So, I am working on the rear suspension of my project GT car and while the koni sport shocks and ground control perches look good, the springs look like they have seen better days. I know they use Eibachs and I can call GC and get their recommendation but I wanted to check here first from people with real world applications. My car is a 2056 GT car, or will be, has koni sports front and rear, stock front and rear sway bars and this car will be mainly street/twisty backroad driven.
My questions:
Does the GC setup accept normal 914 springs or are they a different diameter or construction than other aftermarket 914 springs?
What spring weight do you all suggest? I was thinking 100 -125lbs

I look forward to some input.

We made our springs to fit the OEM application. They are Ibach. Have 100# as well as 140/160 progressive. I think you want the latter.

https://900designs-container.zoeysite.com/1...rear-spring-set

Click the link in my signature on how to build your own custom coilovers using off the shelf parts.

What type of driving will you be doing with the car? Weekend casual? Spirited? Autocross? Short track? Big track?

What do you have for front torsion bars and sway bars (front/rear)?

Weekend casual and occasional spirited.

Front torsions are stock, front and rear stock sway as well.

Already have Koni sports front and rear with GC coil overs, but the springs are beat up and I want to replace them.

How do rear springs get "beat up" ?

The Ground Control springs and spring perches will be smaller diameter that the stock springs. They will be one of the common aftermarket spring sizes, probably 2.25 inch diameter. You do not have to get them from Ground Control replacements will be available from a variety of vendors.

You can switch back to stock springs and spring seats and use the circlip grooves in the Koni shocks to set your ride height, then you can use a set of 914rubber rear springs. You would need a pair of stock upper spring seats and a pair of lower spring seats for Koni rear shocks. Should not be too hard to find.


Jim

I'd say 180lb springs. Just double check the spring length and ID. Typically they are 8" long and 2.5" ID.

Springs we left in a bin by previous owner paint got all tore up and the spring are a bit rusty and have overspray in them. Figure new springs cost almost the same as sand blasting and powder coating. Plus this will allow me to actually know my spring rate.

You can get replacement springs directly from ground control or hypercoils. They sell them in 5 or 10lb increments. You need to know the ID of the spring and the uncompressed length. You can look on the ground control site and look for the full rear perch and spring kit and should be able to find out the physical dimensions

Oh and with your setup I would try 150lb springs

Or 140/160 Progressive.

100#