new brushless emaxx - awesome!
 

Well guys I think she is complete thought you might like to see some pics. Cant wait to get out and kick some nitro butts around !

Its a 9920 with 540C 8XL and geared 51/16.

I was getting a lot of radio interference and it was twiitching a fair bit especially after i rolled and the truck was on its lid. Moving the BEC around has seemed to resolve this and I was suprised the final position was only about a centimeter from where i originally had it and now it seems great.

I popped the endbell off yesterday as well in a small crash. Wasnt that bad I thought and nothing else broke or came loose, but a bit of steel epoxy seems to have sorted it out. If it comes off again I might make up a clamp to go over and hold it tight. It didnt appear to damage anything. Was also surpised at how simple the internals of these motors are. I was sure that I had done some permanent damage when i first saw it!

I also had to glue my tires on again as the power had pulled them off in a few places!

Overall I am very pleased with the results and thanks to a lot of the the guys on here for ideas I borrowed and help answering questions :) and am now considering another brushless project maybe a truggy or 1/8th monster truck.

http://img402.imageshack.us/img402/6...3412ay0.th.jpg http://img260.imageshack.us/img260/3...3411ai3.th.jpg

Nice truck, glad to here your happy with it and solved the glitching equipment placement can be a trial, tyres have been a problem for me too, who's going to be the first company to make brushless wheels and tyres? With wire belts and more area for glueing.

Nice truck!! Have fun with it!! Do you have problems with heat at all on the 9920?

Thanks guys :)

ok just took it for a run on 12 cells and recorded temps, havent had a chance to record them with 14 cells yet (forgot my temp gun lasttime.. doh!)

ESC - 35C (95F)
Motor - 60C (140F)
Batteries 70C (158F)

I'm ok with these for now but will have to wait and see how it goes with 14cells. I am also thinking about trying a 16cell setup as well but realise I will definately need to change the pinion up a for this. Was thinking about going to an 18tooth

I've forgotten the rules about gearing and temps. Is it motor hot, gear down, esc hot gear up?

ok just did a run with 14 cells and took some temp readings.

ESC - 32C (90F)
Motor - 72C (161F)
Batteries - 86C (186F)

Now the batteries are getting pretty hot but i really like the speed of it :) I'm thinking gearing up to and 18T pinion will probably cool it down a bit. would going to a 17T be enough of a change to drop the temp but without too much speed compromise?

Also im interested in why the esc temp is pretty much the same between the 2? My expectation would be that the added voltage of 14 cells would increase current draw and make the esc run hotter? Am i wrong in thinking this?

I've been running on grass thats about medium length, about 2 - 3 inches

Nice setup you have there.

One recommendation is yes, get a new radio as soon as you can, I am getting a spektrum DX 2.0 for my truck. I was using the TQ-3 for a while and it's horrible, glitching like crazy, doing it's ownthing at times, and 150 foot range.

Man those batteries are HOT!

Yeah, they are hot, you might want to gear it down a bit. Or are you running it hard to get those kind of temps?

Well i was running in a pretty open field and doing a lot of long straights at WOT. Not normally the type of running i would be doing.


I have an 18T to try, might give it a shot, may also get a 17T.


How hot is acceptable? Also i'm interested in why doesnt the ESC get any hotter even with an increase in cell count? Is this because its getting underworked as a result of the smaller pinion?

I think 140 is max rating on most batteries. I don't like to get over 130 for nimh, less for lipo.

If the batteries are getting hot, then you're pulling more current than they can handle. Putting a bigger pinion on will pull more amps and make the problem worse, so if you were using a 16t, don't try an 18t with those batteries. I think the max temp for nimh's was about 55C (130f), definitely not more than 60C.
Also if you keep the same motor and gearing and just add more cells, then with the same driving conditions the higher voltage setup will be able to draw more amps, and heat up the batteries more, like you saw with 12 cells versus 14 cells.
If it was me I would gear down to protect the batteries, or get some better batteries that can handle the current. Since the motor and ESC temps aren't too hot you could keep that gearing with the better batteries and if you get some light ones, like trackpower's there could be room to gear up, because your carrying less weight.

Thanks Patrick.

I have GP and IB batteries so they are decent quality. I dont really want to go to LIPO as i like to bash around and I am aware that they are arent as tough as the nimh cells.

I have a 15T pinion as well, but without shaving off the fins on my 8xl there's no way i can get it to mesh correctly (which i didnt really want to do)

Can you please clarify for me the rules about temps and gearing up and gearing down? I cant remember if its motor hot, gear down, esc hot gear up or not. Also does gear up mean increasing the teeth on the pinion or decreasing?

http://www.rc-monster.com/forum/showthread.php?t=2200
You can also find this thread in BrianG's sig.

cheers. I knew i'd seen it somewhere should really have looked harder!

Interesting that theres no mention of hot motor, hot batteries, cool controller which is what I am experiencing.

My drivetrain feels pretty good and theres no binding that I can see but I will go over it again tonight.

Just thinking about it a bit I would have expected that reducing the teeth on the pinion would result in the motor spinning faster and increasing current draw? is this wrong?

Load makes the motor draw current I think.
I think motors draw more current from spinning faster, either because it's a higher kv motor or it's running on higher voltage to get the rpm.
Usually you get your highest current draw when you first gun it off the line, even though the motor is turning the slowest.
Feigao's always get hot and yours isn't dangerously hot, batteries alway get hot if there not up to the task of brushless and yours are dangerously hot. Maybe the controller isn't hot, because it can handle more than the batteries? or you didn't temp it in the hottest spot? I think the caps usually get hotter than the heat shrink.
I like that double motor plate. Does it let you flip the motor to the other side of the transmission? Then you wouldn't have to worry about the motor hitting the tranny with smaller pinions.

I put it on originally as some protection so i didnt get my wires eaten up in the gears but I did think about mounting on the other side while putting it all together and mocking up. It didnt leave me a lot of room for the 7 cell batteries when i did so went back to the current way. i might have another play around with it to see if i cant get a layout im happy with.

Very nice oz, very well done IMO. A new chassis in the future would be in order which would give you more room, just a suggestion. The extended FLM is nice and very cost effective.

Did you mean me neweuser? Thanks for the compliments if you did :) I'm pretty happy with the way its worked out.

Yeah space is a bit of premium in the stock chassis, maybe when i break this one i will upgrade. I do also need a new body as the one I have is battered to bits!

Once i get to the bottom of the hot batteries issue i'll be very happy, im wondering if it maybe is an issue with some sort of restriction in the drivetrain, it feels fine but i guess even a slight bit of resistence could cause the motor to work harder and need to draw more current?

The trans is pretty noisy but i dont remember really if its noisier than before i pulled it apart because the stock titans are louder than the 8xl.

Yes you, ooops! EDIT Just getting better batts may be in order as well.

:027:

Well i've got decent batteries, at least i thought i did. GP3300(6 cell) and IB4200 (7 cell), also have some new TQ4400's (7 cell) on their way from maxamps. If these arent up to the job, the only option i can think of is going lipo which I dont really want to do yet as I like to jump and bash more than race.

i agree with newe - the FLM chassis improves handling a great deal plus gives a lot more room for batteries. and if you're staying ni-mh, a good set of matched 7 cell packs will make your truck seem like it's a fire breathing beast compared to the packs you have. i highly recommend SPC matched packs over maxamps non-matched ones.

ok just took it out for a run, this time on the street and not in the grass.

Again doing lots of WOT runs but the temps were a lot more even. I got a reading off the caps this time too and everything was about 60C. Unfortunately I popped part of my steering out and had to finish a little early but I will do some more testing and see how it goes.

From this initial testing I guess the addded streess of running in grass could be the catalyst for the extra load on the motor and batteries to get my temps so high.

What do you guys think?

You dont want to know what I think about most of the time. With regards to grass, it really does bog down a truck, even if its just a few inches long. Its like a person trying to run on a sandy beach- you quickly get warn out. I like the motor mount idea too- it would allow you flip the motor so its mounted more like this:
http://homepage.ntlworld.com/ryan.co...s/emaxx/16.JPG
Credit to Candyman- old G1 chassis photo.
Obiviously with one motor, and you would need to either change the motor wires around or flip the diffs. But it would allow for more gearing options, and better weight balance apparently. Im getting the X-brace motor mount for that reason soon, but the way you have yours set up is rather cool. On the batts front, side by side packs seem to run cooler than end to end packs (the way they are soldered), so that might be worth considering doing too. And video, I want to see video.....

neil, what chassis is that you are running there? It looks like the GMaxx chassis, but not. It that custom>?

Thats Candymans Gorillamaxx G1 chassis- very old photo I borrowed. You can see the design hasnt changed much, just got a little more refined.