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Brushless Converted T-Maxx

Brushless Converted T-Maxx

Old 08-28-2011, 01:45 AM
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Default Brushless Converted T-Maxx

So the 'hurricane' kept me inside, and I needed something to do to keep me occupied, so I decided to make my T-Maxx brushless powered. I wanted it to be unique, and I can't say I've seen it done this way, plus I didn't want to spend any money on an e-maxx chassis/tranny/rx box, etc..

I made a motor mount and the rest was easy. I had a Sidewinder SCT system sitting around doing nothing, so I used that. I figure the 3800kv 4 pole motor should be enough to push it around. If not, I left enough room for a 550 or a 1/8 motor. I think one of the new Tekin 4 pole 550's should be perfect if this one isn't enough.

I used a Jammin Crt.5/Scrt10 battery tray. I cut off the top so I can use velcro straps, I can also cut out one side of it and use 3s packs. I do plan on mounting a second battery tray on the other side of the tranny.

Due to the tranny being forward only, I had to keep the mechanical brakes, but I like that actually. Just picked up a Y adapter for it. It should be interesting to see how the auto 2spd works with the electric power. I'm sure I'll have to adjust it.

I used a 14t pinion in an effort to match the existing gear ratio, well it's way off. The truck has plenty of torque, enough to lift the wheels off the ground, but only goes about 10mph.

Here's some pics, let me know what you think







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Old 08-28-2011, 09:11 PM
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Looks good. You may have to adjust it so the 2 speed shifts quicker to get a little more speed out of it. It should go faster than 10mph if its in 2nd gear, since your 3800kv motor should make about 28000rpm. Probably will have to gear it up a little though to get to stock speed. The 2 speed may be neat to mess with. 2s should power it ok with the 2 speed and the right gearing.
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Old 08-29-2011, 12:46 AM
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Thanks
Yeah the gearing is way too off right now. After I bump it up, it should do fine. I'll be posting video once I get the kinks worked out.
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Old 08-29-2011, 03:40 PM
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I have been thinking of doing this for sometime. I have a new 1/8 scale mamba motor laying around, and a Tmaxx with no motor. If you haven't decided on what you are going to do for battery trays the trays used in the Redcat Earthquake 8E would be perfect in my opinion. They are just square endcaps that will allow you to mount a battery on each side of the chassis and they will lay flat for LCG. I am also thinking of using a Redcat motor mount as well. I am subscribed to see your progress with the gearing. I plan to use a 15/62 gear combo, just because thats what I have lol. How are you controlling your brake?
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Old 08-29-2011, 09:04 PM
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For the brakes, I left the servo on the truck and used a Y adapter for the esc/brake servo, and I keep the esc in forward only mode. What's cool is that if I were to add reverse to this trans, everything would work just like a tmaxx should.

Whats killing me now is that I can't get to my LHS to get a new pinion. It's all flooded out around there.
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Old 08-29-2011, 09:47 PM
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Ah, I understand. I wasnt thinking that with reverse turned off the transmitter would still send the signal to brake servo. Thats awesome. I seen a brushless conversion kit on ebay for around $80 and contemplated just buying it. If you havent seen one it is pretty much just a transfer case that the motor mounts to. It has some transfer gears in it to step up the gearing to get the proper rpms for the tranny to run at the right speeds. I would have thought the brushless motor would turn similar rpms to a nitro motor, or higher, so there wouldnt need to be so much tinkering around with gear ratios to get the overall speed up. I have been trying to sell my Tmaxx but thanks to you I have some motivation to start tinkering with it again. My biggest concern before was brakes. Thanks for the info.
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Old 08-29-2011, 10:21 PM
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I figured the same thing about the rpm issue. I think I just f'd up and got the wrong pinion. $80 for a 'transfer case' conversion thing.. i'm gonna have to go look that up. Seems a bit much. I know what you mean about trying to sell it. I have tried many times, no one bites. I also just like electric better than nitro.

Edit - saw the thing on ebay. Interesting and clever, but I think it was a bit overthought. I'm confident once I get the gearing right my simpler solution should work. Plus that transfer case only leaves room for 540 size motors. 550 and 1/8 would hit the transmission case or spur gear.
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Old 08-31-2011, 06:57 AM
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I got my mount built today. i can't decide if I want to slot the chassis and move the mount for gear meshing or slot the mount to move the motor. Hopefully between the two of us we can find a good gear combo without buying every size available lol.
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Old 08-31-2011, 09:38 AM
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lol I debated on where to put the slots too. Putting them on the chassis would be better I think, now that I made mine with the slots on the mount. Adjusting the mesh is gunna be tricky, I may end up slotting the chassis anyway Actually, now that I think of it, there isn't a ton of space to move the mount to either side with the batteries mounted. Yours may be different, got some pics?

I would love to be trying out some gear options, but I can't get to my LHS, they are both still dealing with flood issues Stupid hurricane.
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Old 09-09-2011, 01:15 PM
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Update for you guys

Got my gears in today so I was able to try some different combos. So far I have found 19t pinion with 54t spur is working pretty good. 21t pinion will be perfect I believe, gotta order one.

It still has plenty of torque to lift the wheels off the ground, but is engaging 2nd gear at about 3/4 through the trigger. I have set the engagement point as early as the trans allows. Next obstacle is the slipper. It's starting to slip a lot, I'm about to check to make sure its fully tightened. If it is, I will have to upgrade to RRP or something.

I'm really glad this truck doesn't use Mod1 gears, this would be pretty expensive to be trying all these gear combos
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Old 09-10-2011, 10:44 AM
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Shot some video of it running today, kind of proof-of-concept if you will. Now this is of it running with a 3s lipo, i had to try it out, the esc doesn't take very long to overheat lol. It's a decent step down when using a 2s, much more tame. Once I gear it up, I'll have a better idea if I need to get a different esc or not, so I could run it in 4s.

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.

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Old 09-14-2011, 01:41 PM
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wow this is what I was looking into doing also.

Would changing it to single speed eliminate the clutch on this. I was checking out how2rc and he did a forward only and single speed comversion to get it to work.
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Old 09-14-2011, 03:36 PM
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Just now watched your video and Im impressed. That thing gets it pretty good on 3s. Id leave the gearing alone If it were me I like how it shifts though and it sounds smooth. Looks like a lot of fun to drive!
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Old 09-14-2011, 06:09 PM
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Looks good, how are your motor temps?

Perhaps throw a MMP in there, that Sidewinder SCT Speedy IMO is pretty ordinary, I used to have overheating issues in a Slash on 2s with those! (Granted that was in 42-43 degree c days)
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Old 09-14-2011, 09:19 PM
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Originally Posted by all_rice
wow this is what I was looking into doing also.

Would changing it to single speed eliminate the clutch on this. I was checking out how2rc and he did a forward only and single speed comversion to get it to work.
That i'm not sure of. I think I know what you mean though, if it was 1 speed it would use the motor for braking, right? I actually like that it is 2 speed, and I like the mechanical brakes. They are more natural feeling, plus it's less stress on the motor. But I'm sure if it were a direct drive transmission, it would work fine too.

Originally Posted by Cummins Driver
Just now watched your video and Im impressed. That thing gets it pretty good on 3s. Id leave the gearing alone If it were me I like how it shifts though and it sounds smooth. Looks like a lot of fun to drive!
Thanks, It could use a little more on the top speed end. I will probably only go up a tooth or two at most. I wanna try it just to see how it works out really.

Originally Posted by nexxus
Looks good, how are your motor temps?

Perhaps throw a MMP in there, that Sidewinder SCT Speedy IMO is pretty ordinary, I used to have overheating issues in a Slash on 2s with those! (Granted that was in 42-43 degree c days)
Thanks, motor is fine at about 140*, esc however... eh it thermals pretty quick on 3s, that's why the video ended so quickly When I walked over to it, the esc was 175*
I actually just picked up a MMM and a 2650kv motor So those will be going in and I'll be most likely using a 4s setup.
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