Flywheel extractor for 750cc Mastiff

[Dewey]

I'm just about finished with this engine rebuild and thought of all the most useful tools to include at delivery time would be the means to remove the flywheel. I followed Chris's lead with the EW designed extractor and first assumed the flywheels internal thread to be the same - NOT! Firstly, the flywheel internal threads were what looked like 20 TPI, so I turned one out at 1 7/16" - 20. Nope, too small. Turned another at 1 1/2" - 20 - too big! Thru careful measurements of the thread ID and adding thread depth I discovered it to be a 38 x 1.25mm, which is only .010" less than 1.5". This may fit the S6 family too.




[Attachments converted to linked images. 01Dec21 -Doug, Admin]

[eddie]

On the S6 the flywheel nut is flanged and the flywheel is fitted with a retaining ring that traps the nut. Unscrewing the flywheel nut then extracts the flywheel without the need for a puller.
  Regards,
                Eddie.

[Dewey]

That would be too easy. The nut does in fact have a flange but there's nothing in the way of a snap ring or a groove for one in this case so the tool was absolutely necessary.

[eddie]

The retaining ring is threaded and screws into the thread you are using for the puller.

  Eddie.

[Dewey]

Yes, true, but the nut with the flange is much bigger than the hole in the retaining ring in this case so there's no way to grasp the nut to back it out forcing the flywheel to release.