Rex, saw in the previous post you bought a 7207 W. From what I can read up, the ball bearing angular contact in that one is 40 degrees and it is totally unsuitable in the gearbox for reasons I explained in earlier topic. The clutch basket will rattle and wobble with that bearing installed. Especially when the axial play at the mainshaft increases with heat or wear.
SKF has a series of 70- bearings (AC series) with 25 degree contact angle, for example 7207 ACD/P4A. it is expensive super precision but still unsuited since it increase radial play very dramatically when unloaded in the non thrust direction.
Angular contact bearings should or must be installed in pairs mounted opposite each other with a near zero interference fit on a steel shaft. In our gearboxes, since the main shaft has to be floating, mounted with a 0.010" axial play, the bearing has no real support opposite the thrust direction. The original Fafnir has a 15 degree angular contact, still can not take load in the opposite direction but at sideshift does not increase radial play as much as the 25 deg. angle bearing, let alone the totally unsuitable 40 deg. bearing.
It is not recommendable to mount the mainshaft without axial play, it will wear and ruin the thrust washers (at one end or both ends of the axle splines, depending on years) and wear the thin ball bearing at the sprocket end in short order.
I recommend to install a plain deep groove ball bearing shielded on both sides to protect it from gear shards and clutch residue. 6207 2RS. It keeps the radial play very small at all times. Time has proven it can take the side thrust from clutch use, very well for a long time.
By the way, the thrust direction is against the clutch basket since when you engage the clutch, the clutch is pulled outward with the worm on the cover. When the clutch is disengaged and normal, there is no thrust force on the bearing.
