Stretched e-Muggy (Baja-style) Build Thread

[brian015]

I took it out for another test run around the yard on 6s with the rc-raven springs - they do the job - a great $7 purchase. I don't have a scale, so I haven't weighed this thing yet - but I'm estimating about 17-18 lbs. Still haven't finished the last two brackets on the rollcage - hopefully soon.


Edit: Also screws kept coming loose from muggy steering tie rod (I had even put a little blue loctite on them last time), so I decided to tighten them good - until I snapped one of the screws heads off with the rest of it in the bushing. So I got rid of that whole set-up and installed a titanium tie-rod with adjustable rod ends. I used 3mm screws inside a 3/16" plastic sleeve inside the bellcranks and 3mm locknuts. Hopefully it will stay tightened now.


Next edit: I took it out in the yard on 8s geared conservatively - everything worked fine - the steering mod worked. My only issue right now is oversteer. I was tightening down the pre-load in back, but a quick read on fixing it tells me I was going the wrong way - I needed stiffer front and softer back to correct it. Hopefully I can work that out.

[brian015]

Here's how I attached the baja 5b rollcage and its wing mount to the muggy wing mount for what I think is a very sturdy wing mount (I'm waiting on a baja wing in the mail - I put a 1/8 wing on it but it looked too small).

I cut the muggy wing mounts and drilled holes through them for my extra orange tube (from the stock baja 5b rollcage) to fit through and screwed through the baja wing mount.



The baja rollcage is also attached to my rear aluminum shock tower with one screw on either side:



And you can see my new black rc-raven springs installed (also my custom esc mounting strap).

[simplechamp]

Wow, that motor is wild! Awesome truck.

How is the center diff working out with 100k silicone? I know you said your front tires are getting chewed up quickly, is it unloading too much up front?

[brian015]

Originally Posted by simplechamp

Wow, that motor is wild! Awesome truck.

How is the center diff working out with 100k silicone? I know you said your front tires are getting chewed up quickly, is it unloading too much up front?

Thanks.

100k seems good so far in the CD - but this may be because I haven't put enough power through it to see the front end lifting up - so I'll have to wait to see about any unloading problems. I think I'll have to really try to get wheelies with this thing - I have the weight pretty evenly distributed front to back and with as long as it is. This is fine by me - no interest in wheelies.

I taped the front tires and foams to keep ballooning to a minimum and have stayed on the grass mostly - so front tires don't seem to be getting worse - but we'll see.

[Jahay]

you taped the foams as well as the tyres? I heard somewhere that it was a bad idea????

[brian015]

Originally Posted by Jahay

you taped the foams as well as the tyres? I heard somewhere that it was a bad idea????

Many others have done it - I've never heard of problems. And if I'm taping the inside of the tires, what difference would it make if I also put tape around the foams? I can't see a possible problem.


edit: you can also see in the above pics part of the heat sink I made for my motor (when I take the motor out again I'll take pics and show how I did it)


another edit: Since I mentioned the rear shock tower - it's this one (no longer red, though):
dynamite lst shock tower

[brian015]

I got the rollcage finished and the wing installed. I took it to the park for the first time and ran through 8s 5000mAh in about 25min geared for 40mph. The oversteer isn't as bad with the rear shocks softened, but I'm going to do some more testing as to how I can reduce it (or get used to driving it). Outside temp today was about 81F. After I was done, temps were:
batteries 98F
esc 112F
motor 132F

I will gear for higher speed on 8s and give it a try.

Here it is, finished:




edit: I looked at my new rollcage mounting brackets in the center after driving it and rolling it only once - and they're bent. So instead of 1/8" Al angle brackets, I guess I'll go to 3/16". Well, now that I'm finished building the truck, I guess I'll start fixing it.

[Jahay]

Looks great!!! yea with those temps, seems you can get more speed out of the motor without hurting anything!!! GET SOME VIDS UP!!! looking forward to seeing this go

[brian015]

Ok, so I want to try to tune this thing a little to reduce the oversteer by changing the diff oil weights. Right now I'm running 10k/100k/10k. Do you think I should try reducing the oil weight in the center or the rear diff first? From what I read, either should reduce oversteer. Any thoughts are appreciated - thanks.

[brian015]

I just took this out again - I geared it up to 51mph on 8s. That gearing really woke this thing up and it can move (I don't know when I'll have vids). It was really squirrelly at high speeds on low grass - the rear tires were really ballooning, so I'm going to have to tape those too.

After about 20 minutes, temps were:
batteries 112F
esc 119F
motor 152F

I'm happy with the speed and power and temps with this gearing. I'll have to try it on 10s at some point geared for 50mph and see it the motor likes that better. At this point I don't see a need to gear for higher speeds.

[brian015]

I taped the rear tires and I mixed up some thinner diff fluid for the rear - probably around 2k weight. It helped reduce the oversteer significantly and it now handles much better. The only issue is when I punch the throttle, it can easily go off track. I don't know if reducing the center diff weight will help this, but that's what I'm going to try next.

[brian015]

I've been tuning and testing this and have it where it handles well on dry grass on 8s geared for 50mph. It's still twitchy at high speeds if I punch the throttle (lots of power!) - but it's very controllable. I'll continue to tweak it but I'm happy.

Temps after driving it pretty hard for about 20mins (90F ambient):

batts: 114F
esc: 132F
motor: 160F

I also checked my diffs' temps and was surprised to see my center diff was 190F (rear - 145F, front - 130F). I have 25k diff oil in there now - I may have to thicken it up again if the CD temps are a problem.

Anyone know how high is too high for silicone diff oil - or diffs in general? I expect the silicone can go much higher than that - it's used for cooking utensils rated for 400F. I've never paid much attention to diff temps before, so I haven't given it much thought.

Edit: I'll get vids up later this week or weekend when my wife gets home with the kids and the video camera!

[brian015]

I was driving on some soccer fields, getting it up to full throttle for some speed runs across the field. The grass is very dry and dusty - poor traction. So I was about to finish up, but did a couple more runs, the last of which, I thought I had everything under control, but drifted a little at high speed - into the soccer goal post.

I was expecting major damage as I saw one wheel + other parts flying in one direction and the rest of it in another. So I was happy to see it was mainly the plastic arms that broke and a bent driveshaft:



Then I got home and saw the right rear driveshaft



Those arms are bent and need replaced too. Luckily I have a box of extra arms and other parts - I'll have this back together to take it out tomorrow.

[JAILBIRD]

Now that is a trick!! Doesn't all the bad stuff happen on "one more time"? That's the way it goes for me.

-JB

[Overdriven]

Originally Posted by JAILBIRD

Now that is a trick!! Doesn't all the bad stuff happen on "one more time"? That's the way it goes for me.

-JB

Me too!! Blew the rear diff in my e-revo doing "one more" wheely, and the cd in my ofna buggy doing "one more" hard dragster style launch. All this past weekend. Got the parts laying around and a few days before the weekend, so its all good.

Good to see the carnage isn't that bad though. I don't think you'll be able to tune out "all" of the on power drifting. Its inherent in shaft vehicles, especially ones with huge power. Thats why the touring cars are all going to belt drive, to get rid of the effect.