes.

So, if this is my problem, I should change the pinion to a lower number of teeth one, right?

If you are in 'Crawler Reverse' 'Reverse Type' then 'Brake Amount' setting does nothing.

Thought so, but I wanted to eliminate any problems in programming.

It is possible the the AUX wire is overriding the drag brake setting and setting it to a lower value than you are expecting. You can see the aux wire value in the datalogs, or unplug the AUX wire and it will use whatever value you selected in Castle Link.

I will give this a go tomorrow and come back with my findings.

 

[Hydrocarbon92]

High gearing means fast, which is smaller spur with large pinion. Low gearing would use a small pinion. Basically for each time the wheel turns, the motor turns more when you gear down with a smaller pinion. One thing I've noticed is brushless crawlers tend to be geared fairly high. IMO if you want to hit 30mph+, get a SCT or truggy. 10mph is a scale 100mph, and that's pushing it for a full-scale rig.

 

[vvv850]

I've edited my post regarding the gearing. I got things mixed up.

Could you please explain your last phrase? I didn't understand it.

Thanks.

 

[vvv850]

So I retested the drag brake today and I think it's ok. I believe that yesterday I tested it in high gear without noticing.

This is how it looks now: https://www.youtube.com/watch?v=sEuZHTPNsfU

I've verified that the aux wire goes to 100% in the logs and everything looks good. Maybe dropping the pinion from 11T to 9T will lock the model in place. Still, it's acceptable.

PS: While testing I noticed two things:
1. As you know the Castle escs have an idle beep. While the model is on an incline, every time the esc beeps, the drag brake is softened for a fraction of a second. It's funny and not really a problem.

2. As you increase the drag brake with the model on flat surface, the car starts at lower and lower speeds. What I mean is, if the drag brake is 0%, and you try to move the car as smooth and slow as possible, you will notice that it starts moving at a higher speed than if having the drag brake at maximum. A bit weird but then again, you usually need fine movements when crawling, thus using a higher drag brake setting.

Cheers

 

[robert@castle]

So I retested the drag brake today and I think it's ok. I believe that yesterday I tested it in high gear without noticing.

This is how it looks now: https://www.youtube.com/watch?v=sEuZHTPNsfU

I've verified that the aux wire goes to 100% in the logs and everything looks good. Maybe dropping the pinion from 11T to 9T will lock the model in place. Still, it's acceptable.

PS: While testing I noticed two things:
1. As you know the Castle escs have an idle beep. While the model is on an incline, every time the esc beeps, the drag brake is softened for a fraction of a second. It's funny and not really a problem.

2. As you increase the drag brake with the model on flat surface, the car starts at lower and lower speeds. What I mean is, if the drag brake is 0%, and you try to move the car as smooth and slow as possible, you will notice that it starts moving at a higher speed than if having the drag brake at maximum. A bit weird but then again, you usually need fine movements when crawling, thus using a higher drag brake setting.

Cheers

1. On the basic tab of castle link, there is an option for 'Disable Idle Beeps'.

2. That is expected behavior. The software uses the drag brake at low throttle percentages to control the rotation of the motor.

 

[vvv850]

Yes, I know. I already disabled it.

 

[Hydrocarbon92]

That vid looks pretty normal to me. Brushed motors have enough braking to lock it in place, but that's few reasons to really need that. My guess with the slower start speed with more brake is it still mixes brake with throttle. A truck can shoot down a hill with a tiny throttle otherwise.

I've edited my post regarding the gearing. I got things mixed up.

Could you please explain your last phrase? I didn't understand it.

Thanks.

When a 1/10th scale vehicle moves at a real 10mph (gps, radar, etc), you multiply that by the scale to get full-size speed. For 1/10th, you get 100mph. 10mph with a 1/16th scale is 160mph.

So for a 1/10th scale crawler to hit 15-20mph, which the faster trail trucks can, it would be like 150-200mph. Any full-scale crawler geared for 200mph will definitely not crawl well.

 

[mikemcE]

I start the motor at the high setting, with 30%punch. Works well


Hang up and Drive

 

[Taper]

I have the same problem with my MMX with 4600kv motor installed in my wraith