Very recently there was a post here asking about replacement clutch spring studs for the early Jubilee clutch.
This clutch can be identified by a small spline and a hardened ring in the back of the clutch centre.
I have been known to be wrong but ...
When dismantled this clutch backing plate will be unbonded. No friction material. Unique to the earliest Jubilee clutch.
The race plate is unique to this clutch. As is the clutch centre.
This clutch will be something similar to the exploded clutch view in later lightweight parts lists. I believe the clutch shown in the diagram is a very early lightweight Norton clutch. Observe in the diagram no friction pads on the clutch backing plate. AMC never re-drew the exploded diagram to keep up with improvements.
I would advise anyone dealing with one of these early clutches to be very aware that they have many different components and operate in a slightly different way to the 1960 onward lightweight clutches. A bit of a weak design and probably unable to handle Navigator full torque.
Raceplate differences
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Earliest Jubilee Clutch.
Hello Peter,
I accidently deleted the post, I hit the wrong button.
Here are the pics of my clutch:
This is with the new studs in it.
I guess it is the small spline, don´t have it at hand to measure the diameter.
My Jubilee is No 340 of the third batch ever built.
Differences between old an new clutch spring studs :
the rear part of the original studs is longer.
The new studs do not lock into the race plates with those flat sides.
I also had to file a bit off to make them go into the slots that is why the left stud looks "used".
You can also see the bend threads for the spring adjusters on the old one.
Plan A: Find the correct studs ( AMC, Francis Barnett, AJS whatsoever)
Plan B: straighten the old studs and recut the threads with a whitworth cutter which is very easy to find in Germany...
Plan C: I know somebody with a lathe.....
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clutch stud
Hi Uli,
I have been having a look online and found three AMC numbers but no sizes to them (see below). But also found this
British Only Austria
near the bottom (page 4)
Stud AMC Clutch 67.4mm. 2.21/32"
Article number
04-0384. 040384. 04.0384
or got to https://www.vintage-motorcycle.com/en and search for 040384
Could be worth asking for more size details
The Three other studs I found are
043189 for all 7 plate clutches
043174 for 9 plate with simplex sprocket
043338 for 9 plate with duplex sprocket
Hope this helps and good luck,
Stan
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clutch studs
Hello Stan,
I am afraid the "Austrian" stud has the same lenght as the NOC stud.
The original studs are ca. 70 mm over all.
Norton Motors also has studs:
https://nortonmotors.de/de/triumph-ersatzteile-shop-details/15167/stud-amc-clutch-nm23307-04-0384-
I asked Joe about the size details.
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Early Jubilee clutch
I can see you have the earliest Jubilee clutch with smallest spline on mainshaft. There is a hardened ring let into the back of the clutch centre. Your ring shows some marks from the mainshaft splines despite being hardened. Not significant.
My observation of lightweight clutches in general:
Bent spring studs, scarring on the outside of spring housings, and worn/disintegrated/missing shock absorber rubbers seem to go hand in hand.
I might try to straighten the studs before getting specials made.
Best wishes. Peter
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Collar dimensions
Hiya Peter/All - Annoyingly I have misplaced the collar that you identify in your earliest LW clutch centre and main shaft pics. In case I cannot locate it. Do you have the dimensions please? or alternatively a part number please?
Regards
Gary
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Mainshaft Abutment Washer 22196
H Gary,
File attached which you may find interesting. All the dimensions you requested.
Peter
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Clutch studs
Hi. Gary.
There are two clutch studs available in NOC Spares 043441 - 65 mm. and 21481 - 68 mm in length hope this helps.
Peter F.
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Case closed
Thanks for all your hints and help!
On Wednesday afternoon my friend Jürgen and me managed to straighten the original studs and we recut the threads. We used the original spring adjuster nuts because we found out on the new ones from NOC spares the inner thread was bored and cut at an angle so the nut did not sit square on the stud.
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Primary Chain Tensioner
Hi Uli,
I had the same problem with replacement studs from NOC spares about 3 years ago. On all 3 studs the inner threads were cut at an angle and were un-useable. Guess what, after complaining I straightened my old ones.
Well done with the build.
See you are using original steel chain tensioner. Careful. Norton replaced with a nylon type because owners were setting tension in primary too tight to allow for expansion of aluminium crankcases at running temperatures. Steel chain expanded less than centre distance between crankshaft and gearbox grew.
The later nylon block gets chewed by the chain if things get too tight, and the chain and bearings survive.
Obviously one of the problems that emerged as AMC went to unit construction.
Peter
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Raceplate pictures showing differences.
I am afraid I can't definitively say which clutch spring studs are correct for this early clutch, but if your replace a bent stud with another of the same design, all will be well.
When the clutch stud securing nuts are tightened the clutch, and no plates fitted, the clutch centre should be free to rotate within the clutch basket. In the early clutch, even when loading the basket axially towards the mainshaft.
On the later clutch the backplate has bonded pads and you will feel the drag as you push the basket towards the mainshaft.
Good luck Ulrich
Peter