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Painfully slow acceleration - AMP MT.

Taffer

Member
Messages
10
I understood that the ECX amp would be slow in stock form, but what bugs me is that there is no punch at all when starting. No tire spin and very slow build up to top speed. I upgraded to a goolrc 17 turn brushed motor (cheap Chinese ebay motor) and while the top speed is a bit better, the punch is still missing. So now I'm wondering if the ESC was the issue all along? Will a replacement discreet brushed ESC improve this? Is there a way to adjust the stock ESC to increase amperage on start up? (btw: slipper is tight, batteries fully charged, even tested 2s lipo - same issue)
 

Pillowpants808

Well-Known Member
Messages
63
This is my setup
Tekin RS Gen.1 ESC
Flysky FGR4S Receiver & Noble NB4 Transmitter(Recently changed from stock setup)
Sensored Duratrax DTXC3425 8.5T 4450kv Motor
Traxxas 3643 Turnbuckles for front & rear camber
Traxxas 3644 Turnbuckles for front steering
Traxxas 3678 wheelie bar
ECX9001 Metal trans gears
Hot Racing HRASECT288X06 Drivshafts
Hot Racing ECT2106 Steering Knuckles
RPM 73572 Rear Axle Carriers
RPM Suspension Arms Front and Rear
Hot Racing Bellcrank
JX 25kg Servo
Sealed bearings20190824_212636.jpg
20190905_212521.jpg
 
Messages
12
I understood that the ECX amp would be slow in stock form, but what bugs me is that there is no punch at all when starting. No tire spin and very slow build up to top speed. I upgraded to a goolrc 17 turn brushed motor (cheap Chinese ebay motor) and while the top speed is a bit better, the punch is still missing. So now I'm wondering if the ESC was the issue all along? Will a replacement discreet brushed ESC improve this? Is there a way to adjust the stock ESC to increase amperage on start up? (btw: slipper is tight, batteries fully charged, even tested 2s lipo - same issue)
Is your throttle trim turned down?
 

Taffer

Member
Messages
10
Ha ha, nice. I do have a brushless set up for it and I've hit 47mph GPS confirmed. I was specifically wondering about the stock brushed set up because I'm using these trucks in a high school science class to teach the kids a bit about physics and electronics. When we are done building the trucks, we will, of course, be playing with them and I want the kids to use the brushed stock set ups first to get some experience. So in that way it's good that the trucks are a bit sluggish. I love the fact that the throttle dual rate knob on the radio allows you to turn down the power all the way, because that lets them practice driving w/o breaking anything. Eventually, I'd like a bit more power, so we'll probably move up to brushless (unless I find the solution to the brushed issue first).
 

Taffer

Member
Messages
10
This is my setup
Tekin RS Gen.1 ESC
Flysky FGR4S Receiver & Noble NB4 Transmitter(Recently changed from stock setup)
Sensored Duratrax DTXC3425 8.5T 4450kv Motor
Traxxas 3643 Turnbuckles for front & rear camber
Traxxas 3644 Turnbuckles for front steering
Traxxas 3678 wheelie bar
ECX9001 Metal trans gears
Hot Racing HRASECT288X06 Drivshafts
Hot Racing ECT2106 Steering Knuckles
RPM 73572 Rear Axle Carriers
RPM Suspension Arms Front and Rear
Hot Racing Bellcrank
JX 25kg Servo
Sealed bearings


Were you able to mount the traxxas wheelie bar w/o major mods? I noticed that I can't go full throttle on my brushless truck with 3S because it wheelies and flips. (I was able to get it to about 42mph, but any additional throttle flips it) I'm working on a front wing to increase downforce, but I think a wheelie bar would be also a good idea. Thanks in advance for your help!!
 

Pillowpants808

Well-Known Member
Messages
63
Were you able to mount the traxxas wheelie bar w/o major mods? I noticed that I can't go full throttle on my brushless truck with 3S because it wheelies and flips. (I was able to get it to about 42mph, but any additional throttle flips it) I'm working on a front wing to increase downforce, but I think a wheelie bar would be also a good idea. Thanks in advance for your help!!
 
Messages
12
This is with throttle at 10 (dual rate) and trim just a bit less than idling forward on its own. Are other stock Amp MT's punchy or is the behavior I'm describing normal?
I’ve had two that are stock and they were pretty punchy. I’ve since put a brushless system in one and a 15t in the other. I would take it to your local hobby store, sounds like it’s either your battery or the esc the stock isn’t great to say the least.
 

kruzracing169

Well-Known Member
Messages
354
Location
ND, USA
.......but what bugs me is that there is no punch at all when starting........So now I'm wondering if the ESC was the issue all along? Will a replacement discreet brushed ESC improve this?
Your punch is from the programming of the ESC. Motor is your speed. You want punch and more power options, upgrade ESC. Make sure to read in specs of ESC if they offer punch. Most ESC need an programming card. I know GoolRC needs one. Your old motor was probably just fine.
I have no clue on the stock programming of your ESC. I run upgraded electronics all the time.

Smaller the number of turns on your brushed motor, faster speeds.
 

Taffer

Member
Messages
10
I've now determined via the "scientific method" that both the motor and the ESC are crap. I tested a 17 turn brushed motor (not a closed endbell POS like the stock one) on the OEM esc and it was still slow to start up. Then I replaced the OEM radio and ESC and put the OEM motor back in. Still slow. Then I put in the new 17 turn motor AND new ESC in at the same time and voila: Nice punch with satisfactory tire spin. (also a nice increase in top end -- 25 mph vs. 18mph with OEM electronics). All of this testing was done with a 6 cell NiMH.

I have several of these ECX amp kits and will be testing the motor/ESC combos in the days to come. It will be interesting to see if there is a lot of variability in performance with these.
 

Taffer

Member
Messages
10
Your punch is from the programming of the ESC. Motor is your speed. You want punch and more power options, upgrade ESC. Make sure to read in specs of ESC if they offer punch. Most ESC need an programming card. I know GoolRC needs one. Your old motor was probably just fine.
I have no clue on the stock programming of your ESC. I run upgraded electronics all the time.

Smaller the number of turns on your brushed motor, faster speeds.
I'm pretty sure we can't program the oem ESC. If anyone knows something about this, I'd love to hear about it.
 

kruzracing169

Well-Known Member
Messages
354
Location
ND, USA
Just like I said, wola, ESC with punch. Hhhmmm.

Punch is given from ESC. Just saying.

You want wheelies, get an higher AMPerage ESC (programmable ESC), and running higher C rating from your lipo battery.

Nimh batteries are boring and die after 10 minutes of fun.
 
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