I have been following this thread closely,as I have been having similar problems with a motor I am building up at the moment.They are series B cases that I purchased "for spares" in 1973.Being out of use for that time,they weren't too bad.They had the camplate boss repaired by welding,a neat looking job.I fitted new bearings,spindles and oil pump and all went well.Came time to assemble the gearbox and the wheels fell off the cart.Unknown to me,the cases had not been used after the camplate spindle repair.A small blob of weld was restricting the movement of the quadrant gear in the roof of the gearbox.Heads and barrels were on,I hoped not to pull it all apart so soon.I got to work with a Dremel,a mechanics' mirror and a portable QI light,and in 3 hours it was done.
I was using a set of original gears,shafts and selector forks I had accumulated over time,but,on assembly I found the movement of the gear change much heavier than i am used to, with the change into third so heavy that I worried about breaking something.Nothing seemed obviously tight,so I removed the contents of the box.I dremeled the slots in the camplate with a green stone,but on re assembly nothing was different.
I then proceeded to substitute each gear,one at a time ,hoping to find an improvement,but no luck.Substituting selector forks and their bar was also no use.I was at my wits end now,and I recalled Bill mentioning the need for accuracy when repairing the spindle boss.As a last resort,I had a complete new set of gears I purchased on E Bay 6 or 7 years ago.I started by using the E Bay double gear,surprisingly, a perfect gear change.
On removing the cluster again,I measured the width of the double gears I had been using,and I found the 2 original gears I had tried measured 2.623 and 2.625 inches.The new gear which solved the problem measured 2.596 inches.I used a set of digital verniers for this,but close enough to show the difference.
I have always tried to avoid mixing up new and used bits,where ever possible,but it's the one time it paid off for me.I wonder if any other members purchased those gear sets,and if they had any luck with them.
Finally,when tightening the cover plate screws fully,the gearbox tightened up on the last half turn of the screws.Apart again.The layshaft bearings were Timken,and new.Compared to the old one I had taken out,the small radius on the inner race where the layshaft fits was slightly smaller on the new ones .Out with the Dremel again,to remove a poofteenth of metal from the shoulder on each end of the layshaft.Success.
As Bill said,they are all different.Now it's time to go to the timing chest.
