Fit so nice, I made it twice....

Actually, it was the wrong material, so I kicked myself a few times and bought a new flywheel. This time, a *forged* flywheel, not a *cast* flywheel. Had I the sense to do more research ahead of time, I'd have only made it once. Nonetheless, the new version is around 300% *less* likely to break apart during flight.

That's version 2. Same dimensions, but machines a lot more like 4130 than the first one.

In this blurry picture I'm pointing out the locating step for the flexplate. That way I know it's concentric. I did the same on the inside for the prop extension:

Now that this is finished, I was able to start test assembling the crankcase. First, the connecting rods on the crankshaft:

Drop the crank assembly into the case and add some nuts, torqued to spec:

It still rotated freely after it was torqued, so that was a good sign. No rubbing or clearance issues so far. The next step was to add the head studs and check the piston deck height. I painted my head studs to help avoid corrosion:

And then I added them to the pile.

I added a cylinder and piston, and started taking measurements. I used a .030" shim under the cylinder, which is how the engine came to me. I set up my dial indicator and rotated the crank to TDC for that cylinder.

Zero'd up the dial indicator (though the photo makes it look off);

Using a piece of steel rod I had laying around as a straightedge, I measure deck clearance + rod width at 0.428" or so.

The rod I used measured 0.314", which means my clearance distance is 0.114". That's a lot more than I want! VW specs are between 0.040" and 0.080". I went back and checked, and the old pistons are the same as the new ones, and the old cylinders were within a couple thousandths of the new ones. That means that this engine was assembled wildly out of spec.... which shouldn't be a surprise, but it was. And means more work; removing the shims brings me down to 0.084", which is out of spec (and 0.024" more than I really want.) That means I'll have to chuck each cylinder up on the lathe and turn it down to what I want. 

Unless...

...unless the heads are also anomalies, and have a much smaller chamber than normal heads, in which case the cylinders need to be extra long.... Bottom line, the new priority is get the heads reconditioned and blueprinted so I know what kind of setup I need.

There has been nothing straightforward about this engine. Armed with the knowledge I've gained from this process, I believe the next engine I assemble will be from brand new parts that I know the details on.

...And flywheel solutions!

I removed all the dowel pins from the crankshaft, which wasn't super difficult this time around... I think my holes are a light press fit, rather than the super-tight holes that were there originally. I'm not sure if that'll cause problems down the road or not; they are still a press fit, so load should (theoretically?) be transferred just as effectively.

The flywheel face on the crankshaft seemed to have zero runout when sitting in the crankcase, but there were a few problems with how I was taking that measurement that could have absorbed imperfections... so I decided to throw it at the lathe and check runout by painting the face with red dykem and scraping a tool along the face. The goal was to avoid removing any material, just rub the dykem off, and see if it was a gnarly edge on a dowel hole that was causing issues, or if the face itself was not perpendicular to the axis of rotation. I thought I took a picture of the result, but apparently this was another instance where my phone shut off instead of taking a picture... that's been happening a lot recently.

Anyways, the dykem was scraped off of about half the face, and the other half the dykem was still there; it made almost a perfect half circle of red and a half circle of steel. Now, the crankshaft was out about .0005 on each end, and I failed to document whether it was out the same direction at the same point in rotation; so when I did the math, I had to assume worst-case of the crankshaft being out a full thousandth of an inch. Even so, the pattern was much too extreme to blame it on a misalignment of that magnitude, so I turned a couple thousandths off the entire face. When I re-attached the flywheel, it was only out about 1 thousandth of an inch as opposed to the 8 I had before, so I put the dowels back in and put the flywheel back on. I put the whole thing on the lathe as an assembly, because I have to do a little more work on the flywheel.

Now to the part I have pictures of! The final flywheel is going to be two parts riveted together. The inside part will be turned from the original flywheel, and the outside is from a much lighter flexplate (which basically just positions the ring gear and transfers the load from the starter.) I cut the inside out of the flexplate on a CNC mill at work, since it was too big to turn on the lathe.

I also cut the outside off of the flywheel on the mill, but left it oversize so I could finish it on the lathe.

I could have programmed the mill to cut a circle, but I wanted to use a rotary table to get a true circle on the flexplate, since I can't touch that up on the lathe. Once I was set up to do that, it was just easier to do the same with the flywheel.

Once the flywheel and crankshaft assembly were on the lathe together, I started working towards the final shape. There's a step on the outside of the flywheel that needed to be turned flat with the rest of the face, and then a new step needed to be cut out from 5" diameter outwards to accept the flexplate. I've got the whole thing turned flat, and I used some red dykem to help me visualize where that 5" diameter will be.

It's been a little tough to find time to work on this stuff, but I think I see the light at the end of the tunnel. I have a few more parts on order, and once they get here I should be able to begin the reassembly process... which should be a pretty quick process, given how much documenting and adjusting and tweaking I've done *before* started to put it all together.

Lathes + Flywheel Troubles

Having a metal lathe, even a small one, is a fantastic way to avoid paying a large amount of money for a small amount of work. I started by chucking up the crankshaft and adjusting until I had less than a thou of runout. That's still too much for bearing work, but I'm not doing bearing work. I put a 45º chamfer on the flywheel mating face, and knocked the burrs off of the pulley hub mating portion of the shaft. A little polishing to make sure the pulley hub slips on, and we're off to the races. The pulley hub was heated to ~400º F, the crank cooled to ~10º F. I still had to use some persuasion with a hammer to seat it fully, but she's on there now.

The two aluminum rings are the replacement seal housing, complete with seal installed. I must've walked through the assembly process a dozen times to make sure I put the seal housing on the correct way, and I still checked it half a dozen times afterwards. The red material is a cut up silicon baking sheet to help keep the rubber on the seal from melting/losing its elasticity.

After I turned the chamfer on the flywheel end, I re-installed the 4 dowel pins. The bottom pin in the picture is larger than the rest, allowing me to index the flywheel. My plan is to mark TDC on the flywheel, since it can only line up one way, and with very tight tolerances.

When I attach the flywheel and snug up the nut, I still end up with about .008" of runout at the edge of the flywheel. Not a lot, but more than I'm willing to put this together with. I used some more PlastiGage between the flywheel and the crank surface to make sure I was fully seating the flywheel... sure enough, I wasn't, and the place where I wasn't touching the crankshaft is the same angle where the flywheel is furthest out. There are four factors at play here; the crankshaft face, the dowel pins, the flywheel face, and the flywheel holes for the dowels. The crankshaft face is most likely true, since that's how it was run successfully before, and my PlastiGage test seems to confirm it. I proved that the flywheel face was true by using a rotary table and a dial indicator and getting less than a thousandth of runout. I think that leaves the dowels. How did that happen?

It happened pretty simply - I used the flywheel to drill the dowel holes. Normally, this would've been the best way to go about it. However, because of that radius on the flywheel that I chamfered the crank to match, the flywheel wasn't sitting quite right on the crankshaft, which means the dowels are *slightly* cocked to one side, which means they *want* to pull the flywheel that way.

So my next step is to torque the flywheel to spec, which is some ridiculous number above 200 ft/lbs, and see if that fixes the problem. If not, I may have to get creative. On a positive note, the only bit of clearancing that I still need to do involves grinding a little material off one of the connecting rods. Once that's complete, I can start setting things out for assembly. I do, however, need to get this flywheel thing straightened out before I can move forward.

Engine DISassembly (Part 3)

I've been stuck trying to find the right tools for the last week or so, and then trying to find the time, but I finally made some progress. The pictures below show a collar assembly on the front of the motor, behind the prop hub. Apparently this setup is an anomaly - no one I spoke with was able to identify it. There are 4 screws that hold the front collar onto the back collar, which has one screw into each side of the case. Once I got the right size hex key, these came off and the case came apart.

These two collars house an oil seal around the crank shaft where it exits the case. My first inclination is to replace the seal, but I'm not sure what kind of damage I might do removing the prop hub. I'll have to think about it.

Once the case was split, I pulled all the cam followers and labelled them so I could replace them in the same locations. I'll be taking a lot of pictures once I've cleaned things up, but the camshaft looks like it's in great shape, so that and the followers will probably stay.

The inside of the engine wasn't as pretty a machining job as I'd expected, but everything turned nice and smooth when it was all together, so I'm not too worried about it. I haven't found a reason for the fine metal shavings yet, which makes me uneasy. 

This is where I left it. There are only a couple of things left to do on the case before it can be cleaned up and inspected, and I don't expect the crankshaft assembly will be difficult to take apart. After that I can begin blueprinting, clean and inspect, order my parts, and put this thing back together.

Engine DISassembly (Part 2)

Not much progress today, but I got a little further. I keep running into bolts that I don't have wrenches for, although hopefully that will stop soon. The main thing I accomplished today was setting up a table to work on, covered in plastic, and transferring the engine block from the stand to my new "workbench."

I got the pistons out, which ended up being easy enough... the Teflon buttons really were just floating in there, but I needed something sharp to stab the sides of the buttons to get enough grip to remove them. I forgot to take pictures of them tonight, but when I get into working on the cylinders I'll be spending about a paragraph on how crummy those buttons are.

Removed cylinders yesterday, but they're all laid out in order here. You can see the lower right cylinder has a lot of corrosion on the outside of it - the other three cylinders aren't corroded much at all. I think the corroded cylinder was a quick replacement to avoid a more serious rebuild earlier in this engine's life.

Another disappointing discovery when I removed the accessory case that covers the flywheel - the teeth are chipped pretty bad on about a quarter of the flywheel. Not messing around with that - I'll have to replace it.... unless they sell just the ring gear for it. I'll look into that...

I also removed the valve springs, and while those all seem to be in good shape, I did notice that the same cylinder with lots of corrosion also has mismatching valves.... the valve on the far left below has almost no carbon deposited, not to mention is shaped different. I'll have to make a decision on whether or not that is an issue/will bother me enough to get new valves.

And here's the part where I don't have a big enough wrench - or rather, big enough socket. Not sure a wrench would be really effective, since this is recessed inside the flywheel.

Tomorrow I'll pick up some more specialty sockets, and hopefully make some more progress on tearing this thing apart. My goal is to have a semi-final list of parts to order by the end of the coming weekend, as I suspect some of the parts will take some time to acquire... especially if I wait until the holiday season.