twin motor on axle - different motors?

[SqueakyBum]

New guy...hello!

Got my son a HBX rockfighter for his christmas, put a midnight pumpkin metallic shell on it, 13 leds, proline light bar, 2.4ghz camera, beefier springs.

It's pretty sweet.

I know he'd wish it could do donuts (I know,I know,I know) so I'm just gonna ask....it's a monster crawler now, so fair game.

I have a brand new 15 turn motor pulled from my Anderson M5, just sitting here. :lmao:

Could the ESC handle it? and can ESC handle 2 vastly different turn motors?

If I put it on the rear axle, what effect will it have on the front motor?

Given it's a crawler the motor will be maybe 50-70T (again, no idea what it is) so it'll get spun a fair amount faster than it normally does by virtue of it being shoved from behind.

So in short,

can the ESC handle 2 different motors? (one being 15t)
Can the front motor handle being pushed beyond normal rpms by rear motor?
:mrgreen:

 

[Trubble]

I have a brand new 15 turn motor pulled from my Anderson M5, just sitting here. Could the ESC handle it? and can ESC handle 2 vastly different turn motors?

Very seriously doubt it'll handle two 15 turn motors, but can't say for sure, having trouble digging up info on your speed control's specs.

If I put it on the rear axle, what effect will it have on the front motor?

Leaving the crawler motor in the front and putting a hot one in the rear, you'll burn up the rear motor very quickly.

 

[SqueakyBum]

Very seriously doubt it'll handle two 15 turn motors, but can't say for sure, having trouble digging up info on your speed control's specs.



Leaving the crawler motor in the front and putting a hot one in the rear, you'll burn up the rear motor very quickly.

Only the one 15T motor lol, do you reckon the front (crawler) motor will give too much rolling resistance (ie;braking) causing the rear(faster) motor to overheat and burn up?

please elaborate for me


Edit: what about a secondary receiver and speed controller? (have those available - esc is matched to 15t motor - pulled same time)

Then it's still the same question as before I suppose....hmmmm

 

[Charlie-III]

Running a single ESC with a 15T and a ~45T on it would not be great. Yes, the rear motor would be trying to push the front and likely burn up.
Even if you messed a bunch with gearing (small spur/large pinion on front, large spur/small pinion on rear) it would be marginal, but, it would work, sorta.
As mentioned, we don't know if your ESC could handle a single 15T motor, let alone that as well as a ~45T motor.

Running 2 ESC's would really need a 4 channel radio capable of mixing the 2 ESC's. Otherwise, it's not much different than what you currently have.

For a time, I ran a 40T front motor and a 35T rear motor off a single ESC. It was OK, but I could feel the differences.

Best bet is to get 2 similar motors (35T - 45T) and go from there. Your ESC will likely be able to handle it.

 

[SqueakyBum]

Hi charlieIII, cheers for the info, makes perfect sense.

All this is exactly as I'd imagined.

Funny, I put a brushless combo and bigger pinion in my Anderson M5.
I put a larger pinion in my RC4WD T-finder also as I like a bit of everything.

Knew it would be a PITA to get more out of the rockfighter somehow.

What about just maxing out the pinions in both axles (same both ends)? not really wheel-spinning action but will at least get more top end.

It was just an idea, hence why I came here to ask (and become part of the community as I love crawling and trailing)

I guess my son will simply have to embrace it :mrgreen:

Just while I'm here, I see you have a Bully charlieIII; do you know why my T-finder (3 link) has one long punisher shaft at the back and one short shaft at the front?

I wanted to do the scale thing, then when I got it I went all backcountry and decided I wanted to jack it up and put larger wheels on it :lmao:

The rear is perfection but the front is complaining because of the short shaft getting too much angle on it.

Looks good jacked up with 2.2 monster wheels and Axial honcho body (removed rear floorpan thingy as it felt cheap and nasty to look at). Looks better without it on the t-finder chassis for sure. Would look spot on if the wheelbase matched, longer shaft required at the front for sure.

 

[Trubble]

do you reckon the front (crawler) motor will give too much rolling resistance (ie;braking) causing the rear(faster) motor to overheat and burn up? please elaborate for me

No real need to elaborate, as you just answered your own question. That's exactly what'd happen.

what about a secondary receiver and speed controller?

One can only assume you're looking for a completely isolated system to use as some sort of electronic 'high-low range' setup. With this idea you'd wind up with a FWD when in crawler mode, and a RWD when in go-fast mode. And now, you'd wind up burning up the front motor by dragging a static rear motor in addition to burning your fast motor by pushing a static crawler motor.
Your best bet right now (if you want a compromise between crawling and speed), is a matched pair of lower turn motors than you're currently using. If you just bump up to monster sized pinions on your stock motors (at both ends), your amp draw will start to skyrocket. The fact that I can't find any specs on that ESC, coupled with the fact that it looks to be pushing 380 sized motors, leads me to believe it probably won't handle much gearing up.
Best of luck in finding the compromise you're seeking with that rig.

 

[Charlie-III]

What about just maxing out the pinions in both axles (same both ends)? not really wheel-spinning action but will at least get more top end.

Just while I'm here, I see you have a Bully Charlie-III; do you know why my T-finder (3 link) has one long punisher shaft at the back and one short shaft at the front?

I wanted to do the scale thing, then when I got it I went all backcountry and decided I wanted to jack it up and put larger wheels on it :lmao:

The rear is perfection but the front is complaining because of the short shaft getting too much angle on it.

Maxing out the gearing would still leave the same issue, one motor is driving the axle too fast for the other motor. The "cheaper" motor will likely burn up.:roll:

My Bully is a MOA, thus 2 motors (and now) 2 ESC's. Not sure why that qualifies me to answer a shaftie question. I will say that a large angle in a drive shaft will make it very inefficient. You can "clock" the front axle to reduce the driveshaft angle, but then you mess with the kingpin angle (the pivot in the front steering knuckle) which will hurt steering in certain situations.
You may be able to drill new trans mounting holes to fix the angle, but then you would need to get a longer driveshaft to accomodate the change.

As I remind my son, "You fix one thing, you likely mess up something else".:roll::shock::lmao::lmao:

 

[majatra]

According to this link, E401 - 100A Brushed ESC With Fan (CAR & TRUCK)
the esc in the HBX Rockfighter is a 100 amp capable model E401.
I think Redcat sells the same esc with a different coloration, but they rate it as 50 amp with a 100 amp peak.
E401
They also describe it as a crawler only ESC, so check your warranty for any mentioning of changing the motor.
I always have trouble converting amps to turns, but I think a single 15T would pushing the limits of this esc and would not be worth the bother since you would also have to remove or disengage the front motor.
A RWD short course or stadium truck would do donuts better anyway.
Locked diffs=bad for donuts.

 

[SqueakyBum]

Cheers guys, absolutely no point in trying to get the rockfighter to do something it's not designed to....

With regards to the axle question on the T-finder, sorry CharlieIII - I was referring to the fact you have an RC4WD machine; therefore you maybe know a thing or two about them in general.

I live in Scotland and crawling isn't a big thing here yet, wasn't sure how many folk out there have an RC4WD - I just discovered them and said "got to have one!". "thumbsup"

Anyway, I'm not going to attempt to change the rockfighter, agreed that by changing something it will always have an effect on something else.

I discovered through tinkering that the shaft becomes hugely inefficient above a certain angle and that the steering kingpin angle can quickly become a problem. Be tearing off steering links left, right and centre. Only solution to get the lift and wheelbase I desire is to get a longer shaft for the front.

One upside I did notice is that the high kingpin angle makes the wheels turn into the turning direction and lean the body the same way......surely a handy way to get extra grip and stability when traversing slopes etc?

Thanks for the replies and all the best

 

[Charlie-III]

Hey SB.....no problem, just commenting."thumbsup"8)

Hope it all works out for you, feel free to come back and ask more questions, that is part of why this forum is here.;-)

I'll lift a pint for you, hope you'll lift a pint for me.

 

[SqueakyBum]

Absolutely mate, first round is on me, cheers! :mrgreen:

 

[Charlie-III]

Absolutely mate, first round is on me, cheers! :mrgreen:

Be careful, I travel a lot for business, I may show up at your house with mug in hand!!:shock:

:lmao::lmao::lmao::lmao: