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Misc: Everything Else Electric start shear pin


vibrac

Well Known and Active Website User
VOC Member
The shear pin in the Grossett electric start is there a spec for these? or a UK supplier?
 

vin998

Well Known and Active Website User
VOC Member
VOC Forum Moderator
I don't know as I don't have one fitted, but I know of two people who have had teeth break off the sprag clutch and the shear pin has not even been slightly damaged, so it didn't appear to do its job.
 

deejay499

Well Known and Active Website User
VOC Member
I have had a couple of shear pins go and got replacements from Francois. Conways fit the starters so may have, or can make, shear pins.
 

Bill Cannon

Well Known and Active Website User
VOC Member
Sorry I don't know the spec, but I also had three sprag clutches lose teeth but never broken a shear pin.
Bill
 

vibrac

Well Known and Active Website User
VOC Member
My first electric start teeth failed on first startrtup the replacement was fine I think there was a bad batch, we are talking about 4-5 years ago?
 

craig

Well Known and Active Website User
VOC Member
Extra pin comes with kit.
Large OD=4.03mm
Small OD = 3.11-3.25
Length = 20mm > 3, 3.5, 7, 3.5, 3

seems to be magnetic
 

Attachments

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vibrac

Well Known and Active Website User
VOC Member
Thanks for that, I suppose shear strength also depends on what its made of: stainless ? mild steel? hardened steel?
 

Albervin

Well Known and Active Website User
VOC Member
It should be a loose push fit but I have seen some that were a tight push fit.
 

peter holmes

Well Known and Active Website User
VOC Member
I have to say that a shear pin does seem to be a fairly crude method of controlling mechanical damage, it has been used to protect propellers on marine engines for many years, but with the Grosset starter it is all we have so we have to live with it. When I was having my Grosset starter fitted last year (by Francois) it was a bit of a joke from Francois that a few users had found it a great solution to install a nail of the correct size to avoid any further problems, I don’t think it amused Francois that much though.
 

SteveO

Active Website User
VOC Member
I had problems with the electric start - the teeth sheared on the double gear that heads the train to the starter, not the starter clutch itself. BTW Trevor can supply the gears as well as the shear pins. He told me that the early batches were soft and tended to go, but the latest ones are made of better material. My shear pin hadn't either (sheared that is!). Maybe silver steel is too good and you need something softer - like a nail?
 

peter holmes

Well Known and Active Website User
VOC Member
No, a nail is not a good idea, a shear pin is exactly that, it should in theory be calculated to shear before anything else lets go, think of it as the mechanical equivalent of and electrical fuse, now you wouldn't put a nail into an electrical plug instead of the correct value fuse, would you?
 

Vincent Brake

Well Known and Active Website User
VOC Member
best to make a shear pin of would be brass as it does not dammage the steel axle so much, than again whats the shear strength of brass.





Unknown....
 

SteveO

Active Website User
VOC Member
Not enough in this application I would think. However the silver steel obviously has a higher shear strength than the gears!
 

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