PRIMARY & CLUTCH SEAL SCHEMATICS - 2000 Harley Davidson FXSTB Night Train

Its not to bad .You will need to purchase a shift shaft a shift shaft seal and a primary cover gasket and oil.First drain your oil.Remove your kick starter .Remove your primary cover.Remove entire clutch assembly.You will need air gun or a clutch holding tool to remove the clutch.Once you have the clutch assembly removed yuo can remove the shift shaft .Pay attention to the postion of the shift shaft in relation to the shift drum .Also pay attention to any shims on the shift shaft as that will need to be installed on the new one.Now remove the seal that the shaft was coming out of.Replace the seal install the new shift shaft.Make sure to center it in relation to the shift drum.clean every thing with brake cleaner.clean gasket area .Install the clutch assembly .If you have any trouble with the oriantation of the parts you can look at world of power sports for parts diagrams.Make sure you tighten the clutch hub to the proper torque spec.I would use blue loc tight on the nut as well .If you have a shop do it expect to pay about 2 hours labor max.Plus parts

First off, determine if it's transmission fluid, or primary chain case fluid.
I had the seal on the transmission main shaft go on me once (the seal under the transmission rear drive pulley, behind the inner primary cover).
This can be changed with the transmission still in the bike, but the entire primary needs to come apart, and the transmission sprocket/pulley removed to access it.

If it's primary fluid, it's probably the seal on the inner primary case that the transmission shaft runs through and that the clutch assembly bolts to.
Again, the entire primary needs to be torn down to access this.

Either way, the cost of the part isn't bad, but the labor is the killer, as it's a 6-10 hour job, if I remember the book's quote.

It could be the drain plug, the primary gasket, or the seal on the shaft coming out of your transmission that the clutch hub bolts to.

I have had this problem with the transmission shaft seal before.

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If it is indeed coming from the primary case, most likely it could be the primary cover gasket, or the oil seal for the transmission shaft that extends into the primary (the black seal around the rear shaft in the pic), that the clutch hub mounts to, or the gasket for the round plate (with the 6 screws) that the above mentioned seal presses into.

Grey color to me means water contamination..there is a seal there in mainshaft hole replace id replace the starter one 2 .. is scoring sounds like clutch wabble check shaft & clutch basket.. replace as neded...good luck...

Right where the threaded adjuster goes into the outer primary case, there's a locknut. There should be an O-ring on this treaded piece to seal in the oil. To replace the o-ring, you must go through the procedure to replace the clutch cable by removing the primary outer cover, disassembling the clutch release mechanism, and turning the cable out.

Good Luck
Steve

If the primary is leaking on the backside, you must pull the entire primary drive to gain access to the backside.

Start by draining the primary. Disconnect the battery, remove the outer primary cover, jackshaft for the starter, the engine sprocket nut, remove the circlip and remove the clutch rod adjuster, remove the mainshaft nut to get the clutch off (left-handed threads), primary chain adjuster.

From the right side of the bike, remove the exhaust system to gain access to the starter. Remove the starter.

Go back to the left side and remove the bolts that secure the inner primary to the engine and transmission. Once you have all the bolts out, the primary cover should come off easily. If it doesn't, look for a bolt that you may have missed including on the backside.

Now that you have the inner primary cover off, you can replace the seal on the backside of the cover. Install the seal but before you put the cover back on, you must lubricate the inner lips of the seal where it rides on the mainshaft. Many people don't do this and they destroy the seal in the first five seconds of running. Without lubrication, the mainshaft turns so fast that friction will build up heat and damage the seal within the first few seconds of operation before oil can get to the seal. Lubricate that seal.

Now , Since you've got the inner primary off, there are some seals in the transmission that should be replaced as well. I always replace every seal back there everytime I go into that area. Replace the large final drive gear seal as the thin seal between the mainshaft and the final drive gear. I also replace the Quad Seal behind the spacer behind the belt pulley. This will require the special tools necessary to remove the pulley. If you have those, I'd recommend doing this job as well.

As you can see, this is not a job for the faint of heart. It's a complicated job and a lenthy job. This is why the dealer charges so much to do the job. Now, my experience on doing this job is on the earlier Evo and Shovelhead models but the Twin Cam can't be that much different. I'll help as much as I can via this medium but I must recommend that you purchase a service manual. This medium does have it's limitations.

Good Luck
Steve

Replacing the inner primary seal is a major job. You must remove all the primary drive components such as the primary chain and the clutch assembly. Then the exhaust system so you can get to the starter to remove it. Then you must remove the inner primary itself from the engne and the transmission. The seal is on the backside of the inner primary. If you replace the seal, remember to lubricate the lips of the seal as well as the mainshaft before you reinstall the inner primary. If you install the seal dry, when you start the engine the mainshaft will burn up the seal in about three seconds before the oil gets to the seal. Put some oil on that seal.

Now, once you're in there, you may find that it isn't your inner primary leaking at all. It could be a transmission seal. One of the worst culprits is the Quad Seal behind the spacer that is behind the front belt pulley. You'll need some special tools to remove the pulley and replace this seal if it's leaking. It looks like a standard O-ring but it isn't. Both the compensator sprocket nut and the front pulley nut require a LOT of torque. The compensator nut takes 150-165 foot pounds and the front pulley nut takes 150 foot pounds. Also, the mainshaft nut that holds the clutch assembly on takes 60-80 foot pounds of torque LEFT-HANDED. You will need a way to lock the front pulley and the primary chain in order to apply these levels of torque to the required fasteners.

This is a complicated job. That's why Harley charges so much to do it. I would suggest that you purchase a service manual as there is far too much involved in this job for me to type it in step by step here.

Good Luck
Steve

There are several things behind the inner primary case that could be leaking. There is a seal behind the inner primary where the transmission mainshaft goes into the primary. This seal sometimes starts to leak. Also, there are seals in the transmission in that area. The final drive gear seal is the big seal right behind the front final drive belt pulley. Somethimes this pulley wears on the splines of the final drive gear and it loses tension on the "quad seal" on the final drive gearshaft.

You'll nee some special tools to get to this area. You'll need sockets to fit the compensator sprocket nut and the clucth nut. You'll need an airwrench, a primary locking bar, and a torque wrench that will pull 150-165 ft. lbs. torque in forward direction, 68-80 ft. lbs. LEFT-HANDED on the clutch nut, a primary locking bar, a final drive sprocket locking device, a mainshaft nut removal tool, and some seal pullers and installers. Good Luck.

Spray it off at the car wash to remove all the oil , then spray Right Guard (Yes, that Right Guard) on the area of the leak. It will show up, but you may not be able to see exactly where. There are a couple spots where it can leak. The jackshaft oil seal, as you said, transmission output shaft (clutch shaft) on the trans itself, the inner primary seal where the trans shaft runs thru, the engine sprocket shaft oil seal, inner primary O-ring, the bolts that hold the inner primary to the engine/trans, the primary chaincase gasket and the drain plug. Hopefully when you get it apart, you will see which seal is leaking. If not, replace them all. Still want to fix the leak? LOL