The ultimate upgraded rear main thread

Hi Dick I got this drawing from an engineer in Australia back when I though I’d get one made. I’m now concerned that it may not be truly representative of an actual Churchill tool. Unfortunatey JCNA tool loans to Canada with our customs rules can be a p.i.t.a. - not to mention shipping and brokerage charges. I’m curious about the critical measurement of 3.119" for the actual seal portion shown in the drawing. I measured the diameter of an old crankshaft in my garage just now and the oil throw diameter is the same 3.119". If you have an actual Churchill tool is is possible to advise what it’s diameter at that point is?


Not sure how much it would cost to make one, but Rob Beere sells one for not too much money

Just made sure my micrometer was calibrated and I come up with the 3.119" also.

Hi Terry,
Check out this older thread for measurements.

Thanks Doug I just re read it. I don’t recall this thread but see I got the last word in (always late to the party). I read with interest the different dimensions of the tools JCNA has, as reported by George Camp. I can’t say I’m surprised. In dealing with Jaguar stuff from 50 years ago we need to remember that when Sir William bought Standard’s tooling to make his engines (1930’s ?) Standard sold it because they believed it was worn out. Subsequent events I believe proved them correct - notwithstanding that Sir W soldiered on with the tooling until the end of the XK production, and then sold it! To get to the point - Jaguar was a company that needed multiple piston sizes all marked with letters to fit the sloppy bores. Consistent sizing of the scroll on the back of the crank to say 3.119" would be a dream only. I think sizing of a flexible seal to thousands of an inch must also be in the same category, and in any event what thousand of an inch would you pick from the variety of thousands on the JCNA tools.

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Viewing this picture reminded me of something…

30+ years ago, in parking lots all around the world, that was a common sight, and no one ever really thought much of it.

Leaking hasn’t been completely eliminated, but it has been greatly decreased, the amount of oil spots in parking lot areas. I think when one sees it today, it’s a result of an older car: my Ford now has 63,000 miles on it and the engine is bone dry.