Ispeed

I don't want to say that my set up is the only way to fly in a 928. It's a bit extreme, and only makes sense when you are pushing the car and not on rough roads.
Here are my thoughts on combinations of springs/shocks (and I don't have any Koni experience):

stock springs/good Boge shocks: soft ride, easy on bad pavement. puts your underside at risk for bottoming and doing damage to the alternator and oil pan.

stock springs with bilsteins: a good mildly sporty compromise between bump absorbtion and control. Many people would like this, but still a lot of body roll and dive on braking. If you drive fast, it will feel soft.

eibach/bilstein combo: less body roll and dive than with stock springs, but this combo is under damped and when pushed or on bumps gives a pogo bouncy feeling. The Bilsteins are not valved to handle stiffer than stock springs.

600/400 hypercoils/ revalved Bilsteins: bad on holes and expansion joints, but minimal body roll and brake dive. Very sport oriented, but not plush. The eibach progressive springs have similar rates, but the initial softer rate allows body movement and roll before the stiffer rate comes in. The straight rate hypercoils dont have the initial softness and don't let body roll start when turning and the car feels very flat.

my long $.02

FLYVMO

Carl,

When you had your Bilstein shocks rev-valved, did you need to provide a vehicle weight, or do they just use "standard" curb-weight for your model year? I am getting Hypercoils for my Bilsteins but will go with 350-400 up front and 225-250 rear. I tried the 600/400 Hypercoils with Koni's (Devek kit) but my kidneys did not like it too much. Car was very flat though. Then went with the Bilstein/Eibach combination, but did not like the unsettled feel of the Eibach springs.

How long did it take for the re-valve?

Cheers!
Carl
1986.5 928S 5-speed

AO

Just another data point here.

I have the Bilstein/Eibach setup but with the addition of DR swabays.

One of my boys just put the B/E on his car but we haven't done the swaybars yet (due to a blown HG).

His car felt much boucier in the turns and less flat. When I was at SITM this past summer, Tim Murphy was behind me for a good portion of our spirited drive through the mountains and he said my was looked dead flat in the turns. It felt that way too.

So, I guess my point is that the swaybars have a huge affect on the overall suspension performance. Just something to consider.

tv

This whole thread should have been continued on ptuomovs thread, we always have 20 threads about the same topic.

I think 928's handle exceptionally well and comfortably with the only thing lacking - a modern shock.


When will a vendor(s) get together and approach koni or the other company that makes these new tech shocks and get us one.

RyanPerrella

a revalved bilstein is as top of the line as you can get short of $4,000e shocks (which you can get from any of the top shock manufacturers.

The Koni adjustable FSD is just marketing, its nothing special and its not at all comparable to the mag shocks or Porsche's PASM both of which require mega electronics.

Bilsteins are a steal, they are a quality product and rebuildable (with custom valving) for a nominal fee.

Jim M.

That's your opinion Ryan, not all agree, me included. I had Koni Eibach on the 89GT and loved them. Adjusted full soft for street driving they were great, stiffen them up for spirited drives and they were also great. Today I have the Bilstein Eibach set up on the GTS and find they are harsh for street driving but great for spirited driving. And Koni's can also be revalved for a mominal fee.

I still think a cockpit adjustable shock would be an improvement over what we have available today.

mark kibort

you need a set of springs and shocks, thats it!
the bmw is pretty nice, as I have an e46, but the componets are cheap and flimsy. you want to race one, all of that stuff goes in the trash, it has to! with the 928, you just use the old stuff and just bolt on new springs and shocks to suit your use. short wheel base? you are kidding right? 100" of wheel base, and an much wider stance, AND the ability to use wider tires.

do yourself a favor. get a new set of adjustable shocks and springs and some wider wheels and tires. It will hang with any bmw, trust me, I know!

tv

Baloney

From everything I read it IS a different technology from what we have available to us.

They even make them for huge motorhomes, but not us

http://www.irv2.com/forums/f22/the-k...n-23420-2.html

Lizard928

I run koni at full hard with 1000/600 f/r
Even with 11" wide slicks on all 4 corners I have very little body roll or nose dive.
I am using bone stock sway bars and there is IMO no need for anything stiffer.
The Konis could use slightly more dampning but they aren't bad at all.
If you live in an area with bad roads. Like the concrete on I5 going to Seattle this would be a bit tough for most people but on our roads up here it is more than acceptable.

However with the rates I run you need to be smooth or you will upset the balance easily and this will lead to snap oversteer or a slide.

RyanPerrella

Well Perhaps the Eibachs are the problem. I think everyone complains about the Eibachs. As to your comparison of the Koni's to the Bilsteins with Eibachs, that would make sense as the Koni is adjustable and the Bilstein is valved to match the stock spring rates.

I think as others have stated that the Bilsteins would benefit from being revavled to match any change in springs other than stock. Thats one thing that makes them so valuable in my opinion. Have you ever price checked Moton's or JRZ or Ohlins? They are very expensive but if you want a custom shock for a custom spring rate you can have 4 new Bilsteins for about $1000. If you run 600/400 springs like one member here, or if you wanna go with 400/250 springs, you can get a bilstein shock to match your spring rates.

I think harshness is mainly a byproduct of springs rates and to a lesser degree shocks. You can still get harshness from a soft spring and a firm damper, but not to the same degree that too stiff a spring and a softer damper will.

Again, these things need to be balanced, the Koni is just 1-9 and its up to you to determine whats best. Thats tough for the consumer who has no idea on such a subjective measure.

But if you were designing your own suspension system, you can choose your own spring rates with Hypercoils and then match those to revalved dampers and i suspect this wouldnt be an issue to so many.

I think the progressive nature of the Eibach is the biggest problem here. Perhaps the market needs standard rate spring that can simply drop into the stock suspension unlike the hypercoils which require a number of modifications. Although I would still go with the hypercouls, i much prefer the smaller diameter springs, it opens op more room in the wheel wells and they are often much lighter likely saving you 2lbs per corner.

I didn't know that, but I still think the Bilstein is a superior product, just look at a bilstein next to a koni. Koni made with a stamped steel tube, glued on threaded height adjustment sleeves and I believe a smaller rod.

The bilstein looks like a billet tube with machined threads for the height adjustment nuts and (I believe a larger rod)

When they cost the same price which they basically do, the Bilstein is always the way I would go, its just a better product if you ask me. Again, thats my opinion but I think its hard to argue with the points i just mentioned.

Agreed, but how do you propose doing that and not spending years and tens of thousands or likely hundreds of thousands of dollars to develop and produce?

Again, this is a car designed in the early 70's and the last update was done in 92 over 18 years ago. I say make do, there are very good options. And if you dont believe me, listen to the two guys who STILL RACE THESE DAMN THINGS AND ARE STILL COMPETITIVE. (Caps because i still find it hard to believe but damn them they are still kicking ***!)

First off your comparing Bilstein V Koni FSD MOTORHOME SHOCKS! There are far different needs for a motor home shock or truck than for even a regular car, let alone a car capable of 170 plus MPH! All a truch shock does is try and eliminate the spring oscillations from 30,000 lbs going 60mph. NICE EXAMPLE

There is more adjustability in the standard Koni red than there is in the FVD

The FVD has a secondary oil passage that can manipulate damping rates between TWO settings. Yes it does it on the fly and without any electronics which is nice

but
a) its not available for the 928
b) its in my opinion a compromised solution

and yes there is more marketing behind it than technology, its a simple bypass valve nothing more. They gave it a catchy name and market the hell out of it. Its on other shocks but with differing methods and with differing names. FVD is no be all end all technology.

Offroad shocks have this but the bypass pipe is outside the shock tube body and not inside like it is on the Koni for example.

RyanPerrella

and the reason there is nothing new produced for the 928 anymore is because there is no market!

We have a few great suppliers but trust me, Ive got a dozen product ideas on the table but I would never make them for the 928 because a few enthusiasts on RL is not a viable market. Most 928's being picked up for less than $5,000 should give you an idea of the budget of this small market as well.

If I were going to make parts, which i still may, I thought AM's I love those cars but thats still to narrow a field. Think where all the part development money goes, to Mustangs and Camaros and Corvettes and so on. Why? Because they sell between what 50,000 and 500,000 of those cars EVERY YEAR!

They sold about 350 GTS's from 1992 to 1996.....

To those making parts, THANK YOU but to those consumers complaining for a new shock, give me a break, does that make sense?

RyanPerrella

And as to Andrews comment regarding swaybars... again everything must be matched

youve got springs, and shocks and sway bars and end links and bushings.... everything should be matched

if you throw in something that doesn't match into the mix its going to compromise everything. This makes suspension tuning very expensive but If you had a plan from the get go and stuck to it and had every component to match the goal you would have something that works better at doing what you want it to do than the factory setup.

Porsche didnt just bolt up any old spring up to any old damper and magically it worked... this takes years of development and the 928 was a street Grand Touring car. Its supposed to be soft and supple, if you want it to handle and change direction faster with less roll then you likely need to change everything towards that goal. If you want it softer, you need to change everything towards that goal, whatever it is, there are many components that all effect one another and changing only one likely leaves you with a big compromise.

But you guys all know this already, your just being silly starting another thread on suspension.....

tv

there are 17,000 928s (roughly) still in existence in the US going from a past posted fact. I'll bet 16,000 of those people have never heard of rennlist and only 100 show up to the largest gtg.

But all of them will need replacement shocks bought from some where. I don't know how many big-*** motorhomes exist but the 928 market should be large enough. We need a concerted effort from the 928 vendors to become a squeeky wheel at Koni or edelbrock.

RyanPerrella

Hey if you wanna try im not going to tell you not to. If you got them to make more stuff then that benefits us.

But I can tell you logically speaking that its just not going to happen.

But really, if you wanna try I do wish you luck, the more the merrier.

Ispeed

I think my valving specs would work with a softer spring, but if you are going to go 350/225 you could most likely get away with a normal Bilstein shock.
As far as sway bars, our cars have pretty beefy bars stock; we just have mush springs especially at 20+ years old.
My valving specs are under my name at Bilstein in CA. The turn around can be 2-3 weeks, it depends if they are busy.

TV: are you running original shocks and springs on the '85 euro? You could just send your shocks back to Bilstein for a rebuild (the euros came with Bilsteins) as I'm sure they need it. It's a cheap fix. And get some new wheels while you're at it.