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rampant rivet

Norton 16H Clutch

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HI All

Thought that I would have a look at the clutch on the Norton, I've not been happy with for a while so before Normandy looms on the horizon I though it a good idea to sort it.

On removing the chain cover the first thing I noticed was this -

 

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Wear to the inside of the chain cover !

 

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wear to the clutch spring screws

 

On removing the clutch basket I noticed the clutch plates almost proud of the basket

 

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looks like new friction plates were put in when the clutch was "professionally" rebuilt !!!

 

100_3662.jpg

 

friction plates look ok but will replace them along with the steel plates that aren't too good.

 

Pulled the clutch thrust pin and found this -

 

100_3663.jpg

 

Is this correct ? looks like someone has added it because of the thicker friction plates hence the wear marks on chain case, also circlip missing along with outer band.

 

How many plates should there be ? at the mo there are five clutch and five steel plates, can I fit four plates intead and do away with the add on piece of clutch rod ?

 

Help please as the rivet hasn't worked on a Norton clutch before :blush:

 

Thanks RR.

Edited by rampant rivet

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There isn't much room inside the Norton chaincase and it's a fine line between catching the outer cover or the inner case. A common cause of witness marks on the inside of the outer cover is wear to the bronze mainshaft thrust washer. There is no positive location of the mainshaft in the 'Doll's Head' gearbox and if the thrust washer is below limits, it will allow the shaft to move into the chaincase (with clutch attached). It's worth pushing and pulling on the end of the mainshaft to see if there is excessive end-float.

 

The original internals included five plain and five friction plates but these had cork inserts rather than the bonded plates that you have. The original stack height is pretty much in line with the drum. I'd have thought that you'd be sitting low with two plates removed and perhaps not be able to obtain spring tension.

 

It's pretty usual to put a ball bearing between pushrod and mushoom on Norton clutches and this gives a degree of self-alignment and a generally easier operation. I can't see the point of putting a roller in ! If you fit a ball, you can compensate by altering the position of the operating arm on the worm which is part of the normal set-up procedure anyway.

 

The original steel band was designed to keep oil out of the clutch. It was originally a dry clutch and didn't take kindly to the oil bath but this was only a problem with the cork inserts and you don't need it with modern bonded friction plates. The circlip is a puzzle as its only function seems to be to retain the plate pack when dismantling. It serves no function in use and I've never found one still present....

 

If you've got the time, it might be worth considering a conversion to bonded friction material on the drum as well. Several of the racing specialists offer this service (the clutch being the same as the International competition models).

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Funnily enough I just pulled the clutch off my Norton Big 4 yesterday and found exactly the same problem. Mine is also rubbing on the inner chain case also. Some investigation required........As well as some pulling on my shaft!!

 

Ron

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There's nothing worse than having to pull on your shaft when your clutch is rubbing so they say :wow: am going to speak to Russel motors tomo and order up some parts as you say some investigation needed.

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Checked end float on main shaft and there does seem to be a lot of movement so this could turn into a lot of work :-( but if it needs to be done then so be it better now in the workshop than on the side of the road in France :shocked: how difficult is it to rebuild the gearbox ? :nut: Ok the plot thickens as I now think that the clutch fitted to my 16H is not the original type but a later one.

 

100_3664.jpg

 

 

100_3666.jpg

 

100_3667.jpg

Edited by rampant rivet

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Yes, you've got a later one, as used up to and including the 50bhp Atlas models. So have I, but don't tell Ron or I'll never hear the end of it. This is a better clutch but does have a slightly thicker backplate which makes the clearance on the inner chaincase even more critical. You may need to gently 'ease' the backplate. Certainly, you don't want the studs and retaining nuts standing any prouder than they have to.

 

There is nothing to stop you modifying the outer screws as well to give a bit of extra clearance. I have matched springs and a slightly different screw set-up from Ken McIntosh and they did need a slight mod to fit under the 16H cover.

 

The Norton gearbox is a nice simple one to work on, but you will need a manual just to set up the change mechanism correctly. There are few shims to get wrong and as long as the gears aren't 'too bad', they'll cope with your 12bhp !

 

Bearings are as per much more recent Norton / AMC boxes and widely available. The only source that I know for the bronze thrust washer is Andy Molnar.

 

http://www.manx.co.uk/pdf/MPL-Norton_Singles.pdf

 

If it's worn so that the grooves are no longer visible then it requires replacement. The biggest problem with these boxes internally is that the hardened retainer for the sleeve gear rollers is sometimes cracked (I'm not clear how this happens) and it was never listed as a separate spare which means finding a decent secondhand part.

 

You have to be in Normandy whtever it takes !

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Thanks for the info very usefull will take a look at the gearbox over the next couple of days and see what state its in :shocked: hopefully bronze thrust washer will help but will also check for other wear and tear.

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Here is my clutch. Is this an original type Rik? I have the new type friction plates also.

There is very little end float on my main shaft. So I'm ok there. The outer clutch cover has a slight rub mark from the three screws with the square holes. But my inner cover is badly scored as can be seen by the wear to the back of the clutch hub. I haven't studied the situation fully yet as I need to gain better access by removing the side car body. I Need at least two strong men working under my instructions for that!! Removing the primary side whilst standing on my head was a right farce.

But my initial thoughts are that the inner cover can't be moved much further in easily, and that in turn will bring the outer cover even closer!! and the clutch is on the main shaft where it belongs. Therefore I'm wondering if I can dish the inner cover a bit where the clutch runs. Ron

Big 4 160.jpg

Big 4 162.jpg

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I used a NOS WD clutch basket with NOS steel plates but the modern bonded fibre friction plates..........new springs too...........one less friction plate (on account that the modern versions are thicker) and one less steel and it works very well........beautiful light clutch, and a gearbox that just snicks into place...............no issues here in the transmission department.......

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Ron,

If you want to gain a little extra room you could use the manx type clutch spring adjuster setup. From memory (it's been a while) they are have a recessed square drive (like an allen key) so you get a little more clearance. God knows why they bothered with all that on the Manx, seeing there's room to spare, but there you go. Maybe it was to stop the clutch studs from chewing up the riders ankle if it somehow managed to get past the brake pedal guard......

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Steve/Stefano. Thanks for the advice. Have a look at my pictures Stefano. Is that the spring nut you speak of? Although my rubbing issue is to do more with the inner cover. Ron

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Ron, might Lex have suggested to me that the swd Big 4 clutch had some alternative parts from the WD16H ? I don't have enough B4 parts books to check though.

 

I wouldn't expect a worn thrust washer to cause contact on the inner case. the tendency is for the clutch to move outwards so I'd agree that you're probably OK there. It takes very little error to cause these cases to rub. In fact, I think it's possible to have it rubbing on both sides of the inner case and inside the outer case all at the same time !

 

It can be something as minor as the rear chainguard pulling the primary case out of line...or it can be caused by bent gearbox plates.....

 

There are variations in the inner cases, in terms of depressions for a sealing ring and indeed the outer lip (some have a welded-on lip and others are a single pressing). Both types are for 'open-diamond' frames and I can find no changes of part number so it's difficult to pin down which are earliest.

 

Chaincaseinnerccasemount_zps75044662.jpg

 

It's worth having a look at the splines inside the clutch centre. There is a shoulder which provides the positive location and if they've been run loose then that can become pretty chewed up and allow incorrect positioning.

 

I don't think it's a new problem as pretty well all used Norton chaincases show witness marks. Most are worn right through. There is no harm in skimming the clutch backplate a little.

 

You certainly have the early type clutch drum with friction inserts and a plain backplate. That screw with the square broached adjuster looks like the Manx type. However, even they can sit a little high, although that can be corrected my making deeper spring cups and reducing the length of the shoulder on the screw and indeed by making a low-domed slotted screw, which is what I now have.

 

Primary_zps81cd57ae.jpg

 

I hope that you approve of the use of the correct tool kit....

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Have parts on order and am lucky to have the large A4 size manual that contains some nice exploded views of the gearbox which I am now scanning to take copies with me into the garage before I start to tackle the gearbox :cool2:

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Thanks for those tips Rik. I'll be taking a long and close look at all this in the near future. Where/who did you get those shallow slotted spring screws from? They look a good idea when every fraction of an inch counts. Ron

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Steve/Stefano. Thanks for the advice. Have a look at my pictures Stefano. Is that the spring nut you speak of? Although my rubbing issue is to do more with the inner cover. Ron

 

Ron,

Ah, I should have looked better at your photos before I spoke. If you had any significant wear between the mainshaft and clutch backplate I would have thought that it would show in the chain run between clutch and engine sprocket, or if the chaincase was out of alignment for any reason you could again check it against the chain run. In any case, if outer clearance is a problem, wouldn't it be possible to shim the cover out a bit to give a little more room?

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Never ever throw anything away !!

Having removed the outer chain case to get at the clutch I noticed one of the fixings was missing between front drive sprocket and clutch note oval shaped hole.

 

100_3665.jpg

 

, on further inspection something seems to be amiss. there is supposed to be a threaded stud that carries that part of the chain case.

 

 

Roll back a couple of days and knowing that I was going to have a look at the clutch I remembered seeing a box of odds n ends that was left over when we first got the Norton together when I was in my early 20's so a quick trip to my parents and there tucked away in a corner of the garage was the box of bits which I thought may come in handy, So bought them home.

 

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So I thought I wonder if by any chance ........... and yes :-D after a good old rummage this afternnon there was the stud and bolt that looked like it would do the job :banana: :rotfl: :banana:

 

100_3668.jpg

 

Another rummage and a nut was found along with front engine stud that carries the exhaust clamp :-D

So there you go Never ever throw anything away ever ! those parts had been waiting the best part of 30yrs to go back on the bike :nut:

My only defence in not fitting this stud in the first place is that I found the bike in bits in a couple of tea chests mixed up with othe parts from a Triumph and a BSA and being only 19 yrs old and at the time I did the best I could with limited knowledge and skill :blush:

Doh ! looks like I am missing the crankcase breather now am off for another look you never know :cool2:

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Well I'll be watching and bidding on that bolt. Mine is a bit home made and could be the wrong length. Like rivet, built in the days when I had less knowledge and with the piles of bits I had.

 

Rivet please could you make a drawing of the extended nut with stud in case I have to get one made.

 

Ron

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Well I'll be watching and bidding on that bolt. Mine is a bit home made and could be the wrong length. Like rivet, built in the days when I had less knowledge and with the piles of bits I had.

 

Rivet please could you make a drawing of the extended nut with stud in case I have to get one made.

 

Ron

 

Ron, did you get it ? A bit expensive but you couldn't get one made for less. I wouldn't have posted it on the forum if I'd known you needed one.

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Yes a bit steep with the postage I'm sure Russells would have one I've just got a pair of N.O.S. top and bottom fixing bolts with nuts and washers for the gearbox at very reasonable cost :D

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I didn't bother to bid as I only needed the extended nut with stud part and Les sent me one for a fiver. Along with some other parts I needed. Ron

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Did 5 miles on the bike today as a test run and clutch seems ok I removed a plate in the end because the cover still rubbed the inside of the chain case, it does make it a lighter clutch to use but I'll get a good few more miles on it and the gearbox before le belle France in June :D

 

Thanks for all your advice and help.

 

RR.

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