So the magnet moved on the shaft
 

So I was diving my MT today and I hit the brakes pretty hard. I hear a crunch which usually just means the spur is stripping more than it already is (I have the slipper on order). It's making A LOT of noise though so I look at it and the pinion is almost off of the spur like it had moved. So I bring it in and take the pinion off and notice the set screw is perfectly tight. Then I go to put it back on and notice there's no way the teeth will line up. Hmm the shaft seems to be sticking out awfully far....yeah that's not right.

So I take the motor apart and the damn magnet moved up the shaft so the shaft was sticking out very far from the front and there wasn't enough to slide into the rear bearing. How the hell does this happen? It took a lot of banging to get it back into a normal position, so how does it just move on its own?

It's all back together and working but I haven't tried it in the truck because the spur is so chewed up. I'm assuming the magnet position is one of those critical things, am I right?

Not as much as you would think, but....Theres a damn good chance it's ruined since you tapped it back in like that...I had this happen to me with a Lehner XL3100. Ruined the rotor, fried the windings, burned $150 bucks... Tap the end off of it and inspect everything. Chances are you need to reglue the magnet back on the shaft. I'm guessing the hard breaking broke the glue loose. CrazyJr had that happen with an HV-Maxx and simply JB welded it back on and it still works great for him.

I have had this happen on a 380c motor too.

I had it all apart and that's how I tapped the magnet back down a little. I really had to hit it to get it to move, but everything inside looked normal I guess. I'll have to wait until the spur gets here to see if it's screwed.

I really need to turn down the braking on this thing because that definitely makes sense. The magnet stops, shaft has too much stress put on it by trying to stop the truck, something has to give.

Since the other end of the rotor was spinning inside there, won't there be a chance that the insulation on the windings got worn away possibly shorting together?

I guess, but I tested it with no pinion and it at least seemed to work fine.

I had this happen with my Lehner 2800XL, very simple fix with JB Weld once I got the magnet off the shaft. Just make sure you try and scrape all the previous epoxy junk off the shaft first, then do a bit of light grinding/sanding on the shaft so the JB has something to bite. On both the motors I have done this with, the JB Weld has held strong despite hard bashing and general abuse.

you may have at the least lose some power though. any impact a magnet suffers can decrese it's magnetism. if it is hit hard enough it will lose all of it's magnetism (by the time it is hit that hard it will be broken anyway)

Thanks for the info guys. I'll see how it is if my damn slipper ever comes.. :mad:1