I'm in the process of rebuilding my Koni Yellows to race valving in order to support higher spring rates.

I'm looking at running 750 and 700lb springs with my Ground Control sleeves however I'm having an issue finding those spring rates in the standard 7" long and 2.5" diameter sizing that comes with the GC kits.

How is everyone getting around this are you just running a taller or larger diameter spring?

 

Most springs come in 7 or 8 inches, I have seen some 6's
Eibach and Hypercoil come to mind in those rates

 

8" long, 700 and 750 rates in a 2.5" ID
http://www.ground-control-store.com/.../II=457/CA=213
http://www.ground-control-store.com/.../II=459/CA=213

You need to keep the ID the same, for the seats. At rates that high, 6" shouldn't present an issue, but if you're worried about coil bind just use 8" lengths.

 

Any issues with running the longer spring?

 

Ride height issues, preload issues, and if it's too long you have to worry about coil stack. So long story short, a spring's free length is very important measure to get right for your setup.

 

So I guess my follow up question is how are other people running higher rates with GCs if the 7" spring stop at 650lbs?

 

That depends on the manufacturer of the spring.
They arent all the same.

 

Hyperco goes up to 1300lb/in and Swift go up to 1567lb/in (28kg/mm) in a 2.5" ID (65mm in the case of the Swift) 7" spring. I would not change your spring length if you don't have to assuming you are confident you will achieve your desired ride height without changing.

 

Hey Chris, simple solution to your problem you just run 6" springs.

ttyl

 

H&R makes a whole bunch of rates.

6" and 8" up to 1300lb/in and 10" up to 900lb/in.

http://www.hrsprings.com/applications/250in_id_springs

Running longer springs isn't really an issue if you have enough adjustment on your collar. I run a 250mm spring on my rally car for tarmac with tender and I pretty much have the height adjustment collars bottomed out, so I couldn't really fit a longer spring in there.

Running tender springs would be wise so you don't have slack at droop.

 

We have 6" and 8" springs in 700 and 750lbs. We make a 7" spring in 700lbs but not 750.

The 6" springs will offer 3.43" in travel for the 700s and 3.35" of travel in the 750s.

The 8" springs will offer 4.35" of travel in 700 and 4.28" of travel in the 750s.

All four springs are available through GC and in stock at Eibach in case they're out.

 

Im assuming you have called GC and asked them about the rates your looking for? Custom rates to fit your GC sleeves shouldnt be a problem.

 

If it's too SHORT you have to worry about coil stack.

 

They are a problem when the springs don't come in that length.

I decided to go with a set of hyperco springs 7" that way I don't need to worry about coil bind or coil stack.

The rates I decided on were F750lbs/R700lbs