8 cylinder front engine iconic vehicle
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By Mongo
#213238
I've decided not to dismantle my factory Boge shocks to build the Konis into a strut (sitting on the shelf collecting dust after 2 years).

Carl used to sell a Hypercoil kit with Konis but that appears to be long gone now.

Last I saw on Rennlist, he used a 2.5" diameter spring 8" long in the front and 12" long in the rear. Koni sells some 25mm and 40mm collars and perches for 2.5" springs. Okay great, that solves one problem.

Now spring rates? 300, 400, 500? What rate for the front? 200, 300, 350, the rear? I am a backroad carver when I'm not working or chasing 2 kids around the house playing with my tools.

Let me know what's an ideal spring rate that is sporty, not comfy. I have a CLK if I want comfort, burlwood, and grey poupon.

Thanks!
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By Mongo
#213242
One more thing, Koni sells their own threaded collars complete with adjustment nut and upper spring perch. Part number for the front and back are below:

80.0000.2 - 40mm top spring perch.
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By maddog2020
#213274
S4 stock is 285 front and 175 rear.

common packages are 600/400 but reports show that this can be a bit of a rough ride on city streets.
800/600 and 1200/800 are for track setups depending on the driver and courses.

I went with a 500/350 but have no miles on them yet. I did have the externally adjustable shocks re-valved. They are sold to work with the factory ranges, and my setup was on the fringe of acceptable performance. The re-valving moved the performance to the middle of the range for the springs that I chose. With this valve setup I can make small changes in either direction without having to re valve.
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By worf
#213316
I have seat time in Hypercoil 600/400 and 500/350. Both are too stiff for Yankee Land roads for my taste. The 5/3.5 setup is livable if you have developed a habit for swerving around tire-size road imperfections.

Absolutely, you need dampers that are matched to the springs.
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By Benno
#213328
I have Koni's and have tried a couple of different spring rates and lengths on the front and read and I have experience with using the Kori threaded collar kit, as well as, the 928MS spring adapter kit.

I used H&R springs instead of Hypercoil. Both manufacturers make the same liner spring in different weights and lengths.

Weights
My car is a GTS so it's a bit heavier than early cars. I started out with 1000 lb springs in the front and 600 lb springs in the rear. I used the Koni's at the maximum dampening. This setup was really good for smooth roads and track driving. The ride quality was smooth and not harsh. The car would take a "set" very predictably on the track. However. I found that on uneven surfaces like back roads and forest roads, the car felt over-sprung and the Koni's were not able to deal with repeating bumps. The rebound was too fast and there was not much compression over stuff like speed bumps. I ran these springs for 1 year.

I decreased the spring rates by 20% to 800 lb in the front and 450 lb in the rear and have been using them for about 6-months now. I find this combination to be much better for off-track driving, bumpy undulating roads with lots of twists and turns and ups and down. I would definitely recommend these weights. I would not say they are track only. My impression is that they are stiffer than new Boge Red spot shock but offer much better compression control than the Boges where sometimes I would bottom out my nose on dips in the road (as stock ride height). I was just out driving last night on 50-miles of Pacific Northwest forest roads which follow rivers and climb up and over 1000-ft hillsides. Roads are uneven sunken grades and pavement quality varies since maintenance is inconsistent. These shocks are not too harsh for this. My GTS is setup for sport driving, not urban cruising and daily driving. If this is the case I might forgo some performance and go with 600/350. BTW, this car originally came with Bilsteins and those were very comfortable for city driving, but vague when trying to initiate a "set" in a turn.

Lengths
As for spring lengths. You want to make sure you don't go too short such that the spring coils with "Stack". Some people like shorter springs because they are lighter. This is more of an issue in the front than the rear because the front shock travel is very short.

REAR: 12" will be fine. I am using a 12" spring in the rear and the Koni top spring perch and that length seems to be just fine. I definitively would not go shorter.

FRONT: 8" is a good place to start. I started out with a 6" spring with the 1000'lb springs but then changed to an 8" spring with 600lb.
Image

With the 600/450 lb springs, I had to reduce the dampers to 50% of the adjustment range and the car seems very happy. I have not fussed wit the damping since installing them. But I am very happy so far and would definitively recommend this setup for a car that is dedicated to fun driving and road trips. Urban city driving with lots of speed bumps can be a bit annoying. But my 928 deals with those better than my 2018 Golf R.

Hopefully you found this useful. If you have any questions, hit me up.
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By Mongo
#213721
I may go the 500/350 route with springs. Found out Koni doesn't make the part number I posted anymore. I was looking at a coil over 'kit' that will fit a 2 inch dia. Shock at Speedway motors with 5 inches of thread as an alternative on all 4 corners. I can't locate the perch height but it appears like a reasonable size all the way around.

https://www.speedwaymotors.com/Coilover ... 046236-BIL

Now the reality, I still have to disassemble the struts so I can reuse my spring plates and shock mounts. Not a big deal, but I don't want to die using the wrong spring compressor since I need to up my life insurance policy.

That being said, what is a good spring compressor to use for disassembly? And will it work with hypercoils or eibach 2.5" springs?
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By worf
#213740
I have one that is substantially similar to this:

https://www.ebay.com/itm/233717747992?h ... BMjq_YqPxh

Best I can say is that it mostly works with the fat stock springs. I doubt it will would work well on skinny springs.
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By Mongo
#213748
Thanks Worf.

Random question, has anyone ever tried to fit aftermarket coilovers sleeves on a Koni shock, and still retain the stock springs, and lower perches?

I assume it may be possible, but I suspect a shim would need to be used between the adjusting collar and the factory lower spring plate in the event the lower plate is larger in diameter, than the aftermarket collar.
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By hans14914
#213975
Coleman Racing also sells the threaded sleeves and hats/perches for Koni bodies. They have an upper that is compatible with the stock upper isolators.

https://www.colemanracing.com/Chassis-S ... k-Hardware

You may have to download a copy of their full catalog and look for it though, there website does not show all their suspension parts.
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By Mongo
#214354
Thanks Hans. I'm tempted to buy the threaded sleeves and adjuster nut to see if I can get stock springs to work without the issues of JB welding.

What have I got to lose? If I'm successful, then we know we can buy coarse threaded coil over kits that are aftermarket for Konis and never have to worry about getting factory threaded sleeves to work. I assume there may be some grinding involved and perhaps a shim to ensure the lower factory spring plate has enough support to sit on top of an aftermarket adjuster.

If I'm not successful, oh well, Hypercoil or Eibach 2.5" springs still go on.
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