High Turn Motor & Long Gearing vs Low Turn Motor & Short Gearing.

[Hardcoretam]

I always wondered what's best from the above with crawlers.

Lets say for example you had 2 indentical trucks and both on 2s lipo

One had a 55t motor and gearing that enabled it to do 7 mph
The other had a 27t motor of identical quality and it was also geared to do 7mph

What would be best for crawling and why?

I noticed on my last outing with my club there were two users on SCX10's both with 550 sized 35t motors, both on 2s and both had kinda longish gearing (57/13 on 2.2s and 57/18 on 1.9's both 32dp)
Both these rigs smoked their motors after a very long muddy hill climb

I've been thinking is it best to stick with standard(ish) gearing and find a motor that suits the speed, or gear as low as possibly then find a motor that suits the speed and that way you get use a lower turn motor with a bit more power

I done the same climb in my heavier rig with a 21t motor on 3s and my motor was hot but not excessively. I was geared 13/87 on 48dp.

[EddieO]

The question above doesn't make a ton of sense....if you are gearing two motors that far apart in turns, with everything else the same....one is either overgeared or one is undergeared...the only way you are getting the same top speed from two motors like that is by incorrect gearing....but to answer your question, which ever one is geared correctly and doesn't blow up is gonna work better than the other.

You gear motors for heat first....then speed within the heat limits. Too many people don't understand how gearing works with brushed motors.

The 550s sounds pretty high...probably why they smoked...you had yours geared over a 6:1, though it was a 21t....they had theirs at 4:1 and 3:1 (appx numbers).....even for a 35t 550, probably on the high side.

The safe way to gear a motor, find a comparison for your rig and motor selection....and start there, maybe even drop a tooth or two to be safe....run it a bit and check heat...if still safe (under 150)....keep running and checking. If the motor stays well below 150....you may be able to gear up a bit, go a tooth at time, repeat process. If motor gets too hot (especially fast), stop and gear back down to the last safe gearing.

Unlike racing, its tough for us motor guys to give concrete gearing info.....there are simply too many variables (weight, tire size, battery, driving style, etc) for us to really know what will not blow up the motor, so we tend to go on the safe side.

Later EddieO

[Hardcoretam]

Thanks Eddie.

I guess the confusion was when ever i tell people i'm running a 21t cheapo 540 in my SCX10 they look at me weird and say i'm silly it won't have enough torque and will burn up etc, (it's fine for what i do) but some of them just change to things like a 55t motor but keep the standard gearing then get confused when motors start to burn or look confused when i'm going able to go faster and slower than them with my set up.
Don't get me wrong, if i was doing serious rock crawling and it was a hot day i'd swap to a 35t motor instead but just seems common for people to select a motor that suits their speed without looking at the gearing sometimes.

[spoo76]

Volt up & gear down lol.

On a somewhat similar note..
Assuming everything else is the same would there be any difference in going for a smaller pinion vs bigger spur? I know they achieve the same thing, but let's say on a stock rig if you went down 2 teeth on the pinion is there any difference between that and going up 2 teeth on the spur?

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[MattySlimz1987]

I was just going to mention Mr.Holmes "Volt up, Gear down!" Quote.. beat me too it. Lol
I too am wondering what spoo76 mentioned about going down a couple teeth on the pinion only and just leaving a stock spur.. can anything be achieved by that?

[spoo76]

Well a smaller pinion has the same effect as a bigger spur as far as gearing, I was just wondering if there were any differences between changing one or the other

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[mikemcE]

Ratio is ratio.
Only reason is physical fitment..... some only allow a max / minor size pinion


Hang up and Drive

[EeePee]

Yeah, numbers are numbers. A spur has many more teeth so it's a finer adjustment than a pinion gear.

[Smokin' Joe]

Originally Posted by spoo76

Volt up & gear down lol.

On a somewhat similar note..
Assuming everything else is the same would there be any difference in going for a smaller pinion vs bigger spur? I know they achieve the same thing, but let's say on a stock rig if you went down 2 teeth on the pinion is there any difference between that and going up 2 teeth on the spur?

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The ratio is what matters. Going up 2 teeth on a spur would have a much smaller impact than going down 2 teeth on the pinion.

[durok]

1 tooth on the pinion equals approximately 4 teeth on the spur with a 32pitch gearing setup. So, 11/60 is about the same as 12/64 and 13/68.

[Hardcoretam]

So the last 15 miles or so of mixed trailing i've been using 1.9's with 108mm tyres, 3s lipo and a 21t cheapo GoolRC 540 motor.
Gearing is 13/87

Seems quite well set up for trailing. Enough punch to throw it up difficult stuff and geared low enough to crawl. The only issue i've found is the RTR radio makes driving with a 21t on 3s very twitchy. Battery life and heat are good as well.

I've always read that the higher turn motors generally have more torque. I've an unused Integy 65t from years ago i popped in tonight. Same gearing but with 114mm tyres on the 1.9's. Also on 3s lipo.

With the very low gearing i've virtually no punch if i gun it (not enough to lift a wheel anyhows) but wheel speed is borderline alright.
I tested the torque out of the motor by trying inclines and some obstacles but tbh i found it a little dissapointing. Overall i'm having to squeeze the trigger perhaps the same, if not a little more with the 65t to overcome any stalling at low speeds where as the 21t felt more torquey as it didn't stall as much on the same throttle input.

What i have found i like though is with the RTR radio having the 65t makes it far less twitchy and the low speed resolution control is pretty good in comparison. So i feel this would be better for more scale driving or if you were on tricky sections of rocks all day

[SkiSteve]

I'm old and until recently have never had anything but brushed motors. I've had all sorts over the years from 30 turn stock sealed can to 12 turn modified with a ton of timing. I've had single winds, doubles and triples in an array of different vehicles running different voltages. I've had them in boats direct drive too.

I wouldnt gear a brushed motor with a target speed in mind, lots of winds does not necessarily mean long gearing. Gear them to rev freely under the loads they experience in use. A lower turn motor in general is a more powerful motor and will rev higher so needs to be geared down to rev freely. If you don't have the speed you want, go for less turns and make sure it is geared to rev. Essentially brushed motors should all run short gearing and more speed comes from less turns

As others have said heat is a good guide, but sometimes damage is done during heating so get a feel for what a happy brushed motor revs like in use. Brushless sounds different to me, you can hear the extra gearing they can push.