D90 differences .... why?
- Thread starter Patch234
- Start date
pauljmcnulty
Active member
And your wheels are more desirable and far more valuable than D90's ....
I think the CS's were forged, the D90's cast. The CS's were the 'desirable' wheel.
There was a spate of CS's breaking on hard-driven cars a few years ago. Was that entirely down to them being skimmed? I thought there was a fatigue issue as well - certainly a few people said that they would be changing their CS's for D90's on the strength of it.
Oli.
There was a spate of CS's breaking on hard-driven cars a few years ago. Was that entirely down to them being skimmed? I thought there was a fatigue issue as well - certainly a few people said that they would be changing their CS's for D90's on the strength of it.
Oli.
blade7
Well-known member
Someone had a set for sale near to me recently, 3 were like in the OP's pic but one had obviously had a fair old skim, the tyres were around 10 years old too. I said I'd be interested around £300 and I'd look for a replacement for the thin one, someone paid over double that [
]George Elliott
New member
Oli, you are correct, CS's are forged, and D90's are cast.
There is no way you would break either in normal use, (excepting perhaps S.Loeb could destroy one on a hidden rock on the Acropolis) and as Markk says, the unsprung weight is an advantage of the CS , and the reason for their development.
Difficulty though is I notice the 245 rear 16" tyres are becoming harder to find. (Conti or Bridgestone)
George
944t
There is no way you would break either in normal use, (excepting perhaps S.Loeb could destroy one on a hidden rock on the Acropolis) and as Markk says, the unsprung weight is an advantage of the CS , and the reason for their development.
Difficulty though is I notice the 245 rear 16" tyres are becoming harder to find. (Conti or Bridgestone)
George
944t
Just having my CS wheels refinished, never been skimmed and wont be.
Side note they are the same forgings as the bin lids or 928 wheels which I also have a set of which I think have been skimmed once so will be painted when I get them redone.
Side note they are the same forgings as the bin lids or 928 wheels which I also have a set of which I think have been skimmed once so will be painted when I get them redone.
Not to Forget the magnesium D90's on the C4RS
Diver944
Active member
The forged process produces a stronger wheel, so they were able to make it with less metal and thinner spokes, hence the light weight.
I don't have one in front of me but the spokes are only about 5mm thick which is half that of the normal Design90. Over the years many of these wheels have been kerbed and then refurbished, if the refurbisher simply skims the metal to remove the kerbing then gradually the wheel gets thinner and thinner. Add in 25 years of bumpy road surface or whacking the rumble strips on a trackday and the inevitable cracking of the spoke happens.
I have personally seen it once at a trackday and seen one or two pics of others on the forum. The other 10,000 wheels out there are fine
Indi9xx
New member
One of the Turbo's I am putting up for sale later this year was one of the first "Post S" cars to have the CS wheels fitted, unfortunately the original wheels were long gone so I had to buy a set of CS wheels for it.
The best set I could find had various areas of growth where the original anodised finish had failed and had to be carefully blasted to etch them, then etch primed and painted silver as I could not find a company who could properly refinish them to the original spec, but wanted to preserve them in a way that the paint could be removed and correct refinishing of them could be performed in the future.
The problem is that the anodising needs the right degree of polishing to refinish these wheels, where it is much easier to recreate the correct finish with the Fuchs polished and anodised rims, these should have a dull finish which is actually harder to recreate (its easy to get it to mirror finish than the dull silver of the originals)
You're spot on about the tyre issue, I could only find Bridgestone SO2 (N-Rated), TOYO T1R and some far eastern 3rd world tyre in this size, so in the interests of potential purist buyers went for a full set of Bridgestones in the right size and N Rated, even though I do not personally put any weight on the Porsche approval of N-Ratings and personally would have prefered ToyoT1R's if I was keeping her... At over £500 a set, plus chrome valves etc, I was not completely impressed with paying out for the wheels, the refurb and the tyres, but I think whoever buys the car will appreciate it.
That is of course if I ever get around to photographing her and putting her on the market! Of course that gets put off partly because it will open the the old chestnut of what to advertise it for!!
The best set I could find had various areas of growth where the original anodised finish had failed and had to be carefully blasted to etch them, then etch primed and painted silver as I could not find a company who could properly refinish them to the original spec, but wanted to preserve them in a way that the paint could be removed and correct refinishing of them could be performed in the future.
The problem is that the anodising needs the right degree of polishing to refinish these wheels, where it is much easier to recreate the correct finish with the Fuchs polished and anodised rims, these should have a dull finish which is actually harder to recreate (its easy to get it to mirror finish than the dull silver of the originals)
You're spot on about the tyre issue, I could only find Bridgestone SO2 (N-Rated), TOYO T1R and some far eastern 3rd world tyre in this size, so in the interests of potential purist buyers went for a full set of Bridgestones in the right size and N Rated, even though I do not personally put any weight on the Porsche approval of N-Ratings and personally would have prefered ToyoT1R's if I was keeping her... At over £500 a set, plus chrome valves etc, I was not completely impressed with paying out for the wheels, the refurb and the tyres, but I think whoever buys the car will appreciate it.
That is of course if I ever get around to photographing her and putting her on the market! Of course that gets put off partly because it will open the the old chestnut of what to advertise it for!!
Indi9xx
New member
Hmmm.. 2pack and celulose finishes can air dry and cure at close to summer day temperatures with a lot of ovens a paints being only set to ensure these kinds of temps all year round, with additional temperature only needed to speed curing by a set amount per degree of increase to oven temp.. this is obviously going to change from business to business depending on how the increased costs of running a hotter oven compare to the additional throughput they could put through their oven/booth due to the higher temperatures. But even then, the maximum temperatures are usually pretty low. Low enough to not endanger someone going in there while the item is curing.
Powder coating though might be a different thing all together, I have no idea how hot their ovens get, but I can find out from the place next door to the workshop. But would it get hot enough to cause a material alteration to the structure of a forged or cast wheel?
Some might even argue that if done in the right way, the process of heating and cooling of a wheel might even make it stronger in various ways with various trade offs... Such as either making the wheel less likely to crack or break, but more likely to deform, versus making it less likely to deform and more likely to crack/break.
A good example of these different properties might be aftermarket wheels for Porsche models, in particular I have seen very wide ones (9J plus) which seem to buckle on their inner edge over time with potholes etc.. This could be a sign that they are too likely to deform but with the trade off of being less likely to break like the wheels in the adverts in the 90's with broken spokes due to being "copies", so I might imagine, with destressing due to heat cycling, all our wheels might be becomming more likely to deform and less likely to break, but that might be traded off by vibrations causing an increase in work hardening.. It might even be that localised heat from brakes even cause an increase in case hardening of wheels, especially near the flange.
But I would guess that all of this might be such a small alteration to the physical properties of the wheels as to make no measurable effect.
Having said that, there are probably some very qualified people out there who might have time on their hands to actually give us some real predictive data on this subject.
There is of course the processes of plating and anodising and I have no idea what kind of temperatures might be involved there.
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