Types of clutch

[DavidLaver]

Just realised my two clutches are different types... 

David

[ColinMarr]

It looks top me like only the top one of the two is an Aprilia clutch. This has a single large spring still held in compression by the large nut (that you cannot see in the picture) on the other end of the tube that goes through the centre. The clutch fork pulls back on the lugs that you can see on the exposed end of the tube.

The other clutch looks more like one from an Aurelia, with its arrangement of smaller springs and more conventional withdrawal levers. With these small springs the Harry Manning approved modification was to fit washers inside the housing to beef them up a bit.

Colin 

[DavidLaver]

Last time I checked it fitted the flywheel which fitted the crank.

An Aurelia clutch is a cast alloy spring housing like this pic attached.  The HUGE circlip is great.  As a unit it was fun and fairly easy to get in and out and apart - which I had to do a fair few times...

A great design - OTHER THAN the small area of lining, the containment of heat, springs fretting on the housings and grabbing, springs loosing temper with the heat, the hit and miss lubrication of an expensive bearing, and I'd expect also complex and expensive to make. 

At least on the early types the linkage is straightforward and effective - what did it take to make the clutch go in and out on your one??

Off thread (as usual  ) but in the same batch of photos is this one looking in one side of an Aprilia head and out the other - now THAT'S a cross flow...   

David

[DavidLaver]

OK - it DOESN'T fit the flywheel.

Thread moved to "Department of Mysteries".

David

[ColinMarr]

David

Let’s stay with this thread for a while.

It’s probably just as well you have decided this particular clutch is not from an Aprilia. Otherwise I might have had to suggest it was from a 4th Series Aprilia – the one fitted with a special clutch mechanism whereby you pulled the pedal up to disengage it and pushed it down again to let it in! I think it was launched on 1 April 1950.

Anyway, the Aurelia clutch you now describe is an early type, which in addition to the defects that you list was also prone to slipping – hence the need to beef up the springs. However, its virtue was the mechanical linkage, which sadly didn’t continue through to the later cars.

The later clutch fitted to 5th and 6th series cars was also prone to slipping when really hot (see contemporary road tests), but its dire weakness was the ghastly hydraulic linkage! When I rebuilt my 6th Series B20 I spent more man-days of brake-fluid flooded frustration in trying to get it to work properly before I gave up and fitted a very simple push-rod link devised by Peter Harding. Thanks Peter, it worked a treat!

And then we might get on to the relative virtues of early vs late-type gearboxes, but that’s another digression.

Colin

[DavidLaver]

Early gearbox - think of it as a three speed on the move with first just as a starting gear and that's not far off.   A frustration in "trickle along" traffic jams in that I'd not want to over rev in first or not put a load on the engine and have it lean but once up into second that's it until the traffic just about stops and can crunch into first again.  In second its slipping the (weak) clutch at very low speeds or it becomes a bit "kangarooee", for example on a mini rounderbout. 

I can't reel off the technical reason - but you can't change back into first above a slow walk without doing damage even if you match revs or double declutch or whatever. 

An Aprilia box on the other hand 

David