My First E-Dune Runner

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
You are one lucky guys with access to machines like that. I think that's awsome that you made a spot for a wrench to go on. Keep on updating
 
With the mods I've made and the parts I've fixed, the machine is starting to pay for itself :)
 
I opened up the shock piston holes from 1.2mm to 1.5mm or .059" (#53 drill bit if you don't have metric). It really woke up the suspension and it feels much more like it should and not dead.
 
This might give us more shock spring options. I built new perches to fit the losi 5ive springs:

8291848892_c55f2f7b43_z.jpg


I hope to get the other one done soon so I can test them out tomorrow at the track along w/ 14s 10A packs.
 
Well I got the other rear shock done. The losi springs are about 1/2" longer than the DR's and I thought they'd be too stiff (thinking the 5ive is much heavier). It turns out the stock blue springs are bit too soft for my ride. I have the adjusters turned all the way down:

8292425500_f6417d7ced_z.jpg


Looks like I'll be order the red's or maybe I can devise a way to stand them up more, hmmmm.
 
Another bad day at the track for the DR.

1. the belt drive broke in minutes. I'm done w/ it. The belt just isn't strong enough for my setup. Maybe for gas but it just can't handle much torque.

2. I broke the cv pin in the front wheel axle stub. I might have to switch to dog bones, what are those part numbers again?

3. I smoked the esc. Yep. I screwed up. Totally my fault. The track had some puddles on it and I thought I could navigate between them and I did for 20 mins. Well, w/ 3wd the steering became too tough and I went right through a big puddle. The esc was toast.

So I didn't get to see if 14s 10A packs would make it for more than 30 mins. Sort of bummed. I'll give this thing a couple more tries but I'm loosing my steam(and wallet) on this build.
 
Since my last post I installed another esc and welded the pin in in the cv in place. Then 2 weeks ago I took it to the track and broke the knuckle in under 5 mins. So I built my own:

8390033472_b2c33ee5b2_z.jpg


This one should last longer than 5 minutes. I only have one built which I hope to test this weekend. If it works out I'll build the other one.

I'm hoping I am starting to get ahead of all the weak points of this car. I knew this car was on the weak side for 5th scale going into this and I was fully prepared to be machining parts. I just hope I can get this thing to a point where I can bring it to the track and expect to get through a full battery pack.
 
I had the chance yesterday to run the new knuckle. I'm very happy to say the car lasted a full battery pack (14s 8A) without any breaks. And the pack lasted 25 mins. so I'm hoping the 10A pack gets me 30 mins.

I'm still on the fence about the nitro challenge. I talked to the organizer and I will run w/ the 4wd losis but I won't be scored. If I can get more testing done and the car doesn't break anymore I'll probably do the race.

I just wish I could get the belt drive to stay together. The belt drive is a lower gearing and the car runs cooler w/ it. I'll revisit that mod once I get the second knuckle built.
 
For the next knuckle I'm going to change the design slightly to reduce the number of fasteners (i.e. less locktite) by using a T-slot instead of a tongue/groove:

8413206015_14260715c0_z.jpg
 
Last edited by a moderator:
Deluge said:
That looks super beefy! Nice!
Click to expand...
Thanks, here it is all finished up:

8417249902_f65fd10473_z.jpg


Next I'll be hooking up an eagle tree logger and some sensors. Then I'll take another crack at the belt drive.
 
I looked into installing the belt drive again and I'm starting to think it's not worth it. The reduction I was getting was minimal. With the belt drive I was running 15:24 tooth pulleys or 1.6:1 ratio. The gears I'm running, 25:35|24:26 I'm at a 1.52:1 ratio. So the reduction isn't enough to justify the headache. But if some day I can run a 2:1 ratio I might rethink it but for now I'm going to table it.

But today I did get to do some testing w/ the eagle tree logger. I'm mostly interested in the max amps being drawn but I do have a temp sensor on the motor, a rpm sensor on the clutch bell and another temp sensor for the esc on the way along w/ a brushless motor rpm sensor.

Just running for a few minutes in my street I was able to compare 12s amp draw to 14s amp draw. When I run 14s I turn my throttle endpoint down by 20% to keep my top speed the same as 12s. I started running 14s so I could run 30 minute races (I still need to prove it though).

This first test isn't very accurate b/c I didn't measure my top speed and couldn't do any long distance runs b/c it was dark out. But I was able to see that on 14s my max amp draw was 76A but w/ 12s it was 89A. That is what I expected to see and I hope that when I get a better test the results are even better.

The whole goal of this conversion has been to keep the max amps down. So if I can manage to stay under 80A that would be a success.
 
jackson said:
i wish i could see it running by the time your done with it you'll have built your own model!
Click to expand...
I hope you're not right. The last outing was really good and I didn't break anything. I'm hopeful I'm ahead of the weak parts and I can start enjoying it more.
 
I got the chance to do the testing w/ the eagle tree and comparing amp draw between 12s and 14s. To compare the two setups I measured the top speed w/ a gps (35mph) and the rpm's of the clutch bell (12500). I turned down my endpoint when running 14s to match those parameters of 12s. And sure enough, the amp draw w/ 14s was only 79A while 12s was 90A. That's over a 10% reduction. I hope it equates to long runtimes and cooler temps. I'll report the temps when I get it to the track.
 
Now that the DR was starting to stay together I decided to charge up the 14s/10A pack and see what the duration of track time I could achieve. I only had to stop a couple of times to tighten up some screws but the overall runtime was 28 mins. Not bad but not the 30+ I was hoping for.

Next I changed batteries and hooked up the eagle tree to capture amp draw on the track. After a couple of laps I checked the logger and it said 58A. It would seem correct that my amp load on the track would be less than street testing b/c there is less grip. I am happy the max amp draw is way below the 120A rating of the esc.

But then disaster struck. I heard a very strange clicking sound coming from the gears. After a close inspection I shattered the center gear on the gear plate. The 24T gear. I could hardly believe it. I thought the gears would be the most durable part on the car. So it looks like I'll be revisiting the belt drive again after all.

I am a little bummed b/c after the first back I was thinking about registering for the Nitro challenge in 2 weeks but w/ the gears breaking like that it seems too risky.

Has anyone shattered their gears before, do you know why it happens?
 
The carnage:

8456177966_052093ca57_z.jpg


Does anyone know where I can get these? Everywhere I check seems to be out of stock.
 
Re: My First E-Dune Runner

Wow! I've actually never seen the 4 pin gears up close from the back they sure don't look as beefy as the square drives that were on my MT...you might consider trying to buy a used set from one of the guys that changed to the belt system...just an idea....

Sent from my Shoe-Phone using Tapa-Toe 2
 
RCDAD said:
I've got a used set you can have.
Click to expand...
Thanks I'll probably take you up on that and order some more center shafts and cups b/c they are wearing pretty bad. I'll post a pict so you can recommend part numbers.

Thanks, glad to see you back online again!
 
Back
Top