Ascender/SCX10 to Bomber???

[Stray]

I went the ssd 2 speed. Not really needed, but my misses got me a dx5r Pro, so I figured I needed to load it up haha. It's also awesome. Quite a big difference between high and low

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[2mtech]

Stock kit gearing is high.

I personally did not enjoy having a 2-speed (in another rig). Another servo, more moving parts, more to break/fail...meh. RC3WD cured me of that unless I get a semi.

If you're going brushed you may appreciate the 2-speed more. I can crawl slow enough to count the sipes on the Hyraxes as they hit the rock; lower gear would be useless to me. YMMV.

 

[TheLetterJ]

Remember that turn counts are not the same when comparing speeds of 540 and 550 motors. As a rough comparison a 21t 550 = 27t 540, and 27t 550 = 35t 540. That being said, the 550 also produces more torque for a given speed (it is a bigger motor afterall) so you can get away with a little faster motor when going 550, hence my 21t on 3s suggestion.

I run a 27t 550 (in 3 cars) and it's great for crawling, but it doesn't exactly haul but.

 

[durok]

What is a good motor speed with the 2-speed transmission to give a good low crawling speed?
I see Axial has a variety of brushed and brushless options - 2900Kv seems like a common option. Or 21 or 27T brushed.

Holmes has the castle esc with his 540 'revolver' motor? 1800kv? Sensorless though - for crawling I would think sensored, no?

The Holmes Hobbies Revolver is the exception to the rule that sensored always beats out sensorless for slow-startup and low-speed control...

One of the main reasons is that it is an outrunner design, where the exterior of the motor spins rather than the in-runners we're used to seeing.

Very torquey for its size, and responds extremely well to the more modern ESCs such as the Mamba X and Sidewinder SW4.

Go watch John Rob Holmes' YouTube channel where he compares them to a couple other brushless designs in 3 identically set-up TRX-4 Defenders - it's a true eye-opener.

 

[Browneye]

You guys have this stuff dialed. ;-)

 

[durok]

Revolver installed - early build process pic (the silver metal plate on top of the cut-down shift servo mount is my ESC mounting plate) - the section of the can with the lettering and the cap on the end of the motor with the "bullet chambers" - that is the part that rotates when you feed 'er some go-juice:

 

[Jim85IROC]

2 speed trans is unnecessary with a good brushless setup. My 2850kv brushless has all the low speed control I need and goes too fast for anything other than big open spaces. There's absolutely nothing that I could gain from a 2 speed.

 

[WHITE-TRASH]

2 speed trans is unnecessary with a good brushless setup. My 2850kv brushless has all the low speed control I need and goes too fast for anything other than big open spaces. There's absolutely nothing that I could gain from a 2 speed.

I've built bombers with stock single speed trans, stock trans with 2 speed, wraith trans, ssd high ratio wraith trans, scx trans and rc4wd ax2 2 speed. For general use 2 speed wins every single time.


The 2 speed allows for a higher kv motor to be used allowing for decent crawling performance and high speed bashing. The ax2 has a roughly 5:1 low and 1.78:1 high so it splits on both sides of and standard single speed out thwre.

 

[Browneye]

$150 or so for a revolver and SW4. Not bad. They’re that good huh?
Are John’s servo cases plastic or alloy? Or does it matter? Plenty of options for 400oz servos.

I dont need mine to go that fast - I’m old. LOL

 

[2mtech]

Word of caution before you pull the trigger on a Revolver...watch some videos. They have a very unique sci-fi sound that I think sounds really cool, but has been known to drive some to insanity.....

 

[FnFancy]

Word of caution before you pull the trigger on a Revolver...watch some videos. They have a very unique sci-fi sound that I think sounds really cool, but has been known to drive some to insanity.....

It is quite star wars ish! I love mine though, the sound was part of the reason I went with it! Side note, if you get the Holmes hobbies esc, you can change the frequency and tone down the noise some.

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[Exiwolfman]

Word of caution before you pull the trigger on a Revolver...watch some videos. They have a very unique sci-fi sound that I think sounds really cool, but has been known to drive some to insanity.....

I just watched a video, I would be driven to insanity from that sound....my ears are still hurting.
Cool motor but....that sound [emoji344]

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[durok]

Watching videos is not an accurate representation of what they actually sound like in person.

Audio recordings from your typical smartphone or GoPro type digital camera are not accurate - the high frequency noise of both brushed and brushless electric motors is exaggerated by the poor-quality microphones.

I've noticed this in practically every R/C video I've ever seen other than those from the manufacturers, who tend to be using more expensive high quality gear and better production values.

Likewise the electronic tones from speed controls and servos...

The sound of the Revolver is not hard to get used to, and smooths out considerably with increased RPMs.

Mine doesn't bother me at all!

BTW - Holmes servos use all-aluminum housings.

My SHV500 v1 is still taking on all comers...

 

[Jim85IROC]

I've built bombers with stock single speed trans, stock trans with 2 speed, wraith trans, ssd high ratio wraith trans, scx trans and rc4wd ax2 2 speed. For general use 2 speed wins every single time.


The 2 speed allows for a higher kv motor to be used allowing for decent crawling performance and high speed bashing. The ax2 has a roughly 5:1 low and 1.78:1 high so it splits on both sides of and standard single speed out thwre.

If my Bomber goes as slow and as fast as I need, I don't care what KV the motor is. My Bomber already goes faster than the solid axle suspension can deal with, and crawls as slowly as I could ever need.

I could also just go to a higher KV motor to get more speed and maintain the same low speed capability too. There's nothing that the 2 speed can accomplish that can't be done with a well chosen and well geared brushless motor.

With a brushed motor an argument for the 2 speed can be made.

 

[DukeMinnix]

$150 or so for a revolver and SW4. Not bad. They’re that good huh?
Are John’s servo cases plastic or alloy? Or does it matter? Plenty of options for 400oz servos.

I dont need mine to go that fast - I’m old. LOL

Its not so much the case thats the issue, its the end cap/ mounting ears. and yes, holmes are alloy, as are several of the savox, pro mods, among others. Id assume you could get by with plastic end caps if you sandwiched them with the VP alloy mount and clamps, but I haven't tested that theory extensively.

 

[WHITE-TRASH]

If my Bomber goes as slow and as fast as I need, I don't care what KV the motor is. My Bomber already goes faster than the solid axle suspension can deal with, and crawls as slowly as I could ever need.

I could also just go to a higher KV motor to get more speed and maintain the same low speed capability too. There's nothing that the 2 speed can accomplish that can't be done with a well chosen and well geared brushless motor.

With a brushed motor an argument for the 2 speed can be made.

No, just no. A higher kv motor begins to lose the smooth startup as you get above 3000 so low end gets sacrificed at the expense of top end unless you're running 2s and then you aren't going fast. A 2 speed drops the gearing for low speed crawling and raises the gearing for high speed action.


If you get everything you want or can handle with a single speed trans then that's fine but some people want and expect more so a 2 speed is called for.

 

[Jim85IROC]

No, just no. A higher kv motor begins to lose the smooth startup as you get above 3000 so low end gets sacrificed at the expense of top end unless you're running 2s and then you aren't going fast. A 2 speed drops the gearing for low speed crawling and raises the gearing for high speed action.


If you get everything you want or can handle with a single speed trans then that's fine but some people want and expect more so a 2 speed is called for.

That's not consistent with my experiences. In most cases a higher KV motor has identical startup to a lower KV motor, so you don't lose any startup capabilities with higher KV. You may need to tweak the throttle curve in the ESC a bit to retain your ability to control it, but the physical startup properties of the motor shouldn't change.

Jon Holmes has made similar comments:

Different KV doesn't affect the minimum startup speed, but higher kv motors pack more Rpms into your throttle and make it more sensitive.

I'll frequently use a higher KV motor that's geared down instead of gearing up a lower KV motor to get better low speed startup.

 

[Browneye]

Ya, found a youtube vid on brushless with a HH revolver and that sound is awful. Enough to put me off one. I'll look for some more. My inclination is to go sensored brushless if I can find something that isn't too costly - the Castle mamba X with a slate motor is over $200 - ouch. Almost as much as the whole kit - in fact with a servo it is as much as the kit. Ridiculous, since the RTR was only $20 more than the kit. Ouch again.

I also found the Savox 1268 that specs at 3ah at stall which would work with a 1080 bec, and 377oz/in at 7.4v. Seems like a match made in heaven, but appears to be a plastic cap/case. Not cheap either, but then a BEC and a HH V500 is almost twice the cost. I could try out a 550 brushed in 21T for as a pretty cheap date to get started. Gear it appropriately without the 2speed - and those aren't cheap either, would opt for a brushless before I spent another $100 for an updated trans. I really don't need or want a 30mph rig. [shrug]

EDIT: SSD 2-spd kit at RPP for $65.
EDIT2: Axial version at Amazon for $77

 

[WHITE-TRASH]

That's not consistent with my experiences. In most cases a higher KV motor has identical startup to a lower KV motor, so you don't lose any startup capabilities with higher KV. You may need to tweak the throttle curve in the ESC a bit to retain your ability to control it, but the physical startup properties of the motor shouldn't change.

Jon Holmes has made similar comments:


I'll frequently use a higher KV motor that's geared down instead of gearing up a lower KV motor to get better low speed startup.

Pay attention to the quote from Holmes. Minimum startup speed is a key phrase. Higher Kv isn't going to affect the minimum startup since that is mostly dependant on the strength of the magnetic field hence why my 3500xl doesn't have a nice low rpm startup like a 3500 puller or stubby with weaker magnets. With a 5:1 first it starts very acceptably but it quickly runs out of gearing, it is very comparable to an rtr brushed bomber. Shift into high and things get fun. Startup is terrible but the strong magnets on the rotor make the midrange and high rpm stupid on 4s.

Throttle sensitivity is another issue with higher kv. Yea you can dink around with the curve on the esc all day to make it similar to a lower kv but unless you're racing I don't see it being worth the time.


For a basher or trail rig a nice 3000 kv brushless on 3s is solid all around but if you want to boogie couple that motor with a 2 speed and 4s. :twisted:

 

[Browneye]

Pay attention to the quote from Holmes. Minimum startup speed is a key phrase. Higher Kv isn't going to affect the minimum startup since that is mostly dependant on the strength of the magnetic field hence why my 3500xl doesn't have a nice low rpm startup like a 3500 puller or stubby with weaker magnets. With a 5:1 first it starts very acceptably but it quickly runs out of gearing, it is very comparable to an rtr brushed bomber. Shift into high and things get fun. Startup is terrible but the strong magnets on the rotor make the midrange and high rpm stupid on 4s.

Throttle sensitivity is another issue with higher kv. Yea you can dink around with the curve on the esc all day to make it similar to a lower kv but unless you're racing I don't see it being worth the time.


For a basher or trail rig a nice 3000 kv brushless on 3s is solid all around but if you want to boogie couple that motor with a 2 speed and 4s. :twisted:

This makes sense to me.

So, which 3000kv setup???
I'm finally understanding the switchable drag brake thing - you don't want a drag brake for high speed- got it.


I'm coming from crawlers and actually intend my bomber to be a more capable crawler, rather than a racer. I started out in the hobby a year ago with a Arrma Typhon - on 4s it would go 40mph - I couldn't even see the thing, it was way too stupid fast. Got a crawler, SO MUCH more happy - sold the Typhon.


So I already know I don't need a 20+ mph rig. Smooth start and climbing is what I want, as long as I can see a little more wheel speed for trailing and goofing around. A 550 can brushed may well suffice, I just don't know. But it doesn't make sense to buy matching components only to find out I don't like any of them and then have to buy them all again to upgrade.

BTW, all of my crawlers run 35T brushed and I'm more than happy with them, either with stock gearing or 1 or 2 teeth up on a pinion for a little wheelspeed, all 3s - Ascender and SCX10. I'm not really a go-fast guy. 8)
They crawl just fantastically. My 35T's are a HH Trailmaster Sport, stock dynamite, Axial stock, and a Yeah Racing Hackmoto. I don't dislike any of them, they all seem the same to me - all are on HW 1080's except the new Axial - it still has the stock esc.