My First E-Dune Runner

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It was a bearing that caused the e-DR to not finish the Nitro Challenge so I got some new bearings. I got them from http://www.fasteddybearings.com/ b/c they they had all the sizes for the DR and at a great price. And it turned out they are all rubber shielded which means you can service them unlike the stock bearings.

You can see them at the bottom of the image:

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So I ended up breaking the shaft w/ the cocked hole in it. And I got to brain storming. This would almost certainly smoke my esc but it would simplify things and take 1 lbs out of the weight of the car:

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I might give it a go. But I'm sure I need the clutch to keep the esc happy.
 
I'd like to have the pulley shafts supported on both sides with a bearing. Here I made a 3/4" aluminum shaft the large pulley will key into. My only concern is the center pinion being held w/ a 6mm set screw. The stock setup has the pinion keyed into the coupling as a hex. I hope I come up with a better way. Also I'll probably end up using a 1" aluminum shaft so I can mill flats in it to support the brake discs. But for now this will work as a prototype.

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It's mainly to simplify the drivetrain and be able to support the pulleys on both sides w/ bearings. But I'll take the weight savings too.
 
After reading about how to make an internal hex hole I got the idea to broach the hole w/ the pinion gear. The gear is hardened steel and my shaft is aluminum. I bored a hole in the shaft to the same diameters as the flats of the hex. Then I broached the corners of the hex w/ the pinion gear. With a little heat it wasn't all that bad. I feel much better about this holding up than just a set screw. Of course I'll still use a set screw to keep everything in place.

This is my practice hole:

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RCDAD said:
Gotcha. Bearings on the outside of the pulleys will be cool.
Click to expand...
I always had issues w/ the pulleys not spinning tru. I suspect that along w/ the side load contributed to me blowing out the bearing during the NC. With bearings on both sides, it should be much easier on them to carry the load.
 
Here is my practice keyway to transfer power from the pulley to the shaft. I'll be very happy do be done w/ pins for this pulley. Unfortunately I don't have any square stock laying around so I put a piece of 1/8" metal round in there.

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RCDAD said:
That looks pretty cool. Are they hard to remove?
Click to expand...
The pulley slides freely on the shaft so you simply slide the pulley off and take the key stock out. I do actually have square key stock and will not be using the round piece in the image. I put it in there to show the concept of how the full width of the pulley is used to lock it to the shaft. This way the force is spread out across the pulley vs. concentrated at the pin like I had been using.

I just wish I could use the same approach for the small pulley but there isn't enough material. But if I get the square clutch bell I could probably get it to work. Hmmmm, I need to look into that more.

At this point I'm completely doing away w/ the gear plate so As long as the square clutch bell is compatible w/ mine I should be able to get it to work.
 
I'm trying to get a good look at the square shaft clutch bell. Is it really square, I cannot find a good image of it showing that it is?
 
It just ha two small flats on the shaft. There are drive squares that are held on by set screws. The shafts are similar to yours but longer to support the drive squares.
 
I made some progress on the clutch pulley mount:

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I did make a big mistake and put the part in the mill 90 degrees off. I did it early in the morning and I kept telling myself I didn't have enough coffee yet to be doing this kind of work. Sure enough, I messed it up. But I can fudge it to make it look right.

Next I'll make the parts that support the pulley shafts on the opposite ends.

And I still don't have a great way to attach the clutch pulley to the shaft. As of now it'll be a 4mm pin that will be captured in the bearing on the outboard side.
 
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