Crankshaft Roll Pins

[JohnRude]

I just started working on a 1966 Evinrude (6602) 6 hp.  Lots of shifting problems. When I dropped the lower unit and after a couple of hours of pondering and poking, I discovered that the brass shift rod connector had rotated slightly and wouldn’t allow the lower shift rod to slide up and down evenly. On inspection, the threads were partially stripped so I replaced the connector. Easy fix.

Then I noticed that the roll pin at the top of the crankshaft was bent. That pin slips through a slot at the top of the exhaust housing and, typically, holds a brass cup, spring, o ring and plate assembly where the crank enters the power head. I have worked on several fifties motors and if this roll pin is missing, the brass cup and spring, etc., can slip down. However, on the 1966 rude that brass cup and assembly rides on a ledge and can’t slip down. Why does it even need the roll pin?

[frankr]

The roll pin is the “key” that causes the seal parts to rotate.  Otherwise, they would just sit still while the shaft rotates inside them.

[Mumbles]

The pin also allows the spring to apply pressure to the carbon seal against the stationary plate. Without the pin, all of the seal parts will fall down the driveshaft allowing water to enter the bottom cylinder.

Best to replace it with a stainless one, not an over the counter one from an auto supply.

[JohnRude]

So you are saying that the roll pin somehow engages with the brass pan and causes it to rotate with the drive shaft?

 

[JohnRude]

Understand about the bottom pressure pushing up. Makes sense. But even without the roll pin things can’t fall down. It doesn’t need the pin for support.

[frankr]

JohnRude wrote:

So you are saying that the roll pin somehow engages with the brass pan and causes it to rotate with the drive shaft?

 

Yes, pin engages bumps on bottom of spring retainer.

[crosbyman]

 

looking at the 1966 6 hp  parts list I see no  “bumps”  on the drive shaft to support  the   pin/cup assembly.

honestly I never had any issues  upon reassembly of CD 5.5 and 6 hp fisherman using the roll pin/cup

btw.. it also recommended to  replace the brass washer with a stainless one  (red book)

if your roll pin was bent maybe a previous owner  did not line it up with the housing slot and pushed to ahrd.   just replace the roll pin

maybe post some pictures ???

Joining AOMCI has priviledges 🙂

[Steve D]

JohnRude wrote:

So you are saying that the roll pin somehow engages with the brass pan and causes it to rotate with the drive shaft?

 

I’ve seen those bumps worn down from the roll pin and then the retainer and other parts don’t rotate. There’s one of these available on ebay right now if you need it for $9.95 plus shipping.

 

[JohnRude]

Thanks everyone. I understand about the “bumps” now.  But, that brass cup only holds the spring and if it spins with the crankshaft the spring above it can’t spin. There is no connection aside from some oily friction and the spring isn’t attached to the stainless washer and cork seal above that so they wouldn’t spin. Upward pressure makes sense for a better seal overall

[fleetwin]

Admittedly, it has always been a bit of a mystery just how this set up works….  But one thing for sure, it does work!.   Seals the crankshaft and protects the splines…

[Author]

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