My First E-Dune Runner

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You could route the belt above the center shaft instead of under it. That would take some of the bend out of it. It is a shorter run that way so you would need a center pulley to take up some of the slack. If ya want one to play with I can get one to you. Just an idea...
 
RCDAD said:
You could route the belt above the center shaft instead of under it. That would take some of the bend out of it. It is a shorter run that way so you would need a center pulley to take up some of the slack. If ya want one to play with I can get one to you. Just an idea...
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That is an interesting idea. I have more belts coming that may allow me to do that. I'll keep you all posted.
 
Here is what I came up with. I first made this out of delrin as a guide the belt would rub up against to stay separated. But after a few minutes of running it became clear the belt would rub through the delrin in very little time. So I made this latest version out of aluminum that uses ball bearings to guide the belt. Please excuse the rubber hose holding the bearings on but I couldn't find a 5mm nut. But I may stick w/ that hose and simply glue it on...hmmm. I may actually change this up to use larger bearings if this doesn't do enough to separate the belt.

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Of course this is all assuming I'm right in thinking that the belt heat is as a result of the belt rubbing against itself.
 
One thing that may help, that helped me before is to sand the tension bar with a fine grit sandpaper. Get it as smooth as you can. Then i used a light oil on the back of the belt (just enough to barely cover the entire belt). I saw a noticable difference in belt longevity. You'll be applying oil often (between each heat), but it does help.
 
What kind of oil? Like 3in1, WD40, motor oil? What does the oil do on the back side?
 
I used some trinity motor bearing oil i had around the house, but 3in1 should work too. The belt will slide with less friction, with the oil and a smooth belt tensioner, reducing heat. As the belt rubs without the oil and a non-smooth tenioner it slowly (or with all the power you have quickly) shave away the belt from the back side until it breaks. I had a friend who had a problem destroying belts, b/c of all the extra power. The oil and smooth tensioner, prevented the belts from shredding as fast. They will still shred, just not a quick. He got a couple of extra minutes.
 
I like the white lithium idea. Is that the same stuff as the white grease the comes w/ some diff assemblies? Do I get it at autozone or something?
 
I picked up some white lithium grease and carefully moisturized the outside of the belts. Thanks RCDAD, I think that will help.

The past couple of days I have been getting the belt drive sorted out. I Received more pulleys and belts and have a handful of options to choose from:

Here's how to read my notes: smallPulleyToothCount/largePulleyToothCount (belt length)= FDR All belts are 5mm pitch 15mm wide

12/24 (280)= 18:1 *

13/24 (280) = 16.6:1 *

13/22 (255) = 15.2:1

15/24 (265) = 14.4:1

*requires idler pulley seen above

When I run the gears I have a 12.6:1 or 13.6:1

My favorite gearing is the lowest; 12/24=18:1 fdr. I just wish it didn't require the idler. It's the slowest ratio at just over 30mph top speed but I think it has the best chance of making a 30min run. The motor, esc, and battery run much cooler w/ the lowest ratio. If the races were shorter I would consider one of the options that do not require the idler.
 
The Nitro Challenge went well. Saturday was a practice day and Sunday we raced. We had 2, 10min qualifiers and a 25min main. I didn't make the main b/c the bearing for the clutch bell seized. When I saw it happen I saw smoke come from the car and I thought I smoked the esc, motor, or battery. I was very thankful the esc has a stuck rotor protection and saved the system.

During practice the battle w/ the car was w/ the belt drive. Luckily the rest of the car stayed together and I just had to focus on one thing albeit very critical.

Race conditions are the toughest scenario I run the car in. And I feel the belt drive can work in race conditions. I discovered white lithium grease definitely helps when the idler pulley is used. But after about 10mins of solid running the belt gets too hot and the teeth melted off. I'll have to post a picture if I still have belt.

Luckily I found a low gear ratio w/ the belt drive that doesn't require the idler. This kept the belt cool but it was just a little too loose. It fell off during the 1st qual when I was in 3rd and I managed to run down from the driver's stand, put it back on, and still qual 6 of 9 for the main. The car can compete. I was among all losi 5ives.

During the second qual I wasn't running on a full battery charge so I ran conservative to make the full 10 mins. About 6 mins in the car stopped, smoke came out the back and it wouldn't go. The clutch bell bearing seized and I can't even move the bell by hand. I still haven't take it all apart to get a better look. I guess I shouldn't of spent some time w/ the bearings on the in between runs.

Aside from the belt, the pulleys kept breaking pins that hold them to the drive shafts on the gear plate. I need to figure out a better way. Pins just can't handle the long abuse in a race scenario. I might have to look into getting some of the old square shafts if they can be had.

More to come w/ pictures.
 
Thanks for the update hope you had a great time. You put in alot of time and effort to run so I am sure you will be rewared and with more time you will get the rest up to par you have done a great job so far. I was too dissapointed that live rc didnt broadcast the 1/5 scale race. Keep up the great work.
 
I've been wondering how you did out there. Glad to hear that buggy is competitive. Sounds like you got more life extended with the white grease, than we did with the oil. Sorry about the problems with the transmission. As ingenious as this build was, I'm sure you'll figure something out to keep the parts from breaking during the race. Do you have any video of you racing?
 
No, I do not have any video that I took. Maybe someone there will post something on one of the 5ive forums and you'll get a glimpse of the DR.

I think the adjustments could be minor. I'll have to look at the old style square gear plate drive shafts. That sounds more promising than the pins. I was running a 13/24 pulley setup w/ a 265mm belt. It really needed a belt that was a just a little smaller, but I don't think econobelt makes a 260mm.

Also, if the belt pulleys could be supported on two sides that would be ideal.....the wheels are turning.

I'd like to also reduce the weight. It would be nice to get 5lbs out of that thing. I'm pretty sure I out weighed most of the 5ives.
 
I think the adjustments could be minor. I'll have to look at the old style square gear plate drive shafts. That sounds more promising than the pins. I was running a 13/24 pulley setup w/ a 265mm belt. It really needed a belt that was a just a little smaller, but I don't think econobelt makes a 260mm.
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I should show you the belts and pulleys we have. They don't seem to heat up. I'm thinking its got to be the style you are using.
 
RCDAD said:
I should show you the belts and pulleys we have. They don't seem to heat up. I'm thinking its got to be the style you are using.
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Could be, or maybe it has to do w/ the idler being on the pull vs. push side of the belt. But keeping it cool is key.

I see you have the square shaft clutch bell, do you have a square shaft for the brake shaft (I don't know what the official name of it is)? Does the square shafts use the same bearings as the round ones? That'll give me an idea the dimension of the square.
 
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