996 C4S Suspension Options

I'm looking for some advice on suspension for my '03 C4S Coupe, I've had the car for a year or so and for most of that time it has been off the road because the suspension has needed replacing. I ordered a fast road kit last November which was due for delivery in February, after months of chasing the supplier and getting lied to, the dampers turned up around June and the springs turned up in late August. I finally got them fitted and the car aligned, and it feels awful, back end is all floaty when you're pressing on and it feels like the front is topping out. I could wind the front down another 5-10mm to get more droop, but I don't know what to do about the floaty feeling. The feedback from my wife is that the 911 is currently handling worse than her 2005 mustang! The rear springs supplied with the kit are an odd imperial size (on metric coilovers) and are very soft, I forget the number but something like 40Nmm, the fronts are closer to the norm at around 30Nmm. Is it worth trying to change the rear springs for something stiffer, or is this a good time to stop wasting my time with this kit and try something else? It looks like you can now get a Koni kit for the C4S which might give the right balance of comfort and handling, has anyone tried this on a C4S?

it shouldn't be like that what brand of parts do you have at the moment ? One of the tricks is to upgrade the anti roll bar to something thicker by H&R to reduce body roll and then run softer springs to retain body comfort You need to be very specific on which model of suspension you are using from any range, as there are many options

There's no point in upgrading the dampers and springs if the rest of the suspension (arms bushes etc) are shot.

Currently I’m running single rate height adjustable Bilstein coilovers, with something like 30N front springs and 40N rear springs (I’ll pull the wheels off later to confirm spring rates). New Meyle front top mounts and genuine rear top mounts, all the suspension arms are new Meyle within the last 3000miles. I’m trying to figure out what the right option is, I think I have three: 1. Keep messing around with this kit, change springs until it handles properly. 2. Fit new standard dampers and springs all round (I was warned this would be too stiff for potholey uk country roads). 3. Fit something else like Koni Active (has anyone tried this?) 4. Sell it and buy an R8 (this suspension saga has really soured me to Porsche ownership)

What are geo settings? Sounds to me like you have too little rear toe in, and maybe the front too, and be interesting to know your camber settings. But geo is everything, without knowing what they are no one can help you. Post the settings up before spending more money.

This is the current geo:

20 year old 996 How are the suspension components doing aside from the shocks and springs ? track arms, wishbones, links, rods, etc etc that is where you get extra value from as those rubber bushes would all need replacing

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Coffin arms, diagonal arms, upper rear arms all new within the last 3000 miles. Rear toe arms new in the last 400 miles. Top mounts new in the last 100 miles. About the only suspension component that hasn’t been replaced recently afaik are the front tie rods and tie rod ends. Engine mounts are on my shopping list, but I don’t think that’s the issue right now

I’ve just jacked it up and take a look at the spring rates. Rears are 40n/mm, fronts are 175lb/in (30N/mm). Per this chart (from this thread ), it seems like my fronts are slightly softer than stock and the rears are about 1/3 softer than stock:

If you ask me, your rear shocks are to soft compared to the front shocks. I replaced my front shocks a few years ago and the car felt like a death trap. Rear end was floating all over the place, especially when braking hard. Put new shocks on the rear and it transformed the car back to how it should be. I couldn't believe the difference putting stiffer shocks on the front, and then same again stiffening up the rear.

I had exactly the same on my Turbo when I put PSS10s on, especially the floaty rear end. I was advised to upgrade the ARBs and it sorted it

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Thanks Alex, that’s the other possibility, dampers are too soft. What springs/dampers did you go for?

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Interesting - you don’t happen to know the spring rates of your pss10s? (Yeh, I know it’s a really unlikely thing to know!). What ARBs did you go for?

Your geo looks good. I would try and get a bit more camber up front, but that won't effect what you are feeling. I think you need a stiffer springs on the rear. Is that the B16 kit? I know some find the rear far too hard, from memory they come with around 600nm spring rate on the rear. Did you buy them used? Looks like someone has swapped in a softer spring, but gone far too soft. I would aim for around 350nm.

Just re-read the original post again. I reckon they couldn't get the springs so have just put those in instead. I would be on the phone.