Clydesdale
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Looking for ideas on spur and pinion gear for my granite 4x4
Granite Pinion and spur gear
- Thread starter Clydesdale
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hattrick300
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Depends on the size of motor you are running. I am currently running a 23T Pinion and 91T Spur with a 4000Kv HobbyWing motor.
If you are running the stock motor, stay with the 14t/91t stock gearing. The motor barely has power to turn that gear, any higher, and it will just overheat quicker. If you are planning a brushless upgrade -
Pinion - the stock motor mount is a 'noob mount' - with paired holes for specific pinions. Makes getting the correct gear mesh easy (no adjustment) but limits your pinion choices (no adjustment). From the factory, your only choices are a 14t, 17t, or 27t. Several of us have simply cut between two of the holes (made a channel) so that we can mount any size pinion you want. Easy to do, but be sure and use a washer under the motor mount screw after you cut the mount.
Spur - If you want to stay with a Arrma drop in replacement, right now your only option is the stock 91t spur. In another month or so Arrma should be (hopefully) stocking the newer BLX4s spurs - M0.8/32p, 57t. (The stock 91t 48p is about equal to a 60t 32p). It will need the whole HD slipper to go with it.
If you like to mod, several of us have fitted 32p spur gears from the Axial Yeti. They are 32p, and available in several sized from 56t up to about 64t? Also metal gear options. A bit of custom work is required, but nothing hard. Here is a video I made on the conversion. Note - for the spur spacer, in this video, I used a strip of soda can as a spiral wound spacer, that did not last, I swapped to a spacer made from .018" SS plate(I think that is 24gauge?). Hopefully this will last longer.
Pinion - the stock motor mount is a 'noob mount' - with paired holes for specific pinions. Makes getting the correct gear mesh easy (no adjustment) but limits your pinion choices (no adjustment). From the factory, your only choices are a 14t, 17t, or 27t. Several of us have simply cut between two of the holes (made a channel) so that we can mount any size pinion you want. Easy to do, but be sure and use a washer under the motor mount screw after you cut the mount.
Spur - If you want to stay with a Arrma drop in replacement, right now your only option is the stock 91t spur. In another month or so Arrma should be (hopefully) stocking the newer BLX4s spurs - M0.8/32p, 57t. (The stock 91t 48p is about equal to a 60t 32p). It will need the whole HD slipper to go with it.
If you like to mod, several of us have fitted 32p spur gears from the Axial Yeti. They are 32p, and available in several sized from 56t up to about 64t? Also metal gear options. A bit of custom work is required, but nothing hard. Here is a video I made on the conversion. Note - for the spur spacer, in this video, I used a strip of soda can as a spiral wound spacer, that did not last, I swapped to a spacer made from .018" SS plate(I think that is 24gauge?). Hopefully this will last longer.
Thunderbird1983
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Ok I’m tired of burning up 91T plastic spur gears and only to go online and see Backorder -Backorder-Backorder apparently everybody is having a problem with these plastic spurs. Time to Cowboy Up and put some Metal spurs in my horse! So that being said if anyone has a shopping list for the Senton 4x4 please Pony it up so I can order parts and finally get this truck to the Moon! I’m tired of replacing spurs. Thanks I’m out.
Dcstyphon13
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I just got this for my granite and I'm about to drop it in. I didnt feel like doing the mod or new HD slipper. I wanted something to drop in instead of plastic to where I could just run again brushless.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/273593072227
That plus the 17t HD diff input should make the Mega pretty reliable for mild brushless systems.
chazekxt46
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any update's on this?
slick2500
Anything will break if you drive it wrong enough.
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Hot Racing makes awesome spur gears. If you get one I would highly suggest using Robinson Racing Hardened pinions other wise the Hot Racing spur will eat them up.
Dcstyphon13
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I have about 8 packs in no issues at all. It has been taking all that I can throw at it and not thinking twice about it.
chazekxt46
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did u get the hard pinon to ? thanks.
Dcstyphon13
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If I remember right when i went brushless i just bought the 17t arrma spur which I don't think is hardened, But I wanna switch to the 27t pinion for a bit more fun.
Just be careful, she's gonna get a little warm with a 27... And maybe cog a little.
chazekxt46
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ok thanks I will run the 17t
jonUF02
Active Member
What is the smallest spur available for Granite platform? Stock fitment, or what mods are possible? Looking to make a sort of Granite crawler with crawler motor and ESC for small child to play with.
There are not any other easy to fit spur gears. For crawling, you want a big spur, and I don't think you can fit anything bigger than the stock 91t spur on the Mega.
If you want to gear way down, one of the 3:1 or 4:1 gear reduction units will probably be the easiest way forward -
https://store.rc4wd.com/41-Ultra-Compact-Gear-Reduction-Unit-for-540-Motor_p_782.html
If you want to gear way down, one of the 3:1 or 4:1 gear reduction units will probably be the easiest way forward -
https://store.rc4wd.com/41-Ultra-Compact-Gear-Reduction-Unit-for-540-Motor_p_782.html
https://www.arrmaforum.com/threads/granite-blx-crawler-conversion.8700/
Here's an old thread on someone who was trying this. A few posts down @Jerry-rigged posted a link to a gear reduction unit. Check it out and keep us posted if you move forward with this.
Edit -
LOL, I couldn't get the screen to refresh while I was posting... Looks like you already covered the GRU.
jonUF02
Active Member
If TRX4 crawler is 45/11 stock, then the stock BLX 57 spur with 14t pinion is close to the same ratio. Stock Axial is 56/13, a slightly higher ratio. So stock BLX spur with 13 or 14t pinion would be a good start. I guess it depends on the diff ratios as well. Just trying to do the research before moving forward with this project. I know nothing about crawling, I just want it to go slow with some torque like a crawler.
If I start with the stock Granite Mega with 14t pinion, swap the BLX 57t spur and go from the stock 12T motor to something like a Holmes 21T motor, I think that will get pretty close to what I'm looking for.
The other route would be buy the BLX model, sell of motor and ESC, then get the crawler combo and a smaller pinion.
If I start with the stock Granite Mega with 14t pinion, swap the BLX 57t spur and go from the stock 12T motor to something like a Holmes 21T motor, I think that will get pretty close to what I'm looking for.
The other route would be buy the BLX model, sell of motor and ESC, then get the crawler combo and a smaller pinion.
Don't forget, if you are starting with a Mega, anything you do to increase torque will result in the diff input breaking. The HD17T input needs to be on your shopping list, or the full BLX diffs.
jonUF02
Active Member
Good info. Maybe a better idea to start with the BLX and "down-grade" the motor and ESC. At that point, the cost is more, tough decision whether to go this route for more of a monster truck, or just get a basic crawler.
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Just get a basic crawler. I don't think you will be able to get anywhere near the same articulation with the Granite suspension and chassis you could get with a actual crawler. If you want to crawl over stuff and go slow get a crawler. If you just want to slow things down to learn on then speed things up get a Granite.
