Bad gearing, bad tyre choice, dodgy esc and/or radio settings (brake issue) = fail.

I thought this was RC-Monster, not the traxxas forum :neutral:

Instant brakes sounds like either the throttle profile wasnt changed from the annoying default setting of 'forwards-brake-reverse' that engages reverse without you even letting off the brakes, or the throttle channel was reversed at some point before/ after programming to make it behave that way. You cant guess at these things, or scratch your head and say ' umm, not sure ' (like on the gearing question for example). If you dont pay attention to what you're doing, you WILL screw up stuff that costs alot of money to replace.

Always set the throttle to the 'forwards-brake-reverse with lockout' option that will engage reverse once you have come to a complete stop, then release the trigger & re-enage it to go backwards.

</rant>

Gee... who could have seen that coming? A rant from Suicideneil? What a shock! Actually Neil... aside from your generally awful elitist attitude to those who are less your equal, I will acknowledge that you are a great source of information, and you really do know your stuff.

Anyway... I know for a fact that I had FBR w/ Lockout. I always use that. The only way that it could have changed... was by accident. Sometimes when in CastleLink... if you're not careful with the scroll wheel, it can change settings without you noticing. But I'm pretty sure that didn't happen. And I did not chance the throttle curve either.

The reason I hesitated on my saying what gearing I used was because it's been a while since I've changed it, and I've got like 8 trucks. I would have to look to be sure. But I'm almost positive it's 54/20.

I understand the notion of the bigger tires causing more heat. The Badlands ARE smaller, but come on. The Badlands weigh 9.1oz and the Moabs weigh 14.9oz each. So for 4 tires, that's:

Badlands: 2lbs 4oz
Moabs: 3lbs 11oz

So the Moabs outweigh the Badlands by 1lb 7oz.

My truck weighs 8lbs with no tires or lid, including Lipos. So the total truck weight with tires is:

Badlands: 10lbs 4oz
Moabs: 11lbs 11oz

I understand the theory about size, rotation, gearing, etc. Or should I say....I understand that it matters. You can get all geeky with numbers and figures if you want. But the bottom line won't change for me anyway. Which is, the truck with Badlands geared 54/20 never got hot. The can was warm, but not hot. Easy to touch. Same for the batteries. So one would then have to assume that putting the Moabs on it would increase the heat a bit, but not to the point of a flaming ball of fire. It may be worth noting again that everything was hot after the fire. The can, the batteries, wires, etc. With Badlands, running like mad in near 100 degree weather, heat was never like this. This was the very first time I had ran these Moabs. It was maybe 85 degress that night. Not to mention, I hadn't pushed the truck hard at all. No speed runs, nothing. I was just driving around the asphalt driveway, and a freshly mowed yard, doing jumps off a 12-14" skateboard ramp. I wasn't even thinking "Watch out for supreme heat", when I could run like a mad dog with my 1lb lighter Badlands and not have a problem. It just wasn't something I expected.

As far as my radio goes, It's been set up the same way for months. I'd have to look at it later to see what it is. And it's a shame that I can't check my ESC either. I'm almost sure I saved my Profile though. I don't think that I can load that profile using another ESC that's not a MMM. I only have a Sidewinder for now. I'll be checking that saved profile though when I get my new one, just to see. With the radio, the only way something could have changed would be if it had gotten bumped in my bag or in my hand. I should add that the radio is an Airtronics M3. Great radio. I like it anyway.

I've never been around anyone else's ERBE, so I can't compare. But my brakes have ALWAYS been this way. Also, the truck would make an audible sound when braking. Sounded like semi truck stopping sorta, but on a much smaller level. I can't quite describe the sound. But sorta like a deep squeaking air brake type sound. Having no experience with a MMM, I thought it was the nature of the ESC. And with it flipping onto it's lid when tapping the brakes in the air... I also thought it was because it was a super powerful ESC that I was going to have to get used to.

The reason I'm posting this stuff here is, to put it bluntly, a matter of respect. A "tip of the hat" per se to you guys here. You guys are on some other level of expertise.... and I figured out of all the places to post something regarding the MMM, this would be the place. I also posted the same thing in the Traxxas forum. And so far, there hasn't really been much "geek speak" about what could have happened. No slight to those guys though, because there are plenty there that know what they are talking about. Besides, my issue isn't with the ERBE or Traxxas. It's with Castle. And if it helps... the diff's in this truck are the RC Monster 1/8 hybrid's, my Hyperion was purchased from RC Monster, among many other things. So, I think I have every right posting here.

But hey.... if it's a big deal, we can just drop it right now and I'll go about my merry way. It's no shirt off my back really. I'm not here to cause problems.

J

IMO this isn't a heat issue at all... MMM has thermal protection and will take care of shutting itself down when it gets too hot...

This is either bad fet, too much amp issue or a ripple issue or more likely a combination...

The tires are 50% heavier and this does make a big difference to intertia especially as the mass is on the outside of the wheel:

http://upload.wikimedia.org/math/3/0...9413414ddc.png

where m is mass and r is the perpendicular distance to the axis of rotation.

This would cause an increase in the amp draw of the overall system - Partial loads are also quite hard on an ESC as it is switching the current on and off to match your input.

This switching and high amp draw could have caused ripple - This is worse still by the "longish" battery leads with the series connector across the whole chassis - If the ripple gets too much the caps can't cope and you get FET meltdown...

My guess its a combination of the above - you could add an extra HV cap to the input leads to help...


PS Neil just needed chocolate...

Interesting point. I'll admit, that I'm not experienced enuff to even begin to argue. Sounds good to me though!

So, you think my leads were too long? If they were, they were only long by maybe an inch. I didn't have all that much slack if I remember right.

Also, are you saying that they way I had it wired in series was incorrect? Or... where the wire was located? I'd have to see a picture of another suggestion. I'm a visual learner I guess.

I don't want this to happen again that's for sure. And I'm going to have to make up some new lead anyway. So do you have a suggestion for gearing to try? I realize that you just have to experiment a little. But I don't want to go on a gear buying spree because they are expensive. I'd like to stick with these Moabs if I can, and speed isn't my thing really. It's nice to have on tap, but i'll trade speed runs for medium speed bashing any day.

Thanks!

Those lipos are in series no question about that.

I'm guessing bad fet's or ripple voltage killed the MMM along with running McD's super sized tires.

When you get your ESC back from castle and you still want to run the Moabs thats fine, but I would seriously considering gearing down a bit when running
6s. Going buy what you wrote about gearing,motor etc your topping out at around 58mph, it's a bit much ?

If you haven't seen this it's a very helpful tool thanks to BrianG.
http://www.scriptasylum.com/rc_speed/index.html

Yeah, Neil gets a little grouchy at times. I think he just needs a hug, but I'm too far away (it's a long swim), and it probably wouldn't be welcomed anyway. You just gotta read in between the rants to get to the "meat" of the post.

The tires do look rather large, but as long as you were geared to compensate, it shouldn't be a problem. Temps were ok, so thermaling was not a concern. Maybe something got caught in the drivetrain momentarity causing excessive overcurrent? Or maybe the MMM decided it had enough.

As you know (and was said), wires should be kept as short as possible while retaining enough slack to reach their destination without stress. And, if you had it wired incorrectly (in parallel vs series, or series the wrong way), you'd definitely know it; the truck either wouldn't move at all, or be very slow.

I personally still think the abrupt brakes issue was either caused by improper ESC/radio calibration, or the servo reversing was set wrong. The reason I say this is because you said you used the same radio and has been this way from day 1. The brakes should NOT be that touchy, especially since you turned down the brake force. Once you have it set up right, you'll see how they are really supposed to work.

An indication (aside from heat) of overgearing is short runtime. What kind of runtime are you getting with what voltage/Ah battery? (You may have stated this previously, but I'm too lazy to look). 6s @ 5Ah of decent cells should get you at least 20 minutes. If you were getting 10-15 minutes, then gear down a bit.

Good luck and let us know how things turn out!

Yeah, I know about 'ol Neil. I can take it tho' :wink:

In fact... he went off on me in the TRX forum about something stupid. Which I didn't mind. I took it all with a grain of salt. But he was REALLY on one that day, and just brutal. I responded to his post and didn't back down one bit. But somehow or another the Traxxas Police Dept caught wind of the thread and banned him! HA! I felt so bad, because I didn't feel it was necc to do that. Those guys over there are the touchiest people in the world if you ask me.

Any-hoo.... I'd like to stick w/ the Moabs, yes. But let's be clear on something... 58mph was not achieved using the Moabs! This run where the ESC smoke was the first time I'd ever ran them. And I SWEAR on my life that I was not running hard, or even close to hard. I didn't have a lot of room to do that. I mostly putted around the yard throwing wheelies while everyone there looked in amazement. I also let my Bro-in-Law drive it, and he almost crapped his pants. He could barely drive it, and he for sure never got on it because he was scared too. Then I took over and would do a jump, circle back, do a jump, circle back, repeat... then it stopped moving, and the rest is history.

With the Badlands... I would run it WOT down the street over and over, flew around my giant yard in an oval, pull a jump, repeat. I drove it HARD and never with a problem.

I will admit though, that occasionally after a jump, the landing would cause the red wire from the ESC to pull out of the right battery lead. I'd power off the ESC, reconnect it, turn the ESC back on and go. That's what I thought happened when the truck stopped running the other day. I had just landed a simple jump, started to drive it back to me, and it stopped. I thought the wire had came loose, but it hadn't.

I'm going to try some different Spur gears for sure. But in trying new spurs, what would you suggest? Maybe leave the pinions and change the spur to something bigger? I don't want to smoke the new ESC "experimenting".

I LIKE the Badlands though. Don't get me wrong. They are the bomb on dirt! And they literally RIP grass from the ground. But they are almost too grippy sometimes. I was digging the Moabs because they looked good and they weren't as grippy. I could do some drifting type turnarounds. Perhaps getting some Relux rims and some other kind of tire would be best though. Something the size of the Badlands, just a different tread. I'll say that the Traxxas Response Pro tires I have on my 3.3 Revo are probably the best tire I've yet to run, and I've run lots. They actually "sing" when running across whatever surface. But they are mounted on 17mm splined hexes, and I don't want to covert the ERBE over to that size.

As far as runtime is concerned, I can't say for sure w/ the Moabs. But w/ the Badlands, same gearing, I was getting probably close to 30min runtime. Because I wasn't hell bent for speed the whole time. it would take about an hour to sync charge them both.

It's so strange to me that perhaps the settings with my radio could have been off somehow. When I go home tonight to look, what specifically should I look for? But it's all moot since I can't verify anything on the ESC right?

Also doesn't the fact that I have a Neu 1515 2.df come in to play? Wouldn't it's ability to slow the truck down have anything to do with the uber powerful braking? Heck, I was thinking of going from 30%, down from 50%, and taking it to 20% even!

Plus, since I was running the RC Monster Hybrid 1/8 diff's, wouldn't that have actually lowered my gear ratio a bit more? One thing I failed to consider when putting the Moabs on I guess.

When you get it running again, put some negative curve in your brake curve. This will help with your having to reduce the brakes so much to keep it from diving when you brake a little in the air.

So, are you saying then to pull the curve down a bit? If I could see what it looked like, I would do much better. Or, if you told me what range to adjust it to, and at what point to bring it up, I'd understand.

As to your radio, yes it's possible, and yes, it will be a moot point to check without an ESC (unless you have another MM/MMM just to try it). Definitely something to look into once you get a new/repaired ESC.

Yes, the 1515 is a very powerful motor, but the ESC controls the amount of brake force in proportion to the radio brake input. What you describe sounds like it was all or nothing, and that's not how it should act, no matter what size motor you have. Again, I suspect a radio/ESC calibration issue, or the throttle channel was reversed in the radio. It's gotta be one or the other unless the MMM brains circuit was totally goofy (and I suspect you'd have had other issues if that was the case).

Yes, the 1/8 scale diffs do make a difference. IIRC, the stock diff ratio is ~2.6:1 or 2.8:1, and the hybrids are either 3.3:1 or 4.3:1 depending on if you got the buggy or truggy version. So yes, it was "geared down" just from the diffs. But, a large tire can add substantial amount of speed, more than you'd think. Go into my calc (link in the sig) and enter all your data and see what the speed is.

At any rate, if speeds were in the 35-45mph ballpark, you're fine gearing-wise. Something just happened to the ESC to make it go poof, and we'll probably never know. I would look over the driveline (particularly the center area) to make sure there aren't any rocks or anything that might cause it to jam; just because it rolls freely on the bench doesn't mean it will when running because a rock or something may be in a position where it makes occasional contact enough to jam. I frequently get this on my CRT.5; a rock will jam between the axle and a-arm and I'll suddenly be doing donuts. Since the ERBE doesn't have a center diff, I would look at the center drive line as that is the only area that will actually stall the motor (the individual axles would diff out).

jpoprock, I haven't much to add as it has already been said, but I like your attitude! :yipi: More people should take things on a forum with a grain of salt. Why let written word :rules: on an internet forum from a person you don't know get you riled? :diablo:

As for neil, he just needs to get laid. :surprised: It is fun watching him call people out though.......:yes:

I'd like say I agree,You have a better attitude than most and it exceeds mine for sure ! Linc ruffled my feathers a few days ago and I got pissed off but quickly realized that it's a 2 way street and I can shoot right back without letting anger and emotions get in the way. After all were here to help each other and hopefully have some fun in the process.

kinda on topic but... does lowering the braking power 30% lets say, would that lower the braking amperage spikes? pertaining to the mgm way over my head write up

hmmm.. my MM in my .5 has been doing the same thing. I'll have to check this.