Engine block and gearbox assembly

Brian’s been hard at work assembling the gearbox and engine block. It’s starting to look like a power unit again.

Engine stands are cool.

The old flywheel was cracked, so we had to buy a new one. Sadly, standard cast iron flywheels are no longer available, so we had to buy a lightweight billet steel one. What a shame.

Here’s a tip: test fit your new clutch to your new flywheel *before* having the engine balanced.

It turns out that changing the flywheel on a Mini is a complete pain in the arse, because the thickness of the flywheel changes the way the clutch works.

A Mini’s clutch is a bizarre beast with an over-centre diaphragm spring on one side of the flywheel and the pressure and friction plates on the other.  Changing the thickness of the flywheel changes the static height of the diaphragm spring. If your static height is wrong in either direction you won’t get the full clamping load, but if it’s too high you’ll also destroy the thrust bearings.  Adjusting the static height involves machining down the clamp plate, which can change the flywheel balance- so if you do it in the wrong order you end up going back to the machinist a few times. Ugh.

Here’s a more in depth analysis of how it all works, and why it needs to be set up correctly: Minimania’s Clutch FAQ