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Thread: Guide: Building Custom Koni Shorts (CSKs)

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2015-07-14 06:38:10
Guide: Building Custom Koni Shorts (CSKs)
So I haven't posted in awhile. I figured I'd share this, just for the hell of it really as it is not detailed as much as some other things on these forums. I do want to thank 98sr20ve for a lot of the information he shared about installing Koni's on our cars, I feel that without the information he provided I would not have been able to do this myself. I also want to point you in his direction as he builds them for people, TheKid29 also make high quality Koni kits. After doing all of this myself, if I had the money, I would have totally paid for someone else to do it for me. Not that I honestly found any of this hard but to do a quality job really does take time and energy.

I currently have a AGX/GC setup for a couple years now. The rear AGX struts are beyond blown out and instead of spending the same price for new AGXs as I could for Spec-V Koni inserts I decided to just bite the bullet. I am not scared by a little fabrication and considering this is doing pretty much nothing but cutting and drilling I went ahead and took pictures.

I am going with Spec-V front inserts (Manufacturer Part #: 8610-1409SPORT) in front housing all around on my 93 NX2000, I grabbed the best pair of front B13 housings I could find at the local parts yard and went to work. I believe they are KYB GR2s, though they have no markings, they are different than stock struts. Most notably the spring perch is welded nearly all the way around and the brake line bracket can be mounted on either side.

The first thing to do is drill a small hole in the bottom to release the gas and let drain what ever comes out. Drilling through a plastic cap will help to keep it from going everywhere when it sprays out. Once you have the hole you can pump the strut to get out as much oil as possible.

Next is to cut off the top of the strut. Koni's instructions tell you to measure from the top of their strut to the first set of nubs then subtract 7mm (or 6mm as they say in one of their videos) to see how much to cut off the housing. I used a bandsaw, it was by far the best at cutting and keeping a straight line compared to a reciprocating saw or a cut off wheel on a grinder.

I did not have my inserts in yet as I was prepping the struts while they got shipped. Instead, since I could not find any real measurements online I cut right under the welds, I would cut more off later when I got the inserts in. Another thing to note is you'll be adding an extra 1/2 inch to that measurement since these will be CSKs, you'll see why before the inserts gets put in. The overall length of my housings ended up being 10.5 inches.

You do not have to cut deep at all. While there is no harm in cutting deeper it is a waste of time and your blade, you also shouldn't cut all the way through as it may be harder to remove the guts. Once you are done cutting you can pull everything out of the housing, be prepared for more oil.

You'll want to use a light to check for anything inside, any bumps or uneven spots will need to be filed down. I did not have anything, luckily.

These next couple steps are going to be dependant on your setup, with stock style springs you can skip this. Since I am going to be using Ground Control coils I decided to cut down the stock perch just enough to hold the threaded collar, another option is to completely remove the perch and its welds so it is smooth then weld on your own.

Making a rough measurement around the housing for how much of the perch needs to be cut.

I removed most of it using the bandsaw then used a grinder with a sanding flap disk to get a more exact and smooth edge.

Once that was done I cleaned it up with a wire wheel.

Then paint.

The advantage of preparing these while you wait for the inserts to ship is some time for the paint to dry. I will say, even giving it about 5 days in a hot summer to dry I still had issues with pulling paint off the housings as I was a bit rough with them while putting the inserts in.

You'll need to enlarge that hole in the bottom of the strut for the insert. The measurement Koni gives you is just for the bolt, you'll want to use at least a 13/16 bit or hole saw. I went with a 1 inch hole saw as it is hard to get a dead center drill by hand. If you are not center you'll have to manage to enlarge the hole while your insert is in the housing! It is not easy, trust me!

Before putting the insert into the housing you'll want to cut off 1/2 inch off of the threaded nub. You can also test fit the insert, if there is too much resistance you can sand off a bit of the paint. It really doesn't take much sanding for it to slide in very easily so take your time, don't go overboard. Once you're an inch or two it gets easier.

I personally used a shop press as I had access to one. You do NOT want to be forcing these in, Koni says at most you can use a rubber hammer. The main reason I used a press was for once it got to the bumps on the insert, Koni's instructions tell you to use the screw to pull it in, I was not comfortable with that, more because I just removed 1/2 inch worth of it.

You may have noticed I've kept that little nub around, there is a good reason for that. You'll need to cut down the screw as it is now too long for what is left of the nub. I put mine on minus the lock washer to get a measurement of what needed to be removed. Thread the cut of bit of the numb onto the screw, measuring what is going to be removed. This will be both your guide to make cutting easier and to help protect and repair the threads.

The bandsaw is amazing.

Thread the numb on a little more to file down and clean up the last thread. If you do not round it off it becomes a hassle to thread into the bottom of the strut. When you remove the nub it will help make sure the threads are good.

Another step that are not required, but I live in the rust belt and I want to protect these the best I can. I added some RTV around any spots that can let water in. Koni's little rubber boot is pretty loose and I can't see it keeping everything out.

I am missing this picture. You'll next want to get that bolt torqued down to 55ft/lbs with a dab of threadlock per Koni instructions. Between their washer and the housing I also used a 5mm tall 1-1/4 headset spacer that you can buy at a bicycle shop as 98sr20ve does. While this isn't mandatory I can see why he does it, the Koni washer will start to bend as you torque down the bolt and with a bit of the Koni insert sticking out of the bottom you are going to want it to get tight enough before hitting the insert.

At this point you may have also noticed I did not do one thing everyone else seemed to have done and that is I did not bathe my inserts in JBWeld/Epoxy. This is Not needed and advised against by Koni, as long as the bolt does not come out and your insert went in past the bumps it is not going anywhere. On top of this a lot of places will refuse to rebuild your inserts if you epoxy them in place and you will not be able to remove them yourself without a lot of work, more work than it's worth if you ask me. As mine sit now it will be a PITA to remove when the time comes.

With that done, they are ready for the collars and to be mounted on the car.

There were a couple hiccups while putting these on my car. While a lot of the issue I came across were situational it is a good idea to keep these in mind and double check for them. I am putting them here as a central place for this information.

While swapping over my Ground Control/Eibach setup off my busted up KYB AGXs to the new Konis I had a few clearance issues.
The top spring seat would not fit over the lower portion of the piston shaft, this is most likely because it was designed to fit on the KYBs. I drilled mine out to 13/16ths, though it is a hair smaller than that I did not want it to be too tight.
The Ground Control Threaded Sleeve would not fit over the top of the Koni shock body. The ID of the sleeve is 52mm while the OD of the top of the Koni is 55mm. I personally used a grinder and very carefully cut it down and measured constantly with calipers.

The top of the Piston Rod Shaft on the Konis are not threaded completely down to the main part of the shaft. For the rear I used the stock suspension support to mount these to the car, this is barely thicker than a single washer and I needed to add spacers in to make up the difference. An easy way to see how much space you need to make up is to take the spring off the shock, place on the support and measure the distance to the threads.
It has been mentioned elsewhere that while used with the Ground Control plates on the front of our cars you'll need a specific spacer so it can bolt down properly and not have any play left. This is also because the ID of the Ground Control bearing is larger than the top of the piston rod shaft and is even the case with the KYBs I have on there now. Just make sure you have these parts before you attempt to install it or you'll be stuck at this point.

Koni recommends that you tighten the nut on the top of the Piston Rod Shaft to your vehicle specs, which on the Spec-V is 44-55ft/lbs, for the B13 it is 62-72ft/lbs. I'd personally go with the Spec-V numbers but I couldn't even use a torque wrench. In order to tighten down the rod bolt you need to use a 19mm box wrench on it with a 9mm wrench/socket on the top of the piston rod to keep it from moving. I attempted to use locking pliers on the piston rod wrapped with a rag then rubber but it would always start spinning before I got to the correct torque. Just be careful, you can crack the top of the piston rod off or pull the threads if you over torque it and you don't want to mark up the piston rod or else it could prematurely wear out the top seal.
Last edited by Char on 2015-07-20 at 05-05-25.
2015-07-14 12:41:31
Fantastic writeup! It's extremely easy to get a set fabbed up, so no one should have excuses to NOT go with csk Sutter this writeup
2015-07-14 15:12:49
@Char, long time no see!
Great write-up. I've added it to The Manifesto.

What have you been up to?
2015-07-14 17:05:55
Originally Posted by BenFenner
@Char, long time no see!
Great write-up. I've added it to The Manifesto.

What have you been up to?

Life, mostly, I've had little time and/or money to put into my car. Even this is just being done because it needs to be done sadly.

I updated the main post to have the overall length of the cut housing since I do not have the measurement of what needs to be cut off at the top. To be honest I think thats a better one to have anyway as the length of the insert isn't going to change but the length of the housing might. I'm not sure why I didn't just add that last night.
2015-07-14 17:16:38
woot, you didn't waste the housing or insert by using epozy!
2015-07-14 17:20:33
Can we get some common part numbers from KONI (all sorts of options, red, yellow, fancy 86xx series perhaps) to supplement this wonderful thread from @Char ? He beat me to it. I just started prepping my housings the other day!
2015-07-14 17:24:51
^^ need me to list them?
2015-07-14 17:35:53
Originally Posted by Kyle
Can we get some common part numbers from KONI (all sorts of options, red, yellow, fancy 86xx series perhaps) to supplement this wonderful thread from @Char ? He beat me to it. I just started prepping my housings the other day!

The only part numbers I have were for the inserts. I do apologize for not putting that in the original post and just referring to them as 'Spec-V inserts.'

2015-07-14 17:41:26
Originally Posted by Keo
^^ need me to list them?

If you want, I am sure many other will benefit from the repetition here. I have reds and yellows and they are "meh" to some. OEM plus likes meh.

I have B13 Reds and I believe B15 yellows in the set of assembled CSKs I just recently acquired from my buddy.
2015-07-19 17:40:05
I updated the original post to credit 98sr20ve.

A quick update myself. I got them on the car.

I got snagged on a couple things doing it though.

First off, the tophat for the eibach springs would not fit over the shaft of the Konis, the center bore was too small. Again, this is mostly my personal situation as these were on KYBs first, I had to drill it out to 13/16ths.

Second, the adjuster for the spring height is seized into place. This is a well known problem with Ground Control collars, the set screw gets seized and if you can't get it out you have to cut it off. As soon as I can order a pair from Ground Control I will be doing that as mine are currently too high and putting far too much pressure on the spring.

Third, the Ground Control collars do not fit over the top of the Konis. I mentioned this might be an issue before, it sure is, but I have a measurement this time. The ID of the collar is 52mm, the OD of the Konis are 55mm. Not much at all, a light touch with a grinder got it down to what I needed.

Fourth, I am having a hell of a time getting the top bolt on the strut torqued down to spec. The only way I see to tighten the bolt without the strut spinning is using a wrench on the end where the adjustment for the strut is but you obviously can't use a torque wrench of you do that and I don't feel comfortable torquing down on a hollow end like that. The only other option is to clamp down on the piston itself with something while you torque the nut down and we all know how bad of an idea that is.
Last edited by Char on 2015-07-19 at 17-45-39.
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