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Discussion Starter #1,781
..Thinking about this more, trying option 3 means that you are only using your time, and if not happy go with option 2. I wouldn't by used springs myself as they age.
True enough but if they are still within overall specs they should be much cheaper than new + shipping + taxes. Though used ones will have some unknowns ....hmmm.

My other suggestion is to remove the wood from under the wheels, will make a huge difference to the ride height ;) Pete
yeah but it sure makes crawling under the car a lot easier..
 

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Your calculations show your OE springs to be 500 lb/inch. I don't think they are that stiff other data I have seen show them at about 400lb/inch.
 

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Discussion Starter #1,783 (Edited)
Here's how I calculated (based on data provided in IS 21.71.2.1) ....measured values presumably...

SR = P/ DL = 911.5 kg / (313.5-214)mm = 911.5kg/99.5mm = 9kg/mm or 2004 lbf/3.92" = 511 lb/in. (for the US springs)
and
SR = P/DL = 749 kg/ (307-214)mm = 749kg/93mm = 8kg/mm or 1647.8 lbf/3.66" = 450 lb/in. (for the Euro springs).

strange huh?
 

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The calculators show no difference in spring rate with a change in free length. It will take more weight to compress the US spring to the same ride height or compressed length of 214 mm.
Check out Eibach on CA they are cheaper than the fast road springs. Only OE replacement springs are cheaper than Eibachs. Eibachs are only slightly stiffer than stock and 40mm lower. I emailed CA asking for more technical data on the springs they sell for 105 Alfas.
I got 466lb/in in the calculator above using 5.25 working coils and A2330 material and data you provided in DIASS.
 
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Discussion Starter #1,785
The calculators show no difference in spring rate with a change in free length. It will take more weight to compress the US spring to the same ride height or compressed length of 214 mm.
Check out Eibach on CA they are cheaper than the fast road springs. Only OE replacement springs are cheaper than Eibachs. Eibachs are only slightly stiffer than stock and 40mm lower. I emailed CA asking for more technical data on the springs they sell for 105 Alfas.
I got 466lb/in in the calculator above using 5.25 working coils and A2330 material and data you provided in DIASS.
All good stuff these calc's....but the variables are the biggest unkowns it seems to me. Such as the true effective # coils (which should change with the change in free length)....the modulus (we don't know what the OE spring steel material is do we?). I would trust more the IS 21.71.2.1 official publication which gives spring load at length than the formulas. Though for me.....whether we're talking 440 or 550 lb/in....is not the deciding factor ....it's the ride height change that I'm after. I think my initial option will be the cut spring approach.....if this does not give me the result I want....I'll look at the buying option later on.
 

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I'm contemplating some of the same issues. I want the compliance of the stock springs, with the reduction in ride height. Perhaps they are mutually exclusive solutions. I'm avidly following for the information provided.
 

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I found info on a few older threads that state Eibachs are 616 lb/in front and 101 lb/in rear. Stock 105/115 are usually in the 300-400 F and 75-90 R. Where most performance springs are 600-1300 F and 115-200 R.

Our fast road springs are as follows;
SU116 – 650lb free length 26cm
SU117 – 180lb free length 32cm
I don’t have this information for the Eibach springs as they are not our production and the supplier doesn’t share this information. They lower the car roughly the same but are slightly softer than our fast road springs.
From Classic Alfa
 

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I'm contemplating some of the same issues. I want the compliance of the stock springs, with the reduction in ride height. Perhaps they are mutually exclusive solutions. I'm avidly following for the information provided.
If you lower a car you need stiffer springs to keep the suspension off the bump stops. Once the suspension hits the bumps stops you have effectively lost your suspension and the car has turned into a go kart, but a heavy and powerful one.

I encourage all, if they make suspension changes, to put a cable tie firmly on your shock absorber shafts and go for a drive on your favourite road and check when you get home that the cable tie shows that your suspension never bottomed out. Note put the cable tie near the other half of the shock absorber so that when the suspension moves it will get pushed up the shaft.

If you suspension bottomed out, that end of the car needs stiffer springs. Repeat this test until it doesn't, and then start worrying about camber settings to work with that stiffness. This is crudely what circuit car setup involves

A lowered car that uses the bump stops as actual suspension movement should be removed off the road as a dangerous vehicle
Pete
 

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Discussion Starter #1,789
Good suggestion Pete....will keep that in mind. I've read a few threads where some folks have cut out a full 1 1/2 coils and found that that was too much. I'm going to do a 1/2 coil cut initially with a heat reform to get the coil to conform to the cushion pad angle. This will yield a free length reduction of 36.7 mm (1.44"). We'll see what that translates to at the wheel arch.
 

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I measured my cut springs. I think I cut 1.5 coils, and the free length is about 263mm. I didn't reform the end, there are 5.25 coils remaining. Might be 4 active coils left, they were too low. I don't recall if I tried adding spacers, This was done over 20 years ago. See post #1787 for CA fast road free lengths.
Your spring modification should yield a 10% increase in the spring rate.
 

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Hi Anthony....that's a good look. I do have a few questions though...1) Which springs did your car have to begin with? The US model springs are different than the Euro ones in that the free length is greater @318mm vs 307mm. 2) How many coils did you cut off from the front? 3) I presume you also cut the rears?...if so, how many did you cut here?
Hi Rossano,
I bought my (used) GTV completely stock and it sat very high, factory NA regulation height. I did the work awhile ago, I do recall somewhere around 1/2 a ring at the front and 1 ring at the rear. It also took a few attempts to get it to a height I was happy with. No spring pan spacers. I have factory black Spica shock absorbers on the car and love them.
 

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Mine is currently at the factory US regulated (4x4!) height. I do understand that there will be a need for additional stiffness, just, hopefully, not much.

I have a track car, I'd like to make sure the '74 Coupe remains a compliant road car.
 

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Discussion Starter #1,794
..... I do recall somewhere around 1/2 a ring at the front and 1 ring at the rear. It also took a few attempts to get it to a height I was happy with. No spring pan spacers. I have factory black Spica shock absorbers on the car and love them.
Thanks for confirming that Anthony. I've got new SPICA's all around now as well (will keep the KONI's for the other project) so I hope to end up with the same result as your car.
 

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Rossano,

If you're interested, I measured the rates (using the Instron at work) of the factory springs of my Super and the rates of the springs I bought from Classic Alfa. Let me know if you're interested and I can dig up the graphs.
 

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SuperFab, I would be interested in your data as others may be as well.
 

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Count me as one interested in the results.

Bob
 
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