05.01.08
The Motor Gets Disassembled
Ever since I removed the motor from the transaxle with the help of a pair of landscapers, I had wondered how I was going to lift the 180-pound behemoth into the back of my Ford F-150. Today, that problem solved itself.
This morning, I started out by working on the G.E. motor. My intention was to remove the clutch pressure plate, clutch plate and flywheel and then bring the motor in for service. However, by the time I was done, I had the motor pretty-much apart. The pressure plate and clutch plate came off without a hitch. When I went to remove the flywheel, I discovered that it was not held in place with a standard Volkswagen gland nut. Instead, there was some kind of round and notched nut that had been banged in place with a drift or screw driver. After messing around with it (and some WD-40) for 15 minutes or so, I was convinced that it was not going to come off easily. After all, a Volkswagen gland nut is torqued to about 300 foot-pounds, requiring a special tool (or a long cheater bar) to install or remove. I gave the nut a few more whacks with a hammer and drift and, to my surprise, it came off, along with the flywheel.
The removal of the flywheel revealed 12 bolts inside the motor’s bell housing – 8 on an outer circle and 4 on an inner circle. All 12 were removed; the 8 outer bolts held the bell housing onto the motor’s case and the 4 inner bolts captured a bearing retaining plate on the rotor. The bell housing and rotor pulled out of the motor casing quite easily. A few tugs with my slide hammer and bearing puller removed the flywheel adapter from the motor shaft and the bell housing then separated from the rotor. A few more screws removed the ventilation screen from the front of the motor and the cooling-air shrouds from the rear end.
A quick examination of the motor showed nothing unusual. The bearings sounded fine, the brushes looked great and the insulation on the rotor and stator didn’t appear to be damaged. Sooo….
I bundled everything up in the truck (easier to lift in parts than assembled!) and hauled it off to a local service company. The owner said that the insulation looked fine and that the bearings were probably OK but, because the motor had been sitting outside, under the body of the car, for 15 years (Think: blowing dust), the bearings should probably be replaced. He also said that he’d check everything out, polish up the commutator and perhaps sandblast and paint the case for me. No price was quoted – he said that he’d call me after he had a chance to check everything out.
After a trip back to request a receipt for the motor (he gave me a business card) and another to ask for a hand-written receipt (which he gave me), I was off. I should mention that this motor shop looks like it was hit by a tornado. Hopefully, the conditon of the shop is not reflective of the condition of the work it produces.
After that, I was off to Gilbert Machine to have them make me a new notched nut for the flywheel. The old nut was very gouged up by repeated attacks of trying to install it (to 300 foot-pounds?) with a screwdriver, drift or chisel. I decided to ask Gilbert to make the nut so that I could tighten it with a 36mm socket, as is done with a VW gland nut. Imagine my surprise when the machinists told me that the nut was a stock item! It is actually an SKF W 05 pin nut! The notches in the nut are for a pin wrench. They told me to save myself about $100.00 and run over to Bearing, Belt & Chain to buy a new one.
So I did – I got two, actually — along with a new W 05 tabbed locking washer. The SKF nut is actually somewhat thicker than the nut that held the flywheel in place. It looks like Bradley or G.E. had the nut turned down on a lathe so that it would clear the clutch plate. I may have to turn the new nut down on my lathe to make it fit properly. We’ll see.
I noted that my flywheel has 130 teeth. I’ll need to check its diameter to see if it’s a 200mm (probably) or 180mm (unlikely) flywheel. While I might be able to re-use the old flywheel, it seems to fit a bit loose on the dowel pins of the motor adapter. This isn’t surprising. Volkswagen does not assume that the dowel pins will accomodate the engine torque between the crankshaft and flywheel — they use the dowel pins mostly for positioning and use the friction created by the immense torque of the gland nut to hold the flywheel against the crankshaft. If the gland nut is undertorqued, the engine’s torque will cause the metal between the flyweel and the crankshaft to gaul and the dowel-pin holes in the flywheel will elongate. This may have happened with my old flywheel, because the previous mechanic had under-torqued the SKF pin nut.
At home, I spent the rest of the afternoon cleaning up more hardware on the bench grinder – mostly bolts off the VW chassis. I also ordered a pin wrench from MSC to see if I could properly tighten the new pin nut. The wrench won’t work as it comes from MSC. I’ll have to grind the two pins down a bit to make them fit the slots in the nut and I may have to heat and bend the wrench handle to get it to clear the sides of the flywheel. We’ll see when I get it. I need to examine how the assembly goes back together, to see if 300 ft-lbs of torque is justified in this application.
I did take some measurements of the dowel pins on the adapter and the dowel holes in the old flywheel. The micrometer was reading a bit funny, but the pins all seemed to be about the same diameter – 7.92 – 7.93 mm – both radially and circumferentially. In other words, the dowel pins don’t seem to be out-of-round. The holes in the flywheel were somewhat larger, but I couldn’t sense that they were consistently larger in the circumferential direction instead of the radial direction (which is what I would have expected if the flywheel was loose with respect to the adapter hub. I did note that the flywheel was missing its O-ring – not that it mattered in this case — there’s no oil in an electric motor! I also noted that the flywheel was considerably looser on its dowel pins than I was used to in rebuilding VW engines (although that could have been a result of the missing O-ring). The flywheel will need to be replaced, along with the clutch plate. The pressure plate actually looks fine.
The small wire brushes for my Dremel (from Amazon.Com) came in today so I can continue cleaning up the VW parts – especially the front brake calipers and rear brake parts.
