Misc: Everything Else 1951 Black Shadow Restoration

greg brillus

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VOC Member
Ideally it should be a hard shim washer........You can do the whole job just on the drive side case half only, with the primary side of the case sat on some blocks of wood, lower the crank with scroll ET 77 and your modified "Test piece bearing" in place.........If your unsure you can lower the timing side case on without bearings in place to check the rods are central, perhaps slip the small outer race on the mainshaft to hold the crank.......... i just do it with the drive side case only, saves a lot of time. Move the rods to their left/right when checking how central they are........The crank often needs a shim.......Make sure it is sitting dead flat against the boss on the flywheel.......often the inner edge of the shim hangs up if there is a slight radius on the shaft for whatever reason.........Just add a small bevel to the shim with a dremel if needed to get the shim nice and flat against the flywheel boss. The weight of the crank assembly should be enough to check this, unless the shaft is a tight fit in the E91 bearing........This can happen, and it is a bugger...... Just see how you go with that first.
 

Bill Thomas

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VOC Member
Well I have just looked it up and it's a SHIM, So good job I don't work anymore !,
E76 came in 10 thou up to 31 Thou, Not sure what is sold now,
The last one I saw was worn away completely , So that just a ring was left,
And somebody had fitted a new one in the gearbox as well , Which took all the play away,
I knew something was wrong, But it was so hard to see,
I always like to give the shaft a little pull and push, And there was no play !.
 

Martyn Goodwin

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Non-VOC Member
Thank you, I am going with my current 46% balance factor.
I will report on vibration when road tested.

Moving on to using Loctite 638 (exp 10/22) on ET92 roller races and centering crankshaft in cases.
I have honed out ET92 inner races without rollers to allow mock assembly of crank/cases.
Where do you place shims to shift crank?


View attachment 39825
take care with the loctite - it 'sets' in the blink of an eye!
 

craig

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VOC Member
Starting to look at crankshaft centering, again setting up select soft woods in a convoluted fashion to form a Vincent engine work stand. this setup requires a 3/4 shim at right rear corner.

This assembly has allowed me to see how the right outer roller fits in its hot installed outer race and in this case it is a very nice fit, cold assembly.

What instruments, measuring where, are best to determine crank in center?

20210125_CrankCenter1.jpg
20210125_CrankCenter2.jpg
 
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timetraveller

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VOC Member
I did not want to get involved in a technical discussion Bill but in some of the construction of domes, instruments and telescopes I have been involved in shims are a regular thing. Think of them as packing pieces. However, not all shims are shaped like washers. They can be rectangular or a variety of shapes and are there to pack something up or out. They are not always required to be an accurately thicknessed item. I think of a washer as they type of things which goes under a bolt head and can have a range of thicknesses depending upon the size of the bolt and where it is being used. On the other hand, I regard the item in question as a shim because it has to be accurately shaped and of an accurate thickness and also hard enough to withstand any compressive forces.
 
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timetraveller

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VOC Member
Regarding what measuring device to use to centre the conrods. I use a digital Vernier and press the small end away from the side of the bore from which I am measuring. That way any play in the big end is taken into account.. So, for example, I would push the front conrod to the timing side of the engine and then measure the distance from the left hand side of the conrod to the drive side of the bore in the crankcase. Repeat this for both sides of the front pot and then again for the rear. Take differences between left and right hand side measurements for both front and rear and that will tell you whether the conrods are central and if not how much to move them . Be patient.
 
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