Sunday, 13 January 2019

Dry Build - Primary Case & Chainguard

The primary case and front chain guard were an area which I had difficulty visualising. The chainguard bolts to the horizontal frame gusset using two folded ears and two round head 1/4" CEI screws:

The chain oiler goes down here somewhere:

At the bottom, a lug retains the chainguard to a stud on the primary case

The chainguard is shaped around the frame gusset:

Looking through the sprocket hole, one can see the damage wrought to my chain guard which I thought was to allow it to be removed without taking the chain off. Consultation with the AOMCC experts reveals I was wrong about that - apparently to get this guard off, you have to remove the gearbox sprocket; it's cut like that to allow the mainshaft to pass through and to allow you to remove the chainguard without taking the sprocket off. I guess I would have realised that if I had put my gearbox in...

Here is the back of the primary case. That long 1/4" stud is for the lug at the bottom of the chain guard:

With it all together, we have a foul condition. On my SQ4, those nuts are half nuts - Ariel did not list the standard nuts & washers against specific sections of the parts lists, so we must use our common sense here. I think I will machine the studs & nuts short in this application, but several of the good folk on the AOMCC forum (thanks Simon, Steve and Mick) tell me that their machines have full nuts here:

Here is the chain guard lug on the 1/4" primary case stud, and primary case on the slim section at the end of the gearbox lower pivot:

We need to start getting these parts bolted up tight to understand what fits and what doesn't. To that end, I've ordered some 3/4" round bar in 303 stainless to fit the footrest bar.

Interesting that the 1958 bikes have this oil flinger to prevent oil getting on the clutch, or escaping from the primary case:

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