• Dana

Still more bushings

WTR 74! (Weekends To Race)

I got the bronze stock I needed to make the bushings last week and finally had time to make some this weekend.

My 1932 South Bend lathe

You read the Internet and listen to the old timers and you get the feeling you can just whip these out in a few minutes. Well not for me. It's measure, measure again, math and cut. Then measure, measure again, math, measure, more math, measure then cut. And measure, crap forgot to divide by two. Start over again.

Lessons learned:

  • Don't do the math in your head!

  • Don't forget to divide by two when turning down.

  • Don't put the bushing in the lathes' jaw after you've turned down the ID and OD. You'll squeeze it out of shape.

  • Get a chair and sit, I think better sitting down.

Any way I got the transmission main shaft bushings all done and pushed into the clutch basket and drive gear. I honed the sprocket side bushing to 0.0015 and the clutch side to 0.001. They both fit nicely.

I'm half way done with the cam case bushings. These have three critical measurements. The Inside Diameter, Outside Diameter and the Face thickness. The ID, and OD are easy to measure, just the diameter of the gear shaft plus 0.0015. The face thickness is kinda a bitch. All eight original faces where slanted and I couldn't get a good measurement. So I made two fake bushings that fit into the housing and gear shafts easily, so I wouldn't have to push them in or out, and turned the faces down to 0.040. Now with a known thickness I just assembled the case and measured the run out. But that meant I have to make 12 bushings instead of 8.

I have a few days this week to work on the bike but then I'm off on vacation and a few weeks of travel for work. So I might not be able to work on it for awhile after this week.

Build Notes:


Main shaft Clutch side Bushing Clearance : Honed to 0.001"

Main shaft Sprocket side Bushing Clearance : Honed to 0.0015"

Cam case Bushings

Intermediate Gear E: OD : 0.752, ID : 0.560, Face : 0.044. Gear Shaft : 0.558

Intermediate Gear F: OD : 0.751, ID : 0.561, Face : 0.043. Gear Shaft : 0.558

Intermediate Gear G: OD : 0.754, ID : 0.561, Face : 0.042. Gear Shaft : 0.559

Intermediate Gear H: OD : 0.754, ID : 0.558, Face : 0.043. Gear Shaft : 0.556

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