Quote:
Originally Posted by fe1rx
The Turner part is made by knurling a 2.726" diameter. The knurl crests produce a larger diameter than that. Unfortunately I don't have a record of the crest diameter when new.
For your info, the crests on my worn out part measure 2.742" diameter. Looking at the worn crests it is apparent that they represent only about 50% of the bearing area. It is not unreasonable to assume that when new they only provided 40% (= 100% / 2.5) of the available bearing area, although I would guess even less.
Attachment 2341195
The diameter of the part I made to replace it is 2.758", with 100% bearing surface. |
I took delivery of Millway front tension arm bearings the other day and I thought I'd share their construction. Like others they use a clamping ring instead of a spiral snap ring. The main bearing area starts off with a 70.04mm diameter before knurling, which is darn close to the 2.758" diameter you derived, though not the full, 30mm width of the arm. The overall shaft width is 29.96mm ensuring some clamping force from the retaining ring. The knurling has a 1mm pitch (which on a 70.04mm diameter is almost a perfect 220 knurls) bringing the diameter up to 70.25mm. The lead-in to the tension arm is turned down to 69.75mm. My sample of (2) were identical. The bearings are Lemforder part number 33326792553.
Actual install is a ways off, but I don't anticipate any issues. The Millway rear inner camber bearings and RSFBs are on their way as well, but stuck in UPS limbo. I expect them to be as equally well made. They're also relatively inexpensive. The tension arm bearings were $250.44 shipped.
