Aprilia clutch variants

[apriliadriver]

I have searched through all the Aprilia threads and cannot find anything definitive on the different types of clutch for S1 Aprilias.

Can any of our readers help ?

I have all the parts books exploded diagrams 1937 to 1948, but what I really would appreciate is photos of the various pieces of the variants.

Thanks in advance if you have anything.
Nick

[BlueSky]

The clutch changed at construction no. 5416 from the smaller size with the six hairpin springs to the bigger size with the single large spring. I only have a photo of the early type, plus have attached the diagram of the latter.
Hope this helps.
Noel

Edit. Opps, both 1st series clutches are the same diameter, 2nds series are larger, sorry for the confusion.

[ben]

Does this mean you have a problem Nick?
You are not trying to get rid of the infamous Aprilia judder that we all know and love are you?

And Noel---Do you never sleep?

Incidentaly I dont suppose these clutches were originally held together with socket-headed bolts.

                                                      Ben   (Chief Nit-Picker)

[lancialulu]

Ben

I guess Noel is in OZ??

My OVS doesnt judder. If it did I would suspect oil contamination. Is there another fault mode for judder??

Tim

[BlueSky]

Yes yes, I know it has the wrong bolts, but they work. I now have some of the original type but even they come in two different sizes, see pic. Next thing you know I'll be fitting a 2nd series engine, heaven forbid

They early type of clutch seems to have the judder problem built in, even gets a mention in 1937 Autocar road test, it's only when taking up in 1st and reverse though. However, we need more info from Nick if there is a problem.

It's those tight little red sparkling shoes that keep me awake!

Noel

[apriliadriver]

First, thanks for all the replies, especially Blue Sky.

And, yes, Ben I am trying to reduce the clutch judder in first and reverse ! When I compared my Aprilia to the other 19 at Goodwood Track Day earlier this year, I clearly had a problem magnitudes bigger than every other participant.

On dismantling what seems to be a second series clutch assembly, the pressure plate (claimed to have been relined) was revealed to be defective, friction lining intermittently worn and signs of chattering. Diagnosis : incorrect pattern of rivetting distorting the plate.

So, rather than re-engineer the clutch, I will get it rebuilt with a properly assembled pressure-plate.

Has anyone any experience of using the Cavalitto replacement plates ?   How much were they ?
Yrs
Nick

[ben]

This is pure speculation Nick as I've no first hand experience with 2nd sreies clutches but I'de be concerned that what you are seeing on your pressure plate may be secondary to the judder. As has been said before if the clutch is at all less than perfect the result is magnified because of the potential for backlash in the prop-shaft, diff, and drive shafts.

I believe the judder arises with these clutches because when you put your foot on the pedal to disengage the clutch the mechanism doesn't guarantee that the cover plate remains parallel to the face of the flywheel as it is pulled away.For example in a first series clutch it is obvious that if the hairpin springs are not perfectly ballanced the pressure plate will be released in the zone where the weaker springs are first and conversely as the clutch is re-engaged the pressure plate will be gripped first where the strongest springs are.I think the central spring arrangment in the 2nd series is equally suspect in this regard.
Alternatively, or perhaps as well,if there is wear where the fingers engage to pull on the arms on the release bearing assembly, or if the arms are a bit bent,one side may pull away ahead of the other by a small amount and this will give uneven take-up.
 
All in all it is a poor design compared to a clutch with toggle arms or an inverting diaphram such that dis-engagment is achieved by pushing on the coverplate release bearing rather than pulling it.

Consequently you need to check as thoroughly as possible that all the elements in the release mechanism are true and working evenly when you re-assemble with your new or re-lined friction plate.

[davidwheeler]

Sorry to say this but 2nd series clutches judder as well.  I have no idea why, mine has been rebuilt with new plate and carefully faced flywheel.   I was once told that original plates were riveted alternately so that one side was not directly riveted to the other allowing a degree of springing but the old (!st series) plate I have does not have this feature.   I think the plate I now have fitted is from a much later model of Lancia as it came with the spares sold off by my local Lancia dealer when Lancia withdrew from the UK.