Starter Sprag slipping

[johnbirchjar]

Hi guys,I have oil from the gearbox getting into the Primary Chaincase , I assume there is an oil seal that has sprung a leak, if this is the case,(because this is the wrong oil),would this cause the Starter Sprag to sound like it is slipping?(this only happens when starting a cold engine,it's fine when the engine is warm)hopefully this is the case, 'cos Joe Walker fitted a new Starter Sprag for me about 3,000 miles ago,and the original one lasted 63,000 miles .
Looking at the exploded view if the Gear Shafts and Fittings in the Classic Parts Manual,I'm thinking that the guilty item is the Mainshaft Bearing Oil Seal(pt No 55-0421)if not,any suggestions?rgds,J.B.

[Anthony Duffield]

John,

Gearbox oil is considerably heaver than primary chain case oil so you might be correct in thinking that the heavy oil would cause the sprag not to bite. If I had the primary chain case filling with oil on my bike I would suspect item 3 oil seal PT No. 55-0421, see attached.

Not long after getting my Commander I had a problem when pressing the starter button the starter motor would just spin and not engage, I would put the bike in gear rock it back and forth press the starter and away she would go.

I later carried out a major overhaul and found the sprag to be gummed up with black stuff, as a result of poor maintenance and clutch plate wear I guess, anyway I fitted a new sprag for good measure but when I cleaned up the old sprag it looked OK I think a good clean was all that was needed.

For my own interest what grade of oil(s) do you use in the gearbox and the primary drive?

Hope the above helps

Tony

[johnbirchjar]

Hi Tony,the G/Box oil is Harley Davidsons 90WT Cubiscan,(it helps to make the g/box less noisy) and the Primary oil is "Power Steering Oil",(a tip I got from Del Boy years ago,it seems to make the Clutch feel lighter )
I expect A/N will have the replacement oil seal,BUT how old will it be .
When I take the offending oil seal out I may just hawk it round some local bearing suppliers to see if I can find a match ,rgds,J.B.

[Anthony Duffield]

John,

I tried the Harley Davidson pink gearbox oil, didn't think it made much if any difference so after overhauling the gearbox I went back to straight 140, I also use the red power steering oil in the primary drive, it seems to do the job.

I changed the same seal a couple of years ago but do not remember the size, the seal along with all the other spares came from ANL quality was OK, it will be interesting to see if the seal is a standard size?

Regards
Tony

[Mick Taylor]

For some reason I have always believed that anything related to the starter motor on the rotaries is a bit of a nightmare.....as if they had started with a starter motor and built an engine around it ......so I would be horrified at a slipping starter clutch.

I would love to find out that it's all accessible stuff after all......is the sprag clutch easy to get at?

Mick.

[Richard Negus]

Mick,
Just dismantle all the primary drive and you'll find it in the back of the clutch drum. Some simple tools and about four hours work, end to end. Seemples!
Now if it were the starter motor that needs replacing, that's very character-building.
R.

[Mick Taylor]

Now if it were the starter motor that needs replacing, that's very character-building.

That must be the issue I had at the back of my mind.......lets hope the starter motor is an exceptionally good quality reliable part....

Mick.

[johnbirchjar]

Like Richard says,easy,(if you know how )simple tools?yea,right,but unique,+ a torque wrench rated up to 150+psi(not hanging in everyone's garage )rgds,J.B.

[Mick Taylor]

I was looking at the starter today as I have the right side carb off.....on the face of it, it looks reasonably easy, one of the bolts is a bit hard to get at, but then I had a look at the other side and it looks like it can't be withdrawn without dismantling half the bike........lets hope that is one part that never goes wrong...

The other problem being, that to someone raised on Japanese stuff which looks complicated but is usually simple and sensible, pretty much everything on the Norton is borderline weird

Mick.

[Richard Negus]

.....lets hope the starter motor is an exceptionally good quality reliable part....

Mick.

Of course they are! All made in 1975 by Joe 'Prince of Darkness' Lucas and built in India.

[Mick Taylor]

Of course they are! All made in 1975 by Joe 'Prince of Darkness' Lucas and built in India.

Lawks! I guess the Nippondenso ones weren't available

[Richard Negus]

Those starter motors were originally made for the Triumph T160. The only change for the Norton application was a new drive end plate and an oil seal.
IP2/Classic/Commander motors run in the opposite direction, so had the brush wires reversed and the direction arrow on the casing re-stamped.
F1 motors, placed in an accessible position, run in the same direction as T160 and have a three-bolt end plate.

[johnbirchjar]

They seem to be pretty reliable ,leastways,we don't get many reports of actual Starter Motor problems on our forum (touch wood)
Oh,and Mick,it is an "engine out" job to remove the thing ,and like Richard says,"Character Building" ,J.B.

[Mick Taylor]

it is an "engine out" job to remove the thing

I remember chickening out of removing the engine when it needed Richard's touch.....having looked through the book of words and realised that much of what was required was counter-intuitive and unlike anything I'd messed with before........and I well remember feeling I'd made the right decision when I ran the whole bike up to him and watched Richard swinging on the end of a huge extension bar to release a large nut that had been torqued up beyond reason and bonded with a particular type of Loctite .

I would be perfectly happy to do that if I had someone standing next to me who had done it before and knew what they were doing ......... had I attempted it I know I would have backed out of that nut for fear of breaking something long before it came undone......knowledge (confidence) is everything and the thought of damaging near irreplaceable and expensive parts is quite sobering....

Mick.

[johnbirchjar]

Yep,the nut in question(two actualy,Fly Wheel side& Primary Chain side)are torqued up to 150psi+Locktite which take some undoing(I use a sturdy old "T" bar+ a length of Gas Pipe+ a short lengh of Scaffold Tube )and don't try to undo them with the bike on the Centre Stand,the bike just lifts off it ."Character Building"I like that ,J.B.