RX8 or MMM combo? - RC-Monster Forums

Unsullied_Spy · **RX8 or MMM combo? -** 04.30.2009, 12:29 AM

I'm building up another Hyper 7 (slowly but surely) but I don't know which powerplant I want to put in it. Most everything I bash with uses a MedUsa motor but I feel like doing something different for this build. I've already got a MMM that I run in my Muggy and it's a good ESC and the 2650 combo would be good for my use, but I'm tempted to try out the RX8 combo since I already have the MMM. I don't like how short the warranty is, I don't care for sensored motors, and it costs quite a bit more than a MMM combo but it sure is tempting to try one out. I'm building this one to be an offroad-only basher (my TQ is onroad, so the PCR will be offroad) and all I really need is enough power to bash with and stay cool. I like my stuff overpowered but I think with this I'll take a more reasonable approach so it'll be easier to bash.

E-Revonut · 04.30.2009, 01:08 AM

For bashing purposes only the MMM combo will suit you well. I too am tempted to get a RX8 combo but for racing with my truggy. A sensored system is undoubtedly smoother and better for racing.

jhautz · 04.30.2009, 01:18 AM

The beauty of the RX8 is that it is a sensored system only at start up, making it start perfectly every time, but it still has all the power of a sensorless system.

If you intend to race it its the most precise feeling speedo I have ever touched. For bashing either will do just fine. Although I still never like the huge goofy case on the MMM. And having to remove it to change the fan that dies every other run.

Unsullied_Spy · 04.30.2009, 01:24 AM

I do like the way my MMM bashes as far as throttle control. I haven't had any issues with cogging, so the sensored startup doesn't mean anything to me. There aren't any races around here right now but there may be some soon and I may try it out. Not sure on that right now. I like the design of the MMM and how enclosed it is. It's too bad that it needs the fan to cool it with all that plastic covering the heatsink but my fan has never given me any trouble.

jhautz · 04.30.2009, 01:26 AM

Sounds like you know what you need then.

Unsullied_Spy · 04.30.2009, 01:33 AM

Quote:

Originally Posted by jhautz

Sounds like you know what you need then.

Sure the MMM is nice, but since I already have one I could always try out the RX8. Is there anything to the RX8 other than sensored start-up? If I'm going to spend the extra $70 for one I'd like to get something extra out of it. I do like that they make lower KV motors for them, I'd like to run 5s in it sooner or later and that would push the 2650 too far.

whitrzac · 04.30.2009, 09:19 AM

Quote:

Originally Posted by Unsullied_Spy

Sure the MMM is nice, but since I already have one I could always try out the RX8. Is there anything to the RX8 other than sensored start-up? If I'm going to spend the extra $70 for one I'd like to get something extra out of it. I do like that they make lower KV motors for them, I'd like to run 5s in it sooner or later and that would push the 2650 too far.

210amps continuous,

solder posts, better quality, better everything except the warranty

something to think about, but dodge(known for tranny failures) has a lifetime warranty on the drivtrain, ford, toyota, honda, etc don't...

BTW the tower super saver club has a 60 off of $300 now...

Aceldama · 04.30.2009, 09:39 AM

Quote:

Originally Posted by Unsullied_Spy

Sure the MMM is nice, but since I already have one I could always try out the RX8. Is there anything to the RX8 other than sensored start-up? If I'm going to spend the extra $70 for one I'd like to get something extra out of it. I do like that they make lower KV motors for them, I'd like to run 5s in it sooner or later and that would push the 2650 too far.

I've been tossing around the idea of MMM vs RX8 for a while now and here's what I've come up with:

-I plan on running 6s and there isn't a MMM motor that fits this application. So I either need a Neu, which is going to drive up the cost (to well over the cost of an RX8). Or I need a Medusa which isn't an ideal off-road solution due to the open can and non-captured end bells. The RX8 has a great selection of KVs (even if they seem to be a bit underrated by a variable amount of KV depending on who you ask).

-MMM includes the castleLink and RX8 requires that I pay an additional $35 for hotwire which, honestly I feel is a bit of "nickle and dime" for an already $340 system.

-There are tons of MMMs out there but there are also lots of failures. There aren't a lot of RX8s out there but I haven't heard of one failing yet.

-Sensored vs. sensorless: All of my systems have been sensorless and they perform great. I have tried my friends sensored Novak on his 18T and while I do notice the smoothness in the throttle it doesn't add up to anything in our street races. On the other hand, I feel it's better to have it then to not have it.

What is pushing me toward the RX8 is really the motor selection. I don't feel like hunting down and then paying for a Neu with a bolted can. And 2200kv is just way too much for 6s. And until I hear about an RX8 going up in smoke I consider it the more reliable system (just give it a month...).

whitrzac · 04.30.2009, 09:50 AM

you don't need the hotwire!!! the tekin esc's are brainless to program, unlike the castle's...

the only thing on the rx8 that you gain with the hotwire is the timing adjustment.

Aceldama · 04.30.2009, 09:58 AM

Quote:

Originally Posted by whitrzac

you don't need the hotwire!!! the tekin esc's are brainless to program, unlike the castle's...

the only thing on the rx8 that you gain with the hotwire is the timing adjustment.

The timing adjustment seems pretty important considering Tekin themselves are changing the default timing value with the new software download since they think it was a bit high from the factory.

TeamTekin on RCTech:
"The default timing on the Rx8 units shipped was 32 and would raise the kv another 50 or so on each motor. In the new software coming shortly the default has been reduced to 10 as it was suppose to be to begin with."

At such a close time to the release of the product you're going to want the firmware revisions that are definitely coming, which means you're going to want the Hotwire.

_paralyzed_ · 04.30.2009, 10:18 AM

Quote:

Originally Posted by Aceldama

And 2200kv is just way too much for 6s.

umm, it was made to run 6s. not too much

Aceldama · 04.30.2009, 10:23 AM

Quote:

Originally Posted by _paralyzed_

umm, it was made to run 6s. not too much

55,000 RPM at 25v is a bit much. And it sure doesn't leave you with a lot of gearing options. I don't think anyone on this forum would recommend a 2200kv motor for 6s.

BrianG · 04.30.2009, 10:55 AM

Speed runs...

_paralyzed_ · 04.30.2009, 11:23 AM

Quote:

Originally Posted by Aceldama

55,000 RPM at 25v is a bit much. And it sure doesn't leave you with a lot of gearing options. I don't think anyone on this forum would recommend a 2200kv motor for 6s.

e-revo, savage flux. 2200kv, designed for 6s usage. 55,000rpm is nothing for a neu. I understand what you're saying. But 6s on a neu 2200kv is no problem

Aceldama · 04.30.2009, 11:38 AM

Quote:

Originally Posted by _paralyzed_

e-revo, savage flux. 2200kv, designed for 6s usage. 55,000rpm is nothing for a neu. I understand what you're saying. But 6s on a neu 2200kv is no problem

I'm not saying it can't be used. I'm saying it's far from optimal. I mean, Neus are rated for 60,000 RPM and I'd rather not be pushing it to the edge of what it's rated for. I don't want a 2200kv motor on 6s when something closer to 1600kv is a much better match.