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Post by cozwurth on Dec 10, 2023 5:17:24 GMT -7
Sam. Will a 9T pinion work for this race? Even if it would, my 12T 15 ohm JL/Playing Mantis can run circles around what I just assembled, wobbly bits and all. |
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Post by crazynski on Dec 10, 2023 5:32:55 GMT -7
Sam. Will a 9T pinion work for this race? Even if it would, my 12T 15 ohm JL/Playing Mantis can run circles around what I just assembled, wobbly bits and all. So send it in if it's ready and running well. The worst that can happen is you get door prizes for participation. Or it might be one of those odd cars that surprises everyone. |
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Post by dave632 on Dec 10, 2023 9:49:06 GMT -7
9 might work, but 12 will be slow unless we are running 50'.
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Post by skillet on Dec 11, 2023 18:15:24 GMT -7
Sorry Big Ken missed your question...
Your going to hate my answer...
I used to think the bigger pinion the better, that's not true. Everything has to work together. Your tire size plays into the gears... downforce plays into tire size... it's all a trickle effect...
There is no wrong or right answer to your question
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Post by cozwurth on Dec 12, 2023 3:27:38 GMT -7
The biggest problem I'm having with this chassis right now is drag/friction. All together it drags and gets hot. Apart and everything seems to spin easily. I'm going to have to blow it completely apart and start over, checking everything.
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Post by gnome on Dec 12, 2023 8:26:58 GMT -7
The biggest problem I'm having with this chassis right now is drag/friction. All together it drags and gets hot. Apart and everything seems to spin easily. I'm going to have to blow it completely apart and start over, checking everything. Take a close look at the cluster pinion and shaft. Some times the shaft can be rubbing on the axle or the pinion gear could be pinched between the top plate and chassis or bolth . To much brush tension will also cause this to happen |
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Post by skillet on Dec 12, 2023 15:27:10 GMT -7
One more thing to keep an eye on. Different arms are shimed different.
Make sure your arm has a little float between the top plate and chassis and not getting sandwiched in there
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Post by cozwurth on Dec 12, 2023 17:51:33 GMT -7
I took a close look at the pinion shaft and the arm. Pinion shaft is not rubbing the axle, and it has a very slight amount of play. The axle moves side to side a very small amount as well, even with the pinion in place. Should be no binding there. I removed the magnets and brushes and put the top plate back in place to check the arm for movement. There is a slight amount of up and down play. It also spins very easy when I spin the top gear. Doesn't seem to be any binding there, either. Now for brush tension. With either brush in alone, no magnets, there is not enough tension to raise the arm to the top of its play. Both brushes together are just enough to raise it. I didn't adjust the brush tension, but I did run a ball point pen between the pads on the comm to smooth the edges. That change made a difference. It's still slow enough to hold the throttle wide open all the way around the track, even at 20 volts though. It is smoother. Running the car on a 9volt battery and turning it upside down does not change anything, and lightly pressing on the brush spring slows it down.
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Post by dave632 on Dec 13, 2023 13:10:36 GMT -7
Something has to be causing friction, or you have a BAD armature, which will surely make it run hot and be slow. I have changed many many armatures that were bad, both inline and pancake. Some melted the chassis they ran so hot.
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Post by cozwurth on Dec 13, 2023 15:48:21 GMT -7
Dave, my arm checked out at 5.9/5.9/5.9, all readings steady. But, that doesn't mean that it's flat and true. I did see a slight improvement after running the ball point pen between the pads, but maybe that's just wishful thinking. At a minimum it isn't running as hot, and does not slow down after 5-6 laps around my track. I'll keep plugging away at it, but I have a couple of other projects on the bench, too.
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Post by cozwurth on Dec 13, 2023 17:48:42 GMT -7
I stuck the chassis on a 9 volt battery this evening and tried to watch the whirling bits closely. I can see the idler gear moving a little when I hear an off-key chatter. Things slow a little during the chatter.
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Post by crazynski on Dec 13, 2023 17:56:32 GMT -7
Did you try lapping the gears in?
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Post by cozwurth on Dec 14, 2023 2:37:06 GMT -7
That's next on the agenda. My lapping stuff is in the garage, and I forget to grab it when I'm out there. The two lonely brain cells haven't collided while I was out there, so no dim glow of the 5W bulb over my head. I want to run it without the idler to see how the arm spins up by itself after dressing the edges of the pads, too.
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Post by dave632 on Dec 14, 2023 10:38:36 GMT -7
I have had some bad arms read great.
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Post by cozwurth on Dec 14, 2023 10:53:38 GMT -7
I have several others, so I can do some swapping if needed.
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