B40 clutch

[Stubaker58]

Hi All,

Tomorrow's the big day, DVLA inspection to get the B40 registered.
In getting it ready I looked again at the clutch which was pulling very crooked.
Investigation showed human error! I'd put in a mismatch of 'spring tubes' three long and one short. With four long ones it now, unsurprisingly, pulls square on.
BUT
Which are the correct tubes? The long ones are an inch and an eighth, the short ones seven eighths.
I put in the long ones but the springs went on very easily and then the screw caps bottomed out so I can't think they're correct.
Can anyone point me in the right direction?
TIA

[limeyrob]

I think it should be 42-3218 which is 7/8" but I'm not sure this is for all years.  Is suspect the key is to match the springs to the cups and the number of plates.  The longer cup is listed as 1 1/16" so there's 3/16" difference, I wonder if that is one pair of plates?

[rhyatt]

from Draganfly's site
40-3233
Friction clutch plate   4   1961-65  all years
11
40-3220
Plain clutch plate   5   1961-65  all years

and

40-3218
Clutch spring cup   4   1961-65

40-3217
Clutch spring   4   1961-65 (not Star/Sports Star)

40-3219
Clutch spring nut   4   1961-65

[limeyrob]

That makes sense, so is there a different push rod or does the adjuster make up the difference?

[rhyatt]

The 3218 is 7/8"

[Stubaker58]

Thanks guys.
I'll swap to the shorter ones after the bike has been inspected. Fortunately the bike does not need to be functional to pass.

[cdsdorset]

If the adjuster bolts are 1 inch its the longer tube. If they are longer its the shorter tubes.

[Stubaker58]

Right I've got the clutch exposed again.

Re-reading RR CDS is absolutely correct. Long studs, short cups! Short studs long cups plus the amount the spring nuts extend outwards changes. With the later, shorter cups the nuts go flush with the outer pressure plate.

So the next question is ... can I remove the cush drive unit without taking off the whole clutch (so as to avoid having to remove the alternator etc)?  I need to do this to check whether the centre has long or short studs as the bike is put together from parts and I may have a rogue mixture.

TIA

[rhyatt]

From memory, you can unscrew the retain screws that hold the cush unit plate to the unit.
That'll expose the rubbers and the X vane paddle that moves back and forth as load is applied/removed.
I think that'll leave the tapered centre body and its nut, lock washer alone.
Apologies if not exactly right, but it's been a while

[limeyrob]

Can you poke a rod down or a Vernier and subtract the plate thickness to get a measurement?

[DAVE BRADY]

Hi,

As Above.
No need to strip anything. Take the cups out and measure the bolts with a vernier as a depth gauge adding a bit for the thickness of the plate or measure the depth of the centre and how much the bolts stick out or not.

Dave.

[limeyrob]

Yes "add" the plate thickness doh!

[Stubaker58]

Simple really when you think about it!
Thanks.