MIKE!!!!!!!! (RE: 1st run, MMM/2200kV on 4S...not good) - RC-Monster Forums

Chadworkz

The reason I said "Mike" was because this refers to one of his products, but input from anyone is welcomed.

Ok, I converted a nitro Revo 2.5 into a brushless Revo 3.3, and I am using Mike's RCM motor-mount...I am also running an MMM/2200kV combo on 4S (2 x 4S @ 2650mAh Zippy Flightmax packs in parallel for 14.8v @ 5300mAh). Well, I installed the final pieces tonight, so I charged my packs and went outside to check things out...this is where it all went bad!

I turned everything on and sat the truck down, barely squeezed the throttle to get the truck rolling and set my steering trim to go straight, I then gave her a little more throttle...as the truck sped up, I pinned the throttle to see what she could do, and what she did was do a half back-flip and slid on her top for about 10 feet (no body since I was testing).

The first thing I noticed when I flipped the truck back over was all three of the motor wires on the ESC ground through (but not touching). Since I wasn't running a body, and the ESC was mounted on top of the transmission, the slide just ate through the wires. Anyway, that is easily fixed, now on to my major problem...

WHen I put the truck on my work table, I immediately noticed the motor sitting crooked...the back-end jacked up almost a half-inch...it was easy to see why, the RCM motor-mount was bent way forward! I never saw this coming, since the mount is crazy-thick and Mike does excellent R&D and machine work. Well, it happened, and I don't know why.

Is the Neu/Castle 2200kV motor on 4S THAT stout? I mean, nothing else could have done it. It is geared 16/36, but that shouldn't have done it. ANyone have any guesses? Mike, I mean no offense, but could this have been a defective piece of aluminum with low quality? Anyway, here's some pics...

lincpimp · 04.24.2009, 01:28 AM

I guess the weight of the motor was enough to bend the front as the truck landed from the flip. Looks like something like a large zip tie could be used to keep the motor firmly pressed to the rear support. That would mot likely cure this issue... Not really a materials failure, just a design consideration. While the rear support prevents the motor from going down (like on a hard regular landing) it does not stop the motor from going up (like a hard upside down landing).

Chadworkz · 04.24.2009, 01:32 AM

You know, I almost used an old toe-link to brace the top of the motor-mount, but chose not to because I never thought this could happen...heh, guess I was way wrong!

lincpimp · 04.24.2009, 02:25 AM

Quote:

Originally Posted by Chadworkz

You know, I almost used an old toe-link to brace the top of the motor-mount, but chose not to because I never thought this could happen...heh, guess I was way wrong!

Yeah, looks like you need a hammer and an anvil now!

Chadworkz · 04.24.2009, 02:43 AM

Do you think straightening the mount will be ok, or would you suggest ordering a new mount?

lincpimp · 04.24.2009, 02:45 AM

Its just metal, I would straighten it out if you can do it well enough to ensure it is really straight... If not I am sure Mike will do something for you, he is a great guy!

Arct1k · 06:17 AM

I wouldn't - you managed to do something serious to get it to bend like that - contact mike and get a new one...

One other theory - Rotor play... When you spooled up does the rotor move further out and the pinion get caught in the slipper - I think the motor was probably pulled over...

Chadworkz · 04.24.2009, 07:03 AM

You know what, I was worried about how close the pinion was to the slipper, but I moved the pinion as far onto the shaft as possible...the end of the flat-spot is as far as the pinion would go. I will check the slipper plate really well to see if there is any damage from the pinion hitting it. Thanks for that info, Arct1k!

Arct1k · 04.24.2009, 07:48 AM

Sometimes it works if you turn the pinion around and have the screw side on the end of the shaft.

If you've managed to bend that mount once it is only going to be weaker if you bend it back and if it isn't aligned properly you will only damage the spur and / or the motor bearings.

RC-Monster Mike · 04.24.2009, 10:15 AM

Send me the bent part and i will send you a replacement - we have a few hundred of these motor mounts out there and only a handful have been bent, so the design itself is pretty strong - I guess the term "normal use" comes into play here. The material is 6061T6 aluminum and is pretty thick - pretty impressive bend(must have been quite a forceful flip, as the strength test on this particular part included me standing on the motor mount and "hopping" up and down a few times). I weigh 185-195 pounds(depending on the season). :)

BrianG · 04.24.2009, 10:47 AM

Wow, that's a serious bend there! I bash my stuff pretty hard and have landed on the lid countless times, not to mention cartwheeling, crashing, etc, and never had that kind of problem. The worst I've ever done is bend the screws that hold the front piece to the bottom piece.

lincpimp · 04.24.2009, 10:52 AM

Quote:

Originally Posted by RC-Monster Mike

Send me the bent part and i will send you a replacement - we have a few hundred of these motor mounts out there and only a handful have been bent, so the design itself is pretty strong - I guess the term "normal use" comes into play here. The material is 6061T6 aluminum and is pretty thick - pretty impressive bend(must have been quite a forceful flip, as the strength test on this particular part included me standing on the motor mount and "hopping" up and down a few times). I weigh 185-195 pounds(depending on the season). :)

He probably got it "just right" when he flipped it! Your stress tests sound alot like the one I do when I make something! As far as the desing goes i have to say that the old style revo mount I got way back when is still working fine. I flipped the 4 tec about 50 times at 70mph and stuffed it into telephone pole, not damage to the mount...

Arct1k may have something here, the mount may have flexed slightly and the pinion caught the slipper plate and pulled the motor under power...

Quote:

Originally Posted by BrianG

Wow, that's a serious bend there! I bash my stuff pretty hard and have landed on the lid countless times, not to mention cartwheeling, crashing, etc, and never had that kind of problem. The worst I've ever done is bend the screws that hold the front piece to the bottom piece.

I have done all of the above and never did bend the screws, I did have them come loose once, so I took some red loctite to them!!!

Arct1k · 04.24.2009, 11:04 AM

Linc I'm not even sure the mount flexed - the castle motors have a fair amount of "float" in the rotor so they find their natural position. It could be it moved too far when fully throttled up...

BrianG · 04.24.2009, 12:07 PM

Quote:

Originally Posted by lincpimp

...I have done all of the above and never did bend the screws, I did have them come loose once, so I took some red loctite to them!!!

Yeah, but a Revo weighs a tad more than a 4tec.

lincpimp · 04.24.2009, 12:11 PM

Quote:

Originally Posted by BrianG

Yeah, but a Revo weighs a tad more than a 4tec.

True, I never bent it in the revo, or the 1/8 buggy, or the maxx, or the 4 tec...