I spoke to Ramone at Bilstein in CA tonight, and asked him if he can take note of the valving specs that I have (and a couple others up here) so that anybody can just ask for the same spec re-valve. This will take some of the uncertainty out of doing new valving to match the 600/400 Hypercoil spring set.
The shocks will have 40% more low speed compression dampening and 60% more rebound dampening than the standard Bilsteins. I feel that this is a good set up for the 600/400 hypercoils, and over all it's about as stiff as most would want to go on the street. It corners flat, doesn't dive on the brakes and feels great.
If the Bilstein/Eibach combo feels too bouncy and has too much body roll and movement, this is the next step. Also, if you have done a wheel/tire upgrade and have a lot more grip, you will notice the suspension will now feel too soft and unstable with more G loading at the limits.

When sending your $hit to Bilstein, ask for "Carl Leguia" valving and you will get the same good stuff that a few of us up here in New England have. He has the info in a file now. It has been "Blue Ridge" tested and approved.

 

Any of you with the normal Bilstein/Eibach combo should take a ride in a 996 or 997 GT3 and then see how bouncy, mushy and unpredictable (and still harsh) your 928 feels. I wanted my 928 to feel like the GT3...
At least there is another suspension option now.
1. stock with working Boge shocks
2. bilstein shocks with stock springs etc.
3. Bilstein Eibach combo
4. 600/400 with revalved Bilsteins
5. anything stiffer should be on the track only...

It would be nice to have something like PSS9's, but we don't and they would be more $$$$

Sorry that I don't mention Koni's (and adjustable Koni's), I just have no first hand experience dealing with them so I can't say anything good or bad.

 

good idea. stock cars and race cars can benifit from this cheap way of upgrading the performance of the suspension system.
by the way, scot grahams car is real nice and its a race car. it uses the bilstien set up and cut eibach springs. It handles as god, if not better than mine. I think its a little loose on the rebound side , but really quite an up grade. spring rates cut, I would guess are right around the 600 to 400 rear range.

 

I feel a suspension kit coming on 8>)

 

It's all you Rog........ Thanks!

 

Sounds good to me Roger. Can someone offer more descriptions of before and after examples after this upgrade? Not sure I am reading things right here....

 

I had the Eibach/Koni set up on the 89GT and I loved it. For normal street driving I set the Koni's to full soft. Still good control, just not harsh. Moved up to the GTS with Eibach/Bilstein's. At normal street driving it tends to be harsh, feeling every expansion joint and minor bump in the road. For aggressive driving (read "Blue Ridge" tested and approved") both setups are about equal. Sooooo, there really is an additional option.

 

I have koni internally adjustables with 800front 300 rear springs... there is not enough rebound damping at all.....after driving a "spec" miata with stock bilsteins (far better suspension control than the widow) and an ITA spec miata with JRZ double adjustable shocks....I quickly learned that my konis need serious adjustment....the JRZ adjustable suspended miata was just STUCK to the track....nothing upset it....even going airborne from a poor line choice was no big deal...catch air, land-compress-recover and keep going....everything felt perfectly controlled...no overly bouncy "float" that the widow does now.....

 

The problem with a suspension kit is there are so many variables in the various models and years of the 928. What sway bars and how stiff do you have them set at, what size tires and what pressures are you running? What alignment specs are you using? Wheel offset? The weight of the car, the weight of the wheels, dedicated track car or street only, or some combination of both?

 

I am right by Bilstein and have a rebuild-able set laying around I was going to do this with. I wanted to make a Koni-hypercoil-like kit with the bilsteins and some good copies of the machined hats and spring seats, etc. I have the Koni-Hypercoils on the car now, and will drive with them to see how they go.

 

I personally WOULD LOVE to see a Hypercoil setup for the bilsteins. I like the narrower spring of the hypercoils and i believe you can save at least 10lbs of unsprung weight or more by ditching the factory springs, so you save weight and get more potential performance.

I know Carl threw something together, but i honestly found it a bit crude as there was what looked like 40mm spacer ring thrown in there to make up the spring height difference. I think thats unacceptable and would just prefer a longer spring with the same number of coils. But i dont design these things so i dont know what limitations there are. I just figured there was a better way of making this change. Roger i would be very interested to know what youve got planned! I LOVE THE BILSTEINS

Oh and to the OP, Any comments on your overall dealings with having the work done? Specifically cost, turn around time? Any comments on that, Ive always heard of this service but cant think of anyone ive spoken to thats actually done it.

 

Personally I got rid of my Bilsteins as I thought they were too harsh. Mine were in a S2 and had stock springs. I then fitted Ledas with 600/400 springs and the ride was slightly improved when the shocks were set to soft. The ride seems very "jiggly" with mono tube shocks. The ride is firm with the ledas but that is more spring rate thing than a shock issue.

I think it might have something to do with the "crack pressure" that the Bilsteins have before the shaft moves. This means that small irregularities in the road are directly transferred to the car and driver.

Greg

 

Greg,

You are correct about the bilsteins in that regard.

But the Konis are horrible IMHO they are way to soft with not enough dampening. Esp once you start upping the spring rates!

 

You mean like this?.....750/500 hypercoils..existing bilsteins and some misc hardware....(reusing S4 adj collars)...about $220 out of pocket. Still need to send the shocks off for revalving to better work with the hypercoils, but it's not bad for the couple of times I've had it on the track..

 

Just some other info:
I have a long background racing motocross, where suspension became very advanced and you had to really know how to adjust your stuff to have a good handling bike. I do not have an extensive background in cars and automotive suspension, but I do know when things are working well and when they aren't.
It is difficult to test anything on the street because you need to push the car hard and at that point you are double the speed limit anyways. If you cruise around near the posted speed limit (as my father does) you will have no idea if your suspension works well or not. I really don't have too many good areas to test suspension here in MA, though the roads are pretty rough and hilly and twisty.
Every year when we do the Blue Ridge Parkway en route to SITM, I actually can see how the car is doing because that road combines speed with turns and dips and some bumps that try to unsettle the car. It is a pretty smooth road of course, but when you are pushing the car through a turn and have a bump it gives me valuable feedback on how good my set-up is by how the car responds and stays stable.

I really don't believe in stiffer sway bars and drop links, I think they are kind of a band-aid for soft springs.

I have stock sway bars, the 600/400 hypercoils with revalved Bilsteins, and 265/35/18 tires all around. I run about 1/2 max camber with minimum caster in the front with a small amount of toe-in. I also have the 33 bar brake bias valve which lessens the front dive under braking a little.
I have experimented with the front camber and have noticed how at full camber the front grip is increased, but feel there's enough grip with half.

Is the 600/400 harsh? It depends what you think a sports car should feel like and how you use the car. I think it's firm, and you have to avoid the pot holes if you can. There is minimal body roll and dive under braking, and it responds quickly to input.
I know the progressive Eibach springs start at 399 lbs and end at 560 lbs in the front, so they allow the car to start moving and wallowing before the stiffer spring rate is called on. The 600 lb straight rate Hypercoil front spring really (I think) lessen wallow because it doesn't allow the initial body movement because it is stiff all the time. Anyways, if the progressive Eibachs end at 560 lbs then 600 is not too crazy.

The revalve is $65 per shock, and the turn-around will vary up to 3 weeks. You get new oil and seals like a rebuild at the same time, so I think it's a bargain.

I look forward to Roger setting up a ready kit so that someone can just make one phone call like when buying the Bilstein/Eibach from our vendors. It is a bit of a pain in the *** getting this stuff done yourself.

That's all...