Zahhak GOOL RC Motor help + sound

[rwordenjr 1890]

Finally received GoolRc motor after about 2 months. Now I’ve got an issue, the motor shaft is longer than a standard tamiya one meaning the shaft sticks out way too far. What are my options ? 

 

[nowinaminute 2815]

Does the gear cover definitely not clear it? I know I've had some near misses with my DT03 but it's just about cleared it.

If you didn't mind the surgery, you could always just lop some of the shaft off with a dremel or hacksaw.

Or maybe put a metal motor plate between the motor and mount?

[Superluminal 3750]

Either leave it or cut it off I would have thought. Does it clash with the gear cover?

[rwordenjr 1890]

I just tried the cover and it works ! Seemed to clear okay. Didn’t think it would but the covers still spins freely before being screwed in. Now the ball diff.... who knows if it’s too tight or too loose. We’ll see soon enough lol 

[Champ85 609]

If it didn't clear the cover, one suggestion would be to put a thin metal spacer between the motor and the motor mounting plate so the motor shaft doesn't stick out the other side as far.  Something like a piece of 2mm thick aluminum plate cut and drilled appropriately, though not everyone has the material or tools to make such a thing.  Edit:  Actually I just did an eBay search for "motor spacer" inside Radio Control and Control Line and found a few choices of exactly that:  a round piece of aluminum with holes designed to space the motor out from the mounting plate.

[Finnsllc 917]

n o issue if the cover fits

[rwordenjr 1890]

Motor all hooked up, this sound normal ? 

[Howards 457]

12 hours ago, rwordenjr said:

who knows if it’s too tight or too loose

Here's how to find out! 

Put the car on your lap, facing away from you. Have some dark jeans on. Don't do this with your best chinos on

With your left hand hold the spur gear still. Push the left hand drive wheel down so that it grips on your jeans and cannot turn.

Now grab the right hand drive wheel. Try to turn it. Slowly build up force. If it's easy to turn it, or it breaks away and turns after applying only moderate to moderate/strong force, the diff is too loose. If you cannot turn it all because you are putting so much force through it the car is bending around or you are worried you will break something, the diff is probably too tight, but you won't melt it.

Good luck! 

[TurnipJF 9192]

8 hours ago, rwordenjr said:

Motor all hooked up, this sound normal ? 

FullSizeRender.mov

Sounds normal to me!

[Gazzalene 171]

Going by the photo you may want to move the pinion out slightly,to centre on the spur.

[Juls1 1661]

It’s pretty common with many motors to need to trim the shaft for DT03 and DT02 so it doesn’t surprise me you’ve come up against that with the zahak.
 

many 550 motors come with shafts you need to lop off about 4-5mm. 
 

so don’t feel bad if you have to trim a bit off the shaft I’ve done it many times.
 

This is why we have a dremel on hand lol
 

Juls

[TurnipJF 9192]

Sounds like you are sorted for now,  but for future reference, putting one of these between your motor and motor mount not only acts as a spacer, but improves cooling too.

https://hobbyking.com/en_us/aluminum-cnc-motor-heatsink-plate-36mm-purple-red.html

[rwordenjr 1890]

9 hours ago, TurnipJF said:

Sounds like you are sorted for now,  but for future reference, putting one of these between your motor and motor mount not only acts as a spacer, but improves cooling too.

https://hobbyking.com/en_us/aluminum-cnc-motor-heatsink-plate-36mm-purple-red.html

What does a over tightened ball diff sound like ? 

[TurnipJF 9192]

15 minutes ago, rwordenjr said:

What does a over tightened ball diff sound like ? 

Loose ones squeal, tight ones don't make any unusual noises that I am aware of. 

[rwordenjr 1890]

39 minutes ago, TurnipJF said:

Loose ones squeal, tight ones don't make any unusual noises that I am aware of. 

Oh okay, thanks Turnip !

[Howards 457]

4 hours ago, rwordenjr said:

What does a over tightened ball diff sound like ?

More of a kind of high pitch barking noise. You'll know it when you hear it if you put the power down from a standing start on a high traction surface like tarmac. 

[rwordenjr 1890]

On 8/6/2020 at 1:27 AM, Howards said:

Here's how to find out! 

Put the car on your lap, facing away from you. Have some dark jeans on. Don't do this with your best chinos on

With your left hand hold the spur gear still. Push the left hand drive wheel down so that it grips on your jeans and cannot turn.

Now grab the right hand drive wheel. Try to turn it. Slowly build up force. If it's easy to turn it, or it breaks away and turns after applying only moderate to moderate/strong force, the diff is too loose. If you cannot turn it all because you are putting so much force through it the car is bending around or you are worried you will break something, the diff is probably too tight, but you won't melt it.

Good luck! 

While holding one wheel and spinning the other, the wheel is just short of a full turn. Good? 

[Howards 457]

1 hour ago, rwordenjr said:

While holding one wheel and spinning the other, the wheel is just short of a full turn. Good? 

I’d go a little tighter if all you are doing here is holding one wheel still. 
 

the trick is to try it with both the spur gear and a wheel held still. It should be very hard to turn the other wheel. 

[rwordenjr 1890]

Okay tightened up a bit. Now it’s about a half turn 

[rwordenjr 1890]

This normal ? When hardly on throttle, it’s skips a bit. You have to go more on throttle to make it move smooth. It’s been like that whether diff was loose or tight 

[TurnipJF 9192]

That is pretty typical behaviour for a GoolRC sensorless system. Not a diff issue at all. 

[rwordenjr 1890]

9 hours ago, TurnipJF said:

That is pretty typical behaviour for a GoolRC sensorless system. Not a diff issue at all. 

Oh okay. Thanks ! Why you think that is ? 

[TurnipJF 9192]

28 minutes ago, rwordenjr said:

Oh okay. Thanks ! Why you think that is ? 

I have installed several GoolRC sensorless systems in cars belonging to friends and colleagues, and they all do that at very low throttle.

I believe it is because of how the ESC is programmed to get the motor started. Lacking sensors, it has to run a start-up process in which it energises the stator coils in sequence until they catch the rotor and set it spinning. Once spinning, it generates back EMF that can be interpreted by the ESC. However at very low throttle it can't spin up the rotor, doesn't receive any back EMF, so repeats the start-up process over and over until you give it enough beans to get moving. 

[Howards 457]

Yep that’s normal for sensorless brushless stuff.

[rwordenjr 1890]

On 8/6/2020 at 4:52 AM, TurnipJF said:

Sounds normal to me!

To follow up on this, you have to full throttle then after about 3-4 seconds, the car actually moves. That’s normal? In the video below, I’m on the throttle fully then it finally moves after a bit