Swing arm/chain case interference and more etc (2010)

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Mike , the way to get the inner flat is to shim from the center bolt to align with the surface of the crank face. Adding a gasket here will throw this off. Check the surfaces of the inner and outer by mating them to each other after the inner has been mounted. Check, adjust and repeat.
 
MexicoMike said:
Will do! As I have said before, a glass plate and wet/dry sandpaper should have an official Norton tool number. I have probably used it more on the Commando than any other "special tool!" :)
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http://www.nortonabrasives.com/

I once solved an identical problem , to make a little extra room for a fatter chain , by cutting the mating face of the primary to the engine in a slight angle .
are you handy with a body file and a sanding block ?
But don't overdo it , or you'll get into trouble with the alternator .
 
Mike -

That condition is what prompted me to disassemble my bike down to the frame last year. What I found was not pretty.

If the engine mounting bolts come loose, or the chaincase shims are omitted for a length of time, the holes in the crankcase can become elongated and the engine will twist left in the mounting plates. That puts the back of the chaincase against the swingarm and lets the chain eat into the back of the case. Adding more shims won't correct it.

Do as Ludwig said - check alignment of the engine sprocket to the clutch. If it appears that the crankshaft and gearbox mainshaft are not parallel, loosen the 3 rear engine bolts and check again. If the shafts then come into parallel, you may have worn mounting holes in the aluminum cases. When I pulled my engine out I discovered that not only were the holes oblonged, but the lower one was cracked:

Swing arm/chain case interference and more etc (2010)
 
Thanks Dave...that's really ugly! I checked the cradle for oblong holes but it didn't occur to look at the engine cases for the same problem...

As my wife says, "Is that bike ever going to be right? It sounds like it's a rolling basket case!" :)

My answer is, "It's a Norton, of course it's never going to be right!"
 
Mike — Glad you've done the fix. It's not a proper engineering solution, but it works. As for how it was when it left the factory, I find it hard to accept that the factory would have bolted up the inner case if the end of the swinging arm was preventing it from lying flat against the crankcase, but maybe I'm wrong and someone with experience of what they were like from new might say different. Les Emery at Norvil would probably know.

When I inherited my Commando, it had been rebuilt/restored at least once before, and I lost count of the number of things that were out of line or out of adjustment, etc. It's probably the same for many Commandos that have survived up to now.

I'll probably do the same as you and fit a 520 O ring chain, but I'll wait till the existing chain wears out before disturbing the primary (yet again!).

Dave
 
Thanks Dave

One thing I'm wondering is if there is some general "shifting" that can happen over time but then again, if the cradle was shifting, the chaincase would go with it and maintain whatever relationship that there was.

One thing occurs to me. The entire assembly could be moved left/right depending on the setup of the iso mounts. The rear mount on this bike was fitted sometime in the past with what appears to be the MKIII iso mount. I have never had it apart so I don't know the internal condition of. I did check the clearance a while back and there was .006. But couldn't the entire mount be shifted by changing the location of the shims? For example, on the front mount I have .090 in shims to end up with .005 clearance. Per norton guidelines, I have approx half in each side. But if you put say .080 on the left and .010 on the right, wouldn't that shift the engine to the right? Does it really matter if the shimming is stacked more to one side?

I think I will have to take a closer look at the rear iso and try to figure out if perhaps something there is awry which is causing the engine to be too far to the left. I BELIEVE I read somewhere that it is possible to pull the rear iso without disassembling as described in the manual. I'll see what I can find.

If I'm wasting time by going in this direction, don't hesitate to let me know! :)

Call me embarrassed...I have a copy of removing the rear isos in my computer. I have a bunch of Norton tech stuff and had forgotten I downloaded it there a couple of years ago... ;)
 
Mike — you may be right about the bias caused by the uneven adjustment of the isolastic mount. I changed mine last year. It is possible to remove it without taking the gearbox and cradle out, and I started out with that intention, but it is awkward and things are very tight, and even more so if you try doing it without removing the primary drive. I ended up taking the 'box and cradle out, since it was the first time I had inspected this part of the bike. I reckon it's probably not that much more work to take the cradle out and the mount is then much more accessible on the bench. You will have the primary off in any case when you do the 520 chain conversion, and that's the bit that takes the time.

Dave
 
I'm a little confused at why you believe shimming the isolastics would have any effect on the chaincase? The isolastics support the entire engine, transmission, and swingarm, so the relative position of those three is unaffected by shimming.

More likely the engine/cradle bolts become loose and allow movement. Aluminum being softer than steel, the crankcase holes elongate and the crankcase twists in the cradle. If the cradle has been powdercoated, there is even more likelihood that the crankcase to cradle bolts become loose.
 
"I'm a little confused at why you believe shimming the isolastics would have any effect on the chaincase?"

I'm equally confused as to why I thought that. :(

I should just forget about it for now. The chain and the swingarm no longer hit the chaincase (thanks to the folks at Nabisco) and the engine runs great. Probably ought to leave it alone...but I probably won't. :)
 
Hi Mexico
Sometimes when bikes numbers don't match up where engine and transmission are different, they sometimes miss the spacer washer on the inboard side of the rear engine/transmission mount at the top transmission bolt. (the one the lollypop adjuster runs through.... Part # 030023 item #34 Group 7 (Gearbox Top Bolt Spacer) this is about 1/8" thick and sometimes is left out of the commandos if the person who put the bike together is not aware of this. Without it it pulls the rear engine mount out of wack and causes problems at the inner primary side. Check your bike to see if its there. I might be wrong but sometimes I'm right. :wink:
Regards,
CNN
 
Hi guys, I have a 73 850 and my bike has the same problum. Dose everyone replying to this post have a 73 850 ? Just wondering Phil
 
"Check your bike to see if its there. I might be wrong but sometimes I'm right. "

CNN, This is one of those "sometimes." You nailed it! part # 030023 item #34 Group 7, is missing.

Nice Goin!!


Another "great job" by a well-known dealer whose motto should be, "We're incompetent but luckily for us, most people don't figure that out!"
 
Great to hear Mike
Its always nice when things work out. Now you can stop supporting Nabisco and put the proper gaskets back in. LOL.
CNN
 
Mike I feel for you on your bike, My 75 was very much the same. But I got mine sorted and have put over 6,000 miles on it now, I am sure you will do the same. Mine was listed as 9.5 out of 10, HA! HA! It was an E-Bay bike, Might I say never again loud enough? If I am not mistaken you have also found little things here and there, But when you finish you will know it inside out and that's the best thing to know when owning a Norton. They are great bikes when sorted out and they are great for the guy who loves to tinker (Me) a little now and then. I guess the guy didn't know where that spacer went, I had a whole bunch of stuff like that. Nothing really bad but you could tell the guy didn't know Norton's that's for sure. Glad it was something easy and not oval holes in the cases or trans. These guys are great and generous with help, Great site.
 
daveh said:
Brian — I had the same imprint from the end of the swinging arm on my inner primary case. I fitted an extra gasket (approx. 15 or 20 thou, can't remember) between the crankcase and the inner primary and re-shimmed the inner case against the stud on the cradle. This helped to create a small amount of clearance. Why not try making a second gasket, bolting it up temporarily and with no pressure on the mounting stud on the cradle. Then, with a feeler gauge between the end of the swinging arm and the inner case, see if you have some clearance. If you have a gap, however small, it should help prevent the chain from rubbing as well. But I guess the chain has worn its own clearance by now! I assume you have a standard 530. I run a heavy duty 530 which is slightly wider. If the primary is apart, it's an opportunity to try this out. I checked very carefully that the extra shimming did not interfere with anything. In my case, it was OK, but of course, it's a point to bear in mind.

Dave
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Dave
This is off the original thread topic but you just mentioned that a heavy duty 530 chain is slightly wider than a standard 530.
I've been having a heck of a time preventing my chain from rubbing the inside of my chain guard.
Other threads have talked about this issue and I've tried various suggested fixes including wedging a rubber hose washer between brake back plate and guard.
Although the rubbing is less there is still some there.
I've guessing the PO maybe put a heavy duty chain on previous to the bike sleeping for 32 years in its garage and I'm the one to discover the rubbing problem.
Could you put a micrometer on your chain and tell me its width so I can compare it to mine? :lol:
Thanks in advance
Bob
 
STD DID 530 chain, 0.712'' across the plates , 0.796'' across the rivets
 
"But when you finish you will know it inside out and that's the best thing to know when owning a Norton. "

Despite my annoyance with the dealer, I totally agree with you. Frankly, I enjoy the tinkering and I actually like finding and correcting issues - though some are a bit obscure and it would be difficult to do without this resource. My real issue is NOT the problems, but the statement by the dealer that there were no problems, and the price I paid for the "perfect" bike. The bike, contrary to the way I may be depicting it, is great and I really enjoy it. I have found myself actually being pleased that something needs work so I can tear it down, sort it out, and KNOW that it's right. Kinda bizarre I guess... ;)
 
Why the hell would they make one mounting lug 1/8'' narrower than the other,both of my 73 850 gear bags have been fitted with the washer missing, you can see where the slots been rubbing on the case.
 
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