Hi Guys I am quite new to the site and loving it!

Anyhow my 1973 Norton 850, makes an interesting scraping noise when being wheeled in and out of the car park.... always assumed it was the chain against the chainguard. But when i read this post below I realised this could be a bigger issue so decided to take a more careful look at the problem instead of just ignoring it and riding in bliss:

post118487.html?hilit=chain%20primary%20case#p118487

So I got her up on a lift and took a very good look today. I found that I have what one might call minimal clearance between the chain and primary case, so minimual that I can hear the chain link (slightly thicker link) tap against the primary case as it rotates. Heres a photo:


Clearance between Primary case and chain by pjr1440, on Flickr

Anyhow not enough to cause me to worry significantly, as there are far worse noises than this coming from the rear .... sure the chain guard is rubbing on the chain so I bend that away, noise is no better even seems louder now and is definitely coming from the brake drum. I pull off the wheel, separate the brake to show the pads inside the cast iron brake drum & Sprocket. Now I can see that clearly the noise is the sides of the steel shoes rubbing the inside edge on the iron brake drum & Sprocket - what the? Maybe missing a spacer or something?

Have a look at the steel brake shoe edge (not the pad) and you will notice it has been rubbing against the brake drum & Sprocket, notice that bright steel edge where it has been rubbing:

Drum Brake showing wear on side of steel shoe by pjr1440, on Flickr


And here is the Brake drum & Sprocket photo for those of you who are interested, you can see where the steel brake shoe has rubbed:

Steel Sprocket and Brake Drum by pjr1440, on Flickr

Anyhow I grease and reassemble, tighten the left had wheel nut very firm, all good and most of the noise is gone (dont know why). But then I put the wheel back in and inserted the axle and tightened her up on the right hand side and if I tighten it to much it locks the wheel, if I leave it lose/firmish it is fine and the wheel rotates with no strange noises.......

I hope someone out there has some ideas to share with me, as I have no idea what I am doing anymore! Tempting just to say well its fixed just don't tighten the right wheel nut up, but I am not sure that this approach is correct or not?

Looking forward to hearing from more informed Norton owners!

Pjr1440 wrote:I found that I have what one might call minimal clearance between the chain and primary case, so minimual that I can hear the chain link (slightly thicker link) tap against the primary case as it rotates.

That looks as if it could be an O-ring (or X-ring) chain?

O & X-ring chains are wider than standard chain so they will rub against the case, owners who want to use sealed O or X-ring chains generally fit the narrower 520 width size chain (and sprockets).

I looked at the chain and it is standard 530, not oring or xring...

This is a long shot; If the shoe pivot and foot aren't square the shoe will lean, if that's the case, try swapping the shoes over they might lean in. Other than that there's a lot of washers seals a spacer and a circlip that influence the brake plate to drum clearance. However, I can't see any rubbing marks on the brake plate, perhaps the shoes are too wide, and it's been a long time since I was last inside a rear drum brake.

Best of luck,
Cash

I had a similar noise on the '71 Roadster I bought last year. Didn't have a centre stand so jacked it up when I got home to check the rear brake and found the chain was rubbing on the gearbox. The countershaft sprocket had too much end float so stripped it down to find both bearings were loose in g/box shell. Got carried away, like you do, so now engine's out, forks are off and it's totally stripped ready for painting...

Good luck,
Graeme

Pjr1440 wrote:I looked at the chain and it is standard 530, not oring or xring...

How wide is it?

Or it could be that the chaincase needs to be shimmed out slightly?

I misread your post. I thought it said "Scraping sound when wheelying bike...." I thought you must have flipped it whist trying to attempt a wheelstand.

Hi

My rear sprocket did the same thing a few months ago, how much slop does your dummy axcel have as what corsed mine to rub the brake drum was where the cirlip that holds the dummy shaft and bearing in place the outer circlip mount had broken away, which made the circlip fall out and made everthing else move and coursed the backing plate rub like yours has done, when mine did it corsed the back wheel to go tight, I was 2 miles from home when it happen but was able to ride it home but it was very hot when I got home, I was able to fix mine on a lathe.

Ashley

Mr Bean wrote:I misread your post. I thought it said "Scraping sound when wheelying bike...." I thought you must have flipped it whist trying to attempt a wheelstand.

No not me, I ride with both wheels on the ground as to do otherwise is surely to result in more maintenance!

ashman wrote:Hi

My rear sprocket did the same thing a few months ago, how much slop does your dummy axcel have as what corsed mine to rub the brake drum was where the cirlip that holds the dummy shaft and bearing in place the outer circlip mount had broken away, which made the circlip fall out and made everthing else move and coursed the backing plate rub like yours has done, when mine did it corsed the back wheel to go tight, I was 2 miles from home when it happen but was able to ride it home but it was very hot when I got home, I was able to fix mine on a lathe.

Ashley

Very interesting, I didn't see anything obvious when I pulled it apart, but can you tell me the part numbers from this diagram please?

http://www.oldbritts.com/1973_g20.html

You may want to check the spacer between the gearbox and the cradle. Plate No 34 Part No 030023. This will make your chain rub on the back of the primary chaincase.

Phil

Wes's '71 was doing this before we left and he took wheel of to check inside drum, found nothing then checked the hub axle nut, found loose, nipped it up for silent spinning again. It'd scrap in few degrees only of wheel rotation then ok then scrap ...

If you compare that photo of your drive sprocket to mine, I have quite a bit more clearance in all places. It looks like your swing arm end is almost hitting the inner cover, and the clearance on both sides of the chain to the gearbox and the primary inner is pretty tight. I think you already checked for the spacer at the top gearbox mount to cradle, so that shouldn't be an issue. If it were mine, I'd still pull off the inner cover and either shim out the cover at the engine and the center mounting bolt so you can get some more clearance for the chain (DomiRacer has some nice sort of ruberized gaskets for the crank to inner cover and they are a bit thicker than the paper ones), unless it's just that the center primary bolt is letting the inner cover pull in as you tighten it because the shim between the cradle and inner cover is not large enough. While you've got the inner cover off, check the drive sprocket with the chain and see what clearance you have to the gearbox, there are no shims there and it should be good. If you get the inner cover away from the sprocket a bit more, you may have to add shims over the clutch location circlip (item 55 here http://www.oldbritts.com/1971_g8.html you should have several spares of this item, they get bent removing them) to space the clutch basket out a bit more or not. Depends on your crank drive sprocket, you need to get the crank sprocket and clutch basket lined up.

The rear wheel; when I installed the rear wheel inner spacer (it spaces the bearings) item 29 here http://www.oldbritts.com/1971_g16.html I had it backwards and tightening up the right side spindle caused the wheel to lock up. The short shoulder on that spacer goes to the double bearing, it's counter intuitive. If yours has been ok in the past that may not be it. When I first installed my rear hub and brake parts, I was getting a lot of rubbing too, but I think mine was mostly the shoes on the drum. I reversed the shoes (swapped one for the other) and it went away. It also helps to have someone hold that rear brake tight while you tighten the right side up. You should be able to put 70-80 ft/lbs on both the left and right spindle heads without any binding. I've got the real early rear wheel so I don't have the cush drive, so it's a bit different. The rubbing of the side of the shoes and the drum may be because you can't tighten down the right side spindle and things are moving around while going down the road??

Dave
69S

Hi

The part numbers that moved in my drum sprocket in you diagram are 23,33,32,30,47,48,46,45,44,and 21, you will see if the circlip has popped out as soon as you look at it, it on the back of the drum where the 3 prongs that sit into the rear wheel, on mine the whole outside circlip mount was comletely broken aways so the circlip couldn't hold in position, but sometimes the circlip just pops out, I fix mine with the use of a lathe, machined the circlip mount deeper and put a bigger circlip in , took about 5 minets to set up on the lathe and 5 minets to machine a deeper groove.

Ashley

Pjr1440 wrote:

ashman wrote:Hi

My rear sprocket did the same thing a few months ago, how much slop does your dummy axcel have as what corsed mine to rub the brake drum was where the cirlip that holds the dummy shaft and bearing in place the outer circlip mount had broken away, which made the circlip fall out and made everthing else move and coursed the backing plate rub like yours has done, when mine did it corsed the back wheel to go tight, I was 2 miles from home when it happen but was able to ride it home but it was very hot when I got home, I was able to fix mine on a lathe.

Ashley

Very interesting, I didn't see anything obvious when I pulled it apart, but can you tell me the part numbers from this diagram please?

http://www.oldbritts.com/1973_g20.html

Problem is the #47 Wheel Bearing Circlip is out of its its groove.
I had exactly the same symptoms as you have and the circlip was out of position.
I had scraping of chain guard by chain and chewing up inside of brake drum.
When putting circlip in place check to see the sharp edge is facing outward so has less chance of working out of slot.

Bob