996 C4S Suspension Options

[Alex]

I had standard porsche on all 4 corners that were original. I changed the fronts to Bilsteins as one was weeping and was picked up at service. After that the handling was shocking so I changed the rears and just put standard Porsche shocks on. Car handled fine after that.

 

[bananaz]

Not a helpful comment at this stage in your suspension refresh, but I can't see what benefit could be achieved on a road-going C4S by modding the suspension towards coilovers?

On a car that vists the track, or one you want to lower, then coilovers are a good choice.

Would like-for-like shocks and stock springs be an economical option? The standard 'turbo' suspension is a good compromise in terms of handling, ride height, and looks.

 

[IUI675]

Not a helpful comment at this stage in your suspension refresh, but I can't see what benefit could be achieved on a road-going C4S by modding the suspension towards coilovers?

On a car that vists the track, or one you want to lower, then coilovers are a good choice.

Would like-for-like shocks and stock springs be an economical option? The standard 'turbo' suspension is a good compromise in terms of handling, ride height, and looks.

The advice I got was the factory suspension on the C4S would be too firm for the rubbish roads around here, otherwise I would have just bought new standard springs and dampers. At this point I’m tempted to either try the koni active kit or just go to Porsche and order whatever is supposed to be on it.

 

[bananaz]

In my part of the UK the roads are also decidedly rubbish but the standard C4S/turbo suspension feels about right for my use.

If I ever refresh any of it it won't be one of those 'might as well upgrade' moments, it'll just be 'like for like'.

 

[drac]

What about talking to Centre Gravity. They have released a kit based around a C4S and Bilstein dampers.

CG launches 996 dampers for 4WD cars - Center Gravity

With the aftermarket offerings of damper never quite hitting the mark for clients who are using their OEM M030 suspension on their 996, it was decided upon to make it our mission to reinvigorate the market with a solution which is modern and durable and suited specifically for British road use...

centergravity.co.uk

 

[911UK]

something had gotta be faulty, this doesnt make sense, you've done what you were supposed to do, the most likely source that causes the most problem is a faulty shock

 

[gizlaroc]

Is it the B16 kit you have bought?


Please answer, it is important to know.

What I want to know is, have you actually set up the bump and rebound on them?

 

[gizlaroc]

One thing I will say, the oem suspension on the C4S is pretty firm at the back, you should get a more compliant ride and better handling on adjustable coil overs if set up right.

 

[gizlaroc]

One other thing, I'm sure that Center Gravity uses those dampers, albeit valved to their spec., and Eibach springs for their AWD 996 custom set up.

So I think it is worth speaking to them, tell them what they have and ask if they can sort it for you.
They may suggest new springs, they may say the springs are fine, they can adjust what you have already and it will be superb.

But speak to them, they are brilliant and they are honest.

 

[IUI675]

Is it the B16 kit you have bought?


Please answer, it is important to know.

What I want to know is, have you actually set up the bump and rebound on them?

This is a Bilstein fixed rate kit, the only adjustment I have is spring rate (by changing springs) and height.

I suspect you’re right and they supplied the wrong springs, although 911uk’s comment about a bad damper is interesting- I hadn’t considered that because it’s new, but it’s possible there’s a damper issue.

 

[angry]

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?

Sorry I don't. H&R arbs. Have you spoke to Centre Gravity?

 

[IUI675]

I’ve just ordered some 300-70-0050 eibachs for the back, approx 20% stiffer than what’s on there today, but still about 10% softer than standard (assuming the table above is correct).

 

[gizlaroc]

Eibach can't even get their rates right.

They say 50lbs in the title, and then 50nm in the description.

Eibach ERM (300-70-0050) 300 Length 70mm ID 50 lbs Rate

Part Number= 300-70-0050 PG= ERM Length= 11.81 (inch) / 300 (mm) Diameter= 2.75 I.D. (inch) / 70 I.D. (mm)285 (lbs/inch) Rate= 5.1 (KG/mm) 50 (N/mm) Block Height= 3.83 (inch) / 97 Travel= 7.98 (inch) / 203 (mm) Block Load= 2280 (lbs) / 10140 (N)) Weight= 4.07 (lbs) / 1.85 (KGS) Eibach Race...

shopeibach.co.uk

I guess when you get the dampers off you can check they are working properly and then make a decision.



I'm not sure about Bilstein, on the front AWD dampers that are meant to be oem replacements they have one damper for all cars, C4, C4S and Turbo, and for different spring lengths of C4 standard vs C4S and Turbo standard, and M030. Many spring are loose under full extension and rattle around.

So wouldn't put it passed them to have got the damper wrong.
When it is fitted is it in snuggly, not lose but also not over compressed? Take note of that when installing.

 

[911munKy]

I fitted Eibach springs in 2018 to my 996.1 C2 with M030 shocks, firm but fair, rides better when the car has more weight in it. Also had M030 ARB’s, X74 geo and main suspension components refreshed + needed to fit adjustable rear toe arms to get camber within spec.

I looked at that suspension rate table when I updated mine and think it’s wrong, these are the rates that I noted down after comparing several (probably unreliable) sources, no doubt they are a bit out but were the best I came up with at the time. Eibach wouldn't say what their rates are.
BTW my C2 sat low at the back so needed perch spacers, I played around with different heights but settled on +17mm. I’m happy with the handling but more compliance would be nice on the crap Kent roads although I’m sure that has more to do with the shock absorbers.

Spring rates N/mm
996.1 C2 F 25½ R 35½
M030 C2 F 29½ R 45
996.1 GT3 F 35 R 65
Ohlins F 60 R 120
GT3 RS F 43 R 80

DesignTek F 50 R 70
Vogtland F 18-28 R 28-42
Eibach ??? F 19-34 R 52-90
PS9 (Track) F 50 R 90
Ohlins F 60 R 120

 

[gizlaroc]

I was thinking about this a bit more this morning. Only because I have a set of H&R springs ready to go on mine, and I would be careful about putting those 50nm springs on the rear.


Where are you located IUI675? Can you meet up with someone and drive cars together to see what someone else thinks?

How old are the tyres?

What I find is as soon as they get to 4 or 5 years old they rear end becomes pretty scary. Doesn't matter how much grip is left, just age kills them. More so than any other car I have owned, bar the M3 CSL, which was even more picky.

The other think I noticed is mixed tyres front and rear make the back end feel really lose, talking about asymmetric mixed with non asymmetric treads front and rear.


It could well be a faulty damper.

But let's just check the basics first.


Also what PSI? Set the fronts at 33 and rear at 36 cold.

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