Very similar issue on mine when I put in the front Konis. I think I searched every thread on Rennlist with the terms "Shock" "spring" "ride height" etc. After a full weekend of reading I learned a lot.

First of all you have the grey boge which are gas pressuriized. They should be paired with the brown (looks dark yellow) dot springs. The Green dot springs are 10mm longer and were made for the Boge non-pressurized shock. I'm pretty sure Porsche would have given you the right springs, but wash them off and look for dots or blobs of paint on one end just to double check.

Second several guys on Rennlist cut either 1 or 1 1/2 coils to get the car to lower. Of course you don't get the full effect of lowering the amount you cut because the spring rate increases as you remove coils. And if you are running worn out original shocks the increased spring rate can give you a bouncy or harsh ride. Maybe - maybe not - just depends on how well your shocks are damping. Results reported on Rennlist were mixed. Some liked it, some felt it was too harsh.

My car had about a 3 inch gap when I replaced OEM pressureless BOGE with gas charged Konis. My sollution was to get a full set of Weltmeister springs which drop the car about 1.5 inches. Combined with the OEM threaded collar I was able to get the gap down to 1 inch and looks pretty good.

Keep in mind no one makes springs for our cars anymore so your only real options to lower the car beyond what you've done is a set of used (or new old stock) Weltmesiters or Eibachs, or to cut a coil off the spring, or to go with Carl's 928 Motorsports extended threaded adjusters which give you a larger range for lowering the spring. That was going to be my next choice if I had not been able to track down a set of Weltmeisters.

My personal preference was for Weltmeister because I like a linear spring rate and the rate of the Weltmeister (400/270 F/R) is the range of the initial zone of the Eibach and about 2X the stock spring rate.

If you go with aftermarket springs, definitely upgrade the shocks. I doubt orignal OEM shocks will adequately dampen the higher spring rates of the Weltmeister or Eibach.

FWIW I LOVE my car now. To me the stock springs and worn BOGE shocks just felt too cushy. Car suspensions have become increasingly firm over the past 30 years, I suppose as a result of better chassis desings. To me the Weltmeister / Koni combo feels like amuch more modern GT car - not as stiff as a Cayman S or new 911, more like an Audi S5 or BMW 3 Series with sports package - a little roll to it, but nice, firm, and pretty flat in the corners.

Lastly, if you do go with aftermarket springs (at least the Weltmeisters) you will need rear spring seats from a 78-83 car. They can be purchased frmo 928 INTL - I think they were about $20 each - two lower, two upper. Porsche changed the spring diameter in 1984 and the aftermarket springs seem to be sized for the early spring seat.

Good luck I know it was really frustrating looking at my 928 "off-road" edition while I was trying to sort out the best way to get the ride back down.

 

Can someone explain picture #2 where the adjustment collar threads are showing. It looks as if the lower perch is hung on the top of the threaded collar. I haven't done 928 shocks in a while, but I've done a number of them and my recollection is the lower perch should clear the collar and sit on the adjuster ring. Am I remembering this incorrectly? I don't trust me memory much anymore.

 

You're correct. In the second picture, the lower spring perch is separated from the adjusting collar and appears to be hung up on something. As the collar is lowered, the spring perch should follow it. And as Roger noticed, the adjusting collar looks like it is installed upside down. The larger diameter portion of the adjuster should fit underneath the spring perch, fully supporting it. As it is installed now it wont do that.

 

The adjuster ring is correctly oriented per diagrams and memory. If it were flipped, the wrench lugs used to turn it would be inaccessible. And it may well be the lower perch center opening fits the shock body rather than over the threaded collar. That's where I'm not too certain.

 

Adjusting collar is not upside down. (IE keeps freezing up when I try to load pictures for some reason, so attaching link).


https://rennlist.com/forums/attachments/928-forum/860291d1407619673-front-shocks-quick-question-402-06.gif

The inner circle of the spring seat (2) where it turns up is flush with the shock body (1) and will rest on the threaded sleeve (15), I'm 99% positive - just finished this job on my car. But there is not much surface area there and the seat is made to be supported by the 'upside down' adjusting collar (14) where the spring seat flattens out and is more reinforced.

I considered taking a dremel to enlarge the hole in the lower seat and allow it to ride down the sleeve to get thge suspension to drop further but in the end decided I didn't want to hack up pieces of the car and I wasn't sure just how many threads of the sleeve are needed to support the weight of the car so I really wanted a sollution that would allow the collar to be fully threaded.

 

the lower perch is made correctly,
it will neatly rest on the inner threaded collar,
The adjuster collar is also positioned correctly

NOTE the lower perch hitting the inner collar is a safety feature ,
as you wouldnt want the adjustment collar to be able to unthread ,
and then have the lower perch fall past the threaded ring, letting the spring fall.

To lower the car you should cut 1 coil off the spring

 

What Stan says makes sense, of course, but haven't we heard of instances where the adjuster ring AND lower perch have gone off the bottom of the threaded collar causing a minor disaster OR was that just someone SPECULATING it could happen if the adjuster ring came off the threaded collar?

Anyway, it looks like in the current instance the height adjustment has reached bottom, so it would appear the issue must be incorrect springs. All the cars I have seen could be screwed down to very low ride heights without issue.

 

Revisiting this thread. I just put in bigger wheels on my 1986.5 and it looks like a 4x4 in front. A quick chat with Roger revealed that I could just lower the front by wrenching the collar downwards. However, I ran into the same scenario. My collar is 5 turns from the bottom thread so I think it would be safe. However, the spring perch would not follow. What exactly is holding the perch? So what Stan said was the threads on the shock body has a larger diameter than the perch hole so it will not go past the threaded area. However, I have seen lower ride heights before and the owners told me that they had stock components.
Steve