Inner primary case got "chewed"

AussieCombat · Feb 19, 2012

Gentleman, gentleman, please. Back to the task at hand.
The broken inner primary.
Mine is worse than that one, from a previous misfortune, before my time.
I chose not to worry about it when the rebiuld was done. Wish I had repaired it, as lube from the
chain is thrown forward, which then runs down the inner case and appears as an oil leak.
Will fix it next time.
AC.

ashman · Feb 19, 2012

Hi All

What I did when I damaged my inner primary case many years ago from a thrown chain was I cut the case out where the clutch housing sits so the the whole back of my inner case is open then up the front of the innercase I cut 2 slots one on top and one below so fresh air flows into the case, then I converted to a belt drive, with this set up I run my orginal outer cover so it looks stock and all inside stays nice and cool and the best part is I can see my belt running around the clutch housing so if there is any problems with the belt I just look down, I have been running this way for over 18 months now and it works very good and the clutch stays cool.

Ashley

Hobot · Feb 20, 2012

Only danger to Norton belt drive is alignment stays good and no grit wearing on the belt edges which causes an other wise great looking belt to unravel and collect in a bunch around the crankshaft area. Norton's can't heat up enough in sealed primary to bother a belt or alternator but venting is ok if not collecting road grit. Chain is much more forgiving to run if tranny not up to snuff so clutch tends to wobble. Then also need way to stabilize tranny alignment beyond one adjuster on far side to keep belt inline. If installing a out rigger bearing the backside of 1' case, lip included must go, so someone may want your busted case somewhere sometime in future un-repaired.

rpatton · Feb 20, 2012

pvisseriii said:
So you are saying that a somewhat negative bow, say .010, to bring the outer cover in home to the inner at the center nut?
That makes some sense but is also to say that shimming in this area has and should not have anything to do with clearance at the main shaft/sprocket area. Yes/no?

I think they do.
Take two bowls and clap them together with a nut and bolt running through them. If you tighten the nut and the bowls are not infinitely stiff then the centers of the bowls will cave in. If the head of the bolt is fixed to a flat surface under the bowls and you tighten the nut then the body of the bowl above the flat surface will actually to drop or move toward the flat surface because the center is fixed. With the primary cases the inner is weaker than the outer and add the fact that it has a big hole in the rear section, the thing is going to bend and move toward the sprocket.

hayabusaman0 · Feb 20, 2012

Hi, I too found this problem. As has been said, fit a shim behind the inner case & measure btween end of case & swing arm, then fit outer case with o ring & tighten centre bolt, I think you will find that it will pull the casing into towards the swing arm, I cured? mine by fitting a washer between the inner & outer casing.

grandpaul · Feb 20, 2012

Shimming the backside of the case at the pillar bolt per the book should mean no case rub on swingarm.

gjr · Feb 20, 2012

When the master link parted company with the chain it did a little worse on my primary. I bent an 1/8" aluminum strap to fit the curve of the remaining bits. A small nut and bolt on either end held the strap in place until the epoxy cured. The patch is on the outside so if you can see it, it looks good. If you are under the bike looking up, you can see the ugly side, except that it is usually covered with chain lube and dirt.

Greg

Hobot · Feb 20, 2012

Inner case is just to hold oil so space so don't hit nothing or bow but mainly not out so far the clutch basket rubs. Its a great task for the JBWeld mentioned and could be ground even-ish and painted so only this forum would know for sure if we ever laid under you bike to look up like ole hound dogs greeting. There is always the distortion risk welding on wide thin casting.

bill · Feb 21, 2012

once again you are wrong!!! Like I stated, IF the pillars at the center stud are to short it can put excessive force on the inner case at the O Ring surface and force it inward!!!! the clamping force of the center case bolt is transferred to the OD of the case and the center pillar is there as the STOP. if you removed the pillar you could break the center out of the case. I know it is hard for you to think, but think of what happens when you forget to put the spacer between the wheel bearings. same thing if the pillar is to short so shimming is required to stop putting to much pressure on the O Ring surface.

grandpaul said:
Shimming the backside of the case at the pillar bolt per the book should mean no case rub on swingarm.

pete.v · Feb 21, 2012

Again, this pillar is for supporting the inner primary cover and the shimming is to bring it as close as possible to "flush" with the crankcase. It has nothing to do the keeping the drive train in line. Any rubbing or grinding on the backside from the chain or gearing is due to another issue.

Related content:
Any disassembly I have done in this ares as in swing arm work or cradle removel has changed this spacing requiring a + or - .010 to .040 to bring the inner back to flush. A new thinner or thicker gasket will also change this spacing.

bill · Feb 21, 2012

You are correct as to the INNER case to the stud so that it does not push the inner case out of alingment and closer to the swing arm. But as I stated IF there is to much clearance between the pillars on the two case halves than the outer WILL push the inner case over to the swing arm by forcing it to bow inward at the O Ring surface.

pvisseriii said:
Again, this pillar is for supporting the inner primary cover and the shimming is to bring it as close as possible to "flush" with the crankcase. thicker gasket will also change this spacing.

Hobot · Feb 21, 2012

btw I'd been happy I replaced the three front bolts with 3 studs as just a bit handier to hands on and off. Hope your felt seals stay whole.

pete.v · Feb 21, 2012

bill said:
You are correct as to the INNER case to the stud so that it does not push the inner case out of alingment and closer to the swing arm. But as I stated IF there is to much clearance between the pillars on the two case halves than the outer WILL push the inner case over to the swing arm by forcing it to bow inward at the O Ring surface.

pvisseriii said:

Again, this pillar is for supporting the inner primary cover and the shimming is to bring it as close as possible to "flush" with the crankcase. thicker gasket will also change this spacing.

Click to expand...

If properly shimmed to the crankcase face, it will move neither in to nor out.

Shims part # 060399
Seen here # 11
http://www.oldbritts.com/1971_g8.html

grandpaul · Feb 21, 2012

pvisseriii said:
If properly shimmed to the crankcase face, it will move neither in to nor out.

That's what I keep saying...

Except, maybe if you want to get the finest point on it, it can't move in or out AT THE POINT WHERE IT MATES WITH THE SHIMMED PILLAR.

If some idiot with a 5' cheater bar torques down that center nut hard enough, I suppose certain points on the inner and outer cases will eventually deflect as the cast-in bosses fracture and the cases are destroyed.

Hobot · Feb 21, 2012

Huh, ain't that the way to adjust the alternator posts? Break em off then put back as desired? I only use half that long a breaker bar on mine, sheeze.

rpatton · Feb 21, 2012

grandpaul said:
If some idiot with a 5' cheater bar torques down that center nut hard enough, I suppose certain points on the inner and outer cases will eventually deflect as the cast-in bosses fracture and the cases are destroyed.

Which cast in bosses would that be?

grandpaul · Feb 22, 2012

rpatton said:
Which cast in bosses would that be?

The ones surrounding the center hole.

bill · Feb 22, 2012

that is NOT where it will deflect. let me try this AGAIN. the point of deflection IF the pillar's are to short will be at the REAR MOST POINT of the case as in AT the point where the swing arm piviot is.NO it will not move at the front as the case is more rigid. try this, put a .125 shim at the REAR of the case between the halves and tighten the outer against it, you WILL see the rear of the case move inward. this is the same as if the inner and outer cover pillars are to short. the pillar is what allows you to torque the outer cover nut as it is the positive stop NOT the outer seal surface

grandpaul said:
it can't move in or out AT THE POINT WHERE IT MATES WITH THE SHIMMED PILLAR.

grandpaul · Feb 22, 2012

That was a better explaination. Same result in all of them. Proper shimming, fixing, and proper torque = no rubbing if the parts you start with aren't already damaged.

grandpaul · Feb 22, 2012

bill said:
...IF the pillar's are to short ...

You can still use a too-short pillar, AS LONG AS YOU SHIM IT TO THE PROPER ALIGNMENT WITH THE DRY-FIT INNER CASE BOLTED IN PLACE AT THE CRANKCASE WITH IT'S GASKET.

Where are we disagreeing here?

Inner primary case got "chewed"

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