Spring stiffness

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John Simister

Spring stiffness

Unread post by John Simister »

Is an HF, be it series one or two, meant to have stiffer springs than a standard coupé? Or are the handling changes and firmer ride just the result of bigger tyres and the negative-camber front end? My car has good-condition secondhand springs which seem fine, but I have no idea which type of Fulvia they came from originally. My S2 has S1-type rear spring attachments, incidentally, along with various other S1 parts (rear upper damper mounts, front hubs, driveshafts, oil cooler, greasable steering idler, cylinder head casting, big sump) which may be because it's quite an early S2 (registered May 1971). So it's hard to guess what sort of rear springs it should have, if there are indeed different ratings.

John Simister
Ed Levin

Re: Spring stiffness

Unread post by Ed Levin »

John,

The answer to the question is yes and no; they're the same springs, but they're effectively stiffer.

According to the S1 parts catalogue, the S1 1.6HF shares the same front & rear springs with the standard coupe (of the S1 coupes, only the 1.2HF & 1.3HF are listed as having different springs). But this means that the S1 1.6HF effectively has a higher spring rate, as it weighs only 850kg against the standard coupe's 930kg. With a weight of 900kg, the S2 1.6HF would fall somewhere in between.

(Speaking of falling somewhere in between, your 'transitional' spec sounds interesting. What chassis number do you have?)

In any event, with age and/or replacement and/or retempering, there may be no two identical sets of springs at this point. In other words, the source of your second-hand springs probably doesn't matter; what matters is how they feel on the car.

On my S1 1.6HF, the rear springs have had one leaf removed, which reduces the 'tail-up' stance and significantly improves the handling as far as I'm concerned (and it would still be described as 'stiffly sprung'). I suppose I could have achieved the same thing by retempering the leafs, but the results of retempering are never wholly predictable. You may have to experiment a bit to see what works for your car and your preferences.
Phil

Re: Spring stiffness

Unread post by Phil »

Hi Ed,

I have a series 2 which really has a "tail up" stance as you say. Which spring should I remove?
John Simister

Re: Spring stiffness

Unread post by John Simister »

Thanks Ed, very interesting. My car is a little tail-up when empty but sits level when occupied, however I might experiment with leaf removal as you suggest. As for chassis number, it's 818.740-001732, registered in Klagenfurt, Austria on 22 April 1971 (not May as I said earlier). There's a photograph of it when new in the original registration book in which it sits very high at both ends. It's much better now.

However, when I bought it, it had truly horrible springs made in the UK out of the wrong spring stock. The leaves were much thicker than Lancia's and the steel itself was possibly harder. The front spring had sagged while the tail was ridiculously high, so it looked like a funny-car dragster. It had the worst ride over bumps of any car I have ever driven, yet still I bought it. A week later I thought I must have been insane, but it has finally turned into a decent car which drives, I think, more or less as a Fulvia should.

John
Geoffrey Goldberg

Re: Spring stiffness

Unread post by Geoffrey Goldberg »

Don't forget to change the interleaving in both the front and rear springs - the rubber looses its suppleness with age, and things get very stiff as the stiction between the leaves makes the spring essentially ineffective.

I've had good luck with both Aurelia and Fulvia (owned a coupe a year or so ago) where we changed this and the supple ride returned, most happily. It doesn't answer "tail high" 'syndrome, but can address the stiffness, sometimes.

The material is not too hard to find - either Mike Kristick or Omicron have it.

Geoff
Ed Levin

Re: Spring stiffness

Unread post by Ed Levin »

Phil,

I want to be very careful about telling anyone that they "should" remove a spring leaf. Doing so will reduce the loading capacity, and you might get decent improvement from simply disassembling the spring set and renewing the interleaving, as Geoff suggests.

I don't ever load my car to anything approaching its rated capacity, as I've always thought rear seat (or what passes for it) passengers were out of the question, and I don't tend to load the trunk with anything other than the spare tire and occasionally possibly 40lbs of tools and spares. Removing a leaf seems to work very well on my car, but it is definitely not something that would have been sanctioned by the factory.

With those disclaimers, I'll actually answer your question. There are 6 leaves to the rear springs; counting the longest as #1, mine has either #4 or #5 removed (i.e. 2nd to shortest or 3rd to shortest). It will make a difference as to which is removed, so you may need to experiment.
Neil Cundy

Re: Spring stiffness

Unread post by Neil Cundy »

All the coupe springs have the same rate

6.1kg/mm front
1.4kg/mm rear

The difference is in the camber. The S1 1.6 has a different camber to the S2 springs (120mm vs 138mm at the back, and 131mm vs 143mm at the front). This translates to different ride hights.

S2 1.6 springs will have a ride height difference (assuming 40% rear, 60% front weight balance) of 10mm higher than an S1 1.6, plus 12.5 mm due to the bigger wheels, so by calculation 22.5mm higher at the back.

S2 1.6 front springs will have a ride height difference (again assuming 40:60 weight balance) of 7 mm higher than the S1 1.6 springs + 12.5 due to the bigger wheels, so 19.5 mm higher at the front.

If my calcs are correct !
John Simister

Re: Spring stiffness

Unread post by John Simister »

Mathematically that all sounds sensible, but period pictures of S1s and S2s seem to show rather bigger gaps between the tops of the tyres and the wheelarches in S2s than in S1s, despite the bigger wheels which would eat into those gaps. It's all very mysterious, and Martin Cliffe at Omicron has told me that Lancia's official spring camber data bears scant resemblance to reality anyway. Still, it's good to know that all coupés have the same spring rates, which answers my original question. For which many thanks!

Neil, I'd love to see your restored Fanalone when finished, and also your father's Aurelia in which I travelled as a teenager when it was owned by Mike Rogers. Mike had an Aprilia at that time, too, and later a Fulvia Zagato.

John
Ed Levin

Re: Spring stiffness

Unread post by Ed Levin »

Neil,

Very interesting to learn of that camber difference (I'm not the slightest bit surprised that you're the one that came up with that answer). And it's a great set of calcs, but I think there's a load factor missing.

Camber, whether for a spring of a beam, is essentially a 'preload'. The difference in camber between the S1 and the S2 would have been, as least in part, to preload the springs against the added dead load of the S2 (900kg versus 850kg for the S1). If the factory had used springs with the same rate and the same camber, the S2 would have sat slightly lower at rest.

Whether or not the camber difference you identify would exactly offset the added 50kg of the S2 is a calc I'm not going to do (lazy sod). But the weight delta needs to be factored in to any set of ride height calcs.

Once loaded, only the residual spring camber (i.e. that portion not offset by the dead load) would factor into the effective spring rate, but this probably doesn't change the values much in practice. But, as I mentioned earlier, the extra weight of the S2 will tend to create a different effective spring rate from that of the S1.
Geoffrey Goldberg

Re: Spring stiffness

Unread post by Geoffrey Goldberg »

Well put Ed. Good research guys!
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