Hi Mario
Sorry about very late respsonse I forget to look on the forum for months.
I just typed a huge long message which the computer decided to dump, don't know if it went anywhere. I was so irritated that I've just spent 2 hours looking for the original file which I haven't found, very annoying because it had all the spring technical info.
Long ago I undertook a joint project with Morris Parry sadly no longer with us, as he had been my major mentor when I put my Augusta on the road in 2012. The project was to specify, find a supplier and purchase a batch of upgraded clutch springs as many people had experienced clutch slip on Augustas.
We circulated the idea through Morris's original newsletters and ended up seeking to buy a batch of 20 for locations in UK,Europe and Australia.
I measured and drew a cross sectional assembly drawing of the clutch on my car, in my case the spring was virtually coil-bound when assembled which limited our choice of material options. After the usual phone and internet searching we found and chose to use; Tested Spring Company based in the Midlands, Morris supplied an old spring and details of the original length. I sent the sample to Tested Spring and their sales chap came back to me in a couple of days and said we can't make a better spring than you have (that's why we like Lancias!). This combined with a lack of axial space limited our choices for the design as we couldn't increase the axial length of the installed spring. As the spring is a 'fit' inside the retaining plate there was no scope to increase the outside diameter so the only option was to reduce the inside diameter of the spring.
Original wire spec was 3/8 x 3/8 " square wire. The revised spec was 10 x 10 mm square wire, ground to 9.5 high x 10 mm wide, thus giving us as slight increase in the width of the spring an a small increase in the spring rate.
The original price quoted was based on modifying the existing spring by increasing the free length but this was was not possible. So 10 x 10 wire had to be ground down to 9.5 x 10. The final price based on grinding down the wire, winding the springs, grinding the ends square and shot peening was £48 each which we thought was a good price for what we wanted. The batch was duly purchased and springs sent to all who ordered them.
I installed one in my car not long after I got my spring as the engine or gearbox had to come out for some other reason. I sent the pressure plate off to be minimally machined in case it wasn't good. Due to heating up at some time probably due to too much slipping at traffic light Grand Prixes it was actually saucer shaped and had been driving on a very narrow band on the outside edge of the driven plate.
I haven't heard from anyone with one these springs installed that they have had problems I've probably had mine in for the best part of 10 years without slipping problems even when a copper rivet came out of the driven plate recently and wandered around between the pressure plate and the driven plate. I try not to slip the clutch to much when pulling away as the pressure plate is very thin and can easily be affected by the heat generated
Long story I hope not too tedious
Separately, John Millham long time Augusta and Lambda owner and my second Augusta 'Go To' man also sadly not with us anymore addressed this problem a different way, he sent me a photo of his modification which was to weld 3 springs to the inside of the circumference of the pressure plate to increase the spring loading, quite simple and must have been good if it survived living with a blower!
Cheers
Dale
