SF2 Case splitting questions

mik667

mik667

Senior member
Location
San Francisco, Ca
Hey all
  almost ready to split the cases on my SF2 after it coughed a piston/valve froze. I have a few questions at the moment - is it necessary to pull the clutch hub, i have removed all the plates etc etc and with the spring retaining clip removed the hub is still as tight a f'all on the gearbox spline - it appears that its not necessary to pull the hub off, but thought i'd ask (it looks in good shape so i don't foresee replacing the hub). Second question is how many bolts/nuts are there to separate the cases, its a 74 if that matters - the green book just says there are up to 21 on a late triple - i'd like to make sure i have them all off and accounted for before i start beating on the cases with my trusty rubber hammer

thx!
mike
 
The clutch hub can stay in place if necessary, they can indeed be bloody tight.
Can't remember the exact number of case studs, however they are all accessed from underneath - except of course the ones from above.  But seriously, let me think, the major case bolts are all M8 (13mm head) and there are 8 along the crankshaft and 4 for the gearbox - the rearmost 2 of which are accessed from above.  There's a row of M6 studs along the front of the case, and a couple at the rear.
They're all pretty obvious, unlike the triple which has the one rogue stud accessed from above and hidden under the starter motor to catch out the unwary.
HTH
Steve B
 
OK thx - was hoping i could access them without putting the motor  on its side or turning it over as its a heavy bastard

breganzane said:
The clutch hub can stay in place if necessary, they can indeed be bloody tight.
Can't remember the exact number of case studs, however they are all accessed from underneath - except of course the ones from above.  But seriously, let me think, the major case bolts are all M8 (13mm head) and there are 8 along the crankshaft and 4 for the gearbox - the rearmost 2 of which are accessed from above.  There's a row of M6 studs along the front of the case, and a couple at the rear.
They're all pretty obvious, unlike the triple which has the one rogue stud accessed from above and hidden under the starter motor to catch out the unwary.
HTH
Steve B
Click to expand...
 
Cases split, everything looks good - debating if i even want to dissemble crank to look at big end bearings as i can discern no play and they move smoothly
 
mik667 said:
Cases split, everything looks good - debating if i even want to dissemble crank to look at big end bearings as i can discern no play and they move smoothly
Click to expand...

pull the 3 shafts out and take both the cases outside and clean them out with degreaser
you have come this far and those engine cases have not been cleaned internally for what, 38 years ?

make certain you don't lose the gear selector shaft retaining pin which will fall out when you turn the lower case over once the mainshaft is removed
and gather up the 4 x half rings that locate the bearings

 
Generally speaking, unless it's got mega-high mileage and/or a poor maintenance history leave well enough alone, they're built like a brick shithouse.  If there's no discernable play and nothing visibly wrong then the only likely problem is the slinger plates filling up.  The slingers serve a dual purpose of force-feeding oil to the big ends and also filtering crud out of the oil by forcing it to the periphery due to centripetal acceleration.  Eventually the slingers fill up and block the big end oil supply, but it takes a l-o-n-g time.  Do not attempt to clean them out unless splitting the crank.  If in doubt, refer again to first sentence. :)
Cheers
SteveB

Edit after seeing Red's response - I had assumed you had already removed the shafts for normal cleaning etc and were debating splitting the crank.  Red makes a good point about the selector fork shaft retainer pin, take care to see it goes back in!
 
Great thanks Red/Steve - was planning on removing everything and get the cases soda blasted before reassembly, while clean internally for the most part the outsides are nastly- i'll have to look closely to make sure i don't lose the mentioned parts, hopefully they are still there after pulling the top off (haha)_- just tapping on the crankshaft and it wasn't budging from the lower so going to examine it a little more intensely next day or two
 
I use a tyre lever to pop the crank out of its position, but be careful you don't damage the mating surface
does not take much force

if you are taking the cases in to get soda blasted ( good call ) then remove the selector shaft and selectors but make certain you install the selectors straight back onto the shaft in their correct position so you don't get them mixed up on reassembly

you have an answer on the valve material yet ?


 
Not yet on valves  - but have pistons in hand (ross) for rebore which i expect to be done in another week or so

you have an answer on the valve material yet ?



 
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