DIY Stator Rewind
Here is a article from the Ofapars' site that is interesting:
- And here are some comments from a forum member (pwtsvwt) who actually did a rewind:
|Stator Rewind Observations|
|Because there is an excellent Instructional Guide to stator rewinding here, I am not going to do an instructional with this post. Follows are a few observations that I would like to pass along from my experience with this endeavor.
The Instructional Guide appears to be European, and the wire gauges are different than that used here in the US. I used 18awg (American Wire Gauge). The 18awg copper core measures 2% smaller (diameter) than the OEM wire. Although this should make little, if any, difference to the stator's output (watts), I still gave each post one extra turn, that being 25 turns instead of 24 (this increases volts). The OEM wire was 1.05mm (0.0415"). The 18awg wire was 1.03mm (0.0405").
The Instructional Guide confused me only once. It said to wind the posts clockwise. I scratched my head with how to wind the posts clockwise, and to go clockwise from post to post. After studying the sketch near the bottom of the Guide, I realized that you wind the posts clockwise, and go post to post counterclockwise. Note: All observations, post to post wiring, tail connections, and harness connections are done on the rear facing side of the stator (the side closest to the rear cover - farthest from the rotor).
Removing the old wire wasn't as bad has I thought it would be. I used a pair of wire cutters to 'bite' the potting off of both sides of each post. And, in places I had to chisel potting out from between posts with a small screwdriver & hammer. Otherwise, it was; cut the lead in wire, grab same with a pair of needle nose pliers, and pull. Most of the posts unwound without a fight. But, the wire got stubborn a few times, and broke a couple of times. Broken wires were fished out with hammer, "chisel", and pliers. Be prepared to make a mess. The potting goes everywhere - including the eyes if no protection is worn.
The stator's posts are coated with some form of insulation. This insulation protects the copper windings from the edges of the posts. Inevitably, some of the insulation will be damaged and / or missing (see photos). I simply put two turns of electrical tape on each post. Since I was using a good double insulated wire, I felt that the two layers of tape would suffice.
Test, Test, Test. I did an ohm test on the roll of wire, and recorded same. After winding a couple of posts, I would do another ohm test, and check for short to ground (stator core). So, for each of the three phases, I would test the roll of wire and check it (and check for shorts) three more times. Better to unwind one or two posts than five or six. Had I found a short, I would have unwound until the phase tested good, cut out the bad wire, and then spliced back to the roll of wire. Fortunately, all three phases tested good throughout.
Use good wire. I used 18awg 200 degree celsius Magnet Wire. This wire is double insulated as follows: Base coat: modified polyester resin, Overcoat: modified amide imide resin. This is really good, tough insulation. I scrubbed it over post tops, and against other wires, and never nicked it. Good stuff.
The actual rewind took around 4 hours. That includes two breaks per phase to flex the fingers. The author of the Guide was right, it is rough on the fingers. I taped up the thumb and two fingers on the 'wire' hand with duct tape and still ended up with a small blister. I started each post at the core end, wound to the top (around 10 turns), then pressed the turns against the post with a piece of smooth plastic. Then 10 more turns to get back to the core end, and five turns up. This left the out bound wire about halfway up the post (and away from the stator's mounting surface). I arched the wire to nearly the outer edge on the way to the next post. This gave enough slack in the wire to bend it out of the way for the next phase(s). After completing the winding I moved all the connecting wires to where you see them in the photos. They are a bit tangled at this point, and little can be done to make it neat looking.
The Guide was somewhat vague about potting, so..... I taped up the stator's core and the outer surfaces with masking tape. I then put three 2" bolts, with nuts, through the mounting holes. This gave the stator three feet on which to stand. For Potting, I used Devcon 2 Ton Epoxy. I used two 25ml 'tubes' in Clear, but I now suggest White. The clear is Really Clear, you cannot see how much is on the coils. I mixed the first tube of epoxy and added a little rubbing alcohol to thin it. Using two aluminum pie pans, I poured the epoxy over the stator's coils (stator upside down for first pour), moved the stator to the second pan and poured the 'drippings' over the stator again. When the drippings would no longer pour, I used a Flux Brush to apply it. When there were no more drippings, the stator sat for 24 hours. The second application of epoxy was not thinned, and all of it was applied with a Flux Brush. Again, transferring the stator from pan to pan to use up the drippings. After full curing, I'm left with some 'drips' hanging from the stator (see photos). I will use a dremel tool and sanding drum to carefully remove the drips.
At this writing, this is where I stand on the rewind. Ready to drop the engine, move the grommets and protective tubing from the old stator to the new, and install same. I will likely remove the 3 pole connector and use solder joints instead.
Costs, stator rewind only: $21.94 200 ft. 18awg 200C Magnet wire - Ebay $13.01 8 ft. 14awg appliance wire (high temp) - Ebay $7.00 (2) 25ml tubes of Devcon 2 ton Epoxy - Ace Hardware $41.95 Also, solder, soldering paste, and misc heat shrink tubing from tool box.
Stator - ready to strip
Stator - stripped. Old potting everywhere
Missing post insulation
Stator - rewound
Epoxy drips and 'flash' ready to sand off
My observation: I hope I never have to do this again!
This site is backed by Number 85, who provide the hosting. If you need a website done, get in touch with them.