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Comet drive side crankcase

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
I am attempting to restore a Comet motor with a need to remachine the main bearing registers accurately parallel to the timing side which is undamaged.I would welcome Hints and Tips from anyone who has contemplated this operation and particularly from any hardy and remorseless soul who has succeeded with it.I eagerly await a flood of knowledge.Cheers, F5AB/2A/7945 since 1970
 

biggles

Forum Website User
Non-VOC Member
Comet drive side cases

I am attempting to restore a Comet motor with a need to remachine the main bearing registers accurately parallel to the timing side which is undamaged.I would welcome Hints and Tips from anyone who has contemplated this operation and particularly from any hardy and remorseless soul who has succeeded with it.I eagerly await a flood of knowledge.Cheers, F5AB/2A/7945 since 1970

Hi Chankly.
Not quite certain what you mean by "bearing registers" as the bearings register against the circlip.
But if you want to check the concentricity and alignment of the bearing housing.Firstly ensure that the
timing cover face is flat by removing the dowels and checking on a surface plate or piece of plate glass.
Then mount and clamp the r/h case on a vertical milling machine and clock the bearing houses true with a dial gauge.
You can then lower the machine table place the d/s case on its locating dowels and clock the housing in that case.
You will have to of course ensure that the mating faces are clean and un damaged it is also advisable to lightly clamp the cases together.
If you don't have access to a mill you may have to chat up a local small engineering shop.

P.S. I have two pieces of 1Ft square 1/2" plate glass if anyone wishes to pay the postage they are welcome to them.
Cheers.
Biggles:cool:
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
Thanks heaps, Biggles! This is how I was going to attack it,but I have always believed "In the counsel of many, there is wisdom." Your thread has clarified my thinking.I have built a jig closely modelled on the Forth Bridge to keep the plot rigid.I plan to get everything squared off from the timing cover face,Get the jointing faces right and then locate off the timing side outer bearing hole and machine the drive side bearing registers and circlip grooves .002" under 2.5".I also have to machine the cylinder register to a nominal 3.562" perpendicular to the bearing axis.I may increase this diameter slightly as this was not always accurate at the Works, and the existing timing side is probably a little bell-mouthed anyway.I can always machine a liner to suit.I'll let you know how I get on.Cheers, F5AB/2A/7945 since 1970
 

clevtrev

Well Known and Active Forum Website User
VOC Member
First thing is ensure the case joint faces are flat, if necessary lap on a plate, applies to each half.
Get a plate large enough to take the face area, with some for clamping, drill and bore two holes for the dowels, and mill a datum edge. Then put the timing half on with joint face on to the plate, clock in the main bearing. Remove case, drill and bore in the same position a datum reference hole.
Remove plate, turn over. clamp down, after setting datum edge, clock in the datum hole, put drive side on to plate located with the dowels. That`s it, you`re there.
Trying to get the whole case in line is near impossible, too many things to add up.
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Did you hear the one about the bloke who did so much " lapping ", He couldn't get the barrels in the holes !! Good Luck Bill.
 

bmetcalf

Well Known and Active Forum Website User
VOC Member
I recall an article in MPH by Jeff Barkes about having to mill off a relatively large amount of the faces to correct some previous butchery and all the things he had to do to fix to account for the narrowing of the assembly.
 
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