Cooked mmm, well done of course - RC-Monster Forums

93firebird · **Cooked mmm, well done of course -** 04.17.2009, 08:07 PM

My new mmm just went up in smoke. I was running a 4s lipo 2200kv neu-castle motor and my gearing was 19-46 on a Cen genesis. I was running a center diff alone and was getting a lot of cogging when starting out. Will the warranty cover it?

BrianG · 04.17.2009, 08:09 PM

As long as you didn't mod the case or solder to the internal PCB, I don't see why not. Although gearing is a little high IMO. 5s lipo on that motor geared down to ~14T would be easier on it.

93firebird · 04.17.2009, 08:25 PM

Quote:

Originally Posted by BrianG

As long as you didn't mod the case or solder to the internal PCB, I don't see why not. Although gearing is a little high IMO. 5s lipo on that motor geared down to ~14T would be easier on it.

Well I was in the process of testing gear ratio I did not run it very much. I did not do anything as far as modding the esc, everything was original.

93firebird · 04.17.2009, 09:01 PM

Here is a pic of the aftermath

BrianG · 04.17.2009, 09:18 PM

Just curious, what version is this, and what firmware version were you running?

93firebird · 04.17.2009, 09:31 PM

its a v3 and I was using the latest version available for download

93firebird · 04.17.2009, 09:31 PM

like I said it was brand new, only had it running like 3 times

BrianG · 04.17.2009, 10:02 PM

I guess you were one of the unlucky ones then.

To help keep this from happening again, I'd drop gearing. The more I think about it, the more I think that it was geared too high on too heavy a truck (especially with those tires!), for 4s IMO. It's probably a simple matter of drawing too much current.

Of course, gearing down will lose top speed, but then you can run 5s or 6s lipo to get it back. Although, on 6s, I'd drop down to 12T pinion and get a bigger spur if there's one available.

e-mike · 11:17 PM

right brian... at the weight of the truck and the gearing im not surprised to see that kind of failure but the monster can take a huge amount of amp ...mine melt exactly the same way....in my e-revo and this is a light set-up(18/68,2200kv 6 cell)...the v3 is solid i know what im talking about

anybody can have a badluck...

93firebird..call castle they take care of you

MetalMan · 04.18.2009, 12:04 AM

Okay, running the numbers...
CEN Genesis has 9/26 diff ratio, correct? And let's say 7" tall tires (even if they are taller than that). 2200kv, 14.8v, 19/46 spur/pinion gearing.

Assuming the numbers I listed are correct, you were geared for a solid 90+mph. No wonder the MMM died.

Even if you could fit a 10t pinion, you would still be overgeared at 50mph.

Patrick · 04.18.2009, 12:36 AM

Poor MMM never had a chance.

twisted8 · 04.18.2009, 12:46 AM

shouldnt the batteries have taken a beating 1st ?

lutach · 04.18.2009, 10:01 AM

There should be a sticky telling people to stop trying to get their vehicle(s) going when it stutters badly, it will always damage the ESC and things can be sometimes ugly. I saw a guy with the same problem at my LHS and I told him to stop as that would cause the ESC to burn, well he didn't listen and in about 10 sec. the ESC started smoking and the cause of this is like others mentioned, geared to the moon or a very high Kv motors geared to the moon as well. I would love to see people do this to their real vehicles.

93firebird · 04.18.2009, 11:45 AM

Quote:

Originally Posted by lutach

There should be a sticky telling people to stop trying to get their vehicle(s) going when it stutters badly, it will always damage the ESC and things can be sometimes ugly. I saw a guy with the same problem at my LHS and I told him to stop as that would cause the ESC to burn, well he didn't listen and in about 10 sec. the ESC started smoking and the cause of this is like others mentioned, geared to the moon or a very high Kv motors geared to the moon as well. I would love to see people do this to their real vehicles.

Well since there are no conversion kits for this truck yet gearing can be hit or miss. No one has a set ratio to use, but it looks like what I was using was too much.

lutach · 04.18.2009, 12:51 PM

Quote:

Originally Posted by 93firebird

Well since there are no conversion kits for this truck yet gearing can be hit or miss. No one has a set ratio to use, but it looks like what I was using was too much.

Your set up is basically similar as most 1/8 scale conversions. I go by BrianG's calculator and if you're not using the transmission it would have saved your MMM.