Gearbox oil leak

[jhg1958]

After carefully remaking the joints on the gearbox I find my oil leak is no better possibly worse. It must be the seal on the main shaft. So I have started to take the clutch off.

A couple of questions
Do I need to take of the inner primary chaincase to change the seal?

Is it worth putting a gearbox sprocket on with an extra tooth?  I am more bothered about vibration than performance and it seems to pull well in first.

Finally, I have a NEB clutch with a belt drive. It suggests as the belt runs hot that the primary chaincase outer should be left off. I am less than happy about this. What do other owners do?

John

[limeyrob]

Inner case has to come off. I would check the bearing carefully. It may be that the seal is worn and or hard, but if the bearing has play it will make the seal work hard. 
Do you know what sprocket is on at the moment?
Personally I would junk the belt drive, the chain case should be running in oil.  The primary chain set ups last 40-60 years, there's not much wrong with them.  OK a belt will reduce leaks on a steel chaincase but BSA ally cases seal well.  If it runs too hot to have the cover on its already more trouble than its worth.

[muskrat]

Inner case has to come off. I would check the bearing carefully. It may be that the seal is worn and or hard, but if the bearing has play it will make the seal work hard. 
Do you know what sprocket is on at the moment?

G'day John.
As above.
I have a belt on the Cafe. I didn't like the idea of no cover at all (like most HD's) so cut out a section.
Cheers

[chaterlea25]

Hi Jhg,
Very often the sprocket oil seals are not fitted properly as usually the rear of the seal needs sanding down to get the circlip to fit into the groove, apply some sealant to the rear of the seal.
Oil will also leak out along the sprocket threads and layshaft bushes, the SRM nut ith seal will fix this.
On other occasions a ham fitted layshaft bush oil can leak between the case and
bush

John

[jhg1958]

That sounds like my problem. Ham and fitted are my middle names.  I changed the bush myself so I am a bit worried what I could have done wrong or missed out.

I have fitted an SRM nut so hopefully this will be ok. I am awaiting some UNF bolts to extract the inner drum so I will have a bit of time to contemplate my incompetence.

The sprocket is standard 19 teeth.

There is something wrong as I turn the rear wheel there is a definite lumpiness to it.

I think I will keep the belt if only to eliminate oil leaks not to mention the money I invested in it. My Triumph primary cover is impossible to keep oil tight.

Musky I love your bike a real eye catcher. A credit to you. Chopping up the cover is not an attractive option for me as I have gone for retro look to the bike.
John

[limeyrob]

Are you sure the extractor threads are UNF?  On an A10 I would expect BSF

[berger]

you could also go for a tatty primary cover that has damage and cut that open

[Swarfcut]

 This is more of a puzzle the more I read. Simple problem, oil leak.

 So, where is it coming from? We all know possible sources, but the first thing to do is to top up oil levels, clean off all the previous drips and weeps, run the bike and observe.

 Once you know the source, the solution is simple, or may require major dismantling.....a failed/hardened main seal or loose sprocket nut is simple, a cracked blind layshaft bush or failing sleeve gear race or bushes, and it's a box out job.

 I would assume this bike has the standard later 4 Spring Triumph type clutch, this needs its own extractor to remove the clutch centre adaptor from the gearbox mainshaft taper.

  Worth adding an extra tooth or two to the gearbox sprocket, speedo will read a little slow compared to true road speed. Seal lips run on the sprocket, ovality in the final grinding of this surface has been encountered with poor quality bits. Worth checking for a bowed mainshaft  along with anything that could put wobble on the sprocket.

 The primary case seal is a poor design, leaks from around the mainshaft  and a drip from the back of the primary chaincase is a standard fitment. Lot to be said for a custom undertray....

 Swarfy.

[jhg1958]

The clutch is a 6 spring NEB clutch from SRM. I have asked about the thread for the puller screws and was surprised to hear they are UNF. They are not cycle or UNC or metric. I do not have any UNF bolts. I will know better.  I may need to buy some BSF bolts.

I can only hope I have not buggered up the mayshaft. I will know more when I get it apart. I can then start to order the parts.

I assume I can take the. Gearbox out and leave the engine in place.

John

[chaterlea25]

Hi All
JHG,
Klaus on this Forum and his friend travelled over and toured Ireland and Scotland (at least) on their A10's a couple of years ago, He runs a belt primary with a full primary cover on, So I  would not worry about running the belt enclosed.

John

[Swarfcut]

  Mainshaft can be examined without removing the gearbox casing from the frame, but involves gaining access to the selector shaft grub screw, which on a S/A bike is relatively easy.

 Try your local motorspares shop for UNF bolts, typical "Oddpak" stock line.

 Swarfy.

[orabanda]

I also run a fully enclosed chaincase, over a belt primary drive on a Super Rocket; no problems.

[limeyrob]

If the clutch is SRM then the bolts could be UNF.  A65s are UNF, A10s BSF and Whit but the SRM clutch is modern.
A belt inside a chain-case?  Is this picking up the "wet-belt" craze that's really taken off in modern cars?
I must admit to not liking belt drives.  The tension is higher, the width greater, and the efficiency is less, that's where the heat comes from.
My first thought when someone tells me they have fitted a belt primary is "I hope you kept the old parts"
Even Harley who made a big deal of their belt drives kept the chain primary.

[groily]

A belt inside a chain-case?

They don't all have to have oil in there though Rob, so not a wet-belt craze thing necessarily, nope.
I have only ever had (got, I should say actually) one, on my 650 Notrun. It seems fine (famous last words I hope not!). Mine is the sort with a diaphragm clutch (Norvil maybe, not sure) - which I like very well compared to other AMC clutches I have / have had. It's as nice to operate as the 4 spring I had on my A, but a tad heavier. (Heavy as hell compared to the jewel-like lasts-for-ever 5 spring Burman on another bike though  . . .)
The belt doesn't need adjustment often - touch wood - and doesn't seem to get hot under the tin cases Notrun persevered with pre-Commando. No smells anyway!
When it breaks, I'll whinge, it's true  . . . but so far so good and it's taken some harsh treatment.

[jhg1958]

Rob

The threads are UNF. I received the bolts today and they fit nicely. A couple if days off the bike to do grandfather duties.

The belt runs dry. That was one of the motivators for going for a belt.  Stupidilly I bought a pup of bike a real basket case.  The clutch was a mess and the primary chain had broken. So I do not have many bits to retain.

The SRM belt retained the Cush drive so I am hoping there will not be too much snatch on the belt.

John