Crankshaft same on GT and S?

[Peerless]

Hi everyone

Years ago I gently tucked away the crankshafts for my 750 S and Sf1 for storing. Last night I unpacked them and found that the one for the S is much heavier then the other. Its obvious when u compare them. Has it slipped my mind that the S and Gt share the heavy crank, or am I stuck with a Gt crank?

Worried

 

[sfcpiet]

AfaIk, the S got the heavy GT crank.

Was changed with the introduction of the SF.

piet

 

[jotacorsa]

early SF, too
i've two 4000 series engines on the bench, both with the heavy crank
the earlier one has stepped crank pins

 

[Peerless]

Allright then. Sorted.

Thanks for the knowledge

David

 

[sfcpiet]

Hi Scott,

Currently got an early SF in the shop, S-type tank and Smiths clocks, already got the lighter crank.  Engine #5101.  Crank had never been apart, but found NJ rollerbearings instead of the more commonly later used NFs.  Second one in the last couple of months.  Thought at first the crank must have been re-conditioned at some point, but this second crank seems to confirm the factory also used the NJ bearings on the assembly line.

What engine# is the stepped-pin crank from?  Trying to work out how long these were used.

Cheers,
piet

 

[Ernesto]

Hi,
I once worked on #4563 and found the heavy crank.
Was convinced that the PO wanted to get rid of it
and had changed the cranks for that.
I asked Marnix about it and he said that early ones
had the heavy crank.
Can't say what pin the one I found had.

Ernesto

 

[jotacorsa]

#4028 had a stepped pin, #4334 did not, both had been into before
i'll have a look at the bearings and advise as neither crank appears to have been apart

 

[MarnixSFC]

This definitely is a vague area. Hard to verify when exactly the switch was made from heavy to light crank.

Marnix