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DynoMike's suspension journey. LONG....

DynoMike

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Joined
25 May 2012
Messages
1,687
This is a thread documenting my 996 Turbo's suspension journey for anyone who may be thinking of doing the same. Best to get a cup of tea, this is going to be quite long...

Not long after purchase in 2012, I was just not at ease with the handling of my car; despite having immense grip and fairly impressive corner speeds I felt 'disconnected' from the experience. Put simply, the car felt so glued to the road that I began to wonder what the hell would happen should I ever push too hard? Would it be lost in an instant or, as I suspected at the time, be likely to bite back very hard indeed. Also, the ride was simply atrocious on our dire bumpy 'B' roads, verging on painful at times which saw me planning my routes by road surface quality rather than by the potential driving pleasure.

So I started what turned out to be a long but enjoyable series of suspension set-ups. Not wishing to veer too far from the standard configuration, I decided to keep the M030 factory kit fitted to all turbos totally stock, but explore the capabilities of the chassis via geometry changes alone. I chose Center Gravity to do the work for me and I am very glad that I did, as their reputation exists for good reason.... They are perfectionists and only specialise in suspension.

The first iteration was an effort to swing the balance of the car back towards me, the driver, along with adding a healthy dose of comfort. The end result was astonishingly different from the car I drove in with; it was at least twice as comfortable as before, being able to absorb the bumpiest of my local roads with ease and adding a real thrill to the driving experience. I was laughing out loud at how adjustable the rear end was via throttle input. The car was a hoot to drive and fling around, if ultimately lacking pace compared to the original Porsche-standard geo, as rear grip had been sacrificed by standing the wheels up to around 1 degree 10 minutes camber, along with the bare minimum of toe. Up front I was given 45 minutes of camber and zero toe. However, I was still hungry for more. With the settings above I was able to slide the rear of the car beautifully with the front end nailed to the road, but once this novelty had worn off I started to want more outright grip.

The second iteration was interesting as I learnt very quickly just how beautifully sensitive the 996 chassis is. Tiny changes to geometry settings wrought noticeable changes to the driving experience, which shows just how well Porsche had developed this amazing platform. At the time I was running Bridgestone S02As all round, a much maligned tyre if t'internet is to be believed, but I really liked them. With stiff sidewalls, the car changed direction like a cat after the second set up which saw a more normal 1 degree 36 minute rear camber angle, with rear toes set to the Porsche minimum settings of 5 minutes per side. Up front, camber was maxed to 51 minutes. Yep, 51, not 50 or 49. Did I mention that CG are perfectionists? Toe was set slightly out at my request. The steering was very quick indeed which is what I needed. I ought to explain here that I drive the car with hand controls as a result of a racing motorcycle accident many years ago, which means I have to be able to control the car with around 180 degrees of total steering wheel movement once up to speed. This inevitably means that these settings will not be to everyone's taste, a point which Chris and Pete at CG keep reminding me. I kept this chassis arrangement for quite some time until deciding to change tyre brands for Michelins, largely because I had read that they were more comfortable than the Potenzas.

Enter iteration three. The PS2 tyres were a revelation in terms of tenacity and consistent grip levels but they had relatively floppy sidewalls in comparison to the S02As. As the 'spring' on each corner also includes the tyre carcass, the car now felt soft compared to before, with a feeling of accentuated body roll. In fact I almost opted to put the Bridgestones back on at one point but was talked out of it by Chris at CG. He suggested that we needed far more camber to optimise the set-up for both the tyres and my particular driving style, so away he went with the third geometry that I had tried. This mainly involved work to the rear end as a quick tyre inspection showed that the sidewalls were tucking under during hard cornering. So the rear camber was set to 1 degree 50 minutes and some added toe to calm the rear-steering that was dialed in during the first two visits. Comfort was starting to diminish at this point, more on this later. The comfort levels had started to be compromised, but on balance I decided that this was a small price to pay for the feeling I had with the car. I should point out at this juncture that sometimes with added rear camber, an 'oversteer' sensation can be felt as the tyre rolls on to it's contact patch. This felt a little disconcerting at first but became a feature that I really enjoyed as the miles went by. It can be negated by changes to toe as I found out later on my journey.

As the miles ticked by I was constantly amazed by how capable the car was and how enjoyable it had become to drive, even on the odd track day I took part in. Nothing fazed it at all. Everything was going swimmingly until the top mounts cried enough at 58000 miles, which set me thinking again.

So then came the final step in my quest for a car which behaves just as I would like it to. After sampling NXi20's GT3 from the passenger seat, which has monoballs at every pick up point possible, I was pleasantly surprised by how quiet and comfortable this type of suspension component location was. Also not to mention how phenomenally responsive his car felt to every input. Granted he runs top-notch dampers all round, but a feeling of solidity emanated throughout the chassis. After discussions with Chris and Pete it was decided that we would try a halfway-house approach that was more in keeping with the stock dampers and springs I run, which took the form of some monoball inserts for my original top mounts. As the suspension was having a good overhaul, new front coffin arms with adjustable caster inserts were also fitted, along with some uprated bushes for the rear coffin arms. Front camber was tweaked to some very specific numbers, caster likewise, with toe set to zero. The guys also changed the rear anti roll bar bushes for new stock items. Rear camber was left alone but a whisker more toe was added. The results were unbelievable! My car felt like a GT3, so composed but with amazing grip, turn in and neutral balance. Just incredible. I ran the car at Anglesey for a PCGB track day back in May, where it acquitted itself very well indeed, easily running with a 991 Turbo S and a couple of GT4s. I had a bit of a dice with a 997 Turbo too but he couldn't corner at anywhere near the pace of my humble 996T. The confidence that the chassis gave me was most evident in the wet morning session where once again, I was laughing out loud at how much total grip I had as well as reveling in balance of the car; it seemingly had no vices at all, the front end grip being the standout feature. Astonishing considering that the dampers were all standard and had circa 59k under their belt. Downsides? Only one, the front monoball cartridges had to go back to CG for a knock to be investigated. I am currently testing this solution on behalf of the guys as I had agreed to be the first person to try these units. I will duly update the forum as to the long term outcome of this scenario.

All was going well with the above geo in place until I heard a bang whilst zipping down a bumpy country lane one day. What followed was a car that was almost undriveable at speed! After much investigation Pete changed the rear dampers for a known good set and the problem was solved. For reference, it felt as if the right hand rear tyre had 10 psi in it on left hand corners which was very disconcerting indeed. The dampers did however fly through a damper test program with ease which was very confusing. Pete then had my originals refurbished at Bilstein for a very reasonable £210 plus vat and refitted them. What a difference! The rear suspension feels quite plush now, not squatting under heavy acceleration like it did before and absorbing minor road imperfections without the crashy feeling it had previously.

Well that's it for now, I have a car that feels perfect for me. I have to reiterate that everyone is different, one man's meat etc, but for my slightly unconventional driving style I have an awesome car. Having spoken to Manic996T who has a far more modified chassis than me, it has made me realise how different driving styles alter what is required from a chassis tune up. His numbers are very front end biased whereas mine are the opposite way around, yet both of us have sweet handling cars set up by different specialists. Time and again I read how folk don't gel with all sorts of platforms on this forum, yet a visit to an outfit who really understand these cars can transform any 911 to suit any driving style.

If you have stuck with this dribble to this point, well done! As for my car, it will be staying as it is for the foreseeable future unless I win the lottery, in which case it will be riding on Ohlins or Quantum dampers.

Adios amigos.
 
Great write up. It's great to hear that you stuck with what you had and tuned it to your style. I have this discussion ofter with track guys that have spent tens of thousands on all sorts of mods trying to be the fastest cat on the track, when the biggest and cheapest gains can be made by optimising the two obvious areas...themselves and current hardware.
 
DynoMike

Great write up and most interesting

So i have a question that your article has raised with me that i had never condidered.

Tyres and their side walls??

Now i run Michelin PS but these are nearly spent and am thinking of going to CUP2s. this along with my PSS10 suspension, set to quite hard and the GT3 bucket seats....once i change do you think i will notice much difference as i would assume that the CUP2s might have a harder side wall than the PS set up

Car is pretty firm already and if it gets much harder, i might find it difficult on long journeys ?

So the wider question, thoughts on how different tyre side wall strenghts / stiffness affects the ride quality
 
Excellent stuff Mike!

It helps if you know what you're talking about when setting a car up as you can describe exactly what you are feeling and what you would like to feel. Something you can do but many of us can't!

Would love to see for myself how yours handles now, especially with some monoball trick kit. Interesting info about the damper which was faulty - I took my car out at the weekend and noticed a very unstable rear end on hard acceleration. Felt like the rear end was bobbing up and down and side to side violently. When I got it back the offside rear wheel arch gap is about half of the other side. Couldn't see any cracked spring or leaking damper when I got it on the ramp though. Doesn't feel safe to drive hard at the moment.. :pc:
 
FRP said:
DynoMike

Great write up and most interesting

So i have a question that your article has raised with me that i had never condidered.

Tyres and their side walls??

Now i run Michelin PS but these are nearly spent and am thinking of going to CUP2s. this along with my PSS10 suspension, set to quite hard and the GT3 bucket seats....once i change do you think i will notice much difference as i would assume that the CUP2s might have a harder side wall than the PS set up

Car is pretty firm already and if it gets much harder, i might find it difficult on long journeys ?

So the wider question, thoughts on how different tyre side wall strenghts / stiffness affects the ride quality



FRP, the tyres do make a significant difference to the ride quality in my experience. I was also thinking of going to Cup2s but judging by the performance of my car at the moment I will probably leave the PS2s on.

I hear that the Cup2s require more camber to get the best from them, so you may end up in a catch 22 situation concerning comfort. In your case though you can adjust the PSS 10 units to compensate somewhat. I would talk to a good 911 expert and see what they advise.
 
Thanks for the great write up. You seem to have spent money where it counts, and as such it's great to learn that there's so much adjustability in the car with the stock suspension. (As an aside, I would assume the reason that many cars are modified is that there is little to no adjustability, and the reason that many change the rims is to reduce the sidewall for precision, or add sidewall for comfort).

Quick question: are you running OEM rims as well or have you changed those or any of the offsets?
 
ragpicker said:
Excellent stuff Mike!

It helps if you know what you're talking about when setting a car up as you can describe exactly what you are feeling and what you would like to feel. Something you can do but many of us can't!

Would love to see for myself how yours handles now, especially with some monoball trick kit. Interesting info about the damper which was faulty - I took my car out at the weekend and noticed a very unstable rear end on hard acceleration. Felt like the rear end was bobbing up and down and side to side violently. When I got it back the offside rear wheel arch gap is about half of the other side. Couldn't see any cracked spring or leaking damper when I got it on the ramp though. Doesn't feel safe to drive hard at the moment.. :pc:

Cheers Rags!

You don't really need to tell them what you want, they drag it out of you with clever questioning!

That was almost the same feeling at the rear that I had, the car became pretty unstable at the rear to the point where I didn't want to drive it. I also had exactly the same difference in height on the right rear which was how CG diagnosed the damper had failed. Not having a ramp, I had my mate crawl around underneath taking photos :bandit:

Nothing could be seen outwardly, no leaks, nothing broken. Time to whip 'em off doc :lol:
 
DynoMike said:
FRP said:
DynoMike

Great write up and most interesting

So i have a question that your article has raised with me that i had never condidered.

Tyres and their side walls??

Now i run Michelin PS but these are nearly spent and am thinking of going to CUP2s. this along with my PSS10 suspension, set to quite hard and the GT3 bucket seats....once i change do you think i will notice much difference as i would assume that the CUP2s might have a harder side wall than the PS set up

Car is pretty firm already and if it gets much harder, i might find it difficult on long journeys ?

So the wider question, thoughts on how different tyre side wall strenghts / stiffness affects the ride quality



FZP, the tyres do make a significant difference to the ride quality in my experience. I was also thinking of going to Cup2s but judging by the performance of my car at the moment I will probably leave the PS2s on.

I hear that the Cup2s require more camber to get the best from them, so you may end up in a catch 22 situation concerning comfort. In your case though you can adjust the PSS 10 units to compensate somewhat. I would talk to a good 911 expert and see what they advise.

Nice write-up Mike :thumb:

Having tried many, many different makes & designs of tyre on my GT3 over the years, I have to contend that sidewall stiffness plays less of a role than treadblock design & depth. As evidence, I present the extremes of the Michelin Pilot Supersport vs. Toyo R888:

The Michelin has a relatively stiff sidewall but also relatively deep & open tread at ~8mm; the result is a comfortable & predictable road tyre that will squirm around a bit under power in corners. A good all-rounder then but challenged when used as a track tyre due to it overheating as the tread moves around too much which generates heat. In my experience it is superior in every way to the trusty old PS2 which is over 10 years old in terms of design & technology. The bad news is that you can't (and never will be able to) buy them in the correct sizes for the GT3 or Turbo 18" wheels.

The Toyo is primarily a track tyre but interestingly has the softest sidewall of any tyre I can think of. There is only 5mm of tread and it can be thought of more as a cut slick (aka intermediate) that happens to be road-legal (or it was up until recently; it's now been reborn as the 888R). These tyres are incredibly noisy at speed (they howl at over 100 & it sounds like your diff is about to explode!) and despite the soft sidewalls, they are not comfortable in any way on the road. I used to dread the drive over to the 'ring or Spa on them.

The Cup2 is actually not too bad on the road but as they come with 5.6mm of tread & relatively stiff sidewalls, they are not as comfortable as the PS2 or Supersport. They do need camber to work optimally; around 3 degrees on the front & 2.5 on the rear seems to be the sweet spot on the GT3.

The future seems to be the PS4 which I've had good reports on & I will be trying out next.
 
Fascinating write up, thanks for posting. I'd love to get a CG set up one day, but I too worry that I would not be able to articulate what I'm after as I don't really know!

I was amazed by the transformation to my 4S just returning it to factory geo settings, a few new bits and bobs and new tyres. I don't drive on track, actually I don't really drive that fast any more! What I do appreciate is the viceless handling, steering feel and arrow straight tracking even on bumpy roads.

In a small way, I recently had new tyres all round and 4 wheel alignment on my '04 BMW X5 daily. Genuinely, it feels like a different car to drive. Its staggering what a difference these things make, yet neglected by many people.

How often to folk think geo needs checking/resetting in normal road use?
 
Thanks NXI20

I had not considered Toyo R888r tyres,,,some food for thought. I run 19 inch rims

Car is mainly a road car with a fast road geo currently, so now i can think of either R888r or Cup2's for the nex set of rubber...ohh the choices

Appreciate the experience and info

Regards FRP
 
NXI20 said:
DynoMike said:
FRP said:
DynoMike

Great write up and most interesting

So i have a question that your article has raised with me that i had never condidered.

Tyres and their side walls??

Now i run Michelin PS but these are nearly spent and am thinking of going to CUP2s. this along with my PSS10 suspension, set to quite hard and the GT3 bucket seats....once i change do you think i will notice much difference as i would assume that the CUP2s might have a harder side wall than the PS set up

Car is pretty firm already and if it gets much harder, i might find it difficult on long journeys ?

So the wider question, thoughts on how different tyre side wall strenghts / stiffness affects the ride quality



FZP, the tyres do make a significant difference to the ride quality in my experience. I was also thinking of going to Cup2s but judging by the performance of my car at the moment I will probably leave the PS2s on.

I hear that the Cup2s require more camber to get the best from them, so you may end up in a catch 22 situation concerning comfort. In your case though you can adjust the PSS 10 units to compensate somewhat. I would talk to a good 911 expert and see what they advise.

Nice write-up Mike :thumb:

Having tried many, many different makes & designs of tyre on my GT3 over the years, I have to contend that sidewall stiffness plays less of a role than treadblock design & depth. As evidence, I present the extremes of the Michelin Pilot Supersport vs. Toyo R888:

The Michelin has a relatively stiff sidewall but also relatively deep & open tread at ~8mm; the result is a comfortable & predictable road tyre that will squirm around a bit under power in corners. A good all-rounder then but challenged when used as a track tyre due to it overheating as the tread moves around too much which generates heat. In my experience it is superior in every way to the trusty old PS2 which is over 10 years old in terms of design & technology. The bad news is that you can't (and never will be able to) buy them in the correct sizes for the GT3 or Turbo 18" wheels.

The Toyo is primarily a track tyre but interestingly has the softest sidewall of any tyre I can think of. There is only 5mm of tread and it can be thought of more as a cut slick (aka intermediate) that happens to be road-legal (or it was up until recently; it's now been reborn as the 888R). These tyres are incredibly noisy at speed (they howl at over 100 & it sounds like your diff is about to explode!) and despite the soft sidewalls, they are not comfortable in any way on the road. I used to dread the drive over to the 'ring or Spa on them.

The Cup2 is actually not too bad on the road but as they come with 5.6mm of tread & relatively stiff sidewalls, they are not as comfortable as the PS2 or Supersport. They do need camber to work optimally; around 3 degrees on the front & 2.5 on the rear seems to be the sweet spot on the GT3.

The future seems to be the PS4 which I've had good reports on & I will be trying out next.


Thanks Nick!

Interesting re your thoughts on tread depth vs sidewall/carcass stiffness. Originally I had S02As on the car which had a pretty good tread depth of around 6mm, however I still found these to be stiff on the road and track. They most definitely overheated the tread gauge on track or during spirited road driving, giving the sudden sensation that the rear of the car was on a very wet and slippery piece of tarmac.

I guess that ultimately, tyre construction is a very sophisticated subject and that in making assumptions, I may have got the correlation of perceived sidewall stiffness/firm ride a little wrong as I only had the data for two trye manuacturers.

In the meantime, I hope you feel partially responsible for my 996 suspension fetishes :grin: :thumb:
 
Robertb said:
Fascinating write up, thanks for posting. I'd love to get a CG set up one day, but I too worry that I would not be able to articulate what I'm after as I don't really know!


Robert, honestly, give them a shout and ask their opinions, they are very easy to deal with (as long as you can get someone by phone). I didn't go there with pre-conceived ideas, merely that I wanted the car to involve me more in the driving process and give me some more comfort. That was at 51k miles, I'm now just on 60k, with a 'bespoke' car set up which is perfect for me.

As far as I'm aware, CG don't do off the shelf geometry settings, preferring to offer a personal set up.

I must stress here that I have ZERO affiliation with this company, I am just a happy customer. I am also a small business owner who trades via word of mouth, so I'm more than happy to give my support to people who have given me excellent service, CG, RSJ Sports Cars and lately, Fearnsport too. Equally, I will be vocal if I end up with poor service!!! Sincerely hope the moderators don't take a dim view of this.....
 
Your fetishes are entirely your business Mike :floor:

All I did was show you greener pastures, you made the decision to join me there!

I can't see how anyone can reasonably object to real customers of businesses praising them when they deliver good service and please them. At least we know that the glowing praise isn't because some magazine journo has managed to blag a freebie from an advertiser...
 
Great write up. It's great to hear that you stuck with what you had and tuned it to your style. I have this discussion ofter with track guys that have spent tens of thousands on all sorts of mods trying to be the fastest cat on the track, when the biggest and cheapest gains can be made by optimising the two obvious areas...themselves and current hardware.


Thanks FZP. Yes indeed, the easiest thing to tune is the driver! I have many bad habits when driving my 911 but the latest generation of settings make up for my shortcomings!



Thanks for the great write up. You seem to have spent money where it counts, and as such it's great to learn that there's so much adjustability in the car with the stock suspension. (As an aside, I would assume the reason that many cars are modified is that there is little to no adjustability, and the reason that many change the rims is to reduce the sidewall for precision, or add sidewall for comfort).

Quick question: are you running OEM rims as well or have you changed those or any of the offsets?

Max, again, thank you. Yes the 996 has huge 'personalisation' potential with suspension settings. As an engineer I am amazed by this, the job the engineers at Weissach did is truly mind-boggling.

I still run standard rims and offsets without spacers currently, though I did try them in the past.

Your fetishes are entirely your business Mike :floor:


As long as I don't acquire your penchant for bigger holes, squeezing harder and more bangs/minute, I will be ok :oops: :oops: :oops: *


*Translated that means bigger bores for a 3.8 litre, higher compression ratio for more power and greater rpm for top end power :floor:
 
Great write up Mike,

you summed it up well with the different strokes for different folks, most people struggle to articulate what they want and rather go with what they think they need in terms of suspension.

RE: tyres- as I mentioned to you I was amazed at how well my PS2's behaved the wear pattern shows that the tyre was being used very evenly and not chewing up inner or outer edges. Although atmittedly I was wasn't at maximum attack but still lapping quick so pleased that the tyres weren't a constraing factor, but I think using appropriate tyre pressures and driving style has a lot to do with tyre/chassis behaviour

I'm going to try MPS Cup2's next as an all round road tyre

Can't wait to test my Dunlop DZ03's on track, however not looking forward to the cut slick whine lol
 

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