Feigao Magnet Problem

[shark413]

Ok, so I took my brushless truggy out to the track and put in a few laps. It was running good, with good temps (135 degrees on the ESC, 140 on the motor and 107 on the battery). The thing was completely unreal, faster than any nitro car out there, popping wheelies down the main straight, just awsome power. Then nothing, the car slowed way down. I could hear the motor spinning but nothing. uh-oh, blown diff, stripped spur, snapped rotor? It turned out to be the notorious Feigao separated magnet syndrome. Now my question is can this be fixed? I did some preliminary research and some people stated they had success using JB weld to glue the magnet back onto the rotor/shaft. A techie at CC recommended green loctite (#290). What do you guys think?

http://i142.photobucket.com/albums/r115/shark413/rotor2.jpg

Ambient air temp - 100 degrees (SoCal in the summer)
gearing 12/46T
Feigao 8XL
Cen Matrix TR Arena (Modified truggy)
MM esc/with fan
TrueRC 4s 8000 mah lipo

[crazyjr]

I'm not sure if the locktite will work, Most have trouble holding of things get too hot. I used JB Weld on two motors and its holding well, one was a 4400 novak and the other was a lehner basic XL1200, all you need to do is clean as much of the glue as you can off the rotor and shaft and slightly scuff the shaft so the JB Weld has something to hold to. One thing to remember though, once its set its permanent. Make sure its in the right position. I never tryed the JB quik, only JBWeld

[shark413]

crazyjr, I think I will try some Loctite #638, it is supposed to be designed for this type of application (Shafts to cylinders) and is one of the strongest (acrylic) adhesives they make. If it fails I will definetly give JB Weld try.

[chilledoutuk]

jb weld is just an epoxy glue the website says it can withstand temperatures upto 500F so it should be fine for this application.

[GSMnow]

Make sure you get the two parts of the rotor aligned perfectly. You need to find the center of the north poles and face them the same way. A single rotor magnet is not an issue, but with the two separate magnets, it is critical. Of course your balance is probably shot as well.

[TheSteve]

Sure would be nice if Feigao used one piece magnets on the longer can motors.

[Duster_360]

I've got one I noticed was moving back and forth on the shaft when I changed brgs, I guess it won't be long til I have same prob, 540 c9XL.

Ever read the back of the pkg loctite comes in? They advertise 7 diff types, low strength to high, high temp, large diameter and penetrating grade (green). The green is good to 300F and the high tempo goes to 450F, even blue or medium says 300F. Since I have some green on hand, guess thats what I'll be trying.

[shark413]

Well there is a black line on the magnet which I assume is for alignment. I took apart my backup Feigao just to verify and yup it also had a black line on it to identify where the two magnets should align. The weird thing is when I push the two magnets together and line up the mark, they slightly repluse each other and it takes some force to hold them in place. I am going to try Loctite #638 which has 3,625 psi of shear strength and good to 300 degrees. They make a high temp version (#620) that is good up to 450 degrees but it has slightly less shear strength (3,495 psi).

[chilledoutuk]

yeah that's because common magnetic poles repulse each other and opposites attract.

[shark413]

I have some updates: I finally got my hands on some Loctite #638 so I applied the Loctite and made a jig to hold the magnets steady (and in alignment) while the Loctite set. I used JB Weld on the end cap and between the two magnets. I have it back in my truggy and will try it out this weekend. I hope it holds up because I have 4 Feigao motors and I hear this happens a lot.

http://i142.photobucket.com/albums/r115/shark413/rotor2.jpg
Separated magnets, shaft, bushing and magnet end cap.

http://i142.photobucket.com/albums/r115/shark413/rotor3.jpg
Rotor clamped to keep the magnets aligned while the Loctite sets.

[Demon-TC3]

Hey bud,
This just happened to my Fiegao as well, does this trick work out well?

Take care,
Demon