I spent 45 minutes writing up a post for the DIY forum but I guess it didn't make the cut and I didn't save the text so let me try again. My resistor was dead so the fan did nothing when tested on the low setting and when I tested the high speed setting it made a brief screech then blew the 30A fuse. Time to dissect.
Spoiler: The problem turned out to just be a worn out SKF 609Z ball bearing. $6 and good to go another 100k miles, as far as I can tell. It seems like a quality unit but 200k miles was too much for the bearing. I couldn't stand to toss it out. Mine appears to have just barely been rubbing the magnets so they were fine and the brushes still looked great. Worst case, I'm out $6 and 4 hours of my life.
Basic procedure:
Unbolt motor from frame then remove spring clip and fan from shaft. Use Dremel or similar to grind the 6 dimples off the case. Use large flat head or similar poked through cooling holes to pop the edge of the front plate up above what's left of the dimples. Pull shaft with a fair amount of force (by hand) to overcome the pull of the magnets. You can then grab the white nylon spacer and washer underneath it and stash them in a safe place.
You will then have this:
Now you can grind the 4 rivet heads off and carefully pry off the bearing retainer plate. Do not lose the 4 rivet bodies as they help greatly with reassembly.
Then remove the bearing centering ring. It just pulls right out. Remove the roll pin. At this point you have to get creative to find a brass drift or similar to poke up in one of the three holes by the commutator to drive the bottom of the front plate upward to push the bearing off the shaft. After you drive it half an inch you can get some steel plates under the strong center part of the plate and drive the shaft on out of the bearing from the top.
Blow everything out well with compressed air then throw the new bearing into the front plate, put in the centering ring, then put the retainer plate back on by snapping it back on the rivet bodies. I then used vice grips and a couple small washers to hold the back of the rivet in place so I could tack weld each one. I let it cool between tacks to avoid overheating the bearing grease.
Now you can drive the bearing (with plate) back onto the shaft. Keep in mind it is possible to drive the shaft out of the rotor so it would be a great idea to mark it with a sharpie or whatever as soon as you pull the rotor out of the motor case. I did move it a little but light wear marks on the shaft from the rear bushing show where the nylon spacer and washer should be so it wasn't hard to get it back in line.
Double check the wear pattern on the rear of the shaft stops right where the washer is to make sure the shaft is protruding the correct amount then put a little grease on the washer to hold it to the nylon spacer and put a little grease on the shaft where it rides in the rear bushing. I'm not sure if that's required but it seemed like a good idea. :D
It's a little tricky getting the rotor back in since the magnets pull hard and the rear bushing is on a ball socket so it can get pushed out of position if you let it slam into that. Brace your hands to where you can slowly lower it in. Then tap the plate into position, roughly aligning the grinder marks so you have clean metal to tack on both pieces. Make sure it rotates smoothly before tacking!
Mine felt good so I put a few layers of masking tape to keep spatter out of the vent holes then tacked the six spots. Mask off the bearing then paint the tack welds.
Finish reassembly then go figure out where to spend the $130 you just saved by not buying a Spal 16" curved fan :twisted: You could always paint the OEM fan red if you want the bling factor of the Spal without the expense ;D No, seriously, don't do that.
Spoiler: The problem turned out to just be a worn out SKF 609Z ball bearing. $6 and good to go another 100k miles, as far as I can tell. It seems like a quality unit but 200k miles was too much for the bearing. I couldn't stand to toss it out. Mine appears to have just barely been rubbing the magnets so they were fine and the brushes still looked great. Worst case, I'm out $6 and 4 hours of my life.
Basic procedure:
Unbolt motor from frame then remove spring clip and fan from shaft. Use Dremel or similar to grind the 6 dimples off the case. Use large flat head or similar poked through cooling holes to pop the edge of the front plate up above what's left of the dimples. Pull shaft with a fair amount of force (by hand) to overcome the pull of the magnets. You can then grab the white nylon spacer and washer underneath it and stash them in a safe place.
You will then have this:
Now you can grind the 4 rivet heads off and carefully pry off the bearing retainer plate. Do not lose the 4 rivet bodies as they help greatly with reassembly.
Then remove the bearing centering ring. It just pulls right out. Remove the roll pin. At this point you have to get creative to find a brass drift or similar to poke up in one of the three holes by the commutator to drive the bottom of the front plate upward to push the bearing off the shaft. After you drive it half an inch you can get some steel plates under the strong center part of the plate and drive the shaft on out of the bearing from the top.
Blow everything out well with compressed air then throw the new bearing into the front plate, put in the centering ring, then put the retainer plate back on by snapping it back on the rivet bodies. I then used vice grips and a couple small washers to hold the back of the rivet in place so I could tack weld each one. I let it cool between tacks to avoid overheating the bearing grease.
Now you can drive the bearing (with plate) back onto the shaft. Keep in mind it is possible to drive the shaft out of the rotor so it would be a great idea to mark it with a sharpie or whatever as soon as you pull the rotor out of the motor case. I did move it a little but light wear marks on the shaft from the rear bushing show where the nylon spacer and washer should be so it wasn't hard to get it back in line.
Double check the wear pattern on the rear of the shaft stops right where the washer is to make sure the shaft is protruding the correct amount then put a little grease on the washer to hold it to the nylon spacer and put a little grease on the shaft where it rides in the rear bushing. I'm not sure if that's required but it seemed like a good idea. :D
It's a little tricky getting the rotor back in since the magnets pull hard and the rear bushing is on a ball socket so it can get pushed out of position if you let it slam into that. Brace your hands to where you can slowly lower it in. Then tap the plate into position, roughly aligning the grinder marks so you have clean metal to tack on both pieces. Make sure it rotates smoothly before tacking!
Mine felt good so I put a few layers of masking tape to keep spatter out of the vent holes then tacked the six spots. Mask off the bearing then paint the tack welds.
Finish reassembly then go figure out where to spend the $130 you just saved by not buying a Spal 16" curved fan :twisted: You could always paint the OEM fan red if you want the bling factor of the Spal without the expense ;D No, seriously, don't do that.