Cush drive

[Minto]

I’ve had the clutch and Cush drive off for a bit of fettling this weekend, put new springs in the clutch and replaced the cable as well as altering the angle of the arm. Clutch feels a heap lighter, I used to get blisters on my 1st and second finger from it, til the cable gave up the fight.
Anyhow, there were some metal filings in the oil from the primary, quite coarse ones. Hence taking the whole lot out, the only thing I could find amiss was some ugly wearing on the cam faces of the sliding sleeve (wish I’d taken a picture now). I’ve put the nut back on and with it done up as tight as I can get it, the spring seems very very compressed and I can only just squeeze the split pin in passed the face of the nut. Is this wrong? Have I cocked some part of the reassembly up somewhere? It all seems as it should be re diagrams etc.
This is pic from a few months back after the rebuild, but shows how tight the Cush drive is.

Cheers folks

[Greybeard]

That looks like mine. The split pin doesn't go in easily.

In case you don't know, the cush drive should not be able to ride over the cams.

[orabanda]

Good to check the cush drive will ride along the cam(s) by leaving spring off and operating by hand.

If the nut is wrong, the cam movement will be reduced (or eliminated!).

After checking the function, then fit spring, and sleep easy!

[Minto]

GB, yeah I get the principle of the set up, and when trying to torque it with a wrench I can see the cam lobes sliding on each other under the massive tension of that spring. I use the pronged socket on a rattle gun method of tightening the bugger.

Orabanda, I’ll get the nut off and check as you suggest, it’s got to come off anyway as like the muppet I am, I forgot to loctite the nut. It’ll also give me chance to take a picture of the sliding cam sleeve part to show the wear on it.

Cheers guys

[Minto]

Here’s a picture of the sliding cam sleeve. Taken some flack by the looks of it, maybe even more than my jeans.

[Greybeard]

I think mine looks like that. Not the jeans.

[Minto]

Cheers Neil,
I suppose 70 years of being tw@tted repeatedly by a lump of iron will leave a mark or two. The sleeve not the jeans.

[Jules]

Modern designer jeans Minto, you should sell them, must be worth a "mint" LoL  sorry, couldn't resist!
Cant comment on your cush drive either..

[Swarfcut]

Jase. Maybe of interest and for comparison here are Plunger and S/A Cush parts to show the confusion that can arise and  scope for mis-matched parts. In all cases the crank nut bears directly onto the drive sleeve when tightened down.

  S/A on left, Plunger on the right.  First picture shows Cush lift available on S/A as the distance from end of the drive sleeve to the end of the sliding member, here its 8mm. Parts from 1957 A7. Cush bottoms on flat face of the big nut. Plunger slider and drive sleeve are more or less level. Cush lift here is the length of the extended nose on the nut 67 2054. Using a S/A flat face nut will lock this drive solid.

 Second picture shows the difference in depth between the two cush members. S/A Tip on lobe to base is 30mm in this example, Plunger it's 38mm. S/A cush will fit plunger splines, but not vice versa, and here the depth of engagement is marginal as the spline depths are different and is a possible source of too much lift if the wrong part has been used on a Plunger.
 S/A Slider lobes do not fit easily into the duplex sprocket face, so another tell tale sign of the wrong part. Also the ramp profiles are different and the cam action is poor.

 Then to add to confusion, three variants of the Plunger Drive Sleeve.

 L to R...  Pre oilseal crankcase. Sleeve with scroll edge.

              Pre oilseal crankcase. Sleeve with plain edge. Both are 46mm diam.

              Oilseal type, Sleeve has plain edge to run on the seal.  43mm diam.

 
 Finally the drive sleeves compared. S/A is shortest, this design application uses a separate spacer to run on the seal, and is splined along whole length. Plunger ones all have a cutaway to the outer splines,  centre example here is a bit blued.....

 Swarfy.

 PS,  Looked for a Plunger Nut. Cupboard bare.
 

[RDfella]

Confused re final drive sleeves - that can be read two ways as to full length spline - inner or outer?

[Swarfcut]

 RD, tried my best here, the pictures tell all. Side by side there can be no mistake which is which, just hard to put into words.....Both types have the same internal splines, outer splines differ in length and depth of profile.

 Swarfy.

[Minto]

Hey Swarfy
Thanks for taking the time to post this, from your info and pics I can see that the “Cush drive bearing” (67 2053)  is definitely incorrect on mine as it has the smaller diameter end for the oil seal motor. I also think I maybe have a mismatched “sliding sleeve” (67 2055) as the cams on these do not mate that well.

I’ve seen a complete assembly on the bay, but I’m waiting for a message back re the diameter of the bearing piece.
On a side note; I think I might’ve found the source of some of the oil which accumulates on every surface under the bike when I take it out…
Seems there may have been a teeny weeny bit too much lateral play in the clutch, I did think on disassembling it that there was a ridiculous amount of wobble, like 1/4” in every direction at least!

So on the look out for another primary case, it was always on the cards as this one has cracks in it sealed with silicon.
On the second pic you can see it’s worn through to the thread, ouch. Not sure what went wrong here, I’m wondering if I’ve put the wrong locking washer on the centre nut, and it’s well, not locked. Off it comes again!!!