Chainwheel differences

Over the Commando years there have been design changes to the clutch basket.
My 70 had 2 pins to locate a back plate.
I have 2 baskets with 3 rivet holes in the back.
And one with a solid steel back but 5 drilled oil holes around the bearing area.
Years of changes and why ?

Aren't 750 and 850 different?

(not sure, just asking, too lazy to check)

I can't say for the 1972 and 1973 750 but 1971 and earlier have the roll pin held lower plate (it can be removed) , that same plate with roll pin holes still there was used on the 850 with the 3 rivet type fasteners.
I see no real difference in the actual basket of either.

I went and found the pictures I posted on Wastebook.

1971 750 and earlier that I know of (1972 / 73 750 I do not know)



All 850 as far as I know.
They must have had a lot of the earlier plates with roll pin holes in stores as there they are unused on the riveted version.



The 5 drilled hole hub might be worthy of a picture but does not sound Commando or a stock part ?
The roll pin basket must go back to pre Commando ?

From Mr Bacon:
'The early Commandos had two small pins pressed into the inner drum surface to locate the first clutch plate. If these came loose it was very awkward to assemble the parts or to modify the arrangement due to the hardness of the drum. To avoid this, the design was modified for 1971 to attach the plate with three rivets...'
He also notes that leaving them out causes no grief.

I don't think Mr Bacon (R.I.P) was very mechanical.

Here is another 1971 basket I fixed for someone here, which included nearly 300 miles of ride time and barely a thank you.
The 1/8" roll pins can come loose but easily fixed using 3.5 mm replacements.
This one got the plate faced then clamped and the roll pins driven home with Loctite.

Time Warp said:

They must have had a lot of the earlier plates with roll pin holes in stores as there they are unused on the riveted version.

Click to expand...

The pin holes are still there now...


I don't know where AN gets the 06.0742 backplate part number from, as, according to the '68 list, the early separate 'pinned' backplate was 060744 and the later 'riveted' backplate was 062483.

The '71 parts book lists 'Clutch sprocket complete with backplate' as, (and still is,) part 062482, above, but also lists, 'Backplate 062483' and 'Rivet 062485' (3).

https://andover-norton.co.uk/en/shop-details/15855

I am surprised AN follow the drawing to that degree (on some things) riveted and the roll pin holes 50 years later.
There are 'Torontonian's 5 holes also. (Oil ?)

Were those 5 radial holes on the Mk111 perhaps ?

​

Time Warp said:

I am surprised AN follow the drawing to that degree (on some things) riveted and the roll pin holes 50 years later.
There are 'Torontonian's 5 holes also. (Oil ?)

Were those 5 radial holes on the Mk111 perhaps ?

Click to expand...

I don't know, but normally 6 holes, not 5.

I believe the three oil drain/fling holes (spaced 120 degrees apart) were added at some point during Commando production.
This old stock riveted drum doesn't have the 6 holes.

My 1971 (March) 750 has the three outer holes/roll pins but none of the riveted drums I have (3) have those 6 holes.

Time Warp said:

I am surprised AN follow the drawing to that degree (on some things) riveted and the roll pin holes 50 years later.
There are 'Torontonian's 5 holes also. (Oil ?)

Were those 5 radial holes on the Mk111 perhaps ?

​

Click to expand...

Because some still use the two holes and some use the rivets, the stock we have left is original from the 70's.

Madnorton said:

Because some still use the two holes and some use the rivets, the stock we have left is original from the 70's.

Click to expand...

"CLUTCH CHAINWHEEL C/W BACKPLATE (06.0742)"

Why 06.0742 when AN list the backplate as 06.2483 and 06.0744 (and 06.1166?)?


"06.2483 BACKPLATE - CLUTCH (06.0744, 06.1166)"

Torontonian said:

Years of changes and why ?

Click to expand...

1. low durability of back plate attachment with little dowels?
2. contamination of clutch plates by:
primary oil
gearbox oil

#! attaching with peened rivets was successful

If at first you don't succeed- try-try again
#2 was never successful IMO

L.A.B. said:

I don't know, but normally 6 holes, not 5.

06-2428/06-0742 Clutch Drum Sprocket / Chainwheel - Norton Commando

06-2482 Clutch Drum Sprocket c/w Backplate - Norton Commando, British Bike Bits

www.britishbikebits.com

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Click to expand...

Yes, 6 holes not 5 , ( I was interrupted counting holes by an emergency stay at home announcement on the radio. More time to count holes correctly now... ).
Here's where I'm at :
Chainwheel #1.
Likely a 1970 model. Small stamping of : DRG 84762. No rivets. 3 holes between the 2 inboard rows of sprocket teeth , equidistant. 2 small holes to locate separate back plate using 2 small pins. ( The little pins could shear off apparently).
Chainwheel #2.
3 large rivets holding back plate to body , equidistant. 2 small dowel pin holes still exist but are unused. 6 drilled holes between the 2 inboard rows of sprocket teeth , equidistant. No drilled holes behind the clutch center.
Chainwheel #3.
3 large rivets holding back plate to body. 2 small dowel holes still exist. 6 drilled holes between the 2 inboard rows of sprocket teeth , equidistant. 6 drilled holes behind the clutch center , equidistant. These holes are angled towards the circular cavity on the back side of the clutch body.

Question : Were all these drilled holes intended to remove oil from the basket or to introduce oil? Centrifugal forces involved ?
Question: Which of Chainwheels #2 or #3 should I use with my MK 111 project ? I'll be fitting a CNW hardened clutch center and either a sealed bearing or O.E.M. bearing to that choice.
Thanks.

I'm going to decide on the clutch basket that has the most holes for lubrication , seeing as I'll be using the 828 cc MK 111 sintered bronze plates for the clutch. They need oil and so does the sprag clutch and chain. I'll knock in the sealed bearing tonight.

Torontonian said:

I'm going to decide on the clutch basket that has the most holes for lubrication , seeing as I'll be using the 828 cc MK 111 sintered bronze plates for the clutch. They need oil and so does the sprag clutch and chain. I'll knock in the sealed bearing tonight.

Click to expand...

Tapped in the CNW hardened (black) clutch center easily with 3 light hammer taps. Nice musical ring with each tap , a nice quality part for sure. New (supplied ) circlip to hold it in place , sharp edge outwards when viewed from rear of basket. O.E.M. bearing used for what I will refer to now as the Swiss Cheese basket.

I've been digging into the parts crypt today ( thank you covid for the free-er time) and found a 4 th different clutch basket. Let's call it #4.
3 holes between the 2 inboard rows of sprocket teeth , equidistant.
No drilled holes near bearing ,solid steel.
The big difference : The 3 large rivets holding back plate to body protrude a lot at the rear of the clutch. There is no countersinking attempt to hide the big heads like on #2 and #3.
Enjoy your day.
Bicycled all aft. with my wife. 4 C. in Sun , in the land of masks.

My March 1975 Mk III has 6 oil drain holes around the circumfrance. Three rivets holding the back plate on, and 2 unused dowel pin holes in the back plate. On the back, it also has 6 holes around the periphery of the center bearing. There are also two drilled and tapped holes, which appear to be unused. Maybe for pressing the back plate off???

chaztuna said:

My March 1975 Mk III has 6 oil drain holes around the circumfrance. Three rivets holding the back plate on, and 2 unused dowel pin holes in the back plate. On the back, it also has 6 holes around the periphery of the center bearing. There are also two drilled and tapped holes, which appear to be unused. Maybe for pressing the back plate off???

Click to expand...

Possibly. Today tore apart my MK 111 primary ( on the street , Jan 21 2021 , +3 C. ) to find that identical clutch. There was a finger pained yellow paint dab spot on the back side beside one of the 3 recessed rivet points. Sintered bronze plates. No wear on clutch center. The sprag fell into pieces , the thin inner race of the 18 roller sprag was in pieces allowing the rollers to just fall out on disassembly. What a junk thin sprag. Well I don't have to sweat that shoddiness any more as the CNW hardened sprocket and thicker cage 14 roller sprag are ready to go into place. Also I tapped the CNW hardened clutch center into place on my other ( same one you speak of ) MK 111 clutch basket so that is ready to go in as well. 10 day cold snap coming up so may be delayed a bit. The street snow rat.