Hi,

Been reading over the posts and my first conclusion is a bad pilot bearing on the input shaft!
It’s buried in the back end of the crankshaft under the flywheel that the clutch attaches too!

The input shaft has to remain stationary when the clutch is disengaged or otherwise the gears will receive constant torque from the input shaft. They will cause trouble with shifting and definitely slipping into reverse, unless you turn the engine off!
You can jack up the rear end or the drive wheel to see if the clutch is totally disengaging while running the engine in gear and the clutch in!


What is concerning is the heat being generated, say from a slipping clutch, since the turning over of gears alone not generate lots of heat at low traffic speeds, but the clutch can!

Bottom line is, Excessive Heat will damage any bearings lubricants.
When at higher speeds, this it is a slightly different scenario, especially, if the oil is low or has been compromised and lost its shear resistance!
This is where the seals lose control!

Oil is the life blood in this particular transmission and a warm stick shifter on a long trip.
Definitely not something you want on cool days, at this time of the year!
Hot summer roads radiation will reduce the heat losses from transmissions but transmissions do run a couple hundred degrees fairly easily under normal conditions.
The oil vapors some, but if reaching like 300 degrees, it’s going to smell more due to the extra quantity reaching the nostrils.
Seals in this design are not vapor containers, like they are in refrigeration compressors!

Yes the two smells you are getting are ”yelling out” heat related!

Good news is the transmission has to come out and all needs an inspection and evaluation of the flywheel and replacement of the pilot bearing. It has only one shot of grease and I Suspect it’s SHOT!
Change the rear main seal and make sure it’s a 92 mm inside diameter one. Elrings have not been so!
I have used this with success.
Crankshaft Seal
Timken/National
355660H

The front bearing and the seals of the transmission are probably needed too but I have not torn into my two project M47s.
I need to learn the whole story involved with them.
Especially the input shafts two bearings along its length. The very front one has issues over time as it spins the most, engine speed and subjected to the clutches spline heat and radiating heat!
You gotta get your foot off the pedal as soon as possible to minimize the scuffing, as with any clutch!
Very slow town traffic is the worst case scenario for clutches!

It’s best to keep in engaged, in Neutral, so the flywheel, pressure plate and pilot bearing to spin as one.
This will help equalize and cool in all the parts involved. Not much air gets transferred within the bell housings due to the fear of debris.
The flywheel gets hot spots too, but mostly on the very outermost surface and can be machined again.
The pressure plate “assembly” can probably be recut with a special fixture system but since heat and use affects the diaphragm flex springs it’s not worth the effort and consequently isn’t done, that I know of!
The SOP, Shop Operating Procedures is R &R as a complete Kit and rear main seal!
If you have none of the above, of which, is unlikely because something wasn’t right to even go in there!
You can get by with just a new disc, but “always” a new or lubricated pilot bearing!
Again, a $6.00 bearing isn’t worth that to chance, unless you like pulling transmissions!

Looking to know what you find out!

Phil