Another basic question - Atlas/P11 Primary cover baseplate

Hi All

Hitting the books on this one but thought it worth throwing up a question too.
P11 now running - need to do break in and tune process.

However, before that - there are a couple of biggies to sort out....

I have done something wrong in the way my primary cover base plate sits - or with the chain/clutch/sprocket alignment - as the chain is running along the baseplate around the rotor (top and bottom) and causing scratching/'polishing' of the base plate.

On crank side it is : Engine - paper spacer - metal spacer - paper spacer - base plate - sprocket - spacer - rotor (as per diagrams and disassembly).*
There is (and was) obviously very little, if any space, between chain and base plate.

Thoughts?

*N/b paper gasket was recommended although it does not appear in the manual - also does not seem crucial as should not be 'sealing' from oil in primary case.....may be that these need to come off but...

Re: Another basic question - Atlas/P11 Primary cover basepla

By baseplate, I think you are referring to the inner primary cover.....this is the sheet metal stamping that bolts to the drive side crank case with three screws, right?

I am not where I can refer to engine assembly diagrams, but from memory, on my Atlas, there is no spacer. How thick is your spacer? Anything more than 1/16 inch would push the inner cover toward the sprocket and give the symptoms you describe. I do not recall even a paper gasket, although one would not hurt anything. I believe there is one screw hole that enters the sump and could cause oil to leak into the primary. This should be sealed with a thread sealer, a gasket would not seal the thread.

Again from memory, there is at least 1/8 inch clearance (perhaps as much as 1/4 inch) between the chain and the inner cover.

How does the chain alignment look? Does the chain run seem parallel with the inner cover? How much clearance do you have on the clutch sprocket?

Slick

Re: Another basic question - Atlas/P11 Primary cover basepla

Its perhaps worth pointing out that the P11 has an alloy inner primary cover,
and the Atlas has a tin one.

Chalk and cheese, chalk and cheese.
The gearbox sits much closer to the engine in a P11 than an Atlas too, so just about everything is different.

Perhaps a photo inside the primary cover, so we can maybe spot why something is not correctly aligned... ?
Matchless's and Ajays also had versions of those alloy covers, for singles and twins, for some years,
so plenty of different variations of them too - if its not all genuine P11 ??

Re: Another basic question - Atlas/P11 Primary cover basepla

Rohan said:

Its perhaps worth pointing out that the P11 has an alloy inner primary cover,
and the Atlas has a tin one.

Chalk and cheese, chalk and cheese.
The gearbox sits much closer to the engine in a P11 than an Atlas too, so just about everything is different.

Perhaps a photo inside the primary cover, so we can maybe spot why something is not correctly aligned... ?
Matchless's and Ajays also had versions of those alloy covers, for singles and twins, for some years,
so plenty of different variations of them too - if its not all genuine P11 ??

Click to expand...

The P11 has a spacer between the Aluminum inner Primary cover. 0.210" thick.
Thomas
CNN

Re: Another basic question - Atlas/P11 Primary cover basepla

Thanks all, will put a photo up shortly (but dinner is taking priority!)

Alloy base plate - as far as I can tell, it is the correct one for a P11.
I have the .210 metal spacer in place (although I will re-measure to be sure that the thickness is correct - looks about that), wedged between 2x thin paper spacers

To my eye it seemed to run parallel - but will have a closer look. It is very close throughout but particularly so on the little circular ridge near rotor (again - photo will reveal) - so it may be running just off parallel and closing up by rotor (which would explain symptoms)

Huw

Re: Another basic question - Atlas/P11 Primary cover basepla

Well - one issue on chain adjustment sorted - now have a bit more slack...
here are the promised photos






THe contact point is directly above the alternator wire entry point (raised section) and directly below the footpeg bolt (obviously where the chain is running)

Re: Another basic question - Atlas/P11 Primary cover basepla

Check rear mounting point(s).....if something is pushing the clutch end of the inner cover outward, it would contact the chain exactly at the points where you note. You should note non-parallel chain run if this is the case. Are you sure sprocket is genuine? Sprocket bore taper governs how far the sprocket slips onto crankshaft. Again, non-parallel chain run would result.

Did you notice any evidence of the chain scuffing the inner cover before you re-assembled the works?

Hope you work it out.

Slick

Re: Another basic question - Atlas/P11 Primary cover basepla

2 things-

1. Don't use the paper gaskets. Use permatex thread sealer on the screws that hold the inner primary and a thin smear of Grey permatex motoseal #1 or Yamabond on each side of the spacer. This will gain just a tiny bit of space. My experience is the main source of oil leaking in this area is weeping out of the crank case. Sealing the threads will keep wet sump oil from weeping out, and sealing the spacer will direct any oil weeping through the seal into the primary, and not down the outside of the drive side case.

2. Make sure the inner primary is square with the crank case. Tighten it up with no spacers on the footpeg stud, measure how much you need, then assemble with exactly the right spacers so that when you tighten the nut on the footpeg perch, everything stays true.

That fouling you're seeing looks like a combination of inner primary too close to the sprocket and the back of the inner primary being pushed away from the trans

Re: Another basic question - Atlas/P11 Primary cover basepla

BillT said:

2 things-

1. Don't use the paper gaskets. Use permatex thread sealer on the screws that hold the inner primary and a thin smear of Grey permatex motoseal #1 or Yamabond on each side of the spacer.

Click to expand...

Thanks for the tip BillT. I was going to do that as well.
Cheers,
Thomas
CNN

Re: Another basic question - Atlas/P11 Primary cover basepla

Well...scuffing is more even than first thought....paper gaskets now off but need to investigate gearbox spacing (point 2 from comments above)


Have taken measurements of the gaps - just need to do the math on it to figure out how much play.
The Spacer is the correct diameter.

Gap between sprocket and base plate is 6.9mm (.27") not including chain - all around (measured in 3 places).
Chain would take a down to a clearance of around 3.5-4.6mm by my measure/guestimation.

Re: Another basic question - Atlas/P11 Primary cover basepla

hrwat1 wrote:

"Gap between sprocket and base plate is 6.9mm (.27") not including chain - all around (measured in 3 places).
Chain would take a down to a clearance of around 3.5-4.6mm by my measure/guestimation."

I happen to have the primary cover off my Atlas.....The Atlas has a stator mount between the inner primary cover and the sprocket. I used Allen keys as a gauge to measure gap. I measure 0.25 + inch gap between sprocket and stator mount...this corresponds to your measurement of 0.27". I measure 1/8 inch (3.2 mm) clearance between the chain pin head and the stator mount. This corresponds nicely with your guestimation. So why are you experiencing interference? Is your chain proper width ...(1/2 inch x .305)? Is there something protruding off one link, such as improper width master link?

Typical gasket paper is about 0.012 inch thick. You can gain about 0.02 inch by eliminating the gaskets per BillT's suggestion.

Slick

Re: Another basic question - Atlas/P11 Primary cover basepla

Thanks All - have taken it all apart and am glaring at it now. Hope to have a proper crack at it this weekend.

BiiT on your second point - and this may reveal the cause of the problem, is there meant to be a spacer on the inner part of the chaincase?
It makes sense, but I don't remember seeing it when dissassembling - will go back over the photos.

No evidence of scuffing pre re-assembly - unfortunately, this one is all down to me!

Best
Huw

Re: Another basic question - Atlas/P11 Primary cover basepla

hrwat1 said:

BiiT on your second point - and this may reveal the cause of the problem, is there meant to be a spacer on the inner part of the chaincase?

Best
Huw

Click to expand...

As I recall, there should be a 3/8 X 3/4 x .072 plain washer on the stud that goes through the chaincase to hold the footpeg perch. I preassembled my inner chaincase and measured what that spacer should be to keep the chaincase square with the crankcase.

I did the same thing with my G15 and Commando. The Commando, of course, has the stud that travels through the inner primary and mates with a shouldered nut that secures the outer primary. The stud has a spacer or two to set the primary square with the chaincase.

The G15 also has a stud supporting the primary chaincase to the rear engine plate, but this stud only goes through the inner primary. Again, there is the ability to set the inner square with the crankcase by shimming this stud.

On another note, if you plan to use a Renold chain, check it very carefully. I had a plate come off my Renold 428 at about 300 miles after I started my Ranger, due to poor riveting. It blew a hole in both inner and outer primary, but thankfully did no other permanent damage. Thanks to my expert welder, the repair is flawless, though not cheap. Never got a satisfactory response from Renold.

Replaced it with a D.I.D. 428HD, which was half the price and rated at about 50% stronger, have gone 4000 miles since with no issues. I used the same chain in my G15CS

Re: Another basic question - Atlas/P11 Primary cover basepla

Well......firstly a confession.

One part of the problem is undoubtedly caused by genius here forgetting the inner spacer entirely (ie between the base plate and the outer cover). Now fixed - really should have checked disassembly photos.

Have also replaced the .072 washer on the footpeg stud where it meets the outside of the inner base plate (ie the innermost point) and removed the paper gaskets from the crank-side as discussed.

Need to start doing some measurements to check how square it is - however, just bolting the clutch basket on quickly now, it seems to be running the raised ridge of the inner cover. If I push the inner cover back by hand it runs freely without fouling. Hopefully gearbox spacers not an issue (ie if the box was out a bit further it would sit 'higher' in the case).

I am using the old chain because my new Renold chain seemed to be slightly wider than what was on it and I didn't want to exasperate my existing problem.

Measurements will be key at this stage - but I am moving to Tokyo for work and need to pack at some stage too!! (P11 will be coming with me).

Huw

Re: Another basic question - Atlas/P11 Primary cover basepla

Hmmm....still haven't sorted this one out.
Current theory is that the kickstand mount was fouling on the bottom and pushing it all out slightly.
I am double checking that the stand is in the right position - and potentially taking a bit more meat off the bracket if necessary.

However, the clutch is still not spinning freely (even without the bracket installed it is just lightly brushing the ring around it on the base plate - so there are still other alignment issues...)

Huw

Re: Another basic question - Atlas/P11 Primary cover basepla

hrwat1 said:

Hmmm....still haven't sorted this one out.
Current theory is that the kickstand mount was fouling on the bottom and pushing it all out slightly.
I am double checking that the stand is in the right position - and potentially taking a bit more meat off the bracket if necessary.

However, the clutch is still not spinning freely (even without the bracket installed it is just lightly brushing the ring around it on the base plate - so there are still other alignment issues...)

Huw

Click to expand...

The original side stand clamp was really quite thin on the outside. As replacements parts were superseded, Norton kept beefing up this clamp. The final version, 06-7719, had the outer part of this clamp nearly twice the thickness of the original. I had to grind the two stiffening ribs nearly completely off to clear the primary. I stopped grinding when I could slide a piece of paper between the mount and the inside primary when fully seated. The back side of the side stand wedges firmly between the frame tube and the front engine plate - wear marks on that plate will show where the original stand fit.

There are 12 spacers on the engine plates. 8 of them are .156" thick. Three are .343" thick and fit between the left hand rear engine plate and the three rear crankcase lugs (3/8 stud top and middle, 5/16 stud bottom). The last spacer is 3/8 ID x .406" thick, and fits between the top front frame lug and the left hand front engine plate. There are no spacers between the trans lugs and the left rear engine plate.

Basically, this arrangement pushes the engine a bit to the right (timing) side, and keeps the trans to the left (drive) side.

You can search either Christian's archive or the Yahoo P11 group for Hy-Cam's list and description of the P11 engine mounting studs and spacers.

Hope this helps

Re: Another basic question - Atlas/P11 Primary cover basepla

Thanks - I based my initial assembly on one of those lists. Although didn't 'click' to the practical effect until you gave your explanation.
Thankfully, with some work on the side stand and minor tightening and adjustment it is now running much better. Will put together and do a further check with chain on but it feels, if not 100%, like it 95% there.

Huw