Gearing Problem?

[Dunlee 4]

Hi guys, I recently built the Neo Scorcher and used the torque tuned motor that came with it. Worked well.

I decided to buy the Absima brushless combo Thust BL Eco. I’m using a 17t pinion and installed the motor using the two holes in the motor mount for the 17t pinion. I’ve tried to use the car and it sounded fine when I held it off the ground and gave it some throttle. When I put the car on the ground, it sounded like something was slipping/grinding.  I decided to put the torque motor back in and it worked fine again.
 

I’m wondering if the problem with my Abisma set up is gearing? I don’t know anything about gearing. I haven’t changed the 70t spur gear and I’m wondering if that’s part of the issues?
 

Can anyone shed some light on the situation?

Thanks in advance.
 

[Gazzalene 171]

I am  newb so might be wrong here BUT I have the same motor and putting that into a beetle blitzer had a very had a very similar problem.Did not have it with the brushed mortor. It turned out it was "cogging" from the motor. I think this motor is not very good quality and not being sensored the initial start is very rough,once moving its ok.

[Dunlee 4]

That’s what I found. The start is really rough but did seem to smooth out when I gave it a wee bit more throttle. I didn’t max it out though because I was scared I’d strip the pinion or spur gear. Did this happen to you?

That’s really disappointing to hear as I thought this would be decent. Hopefully something can be done to resolve it. 

The other thing I noticed was that the metal prong (I’m sure there will be a technical term) on the Absima motor is a lot longer than the one on the torque tuned motor that came with the kit. I had to pull the pinion to the end of the prong on the Abisma motor to get the teeth to meet with the spur gear. This  meant the pinion didn’t sit flush with the motor. The pinion did sit tight on the torque tuned motor. I’ll post a pic because that probably doesn’t make much sense. I’m wondering if that could be another possible issue? The picture shows the pinion sitting flush against the Abisma motor and not meeting the spur gear. I moved the pinion along to the end of the prong so it did meet but I experienced the same issues as yourself with cogging. 

 

[Problemchild 2149]

You always have to position the pinion so it meets the drive spur gear - some models come with a set up spacer or a metal feeler gauge 

It’s better to get the YEAH RACING alloy motor mount as then you can mesh the cogs perfectly - not too tight but not too loose 

JJ

[Dunlee 4]

Thanks for that bud. The cogging only seems  to be when the car starts to move. The cogging seems to smooth out and even stop when the car has gathered a bit of speed. Will the Yeah Racing motor mount take care of the cogging at the start? 

[TurnipJF 9192]

The cogging you are experiencing at low throttle and/or startup is normal with a sensorless brushless motor. In such motors, the ESC has no way of knowing which stator coils to energise on startup, so it energises them in sequence, knowing that at some point the right ones will be energised to "catch" the rotor and set it spinning. Things smooth out once the rotor is spinning fast enough to generate sufficient back EMF for the ESC to detect, but until this point is reached, the motor will exhibit the behaviour you are reporting.

Some things can be done to reduce cogging, such as running a LiPo battery which can deliver more current, allowing the motor to spin up faster, but it is unlikely that a Yeah Racing motor mount will alter the cogging situation at all. (It is still a good idea to fit one as it allows more accurate setting of the mesh, but it won't stop the cogging.)

[Dunlee 4]

I’m new to all this so thanks for the info. Good to hear that the lipo might help. I recently ordered a 3s Lipo, 50c Floureon battery and I’m waiting on it being delivered. Hopefully it that will help. Thanks once again. 

[Problemchild 2149]

Ah I see what you mean now?

I don’t do part throttle haha

JJ