I finally got around to installing the new Variable Speed (VS) and Timing belts I got some months ago. I figured it would be a long and messy process, and it was.
The VS belt was on its last legs, having already lost six or seven cogs, with most of the others about to go as well, judging by the cracks. All the missing cogs were contiguous, so there was a thump-thump-thump as the drive ran.
The timing belt wasn't too bad, but I decided to replace both belts at once, because most of the effort is in the removal and replacement of the countershaft and clutch assembly.
Taking the countershaft assembly out wasn't that hard, but was a bit awkward. Ditto reinstallation. It's really a two-man job, done by one man.
With countershaft assembly on the workbench, take bearing caps off and remove shaft et al from the countershaft frame.
At this point, discover a odd problem - The retaining ring that keeps one bearing on the shaft is not seated in the groove, instead staying in place by friction alone. Remove snap-ring and attempt to remove bearing. It moves a little, then stops. There is this red muck everywhere, the color of rust, but not gritty to the finger. Hmm.
Use bearing puller to remove the bearing. The very tip of the shaft, between the snapring groove and the end of the shaft, about 0.25" in length, is slightly oversize, although it looks perfect to the eye.
The toothed pulley, which is keyed to the shaft, slides freely axially, but won't go over the oversize part. It leads a trail of red muck when moved back and forth. Wipe muck up, time after time.
Clean up and use wet-dry sandpaper to polish the oversize down a bit. Hi-Spot Blue used to see the high spots. The shaft appears to be case hardened. Can almost get bearing on and off, but toothed pulley is recalcitrant. Repeat. Decide not to go any further. Probably, it was assembled from the other end, and seems to work just fine. If I do have to get this all apart, I'll polish the high spot a bit more aggressively with grit embedded in an aluminum tool bored to the correct diameter.
Used WD-40 to displace the water that caused the red muck, chased with Vactra #2. It really is rust, rust that has been ground between steel surfaces into a paint pigment. Nothing else was rusted. I bet that the water came from condensation, and everything else was too greasy to rust.
The reason that the snapring was not seated is now clear. The spacer (a machined thick steel tubular sleeve) between the toothed pulley and the bearing (SKF 6205) is 0.030" too long. This bearing is probably an aftermarket replacement, one that didn't quite fit.
Now the normal approach to the 0.030" problem would be to chuck the spacer up in the lathe, and trim that 0.030" right off. Except that the lathe's drivetrain is in pieces on the bench.
Revert yet again to 18th century methods. Clamp a 14" file to the bench. Holding the sleeve in both hands, file it shorter, rotating the sleeve an eighth of a turn between each cut. Clean swarf out of the file grooves with compressed air. Every so often, flatten both ends of sleeve with sandpaper on a granite flat. Took 20 or 30 minutes to get to the correct length. The sleeve looks like it was machined to length, not hand filed. Deburr sleeve and reassemble countershaft assembly, this time with the snapring properly seated in its groove.
Reassemble lathe. It runs much quieter now. No thump-thump-thump.
Washed hands in paint thinner to get the black gunk off, then with Borax to get the paint thinner off. Old car engines weren't this dirty.
Joe Gwinn