So my car now has a Strange S60 rear and that comes with some trade offs that are not advertised. Due to the fact the axle tubes are larger, the spring perches relative to the axle center line are higher. Thus that even with 15 year old Pro Kit Eibach springs (1" drop) you get this



the springs are seated correctly with the stock third gen isolators in place. The rear is about 1.75" higher then the front. I want to level the car back out. I know some would say there is still a bit of gap on the front, the reason I can't go any lower is this:



Unless I go to shorties that's the best I can do. I looked around and Ground Control weight jacks looked like the ticket to dial this in so I ordered the kit. I wasn't even going to use the front ones but they only sell them as a set so I bought the whole kit. Here is where it goes wrong. Factory GM spring perches use ~ a 2" hole size and the adjusters are designed for this:



Unfortunately I tried to install them and found out that Strange used a heavier wall on their mount. Strange said early on they used the GM mounts, but they wanted to beef up the perches so they started making their own a few years ago. The ID in the perch is about 1.82" with the powder coating on it (guessing the hole is 1.875" ID before paint).

Now obviously I don't want to try and drill out my nice powder coated rear to make it 2". My options seem to fall to the following:

1) cut out the welds that hold the tubes in the adjuster and weld in pipes that with fit (least fav choice)

2) find/fab some other adjuster that sits over the perch and go to a straight (non pigtail) 5" spring

3) ditch the adjuster idea all together since I plan on just setting and forgetting this and just find a pigtail spring

4) switch to one of the coil over rear setups (don't really want to give up Koni adjustables though)


Option 3 is the one I really want to go with but I am totally confused on options. The Ground control springs comes from these guys and thay said they are the 9" spring 175lbs

http://www.bluecoilspring.com/pig.htm

Now when I measure them I get this:



Ground Control says this is good for a 0-3" drop and if I add the bottomed out adjuster in I get this dimension



So if anyone has any ideas on how to achieve my 1.75" (additional) drop I would love to pick your brains. assuming the eibach is still holding an as advertised drop I need a 2.75" drop from stock. I am not sure what length of spring to buy. Maybe 4th gen isolator with the as is spring from Ground Control? Anybody with the S60 rear chime in and tell/show me what you you got going on?

 

Do you want to end up with the same spring rate you have now, or do you care about those things?

If you know the Eibach spring rate, and can also measure the compressed length installed in the car, and you measure the free length when removed from the car, then you can get a reasonable calculation of the weight on the rear springs. Then it is just a matter of ordering springs to get the ride height you want.

 

Cut the cup off the adjuster on the GC unit, all but 1/4". Cut off all but 1/4 of cup on the rear, or completely if needed. Open up the hole on the rear with diamond bit on the strange unit. Clearance enough til they will fit into each other, and throw a quick tack on there if you need too. I had to do this with my Moser. You can do this stuff with grandpas hack saw and rat tail file, or break out the air tools

 

Could you remove the isolator and put a piece of heater hose on the top of the spring?

thats all I did for my S-60 swap.

 

http://www.wolferacecraft.com/detail.aspx?ID=820

 

and in doing that your car went back to the "pre-S60" height? How thick was your isolator?

 

The insulator is about an inch thick above the spring. I called it close enough to good to not worry about it.

I have the same 'clearance' problem that you do..... damn passenger side header/collector.