# Suitable replacements for a 100RPM 37mm Motor?
**URL:** https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141
**Category:** Questions & Help
**Tags:** electronics, beetleweight-1-5kg
**Created:** [9 August 2023 15:41 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141 "2023-08-09T15:41:16Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Ioan](https://forum.bristolbotbuilders.com/u/Ioan)
#### Post date: [9 August 2023 15:41 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/1 "2023-08-09T15:41:17Z")
I basically want a lighter replacement for the fat 200g 12v 37mm 100 RPM motor and was wondering if anyone knows or has experience with a different motor and gearbox with torque values that match or are similar to this one?
As a side note, I was also wondering if anyone has ran a 12v 37mm motor reliably on 4s? I’m aware you can get a bit of leeway by over volting motors a little but I obviously don’t want one dying every match.
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### Author:  [@Hoppin](https://forum.bristolbotbuilders.com/u/Hoppin)
#### Post date: [9 August 2023 18:59 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/2 "2023-08-09T18:59:28Z")
Sup boss, used to run one on OG ares. Motor itself was fine on 4S. I know Toucan also uses one for it’s entire grab & lift system. So they do the business!
Ares now runs a Banebots P61S gearbox with a Leopard LBH3650-32T 1185KV. The motor itself is a bit shite, I’m looking at moving to something else, the setup is pretty solid, but at the cost of being like 370g.
Hope this helps!
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### Author:  [@Strang\_H](https://forum.bristolbotbuilders.com/u/Strang_H)
#### Post date: [9 August 2023 20:10 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/3 "2023-08-09T20:10:13Z")
Hop has talked a bit about bwushless gearboxes so I’ll go on and say that you can go for something like a 24mm 100:1 gearbox with a 2836 outrunner on it for around 150g of weight (please check yourself before you rush to buy) - I ran a 28mm 100:1 with an Overlander 2836 outrunner mounted on the first iteration of my BW Bonbonbonbon, and it lifted with more torque at a higher speed than a 37mm 50:1 that I had ran previously, for exactly the same weight - pictured here:
As for 4S on a 37, it should take it fairly well. I know there are people in the scene who have run those specs, but I’ve not personally so I would take my advice on that with a pinch of salt.
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### Author:  [@T\_Y](https://forum.bristolbotbuilders.com/u/T_Y)
#### Post date: [9 August 2023 22:56 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/4 "2023-08-09T22:56:30Z")
I also had this problem when designing Déjà Two, because I can’t spare the weight for a 37mm motor for the weapon. My solution was this brushed motor: [34 RPM Econ Gear Motor](https://www.active-robots.com/brands/34-rpm-econ-gear-motor-638344.html)
34 RPM 24mm (if I recall correctly) brushed motor, rated for ~110kgf-cm stall at 12V. I run it on 4S with an additional reduction of 1:2 with some hardened steel gears, and this works quite well for a grab-and-lift. I did however lose the gearbox on one at Rapture (having used the same motor in 12 previous fights), so may not be as robust as other options. It only weighs ~100g though!
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### Author:  [@Ioan](https://forum.bristolbotbuilders.com/u/Ioan)
#### Post date: [10 August 2023 16:27 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/5 "2023-08-10T16:27:34Z")
Cheers guys for the help. Good to know I can use the 37mm on 4s if I don’t find a replacement.
Sadly those Econ motors don’t look like they have good rpm for the torque values I’m after. Cheers for the suggestion though.
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### Author:  [@Jack](https://forum.bristolbotbuilders.com/u/Jack)
#### Post date: [14 August 2023 06:09 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/6 "2023-08-14T06:09:13Z")
Yeah 37s are perfectly happy on 4S in my experience. I ran the same pololu one on Luchador MK1.5, MK2 and the earlier iterations of MK3.
Probably 25 fights or so total, about two thirds of those at 4S at a guess.
A 37mm replacement is a tough nut to crack. Their combination of robustness and torque are hard to match in lighter packages.
For Luchador I ended up going with an absurdly powerful and utterly insanely expensive 4S 93kgcm servo. But that brings its own compromises - limited range of motion and extremely high potential cost of replacements should it die.
Probably a more sensible option would be mating a mid sized brushless motor to a high reduction gearbox like strang has on lifter Bonbonbonbon. Although weight savings there are minimal - as such high reduction gearboxes tend to be heavy anyway.
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### Author:  [@Ioan](https://forum.bristolbotbuilders.com/u/Ioan)
#### Post date: [21 August 2023 19:53 UTC](https://forum.bristolbotbuilders.com/t/suitable-replacements-for-a-100rpm-37mm-motor/141/7 "2023-08-21T19:53:56Z")
I reckon I’ll probably stick with the 37 on 4s if there isn’t a much lighter alternative. Cheers for the suggestion though.