Time to educate myself on the rear suspension, it seems that the rear springs and shocks have quite a bit of options. Also seems that rear springs are the way to lower the car (seems obvious when I type that) and will have a big impact on ride stiffness.

Is there a way to tell what spring you have, maybe starting with ride height? Are the springs unique colors (common on Alfa’s) to make identification easier?

Thanks!

Stock springs would have paint dots on them denoting spring rate. They were all in the ~50 lb/in range.

Aftermarket springs may have letters and numbers painted or printed on them.

That's about it, though.

The best way to tell what you have is to pull them off the car and measure them. Compress the spring by some amount of inches, measure how much weight it took to do that. Or put so much weight on the spring and measure how far it compresses.

--DD

Thanks, as always, Dave,

I am asking because on this particular ‘74 the rear suspension seems much harsher than the other cars. Not sure if it is shocks or springs but needed the spring tutorial to start figuring it out.

I've never purchased a 914 (20 of them) where the rear shocks and springs were any good. It could be yours are just worn out no matter what the spring rate is.

Good morning!

Likely this is the case, I like the current ride height so will start with struts.

Easier way:
Calculate the spring rate from a few dimensions you can make, then use the link:

https://www.acxesspring.com/english/compres...lculations.html

I measured my spare set (assembled), so free length is a guess, but spring rate not affected.
Wire diameter = .387"
Coil OD = 4.1"
Number of coils = 10
Free length = 15

That yielded a rate of 62 Lb/inch

vw porsche designed the 914 and 914-6 springs for optimal handling and we like to use the factory spring rates for every day driving. The six and four springs are the same height but the six springs coils are thicker.
The way to lower the car is with a bilstein or koni shock with an adjustable spring plate. That way you are keeping the factory balance but lowering the car correctly and not compromising the ride quality. Important to match front and rear shocks/struts as well so Bilstein front Bilstein rear.
So important was it that we kept the factory handling that we had made original 914-4 and 914-6 rear springs, duplicates of original NOS factory parts we had here

What is the factory rear spring rate for the 914-6?

The only real answer here with out removing the spring and placing it in a press with a weight plate, and compressing the spring.

Somewhere near 50 lb/in. Could even be as much as 60 lb/in.

--DD

I just used the calculator for my set of unknown springs and a set of Weltmeister SP100 100 lbs springs.

Specs unknown springs from the late 80's/early 90's bought at AA IIRC.
Wire diameter = .475"
Coil OD = 4.125"
Number active of coils = 9
Free length = 12.5"

= 160 lbs (159.5)

Specs Weltmeister SP100 (100 lbs), springs are about 4 years old.

Wire diameter = .425"
Coil OD = 4.250"
Number active of coils = 7
Free length = 15"

= 120 lbs (119.64 lbs)

So either the calculator is wrong or Weltmeister SP100 advertised as 100 lbs are actually 120 lbs springs.
My unknown springs 160 lbs sounds about right.

914rubber.com just started producing stock and performance Springs. Check it out!

@mikey914

@matty900

Yes we have. Another GB that is pending. This is one of the items that I had started in process that is now done. These will be coming online this month.
Look for more Group Buys soon