Granite Taking my Granite to 4s!

JJG6908

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I thought I made a post about this the other day but I can't find it. Maybe I forgot to hit 'Post Thread'... Wouldn't be the first time.

I've had my Granite for a couple months now and while it's perfectly capable and reasonably quick with the stock electronics; I wanted more! So a few weeks ago I decided to upgrade the basic brushed system to brush-less. At the time I had on hand a 60 amp, 2-3s Queen Hobby ESC and a GoolRC 3930kv motor. Nothing special I know but I was sure how it would go so I didn't spend a lot. motor and ESC was about $50. I got them from Amazon.
I removed the old parts, cleaned everything and installed the new ESC and motor. It's a very simple swap out. (TY ARRMA!) I then took it outside and let her rip and I was not disappointed! Not at all! On 3s the Granite is pretty nasty! I didn't have my Sky RC meter yet but I'm guessing it was running somewhere around 45 mph. It was fast! My only issue was with the stock pinion which didn't have enough torque to get the truck moving in taller grass or other rough terrain. SO it's all top end. I planned on changing the pinion to a 12 tooth for more off the line torque but I had an accident. While getting used to the 3s I lost it for a second and I hit the corner of the curb with my right front wheel at about 35 mph and the wheel just exploded. lol It looked like a NASCAR wreck. I went to the hobby shop and got replacements. A new Wheel because it blew out the hub, (I got 4 of the Chrome wheels! Upgrade!) I also broke a couple arms and a steering block. Not that big of a deal but the sudden stop caused the ESC to break loose from the hot glue holding it down (no mounting bracket) which I thought; "no biggie" until I went to test it after making the repairs and she wouldn't move. Somehow that crash caused my ESC to go up and also did damage to the motor. So I went back to the stock setup until I could start over.

This weekend I did just that. I removed everything, cleaned it, and installed a Hobbywing EZRUN Max10 SCT with a LD power 3800kv motor. I know for a fact the ESC works great because I put it in my Mojave when the ESC in that went up. It was only 4s but that's more than enough to make it haul ass so I didn't foresee any issues using it in the Granite.

I got the ESC and motor installed and tested on the work bench and it was looking good. I even had a 12 tooth pinion in there. But when I smash the throttle it sounds like stripped gears almost. Like it's spooling up but it doesn't put out. I mean it was fast, but I had to throttle up to that speed slowly and I only hit 38. Which I was handily beating with 3s. So I went back to the stock pinion and it seemed a little better but still not getting power to the wheels when I hammer the throttle. So I don't know if I have a bad motor or if I'm just missing something. First setup worked great until I wrecked! lol I have another Queen Hobby ESC and another 3930kv motor and I could go back to that setup but I wanted to see what this thing could do on 4s with some pinion changes.

Is it possible this motor could be too small for 4s? (3800kv) But that doesn't make sense to me either because I ran my MojaveGranite_4s_setup.jpg with that ESC and 4s and the motor on that mojave is a 20XXkv which is less than this motor and it ran great. Zero problems.

Any ideas/help before I go back to 3s is greatly appreciated. I'm getting ready to take out the 3800kv LD Power motor and swap it with a 3930 GoolRC that I KNOW works correctly. This little Granite should be able to hit some really high speeds with 4s. But 38, that ain't gonna cut it!
 

JJG6908

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Sounds like your slipper is loose 🤷🏻‍♂️
Brilliant! I never even thoughts of that. I'm really great at figuring electronics out but I haven't dug into the clutch yet. I'm a little Leary because I don't know what I'm doing with it if I mess with the clutch.
 

bicketybam

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Is this a covertes Mega? If so, did you upgrade the pinion/spur to 32p? Did you upgrade the input gears and diffs? I didn't see any mention of that. Also, 3800kv is too high for 4S. What size is that motor?
 

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Pretty sure the drivetrain of a Mega will explode on 4s. The 4s Arrma are 3200kv motor, yours sound a bit high on the KV. Gearing is also different on the Mega brushed.
 

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Pretty sure the drivetrain of a Mega will explode on 4s. The 4s Arrma are 3200kv motor, yours sound a bit high on the KV. Gearing is also different on the Mega brushed.
They are 2400kv. I think the 3s models are 3200kv. Either way I can all but guarantee that the motor he is using will melt on 4s along with his spur and input gears.
 

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My bad, I thought my 4s was 3200, that's a big difference to 2400 on the 4s.
 

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My bad, I thought my 4s was 3200, that's a big difference to 2400 on the 4s.
No worries and your point stands regardless 😎 The more cells you run the lower the KV should be. 3800kv motors are usually smaller and meant for 2WD applications or light 4WD trucks. And they definitely aren't meant for 4s.
 

jondilly1974

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Is this a covertes Mega? If so, did you upgrade the pinion/spur to 32p? Did you upgrade the input gears and diffs? I didn't see any mention of that. Also, 3800kv is too high for 4S. What size is that motor?
Well it’s only about 64k rpm. What could possibly go wrong? 🤷🏻‍♂️🤷🏻‍♂️🤣🤣🤣🤦🏻‍♂️🤦🏻‍♂️
 

JJG6908

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Is this a covertes Mega? If so, did you upgrade the pinion/spur to 32p? Did you upgrade the input gears and diffs? I didn't see any mention of that. Also, 3800kv is too high for 4S. What size is that motor?
I'm sorry. Are you asking if I'm converting a Mega? If so no. It's the basic brushed Granite. And as I said before this setup which was very similar, worked excellently before the crash. The difference was 3s on a 60 amp ESC and a 3930kv motor. Now I'm trying to run my Hobbywing 120 amp ESC and a 3800kv motor. So my confusion is why did a $19.99 goolrc 3930kv motor with a $25 60 amp generic ESC installed in my Granite with the the stock pinion run perfectly and it was extremely fast. I know the HW ESC works in my Mojave and it works just as good as the stock ESC. And again, I'm only;y doing this over with a bigger ESC and a 4s battery because why not. After I crashed it I had to rebuild the electronics anyway. I also have another 60 amp ESC just like the first and another motor just like the first. I'm thinking about swapping it out and seeing if going back to that 3s setup works again. If it does I will then install a 13 or 12 T pinion to give it a little more torque. I haven't messed with any of the actual gearing and I didn't need to the first time I had my 3s conversion running. I'm thinking maybe it is the clutch because it runs fine except when I slam the throttle. then it almost sounds like the motor the KV. Gearing is also different on the Mega brushed.
[/QUOTE]
Granite, not a mega. But thanks.
No worries and your point stands regardless 😎 The more cells you run the lower the KV should be. 3800kv motors are usually smaller and meant for 2WD applications or light 4WD trucks. And they definitely aren't meant for 4s.
Okay. This is the best answer so far. I need a smaller motor or go back to 2 or 3s.. And that makes sense since I did try this setup on my Mojave which has a motor with a much lower kv. And that thing ran just as good. Thank you bicketybam! And thanks for everyone else's input as well.
 
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bicketybam

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I'm sorry. Are you asking if I'm converting a Mega? If so no. It's the basic brushed Granite. And as I said before this setup which was almost identical, worked excellently before the crash. The difference was a 60 amp ESC and a 3930kv motor. Now I'm trying to run 120 amp (HW) ESC and a 3800kv motor. So my confusion is why did a $19.99 goolrc 3930kv motor with a $25 60 amp generic ESC installed in my Granite with the the stock pinion run perfectly and it was extremely fast. And like I said I know the ESC works in my Mojave and it works just as good as the stock ESC. And again, I'm only;y doing this over with a bigger ESC and a 4s battery because why not. After I crashed it I had to rebuild the electronics anyway. I also have another 60 amp ESC just like the first and another motor just like the first. I'm thinking about swapping it out and seeing if going back to that 3s setup works again. If it does I will then install a 13 or 12 T pinion to give it a little more torque. I haven't messed with any of the actual gearing and I didn't need to the first time I had my 3s conversion running. I'm thinking maybe it is the clutch because it runs fine except when I slam the throttle. then it almost sounds like the motor shaft is spinning inside the pinion because the grub is loose which I KNOW isn't happening I'm just saying that's what it sounds like.

Hope that helps answer some questions of yours and the others.
A brushed Granite 4x4 is called a Mega. So all of your driveline, including the slipper clutch, is meant for brushed power. You can run 2S on it and a mild 3s setup like you had. My guess is that the 3s system either loosened the slipper or fried it. Forget 4S in that truck. You will destroy it.
 

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I am impress! 4s in stock mega truck😳
Stay with small motor like 3650 and it should work. Take a look for wearings parts: spurgear and input gear and check engine temp since the kv is high for the application.
 

bicketybam

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I am impress! 4s in stock mega truck😳
Stay with small motor like 3650 and it should work. Take a look for wearings parts: spurgear and input gear and check engine temp since the kv is high for the application.
Are there motors that small (3650) that are rated for 4s and a 4wd truck application? I've never seen one.

I had 2 Arrma Megas and when you run them on something like the BLX100 motor and 3S, the spur gear strips and the front/rear input gears snap. This is a fact born from a lot of experience converting the Mega trucks to brushless. 4s is never going to happen. As I've said before it will melt the drivetrain.
 

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I wanna see the Mega on 4S just so I can say

AC9DC669-9FAA-4AB2-9632-B33133B2425B.jpeg

... when you come back and ask why everything is ruined. Every single gear in a Mega is made for up to 2S. Why would you expect it to handle twice the power? And you need about a 2400kv motor for a 4WD 4S rig.
 
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You can buy the 3s diffs and sun gears. Front and rear then the spur gear and pinion and the slipper clutch system
And the motor mount if not yet alluminum
The other option would be to buy the upgraded sun gears for the granite mega will be cheaper but you will maybe need to upgrade and change the slipperclutch for the ones from the 3s line even the motor mount you decide what ever is better for your application
Idk how much money you have put on that stock mega granite but if you wanted to go brushless you should have went with the granite blx 3s for a few bucks more idk when you got the granite mega maybe when the blx 3s line did not exist but buying a mega brushed granite and converting to brushless becomes more expensive at the end
 
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JJG6908

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A brushed Granite 4x4 is called a Mega. So all of your driveline, including the slipper clutch, is meant for brushed power. You can run 2S on it and a mild 3s setup like you had. My guess is that the 3s system either loosened the slipper or fried it. Forget 4S in that truck. You will destroy it.
Thanks for the reply bickety!. Please excuse my ignorance as I'm new to ARRMA and just getting back up to speed with RC after so many years of regular 'adulting'. I had no idea about the Mega. Heard of it but haven't seen one yet. As for 3s on this truck; well it was fantastic. However; like many tinkerers I'm never satisfied and always looking to push it. I realize that 4s in such a small truck is insane and not practical for general use. Since I had to replace my ESC after that wreck I thought I'd try 4s but ONLY for this extremely large parking lot at Northrop Grumman where I do all my speed runs. It's flat and smooth and a HUGE lot. I DID NOT intend on bashing on 4s. I know that pretty much any mistake at those speeds will result in catastrophe and many broken Granite. Many! lol So thanks again blickety! I really appreciate your scorching honesty and input bro. (especially without being a smart ass)

After some more research and talking to a couple of experts; there should be no issue running that 3800kv motor on 4s. None at all. They suggested looking at the clutch and testing each component separately in another machine. And that's normally what I would've done I just thought since I joined an RC ARRMA forum I could get some good answers. And without the smart-ass trolls. This is not how you treat new comers or anyone with a question regardless of how you feel about it. So, jondilly you can SMD with that smart ass poop. I hope you break whatever you take out next. And I hope it's costly and the labor is a pain in your asshole.

This is NOT what I expected from a group of what should be adults coming together to share a passion and to help one another. Half of you don't even know wtf you're talking about and then you have to be a jerk about it. I was so weary of joining this forum but I thought "It should be fine. Should be mostly adults here to help one another." Not talk poop and and be a smart ass when someone has a real question. Reminds me of the old adage- If you don't have anything nice to say, keep your mouth shut.

Jondilly I hope your brake something next run and when you do you can think of me and karma. I want my fing subscription fee back. Why? Because 8 out of 10 people ARE ASSHOLES WITH SMART MOUTHS AND I'VE HAD IT. ONLINE AND IN REAL LIFE.

No worries. I WILL get it working.
 
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jondilly1974

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So it seems that you have a 2WD truck? Maybe the Granite Voltage? If so, it isn’t called a Mega then. Either way, it won’t hold up to 4S for long.
 

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Thanks for the reply bickety!. Preaze excuze my ignorance as I'm new to ARRMA and just getting back up to speed with RC after so many years of regular 'adulting'. so I have no idea about the Mega. Heard of it but haven't seen one yet. As for 3s on this truck; well it was fantastic. However; like many tinkerers I'm never satisfied and always looking to push it. I realize that 4s in such a small truck is insane and n ot practical for general use. Since I had to replace my ESC after that wreck I thought I'd try 4s but ONLY for this extremely large parking lot at Northrop Grumman where I do all my speed runs. It's flat and smooth and a HUGE lot. I DID NOT intend on bashing on 4s. I know that pretty much any mistake at those speeds will result in catastrophe and many broken Granite. Many! So thanks again blickety! I really appreciate your scorching honesty bro.

AS for those of you saying that Motor isn't right for 4WD or 4S
When you purchased your truck new, did it have a brushed motor in it?
 

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I wanna see the Mega on 4S just so I can say

View attachment 60938

... when you come back and ask why everything is ruined. Every single gear in a Mega is made for up to 2S. Why would you expect it to handle twice the power? And you need about a 2400kv motor for a 4WD 4S rig.
And no you don't. You can put 4000kv motor in it if you like. A guy at the hobby shop walked in with a 4s truck and a 4000kv motor and he had zero issues. He was there for a steering servo because ARRMA puts those junk plastic splined servos in their smaller trucks just to save a few pennies.
When you purchased your truck new, did it have a brushed motor in it?
Yes. it came with a brushed motor.
So it seems that you have a 2WD truck? Maybe the Granite Voltage? If so, it isn’t called a Mega then. Either way, it won’t hold up to 4S for long.
NO YOU DUMB ASS. READ THE ENTIRE POST JFC! IT'S A DAMN GRANITE BRUSHLESS. And you are a smart ass little punk you know that? Do you live in MD because I'd like to punch you in your big fat mouth. READ WHAT IS WRITTEN AND THEN MAYBE YOU WON'T HAVE TO ASK A QUESTION I ALREADY ANSWERED IN MY POST! GD!
You can buy the 3s diffs and sun gears. Front and rear then the spur gear and pinion and the slipper clutch system
And the motor mount if not yet alluminum
The other option would be to buy the upgraded sun gears for the granite mega will be cheaper but you will maybe need to upgrade and change the slipperclutch for the ones from the 3s line even the motor mount you decide what ever is better for your application
Idk how much money you have put on that stock mega granite but if you wanted to go brushless you should have went with the granite blx 3s for a few bucks more idk when you got the granite mega maybe when the blx 3s line did not exist but buying a mega brushed granite and converting to brushless becomes more expensive at the end
Thank you,
Surchaufeur

This is the kind of response one should expect in a forum like this. TY.



BTW; Cost is not an issue. I'm not trying to build a permanent 4s Granite/mega. I just happen to have a Hobbywing EZRUN 120 amp ESC and two brushless motors: 3800kv and a 3930kv. So, since the ESC and motor are 4S capable I decided to install them and primarily run 3s on it like I did before with no issues.
 
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bicketybam

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And no you don't. You can put 4000kv motor in it if you like. A guy at the hobby shop walked in with a 4s truck and a 4000kv motor and he had zero issues. He was there for a steering servo because ARRMA puts those junk plastic splined servos in their smaller trucks just to save a few pennies.

Yes. it came with a brushed motor.

NO YOU DUMB ASS. READ THE ENTIRE POST JFC! IT'S A DAMN GRANITE BRUSHLESS. And you are a smart ass little punk you know that? Do you live in MD because I'd like to punch you in your big fat mouth. READ WHAT IS WRITTEN AND THEN MAYBE YOU WON'T HAVE TO ASK A QUESTION I ALREADY ANSWERED IN MY POST! GD!
First, no need to threaten violence. Seriously.

There are currently 3 versions of the Granite in production:

Granite Voltage (2WD)
https://www.arrma-rc.com/rc-cars/latest/granite/voltage

Granite Mega 4x4
https://www.arrma-rc.com/rc-cars/latest/granite/mega/4x4

Granite 3S BLX
https://www.arrma-rc.com/rc-cars/latest/granite/blx/4x4

Based on the fact that you said you said yours came with a brushed motor and it's 4WD, it's safe to say you have a Mega. The Mega slipper clutch, input gears, diff ring gears, spur gear and pinion gear are all designed for brushed power. It has proven to hold up to mild brushless power which is what you were running but long term reliability is not good. If you ran the BLX100 electronics in a stock Mega 4x4 you would strip the spur and break the input gears. I know because I've ran similar systems in it and that's exactly what happened. As for 4s, there is no way a stock Mega would hold up. I'm not sure what the confusion is. You have a Granite Mega 4x4 that you upgraded to a mild brushless system. It doesn't make it a 3S BLX Granite. You would need to change most of the driveline, the motor mount, the pinion, spur, diff ring gears and the turnbuckles. Even the shocks springs and fluid weights are different because the 3s truck is heavier than the Mega. I started on these trucks and know what I'm talking about. I hope this helps because that's all we were trying to do. Would you have rather us say "Sure! Go for 4S!" and then laugh when you have nothing but issues?
 
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