How To: Coilovers and strut tube modification (with pictures!)

[Moto-Mucci]

That doesn't mean you should use HD's...

[E30SPDFRK]

I would strongly advise not cutting 3" off your housings...
You should read this whole thread first.

If you're using IX HD's, cut 2" off. The HD's have large bumpstops and the piston doesn't go all the way into the housing. Koni's may be different, I don't have experience with them.

If you run Bilstien HD shocks like that you will blow them out instantly, they won't make it 5 miles.

False. I used mine for 12,000 miles before I got them revalved and they were still good.

[Moto-Mucci]

The GC kit also comes with a weld on perch.

[downernsp]

That is all on your choice of hardware. I used a round bar stock with the ID to be the same as the OD of strut housing. One thing I would say is this please please make sure whatever you do use to be the same thickness on the thread on sleeve that way you can a sure the sleeve will sit properly.

[T La]

question, what have people been using as the perch for the adjuster, it looks like some people are using a section of piping, while others are just sectioning out the housing from below the stock perch and just re-using a ground down stock perch. Is this correct?

[Moto-Mucci]

You don't need to remove any more then 1.5"
1.5" chopped off with the GC kit and you'll have your skid plate a hair off the ground, if at all.

Here's a good comparison - Mine housings (red car) were chopped 1.5" with the GC kit. Shown, they had about another 1.25" of thread left. It was a fully functional drop with room to really hammer it to the ground if you don't like functionality.

Patrick's car (white) was aired out in this photo, resting on the S50 skid plate. I believe the S50 hangs a bit lower then the M20, however you at least get a comparison of what kind of clearance you have. Keep in mind the M20 oil pan hangs lower then the "I" valence.

[David325is]

The short body Koni shock is 4" shorter than a stock shock or Bilstein. Thus a 4" spacer is needed. It is installed at the bottom of the strut tube housing. Modify the housing and this spacer to go lower.

If you remove a 1" from the housing, you remove a 1" from the spacer.
If you remove 2" from the housing, you remove 2" from the spacer. ETC

Remove more material to go lower, but I would not remove more than 2.25".

[AsharC]

Im confused.

When he was talking about the shock how its 4" long and he cut 1". Why does he need a spacer? I am not understanding it.

[penneroyal]

I see the OP had 3" from perch to the top of the strut tube. Is that what everybody is setting the perch at? Any suggestions? I have the GC kit, 6" 600# springs FYI.

Also, When you guys are cutting your housings, are you removing the 1" section above or below the stock mounted spring perch?

Help much appreciated! working on my housings as i write this!

[wille28]

i have a coilover sleeve ans short spring btw

[wille28]

why? what i have to do?

[CorvallisBMW]

my ix are 3 inch shorter than the oem one and i have the hd i will cut my housing this week and give you feedback i will run no spacer

If you run Bilstien HD shocks like that you will blow them out instantly, they won't make it 5 miles.

[Moto-Mucci]

my ix are 3 inch shorter than the oem one and i have the hd i will cut my housing this week and give you feedback i will run no spacer

I would strongly advise not cutting 3" off your housings...
You should read this whole thread first.

[wille28]

my ix are 3 inch shorter than the oem one and i have the hd i will cut my housing this week and give you feedback i will run no spacer

[!kid]

What I read somewhere is that it increases surface area contact with the outer tube allowing the shock to use the outer tube as a heat sink. By all means it makes sense as a shock absorber converts motion energy into heat energy by means of liquid/gas/mechanical friction. But do they really get that hot?

i was reading through one of my ASE books. adding oil (preferable red ATF) to our style of front strut housing/ shocks is highly suggested because of heat. the amount of oil need is enough to reach the top after the shock is inserted into the strut housing. if oil is not added the life of the shock is can be shortened.