There is a small seal in the end of the shaft where the clutch pushrod goes. If it is bad the tranny juice will make its way into the primary.

On the main drive gear seal - Check the condition of the bearings behind the seal(s). If the main drive gear bearings are worn out, you will never be able to achieve a seal. There should be a cork seal and a rubber/metal seal. When you buy the new rubber/metal seal ask for the double lip version. Also, there is a special sprocket nut (aka Super-nut, or Duo-Seal Mainshaft Nut) available that has a seal built in and an o-ring on the back side. 'Tis well worth the money. There is a main drive gear spacer that slips over the shaft. Most times there is a little L-shaped key that locks that spacer in place, but sometimes it gets "misplaced" by a sloppy mechanic, and then some bikes never had the key to begin with. Inspect the shaft surface where the spacer rides, and the inside surface of the spacer. If there is appreciable wear the tranny juice will escape between the mating surfaces.

If everything checks out OK, install a new cork seal, semi-fill the cavity with non-hardening gasket compound, install the new double lip seal, put a new sprocket on (my history was that a sprocket lasted 2 chains), install the new lockwasher and special nut, and cinch it down.

On the belt drive - I ran one of the first belt drives on a Sportster back in the mid '70s when the belts were Gilmer drives - square teeth instead of the rounded versions now. It ran in the oil bath as the Sporty primary and tranny share oil. It didn't hurt the belt. But different belts are made of different materials. If you think your belt is suspect because of oil contamination, by all means replace it. When you reinstall that outer primary cover, ventilate it! There are complete outer primaries available that are well-vented. Or you can simply drill holes in the inspection cover and the derby cover. Another method is to space the outer cover away from the inner primary with washers between the inner and outer so there is a gap between them. However you do it, do something to vent it. That will help your belt live a lot longer.

 

Many thanks Pococj. I have printed your post out and will have it handy when I tackle that section. This will be another week or so as I need to change over the brake discs and pads on my car and I am only allowed half a day per weekend doing 'grease-monkey-work'! :-(

But I will report back on progress - or lack of it.

Cheers
Paul

 

Hi all,

I got a little further (changing the front brake discs and pads on an Audi only takes an hour and a half!). :-)

I found the two middle oil lines at the back of the inner primary were already disconnected and acting as vents but the oil return line right at the back on the bottom of the case is still connected to the pump... ?

Also, I took the main chain off and found the sprocket nut could be undone by hand! No wonder... ! I did not find a key...

Main gearbox oil seal looks OK still, but as I am here I will replace it anyway. I also found a few 'super nuts' on Ebay, so wil see if I can get one of those, the old sprocket nut was knackered anyway.

Two questions Pococj; you mention a small seal at the end of where the pushrod goes. How do I get to check that one? Do I need to take the gearbox apart?

Also: how do I check the bearing? There is very minimal up/down play in the shaft, but it rolls true and smoothly (with the oil seal still in).

Thanks all for all the help all - I am quite enjoying this journey into the bike - but looking forward to putting it all together again, start riding it, and parking it without a big oil puddle forming underneath!

Cheers
Paul

 

Just a few more things Is the inner primary trans shaft bearing a sealed bearing? (a must for belt primary's ) Does your belt primary have an idler adjuster ? and what mm belt does it run like 8mm / 13mm or ?

 

Not sure if it is a sealed bearing or if it has an idler adjuster - how do I recognise these?

Belt is about 3 inches wide.

Paul

 

No idler adjuster for sure 3 in belts do not have these and you probably have a sealed trany shaft bearing I was thinking of the old 11/2 in belts

 

The pushrod seal is on the clutch side. It is inside the clutch hub nut.

Up & down play isn't good. Main drive gear fit is 0.0005 - 0.002, and end play is 0.003 - 0.013 according to my old manual.

Something else to replace - note I said replace, not check! - is the throwout bearing that's at the other end (right side of the bike) of the pushrod. The little wafer bearings use to last me just a little more than 1 riding season - about 20,000 to 30,000 miles on my old '78 FLH. I just got into the habit of replacing the little thing every year.

 

I used to run the little wafer bearings and found myself going through them too quickly. I went back to the older style throw out bearing. I feel a little more confident in a large hunk of metal rather than the later style.

I had a leak of gear oil coming through my main shaft also at one point. I changed the super nut when i put a larger sprocket on and still had that leak. I ended up putting 2 seals inside the clutch hub nut around where the push rod comes through and have been fine ever since. about 3 years now.

McBoney, you can plug where the return line goes into the oil pump and not be concerned. I still run a chain primary and have the primary sealed off from circulating through the oil system. I have it running through an oil cooler on the front down tubes instead. I just pour a little motor oil in the primary case just enough for the starter ring on the clutch basket to whip it around. You don't have to worry about that since you run a belt, but if you ever go to chain, you can do this.

 

Hi all,

I ended up taking the whole tranny out and taking it to a friend of mine with a little more knowledge. He said bearing is bust and that this has caused all the problems, from the leaking oil seal and the chewed up sprocket nut to the leak at the clutch hub nut.

So, I'll start with the bearing and work my way back to replace all the bits mentioned in this thread. I'll include the throw-out bearing on the R-H side.

I have plugged all the oil lines in/to the primary with bolts that screw into the holes where the oil lines feed in, as well as the line-in into the block near the oil pump underneath. A neat job if I say so myself. Only one oil line remaining to act as a vent, which goes underneath the bike.

Apparently I have a performance main chain sprocket as it has been drilled. I wonder why...? Perhaps it was an old Police bike? How can I find out? The bike has been resprayed in non-standard blue and has an aftermarket speedo that shows double actual speed (ie showing 60 when going 30 etc) so ex-police speedo may have been sold separately (as they seem to be big bucks).

Paul

 

This is really an old post. But I really enjoyed reading it. I've been cleaning and replacing the seals , drive sprocket and cleaning the clutch. I will add there is a hose at the back of the inner primary 3/8 size that's used to suck up any oil in that system. Also a small tube that lubes the drive chain. On the inner primary their is a plug mine is 3/4 inch it has a magnet attached to that plug. Designed to capture any metal that comes off the dual primary chain. If it's been converted to a belt. The vent 3/8 rubber hose is the one in the middle of the inner primary on my bike. It connects to a T fitting thst goes to.the top of the oil tank. For venting. Very important. Those hoses are really close to the rear cylinder exhaust. That crosses over to the left muffler. Any way I've learned alot working on 78 FLH.