Thread: B13 CSK Research Thread - OE diameter springs

It will only turn so far in each direction. So there is a full soft and full hard. If you go even 1 turn up it will be too much rebound and the car will feel wierd over dips.

that's good to know man.

also, when you turn the shaft by hand is that movement adjusting anything? or is the shaft free to move around?

I haven't tried to install CSK's with standard springs, but the 2 things I could think of would be the height of the collar on the housing (if too high or low) or the tophat attachments.

I have measured the B13 front & rear inserts, and I have that posted a few places along with the Koni's that I used. I would compare a front & rear housing side by side, and verify the heights of the collars in relation to the "mounting ears" on the housing.

Also, I had to space my Koni's UP in the rear using front housings - unless the B15 is taller (doubtful), I would be really checking that out. I suspect that was the issue with the "OEM" branded ones that the guy had issues with a couple weeks back - not enough thought/measurement before they were installed. Remember, the rear housing is taller for a reason....you can't assume the rear install is exactly the same as the front and have it be correct.



The shaft is generally free. Reds have to be fully compressed and then rotated to adjust, and the Yellows should only adjust with the little key thing.

I did the measuring for you guys. The short version is that the collar is 1.75" shorter on the front than the rear - so you would be lowering the car 1.75" by just switching housings and not changing the springs.

If you want to use B15's, I think you need to use B13 rear housings for your install. But you will need to measure the heights, so you do not compress the insert too much. Once again, I suspect you will need to space the insert UP inside the housing (I used a bunch of washers that were small enough to fit inside the housing and you will probably need a longer bolt than the one supplied.

I don't know if the numbers are clean on this copy, but it is hosted on the old forum. You will see the measurements of several items including F&R B13 struts (it should be click-able for a larger size):

Whichever housings you use in the back you need to have the spring perch the same distance from the lower mounting bolts since you have no adjustment in your setup. With coilovers this is not an issue since you can just move the spring seat up with the adjustments.

The other issue is if you put the insert too low you will overly limit rebound travel and may eliminate it completely. Your best bet is to space the insert up in a REAR housing so that is same length, to the top of the insert not the top of the shaft, as original. You will still loose droop since the B15 front has less than a real rear insert but that shouldn't be an issue.

If a strut is too short the spring will stack solid before your bump stops touch which is a bad thing.

You said you had konis in the rear already, why not just send them out to be repaired, at the same time they can make them externally adjustable if you want. I was quoted a price of about $100 plus parts by koni for the rebuild. They may even be under warranty.

Problem is, he wasn't able to put the inserts in the rear housings at all.

Something about a thicker wall at the top of the strut. Maybe that part can be removed entirely?

Ah now I get why the coilovers work..

Sending Koni my blown rear struts is something I could do -after- I get something else in my car, this is my only car and daily driver... I can't have any downtime. heck if they can turn a red koni into an externally adjustable strut, that may be the best solution... Perhaps I can call them and see if they can custom build 2 of them?? I don't think they realize there is a market for them...

The b15 insert won't fit into the rear housing as M0J0 pointed out...

Since you already cut the rear strut housing, can't you try cutting it some more, past the narrow part? Since you need to space it UP anyways, you might as well try.

I guess I could...

Oh about cutting housing with a pipe cutter, the sawzaw was much easier IMO... bit then I'm good with a sawzaw and not so good with a pipe cutter, but I shortened one of my front housings a little more with a newly bought pipe cutter... PITA...

i wish i could read those measurements on the picture..