ronan
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Was it Devimead who used to do a needle roller bearing conversion for BSA's? Eliminated that timing side bush and the centrifuge problem with the oil by adding an end feed to the crank. Seemed like a good idea, but I didn't know about it until after I'd blown up a girlfriends MkII Spitfire on the M69!
I will chuck this in here with Shox dr's permission. My own 650 BSA i wanted the needle conversion, but SRM and the few others that do it charge the earth, which i cannot justify. Maybe something similar can be done with the Sunbeam ?
Clocking up the crankcase half to make sure its level and square to the spindle.
Milling off the two ears that protrude to stop the original bush turning in the cases.
Boring out the cases to suit the new roller/ball bearing
Done.
Cutting a "Half moon cut" with a woodruff cutter to allow the oil pass around the new bearing and get to the oil pressure relief valve.
Cutting down the timing side mainshaft to allow the inner bearing race fit.
The new bearing fitted.
The crank in the cases, everything turned nice and free, you can see the new quill in the end of the crankshaft. I was worried, as if you let the tolerances get out of control, the crank will not run true and will lock up. I measured run out at the end of the crank, and i was getting less than 0.01mm so perfect.
The oil comes out of the brass bush you can see in this last picture, out through the top oil pump mounting hole, and into a little manifold with a garter seal that sits onto the end of the crank. I went to make the manifold but it turns out i was out of argon gas.