MN90 Literally Crawling so Slow After Metal Upgrades. Please Help.

[iantaran]

Hi everyone! I am new to this hobby and so
loving the learning process. This is my first post so please bare with me. I started with a cheap NM90 as my base and tried upgrading everything on it because I love the idea of “building” it from scratch. I even repainted the body and make it look realistic, not the plasticy stock. But after I finally put the internals together, the truck is crawling so slow and the motor is so loud as if the body is too heavy now. Is this set up too weak for the all the metals I put?

Here is my setup:

Servo: WPL 17g 3.5kg, 20A
ESC: 20A Double Sides Brushed
Motor : WPL 180 motor with gearbox
Transmitter/ Receiver: DumboRC X6
Upgraded to metal driving shaft, shocks absorber, steering rod and alloy front and rear axle assembly.
Battery: Li-ion 1500mAh




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[HumboldtEF]

I would first check to see if theres any binding in the drivetrain.

Adding weight will make your motor work harder and accelerate slower but it should not be lowering the top speed (well it will but it shouldn't change by very much). That said it is a pretty small motor and it might possibly be effecting the top speed.

[iantaran]

Originally Posted by HumboldtEF

I would first check to see if theres any binding in the drivetrain.

Adding weight will make your motor work harder and accelerate slower but it should not be lowering the top speed (well it will but it shouldn't change by very much). That said it is a pretty small motor and it might possibly be effecting the top speed.

Thanks for the reply! Drivetrain path is ok. I think the motor I used could be underpower? If I run the car with its chassis only, it runs normal. It is when I put the top shell, that is when it struggles to even crawl on a flat surface.


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[ferp420]

you already know the answer
if it were me i would look in to a trans and motor for a ecx temper or a barrage or a redcat everest 16

also i think theres a motor upgrade kit that should bolt right in
here this thread should have every posable upgrade and all the information on it
WPL, JJRC, MN and Fayee trucks: Models, spare parts, upgrade parts

[iantaran]

Originally Posted by ferp420

you already know the answer
if it were me i would look in to a trans and motor for a ecx temper or a barrage or a redcat everest 16

also i think theres a motor upgrade kit that should bolt right in
here this thread should have every posable upgrade and all the information on it
WPL, JJRC, MN and Fayee trucks: Models, spare parts, upgrade parts

Yeah, I ordered 370motor. See if it fix the problem. Thank you!


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[balsamiq]

I took a similar path not long ago with my mn-90.
A 370 motor is definitely a must in my opinion with that weight increase. The only con I had with it, is that it sits too low, and the transfer case gets stuck in nearly everything that gets in its way...

I am now running with the same 370 motor but with a metal 2-speed gearbox (which btw, opposite of what I thought, it doesn’t add any extra speed, but a lower gear instead...), which is way thinner than the first transfercase, and doesn’t get exposed below the chassis. On the other hand, more parts mean more problems, and I already had to fix it twice...

Nice build btw! Once sorted those problems, I wonder if we will see the rest of the rig :P

[iantaran]

Originally Posted by balsamiq

I took a similar path not long ago with my mn-90.
A 370 motor is definitely a must in my opinion with that weight increase. The only con I had with it, is that it sits too low, and the transfer case gets stuck in nearly everything that gets in its way...

I am now running with the same 370 motor but with a metal 2-speed gearbox (which btw, opposite of what I thought, it doesn’t add any extra speed, but a lower gear instead...), which is way thinner than the first transfercase, and doesn’t get exposed below the chassis. On the other hand, more parts mean more problems, and I already had to fix it twice...

Nice build btw! Once sorted those problems, I wonder if we will see the rest of the rig :P

Thank you for your help! Gave me assurance that it is the motor indeed that I need to fix. I already ordered the 370 motor with metal transfer case but will not arrived until Sept 21 so I might first put back the stock plastic rods so I can play with it while waiting for the motor. I will definitely post the final look of the rig here. Thanks again!


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[Undead Jeeper]

At first I was wondering what the problem was.

"Crawling so slow" is what most are striving for.

Add my vote that it is the motor to blame. It is amazing that the 180 size motor even works at all in these medium scale crawlers. 1/12 scale is
not tiny. It is due to squeezing every inch of power out of those tiny motors via the gearing and transmission BUT the stock weight of the MN90 was
light enough for the motor to handle it. Even though the metal axles, gears and bearings may spin freely and smooth, all that weight still requires
a bit more power and grunt {torque} to get them turning.

Be advised they need to 'break in' too, then afterwards you may notice the entire drivetrain runs even better.


Any updates?