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960 IRS II Rear Coilovers Part 1: Boy, I sure hope this works

the poi

Has been
Joined
Jan 5, 2003
Location
Pasadena, CA
Step one: Buy two QA1 Proma Stars. One DR5855B, and one DR5855BP. They're 5" stroke, single adjustable. It may be possible to fit a longer shock--I can't get a perfect measurement, but compressed height is somewhere around 12", so I went shorter to be on the safe side. Get some CO springs. The narrower the better, the only sketchy thing about all this is the spring clearance.

Step two: Buy 0.006 thick (or whatever) brass shim stock. Buy two 80mm M12x1.75 bolts (8.8 at least, obviously). Buy two nice thick fender washers that either come with a ~11.8mm hole in the middle, or one small enough you can drill out to that size. And that's it!

You're buying one poly version and one bearing version because you're gonna have to do some swapping. Swap around the bushings until you have bearings at the top, and bushings on the bottom. At this point, it should like kinda like this:

84308504.jpg


At this point, you may be wondering why the top looks so hot hot hot. Well I'll tell you.

Your poly-bushing shock came with some steel bushings. Cut the 1/2" hole ones in half. Sand/grind/use magic, to shorten them as needed.

Shim stock time. Cut a strip about 54.8mm wide, and "long enough". About 3" is what you need if you're using 0.006 shim stock. Roll it up around a 1/4" extension. Then, slide it into the upper bearing mount. If you haven't figured it out by now, we're killing two birds with one stone: bushing 1/2" hole out to the M12 mounting bolt, as well as making a continuous cylinder that we can fit our spacers on.

So now, slide your spacers onto the shim stock. Grind/sand/conjure demons until the total length of your fancy looking upper mount is "big enough". 54.8m worked for me pretty well. Now, it'll look like this:

84308502.jpg


84308500.jpg


Yay!

This is pretty much all you would have to do, if you had 2"OD springs. But since we're rolling on 3.5" springs, pull out some vice grips, and angle grinder, and The Convincer brand BFH.

Drop the subframe (it's 4 bolts, quit whining). Remove the front subframe perch things. They look like this, before going nuts with the angle grinder:

84308513.jpg


You want it to look like this:

84308515.jpg


And work on the inner lip of the spring perch to get more clearance. You could probably lop the entire spring perch off, but it makes it a little stronger connecting to those two rear bolts. And anyway, it's now completely out of the way. The other problem is the car.

Which I forgot to take pictures of. Oops! Anyway, flare the unibody pinch out a bit in the area of the shock well (this will make sense when looking at it). Then, hammer the living **** out of the "lip" in the shock well thats closest to the outside of the car. Again, this makes sense looking at it. We're making spring clearance on the outside side.

Now, go nuts. Oo, forgot a step. At some point, remove the swaybar. Impossible to load the shocks otherwise. So ya, shove em up there, bolt in the top. Put a jack under the control arm, and jack it up until you can slide the shock onto the lower mount. Slide in the 80mm bolt you got with the fender washer, and crank it down. The cranking makes the 3/4" hole a snug fit on the 18mm stub. I have no idea if this is either wise or safe. Looks like this though:

84308506.jpg


When you're done, it all looks like this:

84308518.jpg


Badical!


On 80lb 12in springs, "snugged" at free length (about an inch above the the end of the threads), ride height is:

84308520.jpg


Bout an inch and a half clearance from bump stops :-)lol:). So I'll crank it up an inch and let you guys know if any of this worked.
 
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Nice! Though why such insanely soft springs? Looking at it, because the shock is forward of the axle shaft (which is approximately the center line of the wheel), the wheel rate of those springs is probably like 60lbs. Though I'll laugh if stock is softer.
Looks like a decent compromise of travel while keeping the nice flat wagon floor, which looks to be the whole point of the MK2 IRS.

Edit: Why is everything so crusty? My cali 81 240 is just greasy, but not rusty at all.
 
80#? Jesus that's soft.

Should plant the rears pretty well though!

OHHHHH. I kinda forgot about that slightly important detail.

This may "only work" on Nivo cars! The composite leaf is still in place, with it's nebulus spring rate (which I could, for the life of me, not determine). The 80lb spring is in addition to the normal spring.

For non nivo cars, the spring will maintain the stock ride height. Increasing the spring rate would reqire raising the car with the CO springs enough so the spring rate doesn't suddenly change on droop.

I don't think it'd be wise to remove the stock leaf ever--the "front springs" are mounted inside the lever arm, and only in single shear on the bottom, and a sheet-metal "cup" at the top. I'm pretty sure a high rate spring and no leaf would annihilate something.


In any event.

Highly ****ing mother**** the car doesn't handle like a tugboat any more sweet jesus christ.



edit:// The crust: the back end of this car was under-water at some point in it's life. The CD changer in the back "pocket" had mud in it. The interior is fine, so I think they drove through 18" or so of water or something.
 
+1, this is TB

are you sure the lower shock bolt is strong enough? its only at single shear load, not ideal.

Well, it is only holding a little bit of weight. And I didn't picture it very well--the lower mount is an 18mm OD protrusion out of the arm (which in turn, is a fully welded cylinder). The bolt just holds the shock onto the protrusion. It's as strong as you're going to get in single shear. It's probably just as strong as the 12mm double shear in sheetmetal up top.

Shocks and springs were $430. Coulda saved about $60 if I went with heavier springs.

In any case, made it to LA without flinging it off a cliff, and it's fantastic. I really need to do the front now so i can start tuning it.
 
Finally took pictures of the "lip" inside. You can theoretically hammer them flat, but my 170lb springs (upgrading from the 80s...) are a little close, so I just buzzed the lip off completely with my angle grinder.

85074901.jpg


85074902.jpg


Everything looks good after about... 1000 miles on em?
 
hows it handle? and ride?

poor on both accounts:-D the fronts are not stiff enough and the struts are just not valved for the cut springs I have in there. It was an enormous improvement over the blown Nivos that I had before. I'll have Koni sports to install in the front this weekend, as well as coleman sleeves and 450s. That up front and the 170s in the back should get me off to a good start in the handling department...
 
Are the rear shocks capable of handling such low spring rates well? I guess 170s aren't nearly as bad as 80lb'ers, but still.

And still, SWEET!

Chris, you're awesome, which in turn has made your 960 awesome. Better than awesome. Have you already been on the main front page as an article? If not, it won't be too much longer before you are... And damn well deserving, as well. :nod: :cheers:
 
So the total price for the rear was in the 500 dallar range?

Love how it looks, The bottom shock mount looks like it could use to be boxed in. Hopefully one day, I can get done with this drafting degree and get some flow to build some bad ass stuff like you build.

Keep it up.

~Kyle
 
I don't know how I missed this thread before. The rear looks positively ORGASMIC. Hopefully the koni's up front do some good.
 
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