rear coil-overs

[Simon]

Originally Posted by petevw

From what i know they are 944T AL arms with Bilstein/Eibach coilovers and Remmele Uniball springplates. I don't know the details of the springrates.

AFAIK they are GWD/Gerd Weiser rear coil-overs.
I was about to call him anyway, so I will ask him about the spacing of the springs in combination with the 944 arms.
They are 60mm ID springs (see below), which AFAIK should fit.
At least they do on 944's.

Originally Posted by petevw

What is the purpose of the dual spring setup? Pulling the bottom one out should get me to where i want.

I will ask Gerd Weiser about this too. I'd suggest to keep it.
The helper springs are there to keep some force on the main springs when the damper is fully extended. They also have some influence on the suspensions force-curve (only on the low forces, since they are rated lower than the main springs).

Originally Posted by petevw

Alex, do you know what it the thread on the inside on the arm? If its M14 x 1.25 or M14 x 1.75, that would explain the M14 x 1.5 bolt stripping it out.

They are M14 x 1,5 x 85mm.

Originally Posted by petevw

The springs are marked,

Top black,
Eibach 41/99
ERS 140-60-120

Bottom Red
Eibach 27/98
ERS 40-60-55

How do we know the springrates?

They are Eibach ERS springs.

For the main springs (the black ones):
- the 1st number is the free/extended length
- the 2nd number is the ID (Inside Diameter)
- the 3rd number is the springrate

Since these springs are "European" type springs (i.e. with a 60mm ID), the values in their names are in European/SI units.
So the free length as well as the Inside Diameter are in mm and the spring rate is in N/mm.

This means the main spring you have is a 140mm long, 60mm ID, 120 N/mm (685 lbs/inch) spring.
It's spring travel is 71mm and it's compressed/coil-bind length is 69mm.

The tender springs (as they are called) numbering works almost the same, except that the first number represents the spring travel instead of the free/extend length of the spring.
So:
- the 1st number is the spring travel
- the 2nd number is the ID (Inside Diameter)
- the 3rd number is the springrate
So the tender spring is a 40mm free travel, 60mm ID, 55 N/mm (314 lbs/inch) spring.
It's a linear spring which free/extended length is 68mm and it's compressed/coil-bind length is 24mm.



For more specs/the search engine, see:
http://eibach.com and go Eibach ERS springs in the top menu.
or their motorsport catalog:
http://eibach.com/eibach/img/ers-catalog-2004.pdf

Originally Posted by Bug@5speed(US)

Here is a better pic of that rear lower adapter for 1/2 coilovers..

I will check my manual as I don't remember the size..
A

Alex, I can't see any pictures?
If you have some, could you post them?
I am interested in those bolts as well (they should be 2 part bolts AFAIK).

[petevw]

Thanks for the info. Please let me know what GWD says.

I'll retap the sleeves, and hopefully it turns out well.

Alex, i can't see the picture either. Can you repost?

[wrenchnride247]

Pete, If you can't get a good thread in the there, you can use a helicoil, or a E-Z LOC insert. They have them for all different sizes.

[Simon]

Pete, I haven't been able to reach him yet, but I will try again on monday.
Btw. Are you using an IRS pan? Or were the mounts for the trailing arms welded on?
Could you measure the extended length of the shocks (middle eye to eye)? I am looking for some double adjustable dampers that might fit.


I have been looking around for 944 coil-over options though, and most of them seem to use 2,25" = 57,15mm ID springs.
They are a little smaller than the 60mm Eibach ERS springs, it might be that those 1,5mm make (part of) the difference we need.

Attached is a picture from the Bilstein Cup coilover on a 944, using 2,25" ID springs. It doesn't interfere with the trailing arms and it's mounting eye is right against the trailing arm (ie not using something like the racers edge bolts to space the away from the trailing arms).
What is visible though, is that the bottom mounting eye is offset from the center of the shock.
What can be seen as well is that it's actually quiet a tight fit, with little clearance between the bottom spring perch and the trailing arm.
I would guess a 60mm ID spring might not fit in this case.

The 2nd attachment is a picture from a Koni 3012 damper + 2,25" ID springs.
It's mounting eye is in line with the centerline of the damper and it uses a spacer (racers edge one) to keep it from interfering with the trailing arms (+it acts as an adapter for 14mm->1/2")
It seems there is more space available with this setup, so a 60mm ID spring might work with this.

All in all it seems a small spacer might fix the problem.

[Simon]

Result from the conversation with GWD:
They have no experience with 944 trailing arms, so he doesn't know if it should fit or not.

He did offer me te send me a pair so I can test it myself.
That's customer-service!


Anyway:
I did some more digging and there is a rss club suspension from KW for the 944 (front and rear) which uses 60mm springs on both the front and the rear.
As far as I have been able to track it down it doesn't use any kind of spacer and the mounting eyes are in line with the centerline for the damper.

Like I said above: Try the Racers edge bolts (if the mounting eye fits) and don't forget to space the uppermount a little inwards too.