Question on motors and genereal initial upgrades

[sleepy floyd]

Can someone help me understand the KV rating on motors? I see that the Roc412 motor is offered with kV ratings from 1200 to 3100, how should you decided which is right? Also, if you upgrade to a motor like this from stock, is there anything else that definitely needs to be upgraded at the same time to insure that the motor doesn't overheat?

Lastly --- just ordered the new Axial RR10...plan on playing around with it stock for a while, but would like to go down the upgrade path fairly quickly. Any recommendations as to what things should be tackled first? I realize it's a new truck so upgrades will be limited initially, but want to know what I should be keeping my eyes on.

Much appreciated.

[Johnnysplits]

Kv = rpm per volt.
High Kv = high speed/less torque. Low Kv = high torque/less speed.

[Johnnysplits]

Originally Posted by sleepy floyd

if you upgrade to a motor like this from stock, is there anything else that definitely needs to be upgraded at the same time to insure that the motor doesn't overheat?

That's all in your gearing. Motors will overheat from being over geared. That's something that you have to find out on your own. Start with a base and then fine tune from there.

[sleepy floyd]

Originally Posted by Johnnysplits

Kv = rpm per volt.
High Kv = high speed/less torque. Low Kv = high torque/less speed.

Got it, makes sense. Do most folks choose something in the middle I'm guessing, like 2300 kV?

[Johnnysplits]

Originally Posted by sleepy floyd

Got it, makes sense. Do most folks choose something in the middle I'm guessing, like 2300 kV?

Depends on the voltage you're planning on running. The majority including myself, 3s is the sweet spot for voltage. I think 2300 would be great with a 3s.

[Johnnysplits]

Now if I'm not mistaken, the drag brake hold on brushless motors isn't anywhere near the hold of a brushed motor.

[new2rocks]

Originally Posted by Johnnysplits

Now if I'm not mistaken, the drag brake hold on brushless motors isn't anywhere near the hold of a brushed motor.

That's also all in the settings. I can set a brushless motor to lift up the entire back end of a Wraith as soon as I release the throttle at brisk walking pace, which is more than enough drag brake, lol.

As far as motor/voltage/gearing, it really depends on how you plan to run it. I run my Wraith (same axles as RR10 but different chassis and tranny) on 3S with a 56/10 ratio. I used to run the ROC 412 3100 and just switched to an HH Puller Pro 3500. Both motors are beasts, offering excellent low-speed control and way more top end than a solid axle, locked diff rig can really use. On an RR10 (which I'll probably build once they have a kit), I would probably still go 3S but might consider a lower kv motor paired with a 2-speed.

Going with that kind of power is lots of fun, but you'll need to beef things up almost as soon as you do it. Stock ring/pinion, lockers and links, are all likely to fail pretty quickly, and stock knuckles/chubs would also benefit from upgrades. So those would be immediate candidates (and will help performance in other ways). You're probably also going to want to upgrade your servo, which will have both performance and durability benefits.

Bottom line: sensored brushless is a blast, but be prepared for a longer rather than shorter list of upgrades. If you're relatively new to this, it might be worth holding off on the power upgrades for a bit to see what exactly is failing on this platform when other people try it.

Enjoy!


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[HahnsB2]

Originally Posted by Johnnysplits

Now if I'm not mistaken, the drag brake hold on brushless motors isn't anywhere near the hold of a brushed motor.

Not in my experience, my Wraith will end up on it's roof if I let off at top speed with high traction at only about half of the maximum drag brake value you can use. Brushless motors DO freewheel faster downhill (any time you give it throttle in the downhill direction), which takes some getting used to.


I really like the 3000-3500kv range. First thing you'll probably destroy is the plastic idler gear in the tranny, next will probably be driveshafts.

[Johnnysplits]

Originally Posted by HahnsB2

Brushless motors DO freewheel faster downhill (any time you give it throttle in the downhill direction), which takes some getting used to

That's why I'm not digging the bl motors yet.

[new2rocks]

Originally Posted by Johnnysplits

That's why I'm not digging the bl motors yet.

"Yet..." Famous last words...


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[sleepy floyd]

Thanks guys, this is all very helpful. I have a number of 2s batteries, as we have a couple of short course trucks that are plenty fast with 2s. Really hoping to stay with the single speed tranny, guess I'll see what I think after playing around with it.

[Helicrawler]

Timely thread - I'm just about to buy a ROC 412 for my wraith and have been debating the kv options too.

I've read lots, but most of the discussion seems to be about running 3S or more. I'd like to stick with 2S, and am wondering how the ROC 412 3100 would perform with the lower voltage. I know top speed will be less, but how about crawling performance? Is there any disadvantage on the low end to running 2S? Would it still crawl okay in a Wraith running 56/12 gearing or thereabouts?

(Sorry for the thread jack, but seems like we're looking for similar info.)

[new2rocks]

I wouldn't recommend a 3100 on 2S in a Wraith. In a lighter rig, or one running 1.9s, you'd be fine on 2S. But the Wraith's combination of weight and 2.2s (esp. if you're running 5.5" or taller tires) can create heat issues even at 56/12 gearing without any benefit in low-end control. And you'll get longer battery life out of the 3S. If you don't want that much top end, you'd be better off with a lower kv motor like the 2300 on 3s keeping shorter gearing (9-11T with 56T spur).

Also, if you're planning to buy new, check out the new HH Puller Pros. I swapped out my ROC 412 3100 for a Puller Pro 3500 in my Wraith, and I find the low end noticeably smoother. They make a 2200 version in the full size and stubby (I'd recommend the full size for a Wraith), and they are available waterproofed out of the box.

[Helicrawler]

Okay, thanks. I was hoping to avoid buying a new battery (3S), but it seems like that is just the best way to do it.

Currently running a cheap 27T on 2S and just wanted a bit more speed, but nothing crazy. I'm pretty sure a 3100 on 3S is way more than I'm looking for. Sounds like something around 22-2300 on 3S would probably be best for what I want (mostly trailing and crawling, with a bit of speed to play around on the flat/boring walk in.)

But it's getting a little pricey with the new battery, motor and brushless ESC, so might go back to my Plan A, which was a Crawlmaster 13T on 3S. Sounds like a great all-round option, but I was hoping to avoid the maintenance with brushed.

[HahnsB2]

Originally Posted by Helicrawler

Okay, thanks. I was hoping to avoid buying a new battery (3S), but it seems like that is just the best way to do it.

Currently running a cheap 27T on 2S and just wanted a bit more speed, but nothing crazy. I'm pretty sure a 3100 on 3S is way more than I'm looking for. Sounds like something around 22-2300 on 3S would probably be best for what I want (mostly trailing and crawling, with a bit of speed to play around on the flat/boring walk in.)

But it's getting a little pricey with the new battery, motor and brushless ESC, so might go back to my Plan A, which was a Crawlmaster 13T on 3S. Sounds like a great all-round option, but I was hoping to avoid the maintenance with brushed.

You save 10% when you do an ESC/motor combo with Holmes

IMO the Trailmaster Pro 3300kv is also a fantastic motor, nearly as smooth down low as the puller and noticeably cheaper as well.

[winnerone23]

New2rocks..
What's the heat issue with 3100kv and 2s? (Seriously asking)
I have never ran 2s on Anything.. Well, my TX runs on 2s. Lol..

I run 3s on brushed rigs and 4s on BL.. (Except the HH 16t Crawlmaster Pro that was in my scx for a year, that got 4s as well)

Is 9-11t pinions, Taller gearing? I thought that was lower gearing.. Lol..

Gearing, kv, and battery Don't make the speed your rig goes.. They only make what your top speed is! ;)

My Sexo/wraith drive train, runs a 3100kv Trailmaster BL, 54/13 gearing on 4s.. With a top speed of 30mph.. With RB2's..

My throttle finger decides the speed it goes and when it goes that speed..

I can slow crawl or hit the track!

It's WAY over geared and gets So Hot, that I won't even touch the bottom of my skid! (After long periods of running and abuse)

This is one of the original Trailmaster motor's too..

My C2 scx runs a 3500kv HH Trailmaster Pro (the new black ones)..
It's a Killer motor!
Low end to top end, it's smooth and full of torque!

It's a hard to beat setup, for the price and customer service of HH.

For a scaler, I like the 16t Crawlmaster Pro. More options for gearing and a longer lasting motor.

[new2rocks]

Thanks for catching me on "taller" - higher spur/pinion (which is what I was getting after) is actually shorter gearing.

As far as the potential heat issue, I smoked a ROC 412 on 3S in my Wraith when I switched from XORs to RB 2s at 56:11. It took all of 5 mins to overheat when I never had anything close to a heat issue with the XORs, which are shorter than the RB 2s. I ended up at 56:9 or 10 with the RB 2s and have been fine since in that rig. Although I've never tried 2S in the Wraith, I'm surmising that dropping to 2S could create enough added strain on the motor (esp. with taller tires) to trigger heat issues. By comparison, I ran a ROC 412 3100 on 2S with 4.5-5:1 gearing in a much lighter 2.2, as well as in a couple of 1.9s, with no heat issues at all.

And for the record, I completely agree with you about top end. I don't mind at all having quite a bit more than I'd ever need or regularly use. A good motor plus expo throttle curve plus judicious throttle finger provides all the low-speed control I could ever ask for, and the top end is there for a laugh whenever I want one.

[winnerone23]

I ran Tekin motor's and esc's from the beginning.. Way happier with them then castle..

Problem was, I couldn't keep a Tekin rotor together.. :/ And they are ROAR approved.. But I guess none are made for 4s.. Lol..

The difference between the HH and Tekin are: HH has No Rules! No one above him, to Approve.. Just US!
To my knowledge and my experience, no one disapproves! If there happens to be a "issue", HH customer service fixes it!
And that makes US All happy!

But in the Years of me abusing the Trailmaster, I haven't done anything but put power to it!

In the last year of having the Trailmaster Pro, I have only conformal coated the sensor board..

Still crawls Smooottthhhhh!!!!

I Love having more then "needed".. ;)

It's always fun to watch the look on faces, when your scx takes off like a rocket to 20mph, handles like a SCT, and slow crawls like a comp rig with a Crawlmaster Pro in it!

[Helicrawler]

Lots to think about here. Thanks, everyone!

Would like to go with Holmes Hobbies, but being in Canada makes it a little more complicated. Some decent local sale prices on Tekin and Castle Creations stuff now, so am inclined to go that way.

Will have to crunch the numbers, but maybe ROC 412 3100 kV, Castle MMP and a 3S battery is the way to go. I never considered that I didn't need to use all the speed if I didn't want to, lol! But now that I think about it, can't hurt to have a little extra - I'm sure I'll get to like it.

[Postclanker]

I only own Holmes....
Then again some call me sick in the head... Tried them all...

except a Brood
I hear they're pretty similar