Photodan

The sleeves I got from Jager seem reasonably snug but not overly tight but I had only slipped one on the end of the shaft. My guess is that with expansion of the bearings with all the heat they'll will tighten up and be fine. The Jager ones are supposedly 25.10mm. I didn't measure them so I can't say for sure. Have you measured the shaft at the points where the bearings will be? It's hard to know how "grippy" Delrin is and how it reacts to with heat and rotation of the shaft. Hopefully someone can chime here with some knowledge. I really hope they're not too big, I'm sure you don't want to make another trip back back to the machinist to have them re done.

Eric_Oz_S2

The OD of the shaft was around 24.97mm at the unworn sections - which is where the new bearings will be. I actually used a soldering iron on one of the sleeves (a spare) to put in 4 longitudinal grooves in the inside. This was enough to make the delrin grip to the shaft with sufficient frictional resistance. I don't think the bearings heating up would be enough to prevent the shaft spinning against the bushing - and not at all when cold. The bushings would then wear fairly quickly in my opinion. The existing bushing are 25.00mm inside diameter (they were a very tight fit).

Eric_Oz_S2

Update: Just fitted the bushing to the bearing and remeasured - the compression of the bearing has reduced the inside dia to 24.97 - it is now a snug fit. Amazing.

For those that think the C4 bearing is a mystical creature, behold - it does exist - at AU$60 ea. airfreighted from France.

Also picked up some aluminium (no that's not a spelling error) flashing tape to recover the slit in the TT.

One more question - if you use the threaded rod to reinstall the bearings, what stops the delrin getting damaged where the washer pushes up against the bushing? Is it hard enough to withstand the pressure? Also, I am thinking of spraying some soapy water into the TT before I install the carriers - as it was a real bitch getting those suckers out. Sound like a good idea? The soapy water will only be slippery when it is wet - as it dries out it will no longer provide any lubrication - this is important because you don't want to move those carriers when reinstalling the shaft.

Eric_Oz_S2

Got the tt back together today. What a craptacular job. I used a threaded rod and a square cyclone washer with the corners trimmed off to pull the carriers into the tube. I then used a jack and some timber to push the shaft in once all the carriers were installed. To stop the carriers moving (the front one in particular is quite loose as it is located where the slit in the tube is) I drilled holes in the tt behind the carrier positions and installed long rivets through the tube wall.

I used 4mm dia rivets with the edges snipped off to connect the carrier halves. I used a spindle kit (hollow brass tube with screw each side used for installing door furniture in hollow core doors) cut down to the right length as a spacer for the rivet gun.

I never want to do this job again.

It actually took me 9 hours to rebuild the bearings/carriers and tube complete.