Brushless FTX Outlaw Stutter from standstill - cogging?

[Eclipsed4ever]

Hi all.

 

I have an FTX Outlaw which I bought second hand. Originally it was brushed but the previous owner upgraded to a brushless setup. That's how I bought it. It has an Absima 3421kv brushless motor fitted - not sure on the ESC off hand. Ever since I've had it its had a stutter when it pulls off. On the flat it judders then goes, but on any sort of incline it just stutters/judders and doesn't move. As soon as it starts to go (like if you help it with your foot) it goes like a rocket.

 

So far I've tried:

- new 2S 7.4v 50C Battery. It came with a 30C.

- been round all the drivetrain (even swapped original brushed motor setup back in - it ran fine but comparatively very slow, then the motor burnt out. Must of been on it's last legs).

- Resoldered all the connections on the motor.

 

It's still on standard gearing. Is a 3421kv too fast of a motor to be able to crawl? I don't really need the level of speed it gives as I quickly run out of space. I'm happy to buy a new motor for it but would a sub 3000kv motor be the fix for this? 

 

Here is a little video of it:

 

Any help greatly appreciated!

 

[Bajadre]

sounds like cogging OP some escs do this sometimes a power cap helps smooth out the power etc

[Eclipsed4ever]

Ah yes, I believe this is the ESC / motor combo fitted:

https://www.absima.shop/RC-ACCESSORIES/RC-Electronic/Brushless-Motor-ESC/Brushless-Combo-Set-Thrust-BL-ECO-1-10.htm?shop=absima_en&SessionId=&a=article&ProdNr=2120002&t=19114&c=19130&p=19130

 

What I found interesting was this bit:

· Battery: 4-9 cells NiMH / 2-3S LiPo

· Motor limit @ 2S: 8T on-road / 11T off-road

· Motor limit @ 3S: 11T on-road / 14T off-road

 

So the 3421kv motor I have is equivalent to about a 13T I think? So should I be running a 3S battery for it to cope in an offroad car? Would that give it the extra 'go' that it needs to get it pulling away on an incline?

 

Or... would fitting a higher T motor be a better plan so I can actually use the 2 x 2S batteries I already have?

Edited August 17, 2020 by Eclipsed4ever

[Redback]

Yay or sorry to hear but happy to know another Outlaw owner with the same issues i had.

The stock brushless outlaw with the etronix 60a ecu & 2700kv motor also does the same thing.
Hobbywing max 10 3300kv works nicer but not good enough for crawling as soon as it hits long grass you have to feather the throttle to get the motor to keep turning over smoothly from standstill.

 

The only solution i found was a complete transmission swap, i made a post about it and am happy to share more details as on further looking its as clear as mud

 

 

If you do find a solution that doesn't require a transmission swap id love to hear it, Maybe a castle mamba x and crawler motor, but my experience with a 1800kv axe system was it would cook the motor, the stock gearing on the the outlaw is pretty bad in my mind.

 

[Eclipsed4ever]

Hi Redback. 

 

That's a great thread you've started, loads of good information. I've not experienced many of the breakages you have, only mullering the hex drives/wheels and a few rear CVDs since I've had it. Just put that down to the much greater power over the brushless. 

 

I find it interesting that a standard brushless car has the same problem... That's pretty disappointing. Surely it should be capable of some general crawling about and driving up and down small banks without issue.

 

Perhaps a motor somewhere in the middle of the 1800kv and 2950kv that you've tried might work? I don't mind some modification if that's the only way. What is the gearbox that you've used from? 

[Redback]

Thank you for the kind words Eclipsed.
I'm not sure about more motors, there might be just enough room for a 550 brushless motor that would have more torque and probably clogg less with a 60+amp ecu. I wasn't able to find a motor that wouldn't melt and haven't seen any other solutions. 3s will give you an extra kick you can also try adjusting the ecu punch and timing sometimes this can help smooth out the launch.

The Outlaws from what I've seen and hear, are known for eating motors and because we have no choice in gearing due to the way they made the motor mount, Its been a hard ride to find a solution.
Also with a stronger motor your spur gear will get thrown at low speeds so finding a middle ground is tricky.

This is the gearbox i used.
https://wheelspinmodels.co.uk/i/230038/
 

I also was looking at the FTX mauler / outback fury transmissions but couldn't get hold of one and was concerned the motor position wouldn't work due to the motor being slung low.
 

Edited August 18, 2020 by Redback

[Eclipsed4ever]

How come the lower kv motors cook? Is it just that they're flat out all the time when driving the car fast? In some ways, I don't drive the car that fast for long periods - more often we have little technical sections to try and drive through. Perhaps buying an 'offroad racer' was the wrong choice. It was only that the videos I had watched of people using them, none of them mentioned that it had no guts whatsoever for crawling type stuff.

 

Are there any alternative diff ratios available?

 

The mauler gearbox looks a nice compact unit - could anyone confirm what ratio it is or what ratios are available for it?

Edited August 18, 2020 by Eclipsed4ever

[Redback]

No they are not flat out, on flat ground there's no issue, the brushed ones seem to cook on the hills, like what happened to yours when you put the brushed motor in.
 

The Outlaw uses carnage / vantage diffs and I'm not sure what other are compatible maybe some others have insight, eg axial wraith diff spurs might fit the diff case, or the diff case might fit the diff, but i don't see the diff gearing being the issue.
 

Yes we might have made the wrong car choice as these are rock racers not really designed to be in a bind.
However if you want to work on it, I think there's a good rig here.
 

If you go for the mauler gearbox please let me know how the build goes, I'm not aware of different ratios, the downside of the g1 gearbox for me right now is no choice of spur gear size, however there is enough room for id say up to a 27t maybe larger pinion.
I was also concerned about the mauler drive train gear width, The outlaw is a wide truck and not that light using larger wheels  like i do to help with roll overs and handling, would put some strain on the gearbox, so the wider G1 gearmesh to me seems less likely to fail.

[Logie]

Few friends with FTX and Abisma models have this problem, guess its cheap electeonics.

 

Mate bought my esc from my Ho bao VTe, night and day difference. Smooth and its even faster on his Abisma brushless buggy with stock motor.

 

Friends FTX Carnage brushless was garbage, bought my esc from HPI WR8 and its nice and smooth,.no jerking or cogging.

 

Shame i ran out of spare ESCs for mt sons brushless Abisma truck lol. If its up against anything it wont go 

[Redback]

I had a similar experience with the hobbywing setup, it was night and day better than stock but low speed startup has been a constistent issue specially with big wheels. Love to see a video of these in a bind to see how they compare.

 

[Redback]

14 minutes ago, Logie said:

Mate bought my esc from my Ho bao VTe, night and day difference. Smooth and its even faster on his Abisma brushless buggy with stock motor.

 

Friends FTX Carnage brushless was garbage, bought my esc from HPI WR8 and its nice and smooth,.no jerking or cogging.

What amps / outputs are the ESCs and what motors are they paired with, thank you.

[Logie]

All motors are the stock, think the Abisma buggy is 3300kv and its a 100 amp 4s capable esc (bit overkill but it was cheap) 

 

 Not 100% on Carnage brushless motor but the esc is 80a 3s.

 

Another mate has the same problem with goolrc combo in his FTX Bugster, but plug in the hpi or hobao esc and cogging/jerking goes and it flies

[Eclipsed4ever]

Well after looking at various bits of gearbox, motors, escs etc... I'm going to try and tackle this with a new motor/esc. This outlaw is the only 'proper' RC car I have so I haven't got other bits and pieces to try and make shafts and stuff up if trying to fit a mauler gearbox in, although it looks like it would go in there OK.

 

Put a bit of a ratio chart together to look at the different options. My outlaw with the 3421kv motor is theoretically capable of 37.8mph. I never get anywhere near this as just haven't got the space. If I fitted a mauler transmission, that drops to 8.4mph. That sounds a bit boring 😛

 

So... I've now bought a sensored 21.5T / 2100kv motor and a 120A sensored ESC. I didn't really want to sink too much money into it, but hey ho. I'm thinking I will end up with a spare matched ESC+motor that might be good for something else in the future. I'm hoping that the drop in speed + increase in torque of 30% coupled with a sensored motor should make this thing do the business. If it does, I could look at gearing it back up with a 23T pinion. Will see how it goes first though. 

 

Got two new front shocks, a new rear CVD (still plastic) and 2 difflock blocks coming for it to fit too. Bloody thing will think it's Christmas!

 

[tomr]

I’ve ordered a 2600kv 3660 (550 sized) motor to try with 60a esc 

Edited August 23, 2020 by tomr

[Cuiken]

The Absima setup in the OPs truck is the same as that in the Absima AMT3.4 (no huge surprise there). The cogging on the AMT makes it unusable on 2S and still problematic even on 3S. I swapped to a Hobbywing MAX10 which made a small difference but I think it's more likely the motor/gearing at fault. It has plenty of speed flat out but can't get going from standstill. Smaller pinion would probably help but then the extra torque might just mash the rest of the drive train.

 

I'm not sure you can say it's cheap electronics, I think it's more a badly conceived drivetrain with inappropriate gearing for the size of wheels and weight of truck. Basically, it's the downside of the platform based approach to truck design. If the chassis/drivetrain is shared with a buggy, it's probably going to struggle with a heavier, big wheeled truck.

 

Anyway, I'm back off to browse the Arrma website....

[Stormbringer]

8 hours ago, Cuiken said:

The Absima setup in the OPs truck is the same as that in the Absima AMT3.4 (no huge surprise there). The cogging on the AMT makes it unusable on 2S and still problematic even on 3S. I swapped to a Hobbywing MAX10 which made a small difference but I think it's more likely the motor/gearing at fault. It has plenty of speed flat out but can't get going from standstill. Smaller pinion would probably help but then the extra torque might just mash the rest of the drive train.

 

I'm not sure you can say it's cheap electronics, I think it's more a badly conceived drivetrain with inappropriate gearing for the size of wheels and weight of truck. Basically, it's the downside of the platform based approach to truck design. If the chassis/drivetrain is shared with a buggy, it's probably going to struggle with a heavier, big wheeled truck.

 

Anyway, I'm back off to browse the Arrma website....

Prob better looking at the Team Corally website 🍻

[tomr]

Happy to say no clogging at all with this cheap 3660 2600kv  and it has a 3.2mm shaft 👍

 

 

Edited August 27, 2020 by tomr

[Cuiken]

Nice, where'd you get the motor?

[tomr]

11 hours ago, Cuiken said:

Nice, where'd you get the motor?

Got from eBay 👍 https://www.ebay.co.uk/itm/Sensorless-Brushless-Waterproof-Motor-3660-2600-3300KV-For-RC-1-8-RCCar/154023765520?hash=item23dc882610:g:bssAAOSwKeBfHqbJ

Edited August 28, 2020 by tomr

[Eclipsed4ever]

What electronics are you running Tomr? That would of been an ideal motor if I had found that  

 

 

I got round to fitting my new ESC and motor on the weekend. Running a non-waterproof Surpass Hobby Rocket V3 540 21.5T now with Hobbyking® X-Car 120A Brushless Car ESC - no cogging at all... it's lovely and smooth with plenty of torque from the get go now.  So much nicer to drive. Although - it's perhaps a little slow 🙊 Going to try a 23T pinion in her next and see if I can get a nice balance.

[tomr]

26 minutes ago, Eclipsed4ever said:

What electronics are you running Tomr? That would of been an ideal motor if I had found that  

 

 

I got round to fitting my new ESC and motor on the weekend. Running a non-waterproof Surpass Hobby Rocket V3 540 21.5T now with Hobbyking® X-Car 120A Brushless Car ESC - no cogging at all... it's lovely and smooth with plenty of torque from the get go now.  So much nicer to drive. Although - it's perhaps a little slow 🙊 Going to try a 23T pinion in her next and see if I can get a nice balance.

just a cheap Hobbywing 60a esc with a 17t pinion 👍

it runs great .

 

 

 

[Redback]

Looking good, 550 can is for sure the way to go, is this on 3s or 2s?

[tomr]

On 09/09/2020 at 15:04, Redback said:

Looking good, 550 can is for sure the way to go, is this on 3s or 2s?

Sorry a bit late but 2s 👍

[Redback]

Got another outlaw so thought id try a new esc and motor combo, after seeing people run 120amp i went for that and a beafy longer motor a 560 can  with 3mm shaft.
Stock gearbox and gearing.
Hobbywing max 10 stc 120amp, with a Hobbywing 3656 4700kv on 2s lipo.
Doesnt clog but can hear it trying too, maybe to much power, very hot motor :(
Why would the motor be stressed on 2s i planned on putting 4s into it later. Nothing is binding on the rig, everything is buttery smooth.

I put the max10 60amp with 3652 3300kv motor back in on 2s lipo, and it is pretty much perfect. Will have to see how it runs on 5.8inch tires, later on.
 

The 3656 motor and esc is now sitting in the modified crawler outlaw and gives lots more speed and power with no motoroverheat. So win for the kid i guess :D

[Lone-wolf]

My thoughts on the outlaw, having got the wife one just 18 months back, its just not right, the main issue is not being able to put a smaller pinion on it also the body shell is so weak at the front, shame as the car could of been great, her car is brushed and has now had around 6 or 7 motors, 3 4 esc`s and 2 shells, next time ig breaks i dont see me fixing it, we call her car "Dirty fairy" and i am looking at "Dirty fairy II" for her, got a few idea`s in mind but she seems to prefer the buggy type car