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Old 03-09-2012, 01:51 PM   #4
Scooby Specialist
Member#: 91212
Join Date: Jul 2005
Chapter/Region: MAIC
Location: Martinsburg, WV
2011 WRX 5DR
Satin White Pearl


Prepping the rear top mounts:

The top of the strut piston has a threaded section that is larger in diameter than the OEM strut.

This requires that you drill it out. Konis says somewhere around 12mm in the directions. Most drill bit sets sold in the US don't measure in millimeters. Thus, let's do math. Or, let's use a drill bit gauge and determine the size of the threaded portion.


What, your DeWalt drill bit set from Lowes does not have every drill bit from 1/64" to 1 1/2" in increments of 1/64"?

Seriously, a 1/2" bit will do, but I like to drill as close to the needed size as possible (see my 1/2" hole in the bottom of the strut body as an example) and I happen to have a 15/32" drill bit. My grandfather was a tradesman at a manufacturing plant and had cigar boxes full of drill bits in every reasonable size. He passed them on to me before he died and I am yet to need a drill bit in a size that he did not have.

Drilling out the top mount was a simple process.

I trimmed the bumpstops that I had to shorten the set that I wanted to use. I still don't know which ones were the OEM rear bumpstops, but I cut the longer of the 2 sets to match the length of the shorter pair. The ones that I cut seem to match up best with the front bumpstops.

From there, I positioned the spring seat on the circlip and held the piston in the extended position to allow me to force the bumpstop over the tophat "ledge" at the top of the piston. NOTE: The lower spring seat is updies down in the picture! Koni directions depict the spring seat in an upside-down position. DO NOT POINT THE SPRING SEAT IN AN UPWARDS ORIENTATION DURING ASSEMBLY!!!

You want to ensure that the bottom pf the spring seat has a notch for the circlip. It looks like this:

After that, I installed the dust boot at the top of the piston. I found that it was actually easier to:

1. Install the bumpstop on the piston, then
2. Place the dust boot inside of the compressed spring.

(If the piston is not fully extended it is VERY difficult to get the top nut started. )

3. Put the nut on the piston and pull out to extend it all of the way
4. Remove the nut
5. Place the compressed spring (with the dustboot inside) over the extended piston,
6. Secure the top nut
7. De-compress the spring

After compressing the spring I seated it on the bottom seat and installed the top assembly. Be sure to keep the rubber upper isolator in the proper position. I did not (I let it slip off to the side) and had to re-compress the springs to straighten it out.

Note: There IS a proper up/down orientation to the springs. Only one end of the spring will match up with the upper and lower spring perch and the tophat. Check this before installing.

To secure the tophat we come back to the go-thru sockets. I used a 19mm go-thru socket and a 9mm 1/4" socket through the middle to hold the Koni piston in place.

Once that is tight, you can uncompress the spring. Work carefully from side to side to avoid shifting the spring and/or the rubber isloator at the top.


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Last edited by phenryiv1; 03-20-2012 at 02:35 PM.
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