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ET77 Main bearing distance piece


Well Known and Active Forum Website User
VOC Member
I am requesting help with ET77 spacer dimensions, not radial , but the width of this spacer. I seem to have two to measure and they vary about .030 in width.
please reference this drawing
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Well Known and Active Forum Website User
Non-VOC Member
Where did this drawing come from???? Is there a stash of detailed drawings some where? Boy, this sure would help me refresh my bad memory! I'd use the spacer that allows full outer race contact. I have nothing here to make comparisons
with.... I had dozens of these at one time.

Vincent Brake

Well Known and Active Forum Website User
VOC Member
To me, its immaterial gents, but as it determens the center of the flywheel check this, as this is important to have the rods both on the same error. (middle it out).
Only thing might be that the bearing inner race interfers with the alu ET19 (have it clear from it by at least 0,3 mm).

roy the mechanic

Well Known and Active Forum Website User
VOC Member
The important part to start with is that the scroll is trapped by the two inners of the bearings, if it can't rotate with the mainshaft it cannot work. The only way to figure it, I reckon is to mock it up, measure for rod centrality then add or subtract to correct any errors. A good motor is never built in one go.


Well Known and Active Forum Website User
VOC Member
What is the procedure for checking rod centrality?
What is the Vincent twin cylinder offset/distance between rods?
here is a drawing to use for reference please
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Big Sid

The reverse scroll on ET 77 needs to be a fairly close fit within the alloy ring ET 19 for it to function . On new motors it often was actually rubbed as the scroll spun and was designed to sacrifice its surface in this breaking in process . the quality of the alloy in the outer ring is purposely soft enough to easily wear away without seizing . A clever bit of engineering .
In our Vincati motor this is all modified , the scroll is a polished slick hard surface and the alloy ring carries a double lip seal , the aim is to lessen oil going towards the primary . There is a cupped drilling in the inner primary wall that catches oil an leads it to that left side seal lip , this cools and lubricates it after which it flows back through the big ball race returning to the primary case .
The other lip is oiled by oil passing the absent scroll from the right side .
This all allows use of a multiplate to live clutch in its own thin fluid in the chain case . Sid .
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