My Revo 3.3 Brushless Conversion

[pfunk]

Just wanted to share the conversion I have been working on for club racing. I also have some questions about gearing.

Setup:
Hobbywing 150A esc
Kershaw Designs Revolver 8XL
RCM motor mount - mounted on modded 3.3 engine braces (not in pics)
Tekno battery tray
Mechanical brakes(not in pics)
Center diff w/ rear brake
Turnigy 4S 5000mah
Zippy 2x2S 4000mah
Mod 1 19/38 gearing with close ratio locked in 2nd - 36mph

My problem is that the motor seems to get a little hot. I see temps near 165 for the motor and 110 for the esc. The truck runs great but I'm afraid that the motor is getting too hot. What should I change about my gearing?

[magman]

First...welcome to RCM!

How long after running does the motor get that hot?

[pfunk]

I got 165 after running a 12 minute main at the track. The temp was checked at the back of the motor almost immediately after running. Maybe the temp is fine as long as I keep an eye on it?

[magman]

I am not familiar w/those motors so I would try to keep temps around 150 if you can. Try going down 1 tooth. Here is a good guide to follow.

Another suggestion is to upgrade to a cc/neu motor. Probably a lot better quality than what you have now. The better motors are well worth the money if you are racing...they generally will run cooler and last much longer, provided the set up is correct.


Hot, warm, and cool vary as well, so here's another general rule:
Hot for a motor = generally over 160F (71C)
Hot for a controller = generally over 150F (66C)(or "thermal" range for the controller)
Hot for batteries = generally over 150F (66C) for nimh, 130F (54C) for lipo
Warm for a motor = generally 100F (38C) through 150F (66C)
Warm for a controller = generally 100F (38C) through 130F (54C)
Warm for batteries = generally 100F (38C) through 130F (54C) for nimh, ambient temp through 120F (49C) for lipo
Cool for all components = generally ambient temp and up to 10 degrees F (5.6C) more

[pfunk]

I remember seeing those guidelines. I wasn't sure if this was a case of under gearing or over gearing though. I don't have the money for a new pinion at the moment. I'll try my 40t spur and see what that does for me at this next race.

As far as I know, these kershaw designs revolver motors are the same as the fiego motors. Are the fiegos known to run hot?

[magman]

Yes they do run a tad on the hot side and they are not the best quality either. Save up for a ccneu...great motors for the price. The 2200kv on 5s would do nicely in your set up.

A suggestion....before you go and race...try different gear combos. so that when you get to the track there are no surprises as far as temps. go. Of course, you can't plan for everything.

Good luck!

[pfunk]

I took you advice and ran a pack through it in the back yard. I'm not sure if I was able to push it as hard as I do in a race though. With the 40t spur, my max temp on the motor was 152 and the esc was 109. The loss of top end wasn't too noticeable. I also had a few more minutes of run time. I should be good to go.

I always hear that the wheel spin on a dirt track is what really heats these motors up. Any truth in that? I was driving on somewhat wet grass with my losi/grp cubes tires. I cant imagine that they would slip anymore on loose dirt than wet grass.

I also now have an issue with the tekno battery tray. The metal tabs that the tray mounts to are starting to bend down. Any easy fix to strengthen this area?

Thanks for all of the help so far! I'm hoping I can get some updated pictures here in the next day or two to show the current state of the truck.

[magman]

Any "excessive" wheel spin will heat things up. On my Revo conversion I actually bent the tabs down on the side where your motor sits now, it seemed to hold just fine. You could make a small L bracket to help support them and just drill a couple of sm. holes into the chassis and through the tray to stiffen it up.

[pfunk]

I think I'll try to make a simple aluminum plate that ties all 3 of the mounting tabs together somehow. Shouldn't be too difficult.

About the castle motors.. If I was to buy one on ebay or something am I still able to use their warranty services if something does come up? I think I saw one for $140... For that price it would be worth switching it out for sure.

[magman]

You can always use their warranty services which are outstanding.

The plate idea sound good as well!

Don't forget that Mike sells the motors here!

[pfunk]

I looked at the castle creations site and looks like you have to be the original purchaser of the item to use the free warranty service. I guess that you need a receipt to file a claim? Doesn't matter though... The motors are only $140 here on the RCM site anyway.

I'm scared to try the castle mamba monster max esc. My buddy was using one and it just suddenly went up in smoke when he turned it on for his 2nd qualifier. He also went through the motor that comes with the hobbywing combo fairly quickly. I'm not sure really sure of what to think. He must have something wrong in his setup to go through both a motor and an esc?

[magman]

The mmm is a great esc. I have one and will be buying another soon. Almost every member here has one....well maybe most do. Don't worry about it...set up is simple and enough of us will help guide you if need be.

Unfortunately, even new esc's fail...just the way it is. A bad set up can lead to failures...but that is why all of us are here to help each other as much as possible to prevent it.

[shaunjohnson]

i belive it's user related how MMM's fail.
be nice to it and it's nice to you....i was nice to it....untill that wet weather..THEN it died lol

dont be afraid of it, it's a kick nuts ESC!!
good luck with it

[pfunk66]

I believe is about time for an update. The hobbywing is still running great. I also have some pictures of the completed conversion.

She did well on the track. I placed first one week and had a few other 2nd and 3rd place finishes. No real issues other than the power switch getting turned on and off during the whole first race. Runs great now though!

Here she is..







I mentioned that I was getting flex around the RCM motor mount.. so I dremeled the top of the nitro engine mount flat and mounted the rcm mount on top of it.



I also reinforced the tabs the hold the tekno battery tray as well.

[Bondonutz]

Looks pretty dam good !
I'm just finishing mine today and hope to test Friday. I elected to not use the TRX motor mount at all, think I found a way around it and still plenty strong. I'll know more about that friday during testing. I also making my battery tray,hopefully it'll be as light as I hope ?