Numpty question; which type of flywheel would a 2cv6 motor which is thought to be untouched and stock from 1986 have?

Light flywheel, diaphragm clutch. They changed over around '82/3.

The heavy flywheel is mandatory for me, I much prefer it. The only drawback is the 3 sprimg clutch feels like stepping on a potato, the diaphragm ones are much lighter and smoother. It's only after fitting a new but old style clutch that I discovered that diaphragm types are now abvailable for the heavy flywheel models too.

Re Sean's comments about the Dyane box and the higher top gear when climbing a hill, the heavy flywheel is how I'd hoped to avoid some of the negative impact of hills in that high gear. The only pain would then be when it needed to go down to third, when (presumably) third would be too low and speed would be lost?

Can't say I've ever noticed that - can't remember what clutch was in the Acad, but it was a light flywheel and '80s engine. Ellie's 2cv is definitely coil/heavy.



I had a chat with One Of The Parts Suppliers about those a little while back. They don't sell 'em, because of problems with the release bearing apparently.

From what I've discovered by doing mine the heavy flywheel must be fitted with the old style clutch, and allied to an older short input shaft gearbox. The light fw uses the diaphragm jobbie, and has a longer gearbox shaft although I think it would still work with a short shaft gearbox too. Whereas the heavy flywheel setup won't work with the later type long shaft gearbox.

There, clear as mud.

Gearbox ratios - the Dyane's 1st gear is lower/shorter since it's a heavier car and 4th is higher/longer because it's a little more powerful and a little more slippery through the air.

In a 2CV, I find a Dyane top gear a little long unless there's a tail wind and few inclines. Equally, I once drove a Dyane on 2CV running gear and setting off up a hill reminded you the car weighs more. On the M-way it felt a little short geared and breathless, although the top gear on all 602s is relatively high.

Heavy flywheels? They're a form of free energy and I love 'em - they suit the character of old Citroëns but not a driver who can't drive smoothly and maintain momentum. Those from the Amis are several hundred weight. Seriously large amounts of stored energy, which if used well can carry you so much further up a hill. On fast undulating roads, use gravity to recharge!

edit: like the idea of carrying the generator as part of the rotating flywheel mass, another clever way of lowering overall weight.

Old-Nail,
it's easier working the other way round.
A long spline gearbox will work fine with either type of clutch, whereas a short spline gearbox has a reduced 'bite' on the driven plate of a diaphragm clutch, so may be more prone to clutch judder.

While I'm on, dug out some scribblings from gear tables,
At peak power, 5,750 rpm, road speeds for each gear on 125/380 tyres...

2CV. Dyane/Ami
18.3. 17.5
35.9. 34.4
53.4. 52.5
72.5. 74.8

In practical terms, I find that it's only if you're towing (or driving a van?) that the bigger 'jump' between 3rd and 4th gears on the Dyane/Ami box is of much significance.

ken
( Heavy flywheel and Dyane box every time... )

Those figures are interesting Ken. Looking at them it isn't so much the jump up top that bothers me now as the chance of feeling undergeared everywhere else! Wouldn't it be nice to have a simple 2cv box with a Dyane top gear.

Am I right in thinking then, that with just a heavy flywheeled 9:0:1 motor, and the Dyane box I will have a briskly accelerating car around town that can slot into and pull a slightly lazier gear on the motorway? That's all I'm after, I don't tow stuff, and the wife's only a size 10

Old-Nail,
maybe I didn't place enough emphasis on one of my comments in the previous post, but to rephrase that comment.
1 or 1.5mph at the highest rpm you're likely to use in 1st, 2nd and 3rd gears isn't going to make much real difference, is it?

On the other hand, the difference between a heavy and light flywheel car is much more obvious, with the former promoting a more relaxed, laid back driving style, but that's just my opinion.
Tbh, it's rare that the rev counter on my old Dyane goes near 5,000 rpm these days.

ken

Perfect thanks!