Granite New Granite 4x4 Motor or Servo?

[RCNewbie23]

So I've had this Granite Mega 550 less than 2 weeks and already broke something. I've reached out to Amain, but just wanted to understand what this could be. It sounds like metal grinding, so I'm not sure if it's the motor, the servo, or something else. It sounds like servo's are common issues with these, so if it's a servo I might be better served just upgrading to one of the other's I saw posted on here, but if it's something else I'd probably be better off using a warranty repair.

If it helps, all I do is run this thing all out around the back yard while my dog chases it. It was basically a xmas present for my pup, which is why I went brushed, though I can already see why folks said to get the brushless. I just couldn't turn down such a good platform for $200 as essentially a dog toy.

https://imgur.com/a/KHedcLG

Thanks in advance for any and all thoughts and opinions!

 

[SrC]

Has nothing to do with your ST. servo at all. Did I understand you correctly in regards?
Sounds like the Pinion and Spur are jacked up. So open up the Power module first, per the manual and have a look see of the gear mesh.
Then you move onto the differentials if all is ok with the pinion and spur gear first
Do you get this wet at all?
Brushed motors are needy in the maintenance dept. And can last somewhat longer if you do. Many just replace brushed sealed can motors when they are already toast. Cheap enough.
If not sure, send pix of your Opened up P Module. and its gear mesh.

 

[RCbuzz]

Like @SrC was saying time to pop out the power module and check your pinion and spur.

To me it doesn't sound bad, a friends granite sounded like this after 5min. Turns out a peice of sand or debris made the spur imperfect and gave it an odd whine. After cleaning it out the sound kind of went away on its own, several packs later it's running fine.

Be sure to set the steering end points. It will make the servo last as long as it can.

 

[RCNewbie23]

Thanks for the feedback, it did end up being the spur. It was pretty much ground down to the point that it spun freely quite a bit. This makes sense considering what started it was the car grinding a bit without moving, the motor was definitely spinning but no power was getting to the wheels.

Amain has been awesome and is sending me a new spur. If it happens again I'll probably just buy a metal spur.

That all said, is there a way for me to secure the motor so there's no play any this doesn't happen again?

 

[RCbuzz]

Thanks for the feedback, it did end up being the spur. It was pretty much ground down to the point that it spun freely quite a bit. This makes sense considering what started it was the car grinding a bit without moving, the motor was definitely spinning but no power was getting to the wheels.

Amain has been awesome and is sending me a new spur. If it happens again I'll probably just buy a metal spur.

That all said, is there a way for me to secure the motor so there's no play any this doesn't happen again?

Glad you found it, I mostly use plastic spurs on my 3S rigs, they are cheap and durable (I keep a couple spares on hand). The problem with them failing is usually due to poor gear mesh and debris getting in.

For debris check this out: https://www.arrmaforum.com/threads/help-me-upgrade-my-senton-3s-for-sand.20322/post-278043

For the spur and pinion mesh, you essentially want the spur gear and pinion gear as close as possible but not touching. When you think you have it set right temporarily put the power module cover back on and gently rock the spur gear back and forth and listen for that satisfying "click sound". Then rotate the spur 180degrees and again rock it back and forth listening and feeling for the "click". If there is no play and no click its too tight.

Hope that helps you out.

Keep in mind crashes and bad landing and knock the motor out of alignment, if it knocks your gear mesh out, your spur will be a toast in a hurry.

 

[RCNewbie23]

Thank you so much! I got the new spur from Amain and after taking it all apart (again) I saw the 2 screws that hold the motor in place and was able to align them. I ran it for a bit this afternoon and both the car and dog seemed pretty happy!

Thanks for all the help, I really apprecaite it.

Also, I definitely see the 3s in my future, maybe a Senton to change it up a bit....

 

[SrC]

Thanks for the feedback, it did end up being the spur. It was pretty much ground down to the point that it spun freely quite a bit. This makes sense considering what started it was the car grinding a bit without moving, the motor was definitely spinning but no power was getting to the wheels.

Amain has been awesome and is sending me a new spur. If it happens again I'll probably just buy a metal spur.

That all said, is there a way for me to secure the motor so there's no play any this doesn't happen again?

>>>A Metal spur wont necessarily solve the issue of dirt migrating and building up into the Power module. You may get some more longevity, however.

>>>That is user error, from lack of frequent PM maintenance. Both metal spur and pinion could still end up being casualties at some point anyway. And metal spurs cost a good amount more to replace. $$ Metal ones are no substitute for lack of PM maintenance is what I am saying. Plastic ones are cheaper to replace, and will fail by themselves first, sparing the pinion when it does. Plastic ones being the "sacrificial" part by itself.
>>Being A Plastic spur is not at fault here at all.
But some do go with metal ones, and for the right reason.

 

[RCNewbie23]

Understood, but I also wouldn't say user error is the case after about a week of use.

That said, thanks to this sub and the helpful people at amain, I now know how to adjust the motor to make sure it mates up properly to the spur. I think Arrma actually recognized that the adjustment isn't ideal and on some of their new cars have the motor adjustment screws accessible without opening up the case. That seems like a good improvement for something that appears to need alignment somewhat regularly but isn't easily accessible (especially if the expectation is that you adjust it every 5 or so runs).

 

[SrC]

That is still user error, along with this PM design be flawed in some respects. The very nature of the 4x4 platforms. All of them.
When you think about it, being closed up, you would think dirt would not enter, yet it does. As you learned.
So frequent clean outs are the norm going forward. A week of use means nothing here. Dirt can migrate into the PM with minutes if you have the perfect storm. In a dirty or wet driving terrain.
I am not sure what "about a week of use" of driving actually means as well. 1 or 2 packs?
I can easily put 30 packs through my RC's in a week. Not common for me , but close to it.
Again much has to do with how dirty your terrain is.

 

[RCbuzz]

That is still user error, along with this PM design be flawed in some respects. The very nature of the 4x4 platforms. All of them.
When you think about it, being closed up, you would think dirt would not enter, yet it does. As you learned.
So frequent clean outs are the norm going forward. A week of use means nothing here. Dirt can migrate into the PM with minutes if you have the perfect storm. In a dirty or wet driving terrain.
I am not sure what "about a week of use" of driving actually means as well. 1 or 2 packs?
I can easily put 30 packs through my RC's in a week. Not common for me , but close to it.
Again much has to do with how dirty your terrain is.

After I sealed my power module it was much better, checked it again after a few packs, nice and clean .

 

[SrC]

+1
Good advice there.