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Splitting Crankcases

Bill Cannon

Well Known and Active Website User
VOC Member
A bit of advice please.
I am at the last stage of splitting my twin cases to have them machined out for a 1200 conversion.
Is it neccessary to remove the oil pump before separating?
Is it neccessary to extract the oil pump drive gear?
While I'm in the mood, I hear it's a good idea to have the case mouths checked for accuracy of 50 degree angle. What should be used as a datum point for this check?
Thanks in anticipation.
Bill
 

clevtrev

Well Known and Active Website User
VOC Member
A bit of advice please.
I am at the last stage of splitting my twin cases to have them machined out for a 1200 conversion.
Is it neccessary to remove the oil pump before separating?
Is it neccessary to extract the oil pump drive gear?
While I'm in the mood, I hear it's a good idea to have the case mouths checked for accuracy of 50 degree angle. What should be used as a datum point for this check?
Thanks in anticipation.
Bill
1 remove oil pump? no.

2 remove drive gear ? no.

3 centre line of the engine. Crankshaft / gearbox mainshaft.

But if you are to be machining, remove everything. Including oilway plugs.
 

Bill Cannon

Well Known and Active Website User
VOC Member
Thanks for that Trevor.
Forgive me if I'm missing something obvious, but how do you decide if it's one or both cylinder bases at the wrong angle? It seems that you need a vertical projection from the crank centre through some other point between the cylinder bases to check this.
Regards Bill
 

timetraveller

Well Known and Active Website User
VOC Member
I think that what Clevtrev means is that the vertical projection you require is at 90º to the line connecting the two centres, engine mainshaft and gearbox mainshaft. The vertical projection should also be centred on the engine mainshaft. :)
 

Vincent Brake

Well Known and Active Website User
VOC Member
machining

Hi there,
I have machined my D casings as follows:
1 have your mating surfaces flat (this took me the greater part in time) They are always bent a little like 0,05-0,3 mm
2 bolt them up, alline them, and ream the 3 hollow mating pins (later you requires new ones)
3 on CNC milling machine alline the main and output bearing holes in a strait to the machine axis, be sure to not bend the whole set up as you fix it. (best bolt through some casing bolt holes, with hollow adjusters under)then aline the holes of the bearings in the vertical plane (both in X and Y direction)
4 have your casing drawings ready and machine each 27.5 degr 0,3 mm of and see how much you really took off. (do this with a milling device of say each stepped cut 5-6 mm, and big enough diameter say 50 mm, as your fixings will not stand milling at a stepped height of 30mm (it will vibrate to much)
5 all this took me (incl inline drilling of the main bearings, timeing side holes etc.) about 160 H but then you get some

any more questions please ask I also have extended Photos on it, and more descriptions.

Best regards and safe spannering

Vincent (brake) Speet
 

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