Use threadlock on your flywheel bolts, and make sure you torque them up properly. You don't want the flywheel coming off at eleven million rpm or whatever they do at full chat.

No external filter on the 435cc A79/1 engine, not to be confused with the earlier 425cc A79/0.

Ken

I wouldn't know about that, but my prediction is that it'll slow down your gear changes, as it'll take longer for the whirly bits to slow down/speed up.

Hmm,
that's two recommendations so far to threadlock the flywheel bolts, however there's no such advice in any of Citroen's manuals.
Since flywheel bolts are torqued above their elastic limit, refitting old ones runs the risk of failure.
You may be lucky and they won't break, but then again you may not...

Ken

Yes, that's the other thing I should have mentioned ... use new flywheel bolts. I know people do reuse old ones, but I'm not among them. Threadlock is a personal choice, but I like it as a sort of belt and braces thing.

No - I'm in Chester. It's here to be picked up if you are ever passing. I doubt very much if I'll ever use it as my next project is a Guzzi engine on a VW gearbox using Blackjack Zero parts. BTW - it's the thickest heaviest 2CV flywheel I've ever seen. I think I have a photo archived somewhere and could post it if you are serious about it.

You can make a really nice tool from an old input shaft if you can find a gearbox beyond economic repair - one that's been sitting around outside and is full of water for example. Just take a cutting disc to it. If you use a cutting torch you don't even have to take the bellhousing off to get access.

My 2 cents worth on flywheels.
Heavy = [*]Stores energy, Good for cruising at speed, bad for aresponsive engine
[*]More stress on your crankshaft
[*]Slower gear changes
[*]Smoother Idle
[*]Better inertia up a hill, down shift comes later, but the end speed is decreased because of more turning mass!

Lighter = [*]Engine revs increase AND drop faster
[*]Requires more revs (torque) on take-off
[*]Less stress on your crankshaft
[*]Faster Gear changes
[*]Rougher Idle
[*]Faster out of corners
[*]Less inertia up a hill, down shift can happen earlier but your end speed is greater.

It all comes down to driving style and preference.

Harley

The faster/slower gearchange thing, while doubtless technically true, is irrelevant in terms of what you notice while actually driving. I can't say I ever found myself thinking "blimey, the gears are much slower with this heavier flywheel" when driving the Ami. I can confidently guarantee you won't notice the difference in real terms.

Harley,
the flywheel is bolted to the crankshaft and a heavier one will have more rotational inertia and can therefore 'store' more energy.
The heavier it is (or to be more precise, the greater its rotational inertia) the more it can absorb any input tending to accelerate or decelerate its rate of rotation.

Because of that characteristic, I think it acts as a sort of shock absorber when changing up or down through the gears and will reduce stresses on the crankshaft from harsh gear changes, for example.

As for the gearbox, that's a different matter, especially if the owner is fond of dropping the clutch at the lights with the engine running at 6,000 rpm...

Ken.