I've been fighting this for 25 years. Im curious about what others have done as I am about to embark on yet another attempt to fix this all-to-common problem with shovels.

Transmission oil likes to weep-out of the area where the output splined shaft goes into the inner primary and onto which the front final drive chain sprocket fits. There are many aftermarket products such as the sprocket nut with seal that are aimed at this problem and I have tried all of them.

Ive even tried the small suzuki oring that you slip behind the spacer that goes over that output shaft and slides into the tranny behind the main trans seal. On a variation of this theme, I even had this spacer machined to accommodate a larger oring and tried that.

Ive use multi-lipped main seals too but I still get an irritating and small drop, drop, drip after a ride. Im about to try a fix once again. Has anyone found an answer ? What about just coating everything with RTV silicone ?

The oil has gotta be coming out around the main seal or slipping past the spacer and finding it's way out the splines of the output shaft.

 

I had the same problem with my 72,she leaked oil around the trans main seal so I pulled it down to change the stator so i decided to fix the seal while I had the inter primary off ,I found that the trans case where the seal fits in was really beat up so I took a dreamal and with a very lite touch cleaned off the burrs and the smaller seal that gos around the shaft is directional ask your parts guy what side is inner and outter if its not marked and I also run a lower level of oil in the trans now,,,,,Instead of filling it up to the check hole I use a copper wire and run it down thru the filler hole till it touches the bottom as long as it shows 1/2 inch on the wire its good.I have had no problems since then with leaking.....good luck.

 

Yes, thanks for that replay but I have checked all those items many time. The seal recess looks like new and my small sprocket/clutch shaft seal is installed correctly. Still puzzled.

 

What shape is the mainshaft and the bushing in ? If you have any play it's going to leak a bit period .

 

Yep, on the wear of the main drive gear-bushing stuff. You can replace the cork and rubber seal 1000 times, use a SuperNut with seal on back, and if the main drive gear is worn it will leak. Worn space will allow a leak, also. Also some spacers had no key and tended to wear more quickly, wearing the spacer ID and the shaft OD. That means "permanent" leak.

I would get 1 year on the sprocket, replacing 2 drive chains in that time. When I tore down for new sprocket I always installed a new drive gear spacer, replaced the cork, filled the cavity with non-hardening gasket compound, installed double-lip seal, installed the sprocket, and cinched it down with a new SuperNut.

 

Yeah, well Im gonna try something else. Maybe I'll just goop everything up with RTV silicone.

 

Too much in the wrong place will wipe out the seal , If the sprocket is tight on the drive gear and you can get any up & down or side to side wiggle or twist out of it the bushing is gone , needs a new one . No amount of rigging or silly cone is gonna fix it .

 

The bushing is usually the problem...and installing a new one doesn't last for long. The true fix is to eliminate the bushing and use a 5 speed bearing...the OD is the same, you have to take 1/16 off the mainshaft to make it work.

 

Done that also and had problems with the mainshaft pitting out , needs a true hardened race to be right and once you cut the shaft to fit now you've got problems with the taper being to too shallow to support the clutch pack . Trick is using a high end bushing not the china crap 90% of places can get anymore and have it honed to size not reamed . Been 8 yrs since I did my mine last time and I'm running a belt rear plus big inchs , no leaks .

 

I'm assuming you are running a ratchet top 4speed. I'm also assuming you have a fresh tranny. On pre-78 1/2 4 speeds there is a very tiny "L" key (PN 35175-38, 1941 to1977 spacer key) that locks the spacer to the mainshaft between the mainshaft seal and sprocket. I left this out once and had leaking problems until someone asked me if I had put the key back. When I replaced the key, my leaking problems ended. The 78 1/2 (cow turd top) and later 4 speeds eliminated the key.
Look in your shop manual. It is very small and can be easily missed. A lot of the time, it will come off with the sprocket and fall off and lost to history.