I have an old (25 years) transmission from a BMW E36 which I want to use. The transmission must have sat outdoors for a while, because there was white scale on the outside and inside of the bell housing. I removed the rusted and seized clutch fork and release bearing guide tube.
Unfortunately there was a lot of rust all along the input shaft and the clutch wouldn't slide along the spline.
I cleaned up the input shaft the best I could using 600-1200 grit wet and dry sandpaper and WD-40. The clutch slides smoothly now (by hand, not installed yet).
There is a bit of pitting on the shaft. I'm not sure what are acceptable tolerances on where the input shaft slides into the pilot bearing on the engine. I am also hoping the input shaft seal did it's job and there is no water ingress into the transmission (I will be replacing the seal).
This is an expensive transmission and replacing the input shaft is not an option. What problems would I face if I go ahead and install this transmission?