making a Traxxas 550 Titan into a crawler motor

[makaveliks]

I started building some motors and ran out of magnet wire... While waiting on more to arrive I decided to post up a build thread and let it marinate to see if anyone with some real knowledge had any tips. I have some small experience re-winding Xmod motors and after 2 or 3 versions I got a winner that was super fast, used very little battery, and stayed nice and cool.

So I have 2 Traxxas 21T 550 Titan motors... Big motor, big armature, big magnets, big winds. This motor produces a good amount of power, speed, heat, and eats batteries quickly. I decided to experiment and see if I could make a 550 crawler motor stronger than the typical 540's That I could run with my crawler ESC's and get decent run times.



First to open the "sealed" can I ground off the folded tabs that hold it closed.


Here's the brushes.(motors have only ran once LOL)


And I didn't take pictures during the first winding. I wasn't thinking about it. BUT I broke off the plastic "fan" on the end of the armature, cut off the old windings because they were glued on something fierce, and then rewound it with 20 gauge wire. Originally it looks like 18 gauge maybe. I could only get 27 turns though. So I then unwound it and used a Dremel to grind out some of the armature on all the arms. I took a little over 1/8 off all the arms, and made the center "hub" narrower to give more room for winds. I then carefully cut and placed electrical tape over the area that the windings go to insulate the armature. I rewound it and got to the current state. I got 35 winds with 20 gauge magnet wire. I ran out of wire and the last arm only got 29 winds... I stuck it back together and it works and has good torque, but I'm not going to put it anything as is. I ordered some more 20 gauge wire, some 24, and 26. I think I might try the 24 and see how 45 or 55 winds fit. Then try the other motor with as many winds as I can get with 20 gauge. I will probably take more off the armature on that one and try to get 45 winds of 20 gauge. Then I'll see which I like better if at all.

Here's the rewound armature:




So anybody try this before? I figure if it works well it should be stronger than a 540 of comparable winds. A big 550 torque monster! I can't wait to get it rewound with the new wire and hook it up in my SCX-10.

[heinz357]

A good friend of mine gave me a 40 turn 55o motor from a childs Powerwheels toy, was designed to run 12v, but on 7.4v it snapped Wheely King axle shafts like they were matchsticks!

No real wheelspeed, but the low end grunt, and smooth motor control were sublime!

[hibbs]

I don't know if I'd have the patience for that. That is awesome though. Let us know how it runs!

[ik632]

Are you going to turn the com too? Looks like it got a little chewed up from pliers or a vice in the one picture. Love to hear how it runs. Next is to replace the end-bell to get some better springs and brushes.

[Duuuuuuuude]

There is a huuuuuuge thread on rebuilding and rewinding motors. Lots of good info.

Lately I've been rewinding brushless motors. That is a whole other kind of fun.

[makaveliks]

I know there is a huge thread on rewinding motors... I guess I should have been more specific, I'm asking for tips from anyone that has wound the 550. It's a bit different than 540's I've seen(longer armature, thicker arms for the windings) and was wondering if anyone did one of these motor sizes before. I know the winding is the same, but the motor is different and the same winds on a 540 is going to be slower in theory on the 550.

[JohnRobHolmes]

Originally Posted by Duuuuuuuude

Lately I've been rewinding brushless motors. That is a whole other kind of fun.

Have any pics of the work? Getting into three phase winding is a very interesting subject, especially when higher pole counts are involved.

[Duuuuuuuude]

Originally Posted by makaveliks

I know there is a huge thread on rewinding motors... I guess I should have been more specific, I'm asking for tips from anyone that has wound the 550. It's a bit different than 540's I've seen(longer armature, thicker arms for the windings) and was wondering if anyone did one of these motor sizes before. I know the winding is the same, but the motor is different and the same winds on a 540 is going to be slower in theory on the 550.

I've messed with the Kyosho 550's that have the regular end bell on them, but have never had a sealed 550 that was worth tearing apart.

Originally Posted by JohnRobHolmes

Have any pics of the work? Getting into three phase winding is a very interesting subject, especially when higher pole counts are involved.

I thought I did, but no. Got a few burnt up "before" pics, but no shiny new "after" pics.

[JohnRobHolmes]

Probably won't find much on rewinding the titan. I would suggest you keeping as much steel as possible for offroading. Without enough steel the motors overheat and stall out.

[makaveliks]

Ya, I had a couple 540 27T that I compared it to. The Titan had a ridiculous amount of steel compared to them. I just thinned it out a bit and it's still a bit thicker than the 27T I was looking at. I figure if I wrap it with high turns leaving the steel still thicker than the others it should be good to go. Even if I thinned it out to the same thickness as the others and wrapped it the same I'd think it would still be stronger than the 540's just because of the extra length of armature and magnets although slower speed. That's another reason I thinned it to use 20 gauge wire. I figure the larger wire should help keep speed reasonable, because if I didn't I wouldn't be able to get even 35T unless I used 25 or 26 gauge wire.

I just had these sitting around and I wasn't going to use them as is so figure let's see what I can do with them, but if it doesn't work as hoped there ain't no love lost here! Should be a fun experiment, and it would be great if it works well!

[Duuuuuuuude]

Less steel = less power. You'll also have balancing issues if you don't take the exact same amount off of each segment. You also run the risk of shorting the windings out if you leave a sharp edge.

550's are ballsy as they are. Just rewind them and go.

[makaveliks]

Ya, I'll try that with the other. I have not done anything to it yet. Then I can see which I like best. Who knows! LOL I was very careful to smooth the corners so I wouldn't have sharp edges.

[EddieO]

Smoothing the corners will help, but all the laminations are sharp as is, once ground they are gonna be jagged and sharp every where. As you wind the arm, the wires will move some as you pull them tight and can cut through the insulation causing a short.

If you want more turns the proper method is to use smaller wire. Just going up a size or two makes it easy to get additional winds on. On most 540 arms 1 awg is good for 5 turns or so pretty easy. You could sloppy wind a 55t with 24 awg pretty easy.

Later EddieO

[makaveliks]

The motor is built. I wound it up to a 50T with 24 gauge wire. It may not be the prettiest, but WOW this has power! I will try to get a video up tomorrow. I put it in my SCX10 with a 23T pinion and you can just give enough throttle to get rolling and it goes over anything. No hesitation or having to bump throttle to get it crawling over stuff. The 23T is the biggest I could fit and wheel speed is still pretty low. After 10 minutes running over things in my living room the motor still felt room temperature to the touch. It goes faster than with a Novak 55T I had before, but I think I'm gonna end up putting a different ESC so I can run it on 3S. So anyways, onto the meat and bones.


So here's the armature before winding. You can see where I sanded a bit on the green insulation. That was all that was required to balance it after removing material from the arms. Must have a pretty good eye.




Here it is filled up with 50 winds of 24 gauge magnet wire. It's not a perfect wind, the last 10 were tough to get on there. As I wound I used a drop of super glue to help hold stuff in place as I wound. That's why you can see some areas that look like they have a white haze.





This is how I balanced it. I used a Grim Racer prop balancer. The 550 was long enough to reach across. I did this before I wound, and after. After winding it needed no balancing. I could roll it to any position and it would stay.



Then timing. I didn't want it advanced so I ground off the white tabs on the fixed endbell that fit into the sides of the can and keep it in place. This allowed me to rotate it. You can see my black line. That was straight before I opened the can. This is now set by eye to around 0 degrees.




This picture you can see what I used for a reference. The brushes are 90 degrees to the wire tabs. The divot in the side of the can is the split between the magnets. So I lined the tabs up to the divot so the brushes contact the comm centered on the magnets.




Last to hold everything in place, I cut new tabs on the can lip and bent them over into the spots I ground out while removing the original tabs. This hold everything closed, in position, and nice and snug. I didn't take a picture of that though. I also removed the diodes.

[mitchr97]

did you test it yet????

[makaveliks]

Well I didn't have time to go get a video outside before my wife went to sleep. I got 2 videos of these motors running inside though. Next time I get a chance I'll get some outside in the snow.

First one here. This is in a Jeep Comanche SCX10. The biggest pinion that would fit was a 23T 48P and it's on there. I'll need to try 3S on this to get wheel speed up a bit. I had to drill a hole in the gear cover to clear the motor shaft and pinion. This motor has some steel removed from the armature to fit a few more winds with larger wire and get 50 on there and zero degree timing.

Jeep Comanche SCX10 with Traxxas 50T Titan 550 - YouTube


This one is in my FJ40 trail finder. It has a 20T 32P pinion. Again, this is the largest I could fit. To get the motor in there I had to reverse the front shackle because the motor hit it, and then put one of the screws through backwards because it would not clear the nut. I also had to grind about 1/8" deep circle into the transmission cover to clear the pinion and shaft. This motor has armature untouched, 45 winds, and zero timing. This was on 2S, but will probably run it on 3S for more wheel speed also.

https://www.youtube.com/watch?v=cZsppAuX55I

[Olle P]

Originally Posted by makaveliks

I put it in my SCX10 with a 23T pinion and you can just give enough throttle to get rolling and it goes over anything. No hesitation or having to bump throttle to get it crawling over stuff.
The 23T is the biggest I could fit and wheel speed is still pretty low. After 10 minutes running over things in my living room the motor still felt room temperature to the touch. It goes faster than with a Novak 55T I had before...
... It may not be the prettiest, but WOW this has power!

A 50T 550 motor with slightly more power than a 55T 540 (as indicated by the speed) doesn't spell "Wow" in my book...
Loads of torque though.

[makaveliks]

Sorry, but I don't understand how the speed indicates slightly more power than a 55T? The torque is the power that I was looking for and even though speed may not match a 55T it's torque surely surpasses it. I needed 2 Novak 55T 540's on 3S in my dually to push the chairs that easily at low RPM. I know there's stronger motors out there, but for a 20$ sealed can motor it's torque is pretty impressive to me. I just wish I had a dyno to show actual difference.

[Olle P]

Torque isn't power. Torque is strength.
Torque multiplied by revs is power. Your 550 motor had more power before you rebuilt it! Now it has more torque and efficiency.

[makaveliks]

Today I finally had a few minutes to try this in the real world. I ran outside in about 4 inches of wet heavy snow for about 30 minutes. It was in the FJ40 with the 20T pinion(largest I could fit) and after 30 minutes the motor had cooled from inside temperatures to 54 degrees. Outside was 27 degrees. It cooled down to where it was only 27 degrees higher than ambient temperature. And this was on a 3s 4000 mah lipo. The truck weighs 7lbs with this battery in it. I ran it full throttle and theres some bits in this video that I went real light on the throttle too just to show it pushing through the wet heavy snow with very little throttle to demonstrate the torque.

As for efficiency, it did real good. After 30 minutes when I decided to put it up that battery had dropped from 4.2v per cell to 4.11v per cell. Considering the conditions, all the weight it was pushing, the big motor, and all the full throttle I was giving it I think it's pretty darn efficient... A 45t 540 in the same conditions and gearing would be struggling, getting hot, and draining the battery. With the RC4wd 45t silver can that came in it, I ran I think it was a 13T or 15T pinion and it would still slow down and struggle in this much snow. Especially compared to a 21T with no modifications on 3s going full throttle for that long. Battery would have lasted 15- 20 minutes and everything would hot. I was even more impressed with the torque.

Now, I'm not trying to sell anything here and I'm no motor/electrical professional. Just googled a bit and felt like trying my hand at making this motor run cool, efficient, and have a good bit more torque than a comparable 45t or 55t 540 to make it more crawler/scaler friendly for how I want to drive these lil trucks. For 20$ motor, 5$ of magnet wire and a couple hours of my time I can say I achieved my goal.

Last, the video is about 8 minutes long... I didn't feel like editing it with my slow computer so it is just 8 minutes straight of running. By the way, all the trails were not "groomed". They were created by about 10 minutes of running before I started the video.

FJ40 with Traxxas 550 Titan 45T motors in snow - YouTube