Zinc interleaves

[Erich]

Hopefully I have not opened up a can of worms, or a Pandora's box. On my recently acquired Ulster, the front spring had zinc interleaves. I presume these were installed as a means to eliminate or reduce greasing. Does anyone have a more complete history on them? We have retained them on the rebuild.

Erich in Seattle

[wild_willy]

I have a set of these (front and rear) on my Nippy. I'm sorry but I don't have any history relating to them except that I believe they may be an aftermarket supply from the 60's. Seem to be an excellent idea to reduce wear and tear on the spring leaves.
Hopefully someone out there will have more info to add.
Bruce (in the Yarra Valley)

[Henry Harris]

Zinc interleaves are original factory fitment for Super sports and Sports models.

Front springs are 9C 141, 7 leaves and later 9E 220, 7 leaves.
Rear springs are 9C 142, 6 leaves and later 9E221, 6 leaves.
All are zinc interleaved.

[JonE]

Fabulous to see these images. They are also mentioned in the index cards on springs, currently in another thread.
It does bring up the whole thing re. greasing. I'm presuming springs were never designed to be greased, and that it was a whole aftermarket thing generating cash for more bits of kit to do it.
Inter-leaf greasing changes the spec of the spring, surely, resulting in more give?
Is there any evidence of two conflicting strategies operating within the factory, one for aftermarket sales, one for perfect operating spec?

[Chris KC]

I'd hazard that zinc interleaving corrodes sacrificially as well as acting as a 'lubricant' between the leaves, obviating any perceived need to apply grease. I don't see that as incompatible with the advice not to put grease on standard springs - grease and zinc are not the same thing.

[Erich]

This is all helpful. Zinc interleaves make sense, perhaps obviating the need to grease, or at least preventing the wear that might occur without them. It also begs the question about surviving springs with the zinc. They must necessarily be thicker and therefore the shackles must be a different by perhaps 3/8".

Erich in Seattle

[squeak]

Shackles no but U bolts and rear king bolt maybe.

[Erich]

If the zinc leaves were standard equipment on the Sports and Super Sports, which were bound, does anyone have a good opinion of the concept and advantages? We know that binding and wrapping the springs with denso tape cause the springs to rust by holding moisture in. I would also guess that if they were designed to be greaseless, it might keep some dirt out which lessens wear. Any confirmation on any of this? I'm not trying to reinvent the wheel...I am curious as to the reasons why the works thought this would be an advantage.

Erich in Seattle

[Chris Garner]

Hysteresis is the key word in fitting interleafing to springs.
Chris

[Chris KC]

In the presence of an electrolyte (water) the zinc will corrode preferentially protecting the steel leaves.