I recently picked up a 1967 B25/C25 basket case. P.O. realy took it apart and "buggered" up some of the engine. I have remedied most of the problems but am having difficulty with a missing crank spacer/shim that is located on the gear side. It goes between the crank and the case bearing. The parts book calls for either a .010 or a .015 thickness. Question is which one? The inside of the gear side case is stamped with a "T" and on the drive side it has "HT" in some type of marker written on it. Any help would be appriciated.
The way I set the endfloat on B25's is to first reduce the main bearing journals on the crank so the bearings slide over them with a tight sliding fit, I hand sand them with rough emery with lots of testing of fit. Once this is complete I repeat assemble the engine and add shims each time, once it binds on torquing up the crankcase bolts I remove one 5 thou shim and double check again, if it still binds I take one more 5 thou shim away.
This works because on both sides the crank nut pulls the bearing inner onto the crank so it cannot spin, make sure you use blue loctite and the tab washers to make sure the crank nuts do not come undone.
The shims are available in sets from your normal dealers.
No idea what the T and HT stand for other than Dumb Previous Owner (DPO)
I try to do the fitting with the old bearings which I give a good polish just enough for them to be finger push onto the crank and into the cases. Adjust as per above then measuer the thickness of the old & new bearings and make adjustments if necessary.
Sort of the same as Kommando I just have a problem with playing with new bearings . I can bugger them quickly enough in use ( missuse more correctly ) without making a mess of them before I start.
Gents thanks for the input, I'll polish the crank main journals with some fine emery cloth so the ball bearing is a snug slip fit on the crank. You mentioned doing the same with the bearing fit in the case. My thought was to warm the cases and insert the bearing and then work with a snug slip fit on the crank to check the end play. Thoughts? One more question, the manual states that the exhaust pushrod is marked with red paint well no red paint now. One push rod is longer than the other, is the longer one for the intake or exhaust? Dave
You mentioned doing the same with the bearing fit in the case. My thought was to warm the cases and insert the bearing and then work with a snug slip fit on the crank to check the end play. Thoughts?
Do not touch the bearing outer or the case bearing housings, they need to stay an interference fit, as you suggest install the bearings into hot cases. Heat cases in an oven or heat with a torch until spit sizzles, bearings in a freezer for 24hrs.
The exhaust pushrod is shorter at 6 7/8" the inlet pushrod length is 6 15/16"
Another option is to use a ball bearing on the drive side. This is then clamped by the crankshaft and the drive gear spacer.
Later engines with the drive side roller bearing specified had a modified crank so the the crankshaft float was limited by being clamped on the timing side. In this case a spacer is used underneath the oil pump driving gear.
I opted for the drive side ball bearing on the basis that I do limited annual mileage and I tend not to thrash the nuts off the bike [anymore!]. :-)