Thursday, 10 January 2019

Small Journal Crankshaft

Holes in the bench are very useful. I have this 1 3/4" hole in my bench covered with a brass plug which I think was intended to cover the parasol hole in a garden table:

I don't use it for parasols though. I use it for crankshafts! It's very handy for when the engine has to come out of the engine stand so you can split the crankcases.

Let's get started stripping the crank. The timing side bush journal on the crankshaft measures 1.357" to 1.359", which according to SRM is fit for regrind to -0.020", so that is a reasonable start.

The sludge trap plugs have to come out, and these have a reputation for being somewhat tricky. I removed the staking with a 3 mm twist drill and attacked the plug with my impact driver - I was lucky, it gave up very easily.

From this end, the sludge trap is about half full:

This is the timing side rod - the bearing material has completely worn away, but the journal is in pretty good shape. This timing side journal varies 1.430" - 1.435" which according to SRM is fit for regrind to -0.030".

Next the drive side - here, the plug did not give up so easily and I ruined the screwdriver slot using the impact driver on it. I had to add a bit of 3 mm flat bar to the plug which I welded in place like this:

The heat from the welding and the application of the trusty Bahco 15" adjustable spanner was sufficient persuasion to get it out.

The drive side big end journal varies 1.425" - 1.432" which according to SRM is too worn for -0.030" but would regrind to -0.040".

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