Wojtek,

Nice to hear from you. I would not really call my S4 a racer but it has impressive potential nonetheless. However, much as I stunned the local 911 and Boxster crowd last year and very nearly won the event outright, this year I went a step too far and went backwards big time so getting it just right is a question of fine balance. At least I could work out what went wrong. I do not think the standard car is too bad but given that I like a firm ride, I found the transition to Eibach and Bilsteins a big leap forward. The big wheels were then something else when they came along. Alignment settings and weight distribution/ride height all play a part in the set up.

Not sure how your springs are rated, but the SE variant had stiffer springs and dampers but probably dual rate springs at that. All I can tell you is that body roll on my car is minimal. I doubt that the Devek bar has much roll impact on a standard car set up but it gives lots of flexibility to help set up the balance of the car. As I am concerned the Devek bar would be a waste on a standard car setup as it understeers quite noticeably. As you get more relative grip on the front you need more front bar to stop the car getting relatively tail happy. A question of balance.

A big mistake on the part of most owners is that they like the look of the car when the front springs sag. Porsche never designed the car for this and consequently a lower front end shoves more weight to the front which further exaggerates understeer and also upsets the "ground effect" aerodynamics. I try to keep to thre proscribed ride heights but a bit lower all round given that stiffer springs reduce "squat". By the way I am an engineer and I am red hot at Microsoft flight simulator.

You feel no changes in roll because the higher rate has kicked in. The initial feeling of "wobbliness" at turn in is unnerving but you get used to it. It is even better when you get rid of it. So which is the best system? I suspect externally adjustable Koni's with either spring design is good for dual street/track use. For fast street use what I have is excellent. Externally adjustable koni's add about $800 to the total bill so unless you are tracking the extra is questionable. My first choice is quite simple. That would be hypercoil and Koni simply because Marc Thomas of Devek specified it. This gent knows exactly what he is doing and of the big three I value his opinion the most. 928 GT are quite good on cosmetic items and I have not really had much to do with 928 International since we had a bit of a falling out when my car appeared in the Devek catalogue. My drive draft broke just after I got the car and whereas 928 International were very helpful, Devek found me a new shaft for a few dollars more. I have had excellent support from Devek and I am a creature of loyalty.

For sure there is a good chance your dampers are tired [age] springs- well they tend to sag with time [more so the fronts or so it seems]. Harshness- you will feel surface imperfections like cats eyes more but other than that you would not really notice much difference. Reduce the tire pressures a bit to compensate, especially with wider sections. I do not think the wheels will change roll characteristics but I would have to think about that one a bit.

With respect to opinions on the Rennlist there are some good ones but the quality of the list is not what it used to be when I first joined in so be a bit careful as to who you listen to. I am not sure what 928 specialists are offering but it may be their adjustable drop links. I cannot open their website at the moment to see what they offer. I have some adjustable links at the rear from
Louie Ott but they are not really needed [now set at standard] with a Devek bar, they are however mechanically superior to the standard rear links that are known to fail.

For brakes I run with Hawk Performance Plus pads. These are a dual street track pad but they are quite harsh on discs and need to be treated with respect. I goofed around a bit and as a conseqeunce of some heavy stops trying to emulate the original 928 adverts I managed to warp the discs a little. Still I did a 0 to 60 back to 0 run in 9.1 seconds [the add claimed 9 seconds]. I also managed a zero to 60 dash in 5.75 seconds. The trick with these pads is to run the pad into the disc gently nd put the pressure on uniformally to stop it grabbing. Of course our exaggerated heat does not help the cooling either. I learnt this the hard way on the new track up in Dubai. The brakes worked well - until I boiled the brake fluid that is! Went into a 50 mph bend at 90 mph with no brakes. I had to put the car into a spin, thought I could recover, mashed the throttle to catch the back end and the rear wheels just plopped over the edge and I was buried. Left two large darkies on the track and probably became the first person to exit the brand new track! I now run with ATE blue brake fluid and new brakes lines. I got away with it once but it could have been devastating had I been on the full circuit as the straight on which they failed allows around 140 mph to be reached on the S4 when the full circuit is used.

The rear spoiler looks quite nice but they used a sealer to cover the rubber prior to painting. I was going to keep my spoiler standard and use a sun spoiled rubber one to paint. They used the wrong one! The rear bumper cover came free of charge from a damaged 928 GTS. I liked the look. I also have the original which is repairable but slightly damaged from a rear end shunt.

Trust the above is useful and hopefully correct. Others helped me and continue to help me so giving something in return to other 928 owners is no problem at all.

Regards

Fred R

Wojtek,

The system used by 928GT has an advantage in that it allegedly avoids the problem of rub on the sway bar. The penalty for this is limited adjustment range. The bottom line is that until you have extra grip up front there is no point in fitting a stiffer front bar. Louie Ott's rear links addressed this in a limited way by offering the possibility of stiffening the rear [equivalent to softening the front] to give a limited form of adjustment.

A good car controls roll at both the front and the rear and the difference between the two shifts the balance of the car from oversteer [rear stiff] to understeer [front stiff]. Hence there is only a need to have adjustment at one end. The 928GT approach seems to be stepwise adjustment at both ends. It may be a good idea if it works well. The Devek bar is very slick, relatively light in weight and gives an enormous range of adjustment but as I said without front grip it is somewhat useless. It also resticts lock with wide front tires.

Most 928's that have not had intervention tend to sit lower at the front than they should. I put this down to slightly tired suspension but it may be by "intervention" in some cases. Either way it is not a good thing in my opinion.

My brother has a private pilots license but when I flew with him I knew more about instrument flying than he did on VFR. I do some sailing here on Hobie 16's as we have a small fleet for racing in our club.

The brake problem was self inflicted by over enthusiastic brake pedal useage for no practical reason other than fooling around and testing the limit. I think it would be better to fit a bigger disc with less contact force achieving the same effect.

Ride height is technically measured from fixed points underneath the suspension arms. It is much easier to measure the height from the ground to the underside of the fender at the centerline of the wheel. A factory spec adjusted car will sit approx 24 inches at the front and 21 inches at the rear. You will probably find the front sits about 23 inches or less and the rear close to 21 inches. Ride height is critical to weight balance and a well adjusted car has a perfect weight distribution [25% per wheel]. To get this the suspension has to be adjusted on scales. Changing ride height changes alignment settings and off you go until everything is where you want it. Alignment is quite a fine art and the 928 is very sensitive in that its suspension design is such that when lifted it does not settle for some period of time/mileage. Most settlement takes place quite quickly but full settlement takes a good thrash to achieve. Set the alignment when the thing is not settled and you will end up with excessive toe and scrub the tires in no time. The front is more sensitive to this.

I can write pages on alignment but suffice it to say the standard settings are very conservative. More camber, less toe and more caster is the way to go but I have no idea how this works on standard rubber.

Regards

Fred

Wojtek,

The only answer to real grip up front is wider rubber. Improvements can be made with camber, possibly tire pressures and of course optimal suspension to keep the lot nailed to the deck. Get this lot right and 1 g or more is possible. I once tested my current set up on a roundabout going faster and faster, topped out at 1g and had to give up- I was going dizzy!. Of course the other improvement was the Michelin super cups [dot legal semi racing rubber- slicks for the highway!]. They do not last too long and they go off quicker than normal rubber but when they are new - handling Nirvana and a very quiet ride as well. The outside half of my front now has no tread [it had little to start with] but they are still impressive and even though they have covered 6k miles they still have quite some life in them subject to the law's interpretation of what legal tread is. I hope to get 10k miles out of them before they are retired about this time next year. Needless to say we have little rain here and when it does you do not want to drive in it anyway. It is challenging on these tires in the wet.

No problem with you putting my thoughts on the web but please remove relative comparisons about products from the big three as I may want to deal with the other two at some stage in the future, they are also pretty good at what they do and I do not want to upset anyone.

Feel free to contact me any time.

Regards

Fred

Sent: Saturday, June 18, 2005 11:29 AM
Subject: Wheel offsets etc

Wojtek,

My engine bay has a special formulation used on all the parts that is designed to withstand high temperatures. It gives all the surfaces a wet look and is visually absolutely stunning. When I arrived at the concourse site my friends knew I had been up to something but I taunted them by refusing to put the bonnet up until the judges came to my car. My arrival was timed to get an early sequence number so that the judges had a benchmark for comparison. I won my class [the older cars], I won the public's vote for their favorite car and I probably would have won the judge's vote for favorite car of the show but they were worried about the reaction of the rest of the members! It was a nice experience to be the centre of attention all afternoon in the middle of some 60 Porsches including all the latest models and various Gemballa variants. My inlet ducting is in fact 3 inch water piping that they use on water delivery bowsers here when there is no mains water [typically when a new area is developed]. The original colour was candystripe green/white and looked truly crap. My standard units are shot on 1 side so we simply painted my home mades using plenty of plasticiser in the paint. Looks amazing when you see it.

If you look at the sizing chart you will see that for a 235 section with 45 profile you could technically fit it on a 7.5 inch wheel; but you have to consider diameter and stability. A tire ideally wants to be parallel with the rim. If you look at my wheels you will see the tire walls are almost perfectly parallel. For this reason, as wheel diameter increases the tire size tolerance range decreases and similarly with aspect ratio. If you look at the column that compares width of tire on rim it is no coincidence that they show the 235 x 40 on a 8.5 inch rim. This is a good indication that your 7.5 inch rims are simply too narrow for this fitment. My car steers like a demon and is so precise you can "put it on a sixpence" but some of this is also due to 18 inch wheels. On the other hand, 17 inch wheels are less tortuous on the wheel rims because the tire has more give in it and all things being equal survives pot holes better. I have already damaged 1 rim slightly.

Mark Kibbort is very experienced with 928's and you must remember that he is an out and out road racer and very good at that. The downside of his recommendations is that lock will be extremely limited I suspect. To a road racer that does not matter too much. To an auto crosser or street driver it could be a problem. I run a 66mm offset up front and had to limit my lock with stops in the steering rack but even so, under really tight cornering on the autocross I rub the sway bar so with 82mm offset I doubt I could get round the tight bends!
One thing that Mark may not have considered is steering geometry. When Porsche designed the 928 they knew the lines of steering geometry they designed for. This is a virtual concept that plots lines of reaction in space and the intent is that they intersect at the centre of the tire contact patch. 66mm offset does not change this but 82mm would be a significant change. How this translates in practice I do not know but I have seen an article on this that describes the impact on handling. I suspect Porsche got its original design spot on.

The calipers were painted off the car using standard cellulose paint. The fuel dampers cleaned up nicely. My tires are Michelin, either Super Cup or Cup Sport. They are road legal semi-racing tires and they are superb while they last which is not too long. I would not use them in England unless I had 2 sets of wheels.
I cannot advise you which suspension set up is best as I have not used the options back to back. All I can tell you is that I am well pleased with what I have and track racers require something that is externally adjustable.

Wojtek,

A sixpence was an old English coin [no longer used] that was originally made from silver and was in its day quite valuable for a pocket coin. Compared to when I was a boy its value in real terms today would be about $1 but when it was first conceived long ago it was probably equivalent to a weeks wages. Either way it was a small coin because of its relatively high value silver bullion wise. Hence we use the expression because of the precision required to hit something small.

The impact damage on the wheels is caused by stiff sidewalls not having sufficient compression and this in turn deforms the flange slightly. So far nothing noticeable in terms of reaction on the road. I am not sure why a 225 section would be used on a 9 inch rim width. I would go for a wider section providing there is no interference. I suspect your estimate of the wheel pricing is about right.

I suspect that tire kicking techniques [like bouncing the suspension] are meaningless on a 928. Even knackered suspension will probably not bounce.

Lock is the term used to define the extent to which a steering system will travel from one extreme to the other. Wide wheels restrict the lock on a 928 unless you put a small offset and then do something with the flare of the wheel arch. I have seen this done on a 928 but it looks awful in my opinion given the wonderful original lines.

I suspect the Bilsteins work pretty much on the lines of the diagram you show. In principal they will have some kind of variable restriction orifice that modifies the rate of damping relative to the size of shock transmitted. Like anything automatic it cannot be optimal for all conditions but it is probably infinitely better a setting that is fixed and suitable for only one type of characteristic. For mostly street driving this has to be a better option. For a hard core track man this would not be the case.

If you want the C2 or similar look then the wheel to go for is the three piece Kinesis wheel as sold by 928GT. It still looks original Porsche in a 3 piece forged design.

Regards

Fred

Info of Fred's new 928 GTS

Fred's old 928 S4 supper car that was totaled after impacting rail while taking a turn and trying to avoid other drivers unforeseen move:

This is the new car Fred is talking about below:

Sent: Sunday, February 15, 2009 10:11 AM
Subject: Re: Great to hear from you.

The GTS is one of the very first issues of the genre. It was registered in 1992 and was owned by the local Porsche dealership owner/manager. He never really used it much and could not believe the way my S4 performed when I took him for a spin in it. He sold it one to a Lebanese chap and immediately it had problems which he stupidly took to a backstreet garage to fix that made matters worse. I then heard about another problem and new the engine was basically stuffed. The poor guy had the car a year or so, most of the time it was not running and then horror of horrors it seized. The local Porsche garage managed to free it up but they should never have let him drive the car out of the garage. He thus had bills in excess fo $10k and a wrecked engine to boot by then. I knew this and waited for the penny to drop in his head. This happened and he decided to sell the car. Of course with no engines for sale in the country or anywhere else for that matter in the Middle East he was in bad shape. He going to sell it as a viable concern but I warned him that if a buyer found out that he had not disclosed the condition he would be in bad shape with local authorities. I offered him $6k for the car, he said he would think about it and I said fair enough but tomorrow it will be $5k and the day after $4k- he took my offer! To me it was worth it because I knew the car's history and it had not been bent and had been repainted to factory spec by Porsche.

Of course I had my externally damaged S4 engine and the GTS had all the bits my engine needed to make it viable plus the possibility of other recoverable spares. The crank was damaged but may still be recoverable. I have two pairs of spare heads plus cams etc. I have a spare gearbox from my S4 plus plenty of other engine spares etc. The crank/rods/pistons are the trump card for a future project but I am still not sure about its viability. The car itself was fully repainted by the Porsche agents before they sold it- not sure why because it really did not need so the paint is in pretty good condition.

I changed the suspension, I revamped my S4 engine, I fitted my exhaust and rrfpr, and resurrected my wheels. I have GTS wheels with a bit bigger than std rubber, and my special wheels for track days etc. I run with an advanced alignment set up and fitted stainless brake lines and street/track pads that stop like hitting a brick wall but drive me up the tree with squealing. The interior is pretty good and cleans up nicely but they re-did the front passenger seat with the wrong leather. I will have them re-done but still- they look good when cleaned up.

The car suffers a little bit because of the S4 engine but more than makes up for it in the handling department. It won the local Porsche club concourse event last year- mostly due to my friends polishing/paint protection business- they knew the 928 is an eye catching car and their efforts paid dividends in the sense of the boost it gave their business when everyone saw my car 4 years ago. The inlet tubes are simply pieces of 3 inch water hose painted black [cost me about $10 - the local agents painted them FOC]. But they need painting again because the paint melted. I also have a pair in blue same as the body colour.

Most of the work was done by my local Porsche dealer. they usually work a really good deal for me because they like the publicity as well as me. For $2k they fitted my S4 engine after stripping the engine, doing the valves, modifying the sump baffle, fitting new water pump/timing belt, fitting my cam selection, timing the cams, painted the rear wing, fitted my suspension, fitted the stainless brake lines and probably a number of other jobs like fitting my adjustable sway bars, exhaust etc. I also fitted an aluminum radiator purchased from the States and a high performance fan kit like the one sold by 928 specialists but purchased for half the price from another supplier. It also has solid rubber mounts, 928 Motorsports bump plates and a lower chassis brace. I am planning a few more mods but really want some more go now.

I would still have preferred a manual but that was not to be unfortunately. Of course today I could probably pick up a very nice GT or GTS in your neck of the woods for not much more than the total cost of my project but then it would need a further $3k to ship and then import duties etc plus putting right anything that was wrong and realistically, I would not get a chassis like this cheaply even Stateside [our cars have no corrosion whatsoever]..

The turbo kit can be seen on www.kuhnperformance.com .

Regards

Fred
----- Original Message -----
From: Wojtek
To: Fred Rourke
Sent: Sunday, February 15, 2009 9:14 PM
Subject: Re: Great to hear from you.

Great Looking Car Fred!

Those rear fenders look really superb, and these are Your old wheels right? Also, I like those clamped air ducts - I must get them as well. Are they factory or aftermarket? Also, who is selling those turbos? Not that I am interested in buying one but it would be fun to read about them. How much time it took You to get all that done? Very nice job Fred!

Wojtek

----- Original Message -----
From: Fred Rourke
To: Wojtek
Sent: Sunday, February 15, 2009 8:56 AM
Subject: Re: Great to hear from you.

W,

All these financial wizards did was capitalize on the fact that the more they sold the more they got. They threw investment fundamentals out of the window and then the shit hits the fan. Those responsible do not pay for the damage they have wreaked but we do! Hard earned money in the bank that has been saved sensibly now returns nothing. Then the pound sterling falls against the dollar which itself is nigh on worthless relatively speaking by most definitions as there is nothing to back it up. I shudder to think where all this is leading to but if we are not careful we wil end up owning worthless pieces of paper with numbers stamped on them that you cannot count [like Zimbabwe].

There can be little doubt that future generations are going to be saddled with all this toxic debt and I really feel for my kids who are just about ready to enter the work phase of their lives. Inevitably I am going to have to help them out and that means that any hope of retiring early or going on to do other things is trashed. Worse still, with oil prices now depressed my negotiating position is non existent and I just have to hope that my company does not jettison me too early as they may well do if prices drop any more. Of course there will be a back lash as the impact of lack of new investment hits home and the supply and demand scenario autopilots itself back to another end of the scale.

The latest 91's are now fitted with Porsches double clutch gearbox [not BMW]. Believe it or not Porsche had a prototype of this gearbox designed a built some 10 years ago apparently- I just forget what car it was in but it was not in a Porsche. Cars fitted with this system are amazingly quick on acceleration, especially 0 to 60 type of thing.

I like what Dave Roberts is trying to do but the fact that he cannot seem to get it to market deflates the whole affair- especially when there are no updates or anything. He should have simply kept quiet until he had a viable package. I think the twin screw concept is a good way to go simply because it would better suit the auto gearbox configuration but I also like the twin turbo concept that is now being offered as it is free power but at $11k ex works it is somewhat expensive although not bad if you consider what is in the package.

Regards

Fred

Thank You Fred for all the time You have put into sharing Your knowledge with me, and others who may read this post.