GregBBRD

Would someone please buy these?

The new Bilsteins are worth $750....and then you can sell the springs to someone who likes kidney damage for $300, ending up with a set of Bilsteins for less than $500!

jcorenman

Just to add confusion to this thread (there is not nearly enough,yet):

Both our GT and our S4 have "identical" suspension setups: Billsteins and Eibachs. Yet they are entirely different. The GT was fitted with B&E's sometime prior to the PO (Louie), more than 9 years and 120K miles ago. But even when we bought car, it was firm but not damaging to car or personal body parts. I don't think it has changed much since-- it is a delight.

We liked it so much, in fact, that we bought a new set of B&E's from Mark a few years ago and swapped the S4. But it is not the same as the GT-- stiffer, harsher on rough roads, but of course terrific on smooth pavement. This is a bought-new 90K-mile car that is still factory tight, yet over crappy roads it feels like the teeth-chattering experience described above.

We're driven the S4 and GT on the same roads, same drivers, similar cars (except for horsepower), but with springs and shocks of different vintages . Something changed: either the miles have softened the GT's springs (and maybe shocks) or the manufacturing specs have have drifted.

I am guessing the springs are the difference, the next step is to swap the stock springs back into the S4 with the Billsteins and see what happens.

worf928

Very interested in this. I hope Mark will chime in...

I seem to recall, many many years ago, Kim Crumb telling me that the Eibach/Koni setup (that he claims to have developed) used Eibach springs for which Mark had an exclusive deal with Eibach.

So... if this is true, is it possible that there are (at least) two different Eibach springs that exist? One that matches nicely with Konis (Mark's) and one that works with Bilsteins???

Or are the assumptions behind that question just a myth and/or bad memory on my part?

Mrmerlin

FWIW the new shocks from Boge and Bilstien have smaller diameter piston rods compared to the originals

ROG100

Worst mod I ever did to my GTS - Bilstein and Eibachs - total loss of ride comfort for a marginal increase in handling. The ride has mellowed with age or my butt has got fatter (probably the latter).

ROG100

This used to happen to all springs so that they matched but that was when making springs was not an exacting science.
They can now make springs exactly the same as far as spring rate and Porsche stopped this practice of colour coding a long time ago.
Springs from Porsche have superseded to one part number for front and one part number for rear relative to year.
Certainly on the later cars the springs are still available as pairs for circa $400 the pair. Once they go out of stock I dread to think what a new pair/set will cost.

GregBBRD

I wish you'd explain this to the people who make Porsche's valve springs. These things vary so much, in terms of pressure and coil bind, that I have to sort them and return the ones that are too far "out of spec".

More likely, they just don't care anymore and just want to sell whatever they happen to have left over.

Keep in mind that main and rod bearing used to be available in three "subgroups" for the same basic size (red, yellow, blue markings with a difference of .0002", per shell, between the different colors.) Porsche thought this to be so important that every crankshaft journal was marked with the required bearing color and each journal of the crankshaft received the proper size bearings, which were also marked with the same colors. These color codes still exist, today, however now they toss two yellows or a red and a blue into a box and call that a pair.

dr bob

Guys,

There's no particular magic to having springs made new to match an existing spec. When the factory runs out of GT springs they can be made. Want twenty pairs of CS front springs? That's readily doable, but not particularly advisable; the CS was a couple hundred pounds lighter and responded to the stiffer springs more than a S4/GT/GTS would.

One thing that's been left out of the discussion is anti-roll bar stiffness, and it's invisible cousin chassis stiffness. New even casual performance cars these days are a LOT stiffer in both than the 928. Stiff chassis and anti-roll bars allow the load to be shared better between front or rear wheels. The cars "feel" like they handle better even though the actual net spring rates are lower. There's less body roll as the inside spring and damper help the outside support the chassis. This moves the traction discussion to modern sticky road tires that are beyond the dreams of the original 928 suspension designers. In the rear there's more than adequate space to put a stiffening channel between the swaybar mounts, allowing for a larger bar. Were I looking to modernize the ride and handling, an adjustable-stiffness rear bar would be almost immediate installed.

Ditto in the front, where some serious reinforcement is needed to the mounts and a cross-chassis stiffener is needed. I would be making the mounts with a horizontal base channel longitudinal under the frame, with multiple mounting positions available fore and aft. The bar would be a splined-end torsion-bar piece with a couple options for arm length, multiple positions for the links on the arms. Thus the front could be easily "dialed in" to balance with the less-readily adjusted rear bar.

With these changes, softer springs (like "stock") with velocity-sensitive damping would maintain decent ride quality while offering better wheel position control.

-----

Meanwhile, somebody needs to buy Mark's shock-and-spring setup if it hasn't already been sold. That is, after all, the original discussion at hand. I can probably take them if someone is interested in the set of Eibach springs currently mounted. Split the package cost?

Fishah

Didn't they sell on post #2?

Kevin in Atlanta

Yes they did.

928NOOBIE

I'm running BOGE/Eibach combo based on recommendation from Roger...indicating the Bilstein/Eibach combo could be stiffer than I'd like. The BOGE's have a good gentle rebound and to me are a good balance with the Eibachs....I could see easily how a stiffer shock could send the ride into the overly firm category...

BC

My other set of Bilsteins is at their rebuild location now. I received the email that they are next now. I can pay 380 for stock rebuild or just over 500 for a revalve. The tech asked about my needs and data on the car.

Someone mentioned a specially named set of parameters in this thread. How would I communicate that? What would it do?

The shocks are for an early car. Probably with eibachs.

Mark Anderson

Yes Kim did develop the springs with Eibach and the same springs were used with Koni and Bilstein. We sold 700 sets over the years but we stopped ordering them as the demand diminished and the minimum order increased from Eibach. I'm sure Eibach could reproduce a stock set as long as they got the minimum order.

dr bob

Mark --

When working with Eibach on an unrelated project, I casually asked them about what they offered for the 928. They said they had a package but it was exclusive/private label to Weltmeister. Is the package that you offered different from a Weltmeister spring package? Descriptions show the Weltmeisters as a progressive spring with several rates mentioned.

Mark Anderson

Back when Automotion was around and their brand Welsmiester,they had a 928 spring set but I think it was wound by Commercial Spring in LA. I thought they were 600lb front and 400 lb rear ( not progressive) but maybe there is a new Weltmeister spring set.
But I doubt it