Very weak motor shaft resistance-is it an issue?

[Forum-Lurker]

Hey Arrma fam I need a little advice, been researching but haven't found much so far.

Just got the Outcast 8s like everyone else, first 8s rig. Was checking it over and noticed the motor shaft has almost no resistance. It can be almost freely spun from the edge of the pinion with just the tip of a fingernail. It almost feels like there is a sort of 'dead space' for a 1/4 turn of the shaft either direction before the gearing even engages and it starts to move the truck. By comparison the 1650kv 4985 Hobbywing motor I have is extremely stiff as are most other stock and generic motors I've handled.

I would just drive it to see, but it also came with a big puddle of diff fluid in the box from the rear diff leaking and it doesn't seem wise to test it dry lol..

I guess my question is about how to proceed: Should I buy the gaskets/diff fluid, fix then test it? Or better to go after the warranty first while it's still new/clean? Or is that premature? Never done the warranty process before but want to keep all the options open.

Any thoughts/recommendations?

 

[SrC]

Yeah out the box mishaps happen. Before you drive it and spend a nickel, just get with HH to warranty all related parts. Have your receipt handy.
You can tear the diff(s) down to look further. But might also want to go over the whole rig for Factory flubs while you are at it and before you contact HH. Having a list in hand. Been there before with much worse issues and a long list, right out the box.
Are you sure its not the shock(s) leaking oil? Check them also. Ask for Oil and any parts you might need, Perhaps even the diff o-rings. If you see that the diff was just assembled loose and leaked, you are ahead of the curve. This is a sign that you check all 3 diffs.
Regarding the stocker 8s motor, run it up to see that it is fine as well, and that electrically the rig runs on the bench well. Wheels taken off and on a stand, when you do this. Check the mesh. As you can see, these RTR rigs are not that Ready to Run. Need some TLC first. Most RTR's are this way. You are not alone.
I have some motors that have less magnetic flux than others. And rotate much easier when manually turned if that is what you are referring to.
Again set the pinion mesh properly. Don't assume it is correct. Don't assume anything is good. Your new rig needs your own blessing. How I do it.
I know you want to run it as soon as possible, but learning and doing some preventive wrenching before your maiden run will make for a better experience. Less frustration down the road.
Some ideas.
Good luck.

Edited.

 

[chris adams]

The big a$$ castle 2028 spins easily also. Like it has weak magnets, but thst thing is monster. Great advice given above

 

[SrC]

^^^My HW sensored 1900kv the same. Its a beast, but feels like there is no magnetic resistance when I manually turn the armature. Is what it is.
Yet my cheap Arrma BLX 2050 kv stocker is hard to turn. This is probably insignificant.

 

[RCbuzz]

My 8s motor has very little resistance as well, I also have the same dead space you are talking about. There is a lot of "drivetrain" on these rigs with big gears and drive cups.

As for the diff fluid, I would pull the diff out and actually check it. Arrma has had a horrible wrap of sending dry diffs (used to happen way too often). Now I have noticed they are sometime very full, if that is the case some will seep out past the seals. Not the end of the world but it does make a mess, just keep an eye on them.

My 20M center diff was half empty on two of our rigs, tires ballooned like crazy. Easy fix, pop in a silicone ear plug.

Hope that helps.

 

[SrC]

^^^
+1
At the center diff of the 8s rigs, you basically have a Transmission of sorts. Because there are actually 3 gears, One is an idler gear which separates the Pinion from the spur. I imagine due to the 30+ pound weight of these 8s rigs.
Unlike simply having a Spur to Pinion on a 6s line Arrma rig.

 

[RCbuzz]

I am guessing the 8S motors are slotless much like some of the Velineon motors. Different design and construction technique.

Come to think of it my Velineon 3S doesn't cog very much and is quite powerful for its size.

 

[SrC]

Do think the Velineon could be made by CC like Trx used to get them from?

 

[RCbuzz]

Anything is possible but I am guessing Traxxas is big enough they probably make them in house?

I just remember the Velineon 3S motor has very little resistance as well and I am guessing its slotless, may explain why it does not cog much, pretty smooth and quick. I have been impressed with it in my brushed converted Granite. It was strong enough to blow up two plastic diffs.

Edit: Found this info on Slotless vs. Slotted Brushless Motors. Good Read
https://www.haydonkerkpittman.com/l...aring-slotted-vs-slotless-brushless-dc-motors

 

[Forum-Lurker]

Yeah out the box mishaps happen. Before you drive it and spend a nickel, just get with HH to warranty all related parts. Have your receipt handy.
You can tear the diff(s) down to look further. But might also want to go over the whole rig for Factory flubs while you are at it and before you contact HH. Having a list in hand. Been there before with much worse issues and a long list, right out the box.
Are you sure its not the shock(s) leaking oil? Check them also. Ask for Oil and any parts you might need, Perhaps even the diff o-rings. If you see that the diff was just assembled loose and leaked, you are ahead of the curve. This is a sign that you check all 3 diffs.
Regarding the stocker 8s motor, run it up to see that it is fine as well, and that electrically the rig runs on the bench well. Wheels taken off and on a stand, when you do this. Check the mesh. As you can see, these RTR rigs are not that Ready to Run. Need some TLC first. Most RTR's are this way. You are not alone.
I have some motors that have less magnetic flux than others. And rotate much easier when manually turned if that is what you are referring to.
Again set the pinion mesh properly. Don't assume it is correct. Don't assume anything is good. Your new rig needs your own blessing. How I do it.
I know you want to run it as soon as possible, but learning and doing some preventive wrenching before your maiden run will make for a better experience. Less frustration down the road.
Some ideas.
Good luck.

Edited.

Thanks so much for the advice man, I'm going to follow it before contacting HH. The shocks are all very nice it's definitely the rear diff leaking the sticky, but who knows it might be an easy fix and was just loose that'd be nice. I mostly was worried about the motor but not anymore after hearing all this testimony. Keep being awesome guys.

The big a$$ castle 2028 spins easily also. Like it has weak magnets, but thst thing is monster. Great advice given above

Thanks for your experience man I appreciate ya!

My 8s motor has very little resistance as well, I also have the same dead space you are talking about. There is a lot of "drivetrain" on these rigs with big gears and drive cups.

As for the diff fluid, I would pull the diff out and actually check it. Arrma has had a horrible wrap of sending dry diffs (used to happen way too often). Now I have noticed they are sometime very full, if that is the case some will seep out past the seals. Not the end of the world but it does make a mess, just keep an eye on them.

My 20M center diff was half empty on two of our rigs, tires ballooned like crazy. Easy fix, pop in a silicone ear plug.

Hope that helps.

Very reassuring to hear this, and yeah I was just playing with it some more and it's like an entire 1 1/4 turn of dead space/slop lol, but now I realize it's probably that extra gear in the center transmission/diff coupled with the little resistance of the motor.

 

[SrC]

You got this.