NineMeister

I mentioned this project in passing whilst posting about the restoration of Kermit, our viper green 964 Trophy Cup car.

This is a customer project to build his ultimate lightweight 964 Speedster. The story so far includes a full body & paint restoration & repaint including carbon bonnet & engine lid; full interior retrim in coffee leather & carpet with dark grey accent; KW suspension package, 993RS 6 speed gearbox with LSD; 964RS flywheel & clutch & a special 9m engine package including Motec engine management (as yet to be finalised).

With respect to wheels & brakes, our customer did a lot of work determining which parts would give the greatest weight saving, the result being that carbon discs, 6 pot calipers & Dymag carbon wheels ended up on the shopping list. Of course, to provide the power to make these calipers worthwhile the car has also been upgrades with a 4 channel 993RS ABS system.

I don't want to get sucked into another debate like on the Kermit thread, so although we think that this combination on a 964 is the first of it's type in the world, I'll correct that to a "probably the first in the World" and I'll let other people post their own carbon brake upgrades to prove us otherwise. I know that Robert Linton has carbon brakes & boron calipers on his GS roadster, so the difference here is that this kit is made from parts that are commercially available. Either way, it's a pretty special combination that I doubt will be repeated on a 964 too often , especially given the cost of the parts....


Here's a few photos of the car on the ramp with the brake assembly underway.

Atgani

What size dia/thickness discs are those ?

I hope the bells are made out of a nice lightweight material ? (unlike the original stainless PCCB items)

P.S. Received your response to my message, I'll respond in due course

chris walrod

are the rotors carbon-carbon or carbon ceramic?

Only bummer part is the use of the wheel spacer -- nice bit of kit otherwise!!

Duck

Sounds like your customer has just tooooooo much money.

NineMeister

The rotors are carbon-carbon, 380mm on the front and 365mm rear. The wheel spacer is a red herring, we only fitted it to hold the hub in place whilst we spun up the disc to check the installed run-out. The bells are CNC machined hard-annodised "aircraft alloy".

964russ

Carbon wheel!
Ive heard horror storys from friends with race bikes.
Are the car wheels better/stronger than bike wheels?

Atgani

There was one well documented failure. Pictures here : -

https://rennlist.com/forums/wheel-an...downsides.html


Dymag modified the construction after this failure and to my knowlege there have been no other documented failures.

This is the reply from Bill Koenig from Dymag-USA regarding the destroyed Dymag wheel :

I handled the situation of the broken center for Dymag.
The wheel was broken at a track event in Mexico the customer runs full slicks all the time at the track and these wheels had about 60 full track days on them unfortunately they were not checked after each event and the spoke developed a hairline crack that started from the engraving on the back of the spoke. They stamp the back of the spokes with the model number of the mold. The crack propagated causing the spoke to break in half and transfering the weight load the the remaining spoke as he continued to run the wheel then broke as he was in a straight line braking zone at the end of a staright away.
The damage to the car was minimal about $10k and Dymag paid for the damage and the full set of wheels the car was back at the track in 10 days time and the customer was fully reimbursed.
The magnesium center was sent to a testing lab here in the U.S. to make sure that it had all the properties it should have for cast magnesium the test results came back with passing results and upon inspection of the wheel it was determined that fatigue was what caused the failure.

These wheels have been used in racing by a BMW British Touring car team that competed two season with no problems and won a 24 hour race as well as a podium in a 12 hour race and many sprint races.
GMG used the wheel for two full season on the Time attack series with no issues and even said they gained time at Infineon as they could drive over the curbs much harder then they could with the BBS race wheels as the Dymag absorbed the impact and the BBS would have bent

Dymag has changed the center disc material to a forged exotic metal called Magnalium this is a hybrid of Magnesium and Aluminum and contains the best properties of each. The magnesium offers the lightweight and strength and the forged aluminum offers the non-corrosive property that is one of the downfalls of magnesium.

This new center disc material will be on every new Dymag wheel starting delivery next month we stopped taking oders in August so that we could be sure of the testing of the new material I will attach the updates I recived on the testing but you can be sure that DYMAG wheels are properly tested to the multiply requirements of TUV,JWL,DOT and they have passed independent test by General Motors in both the Cadillac and Corvette divisions as well as Mclaren.

I want people to understand that many brands of wheels have failed at some point but track events is where you hear and see about them but what you need to know and understand is how does the company stand behind its product and I think you can see from this story that Dymag handled this customer quick so that he was back on the track at his next event.

Following is the test results in progress on the new Magnalium center Dymag wheels these same test were used in the original magnesium centers as well and then you will read they have done real world testing on the track at SPA and Silverstone in the last month.

The wheel has now completed 1 million cycles of cornering fatigue comprising of 500,000 cycles at 550kg static wheel load (2,200kg gross vehicle weight) and then 500,000 cycles at 600kg static load (2,400kg gross vehicle weight). The test load has a large safety factor incorporated into the calculation, which gives a test load of 2,200 ft lbs at 550kg static and 2,500 ft lbs at 600kg static. The British Standard test duration is only 150,000 cycles and so completing 1 million cycles at these loads with no damage or air-leakage is an impressive result." The radial fatigue test has thus far completed 500,000 cycles at 550kg static load, which gives a test load of 1,237kgs. This is the required British Standard test duration. This test will run on to a million cycles, which is twice the required duration and then assuming there are no problems; we will increase the load and retest.

As you have read the testing is very extensive and they used this product for two years in racing before they introduced it to the market in 2006 there have been some issues with leaking and the centers making noise but it was all due to the old technology magnesium centers so in an effort to eliminate these problems more testing and the development of the Magnelium has come to pass.

The new centers will be avilable from December and Dymag stands behind its prodcut and its customers. I have been in the wheel business 16 years and I have run Dymag wheels on my 996 GT3 at the track for two years.

Please understand I am posting this information to clear up any misunderstanding of this wheels broken center which has been addressed and corrected and you can see that the carbon fiber held up very well under the conditions.

Good Luck to you in you choice for wheels and I hope this clears things up about Dymag!

Robert Linton

Has Dymag gone into administration in UK?

demonfish

I believe so yes, very recent too. third time i think.

Nski

Yup its gone into admin.....was gonna ask Colin lastnight if he bought the last of the stock? heard some guys have near me but the 19" ones

pete000

Interesting it is the alloy centers that failed and not the carbon rim it self.

chris walrod

Colin -- is there any concern with you and/or the owner about the characteristics of carbon-carbon on the street related to minimum temps before they bite?

It depends upon the matrix of the carbon as to what their turn-on temperatures are, but generally speaking carbon-carbon friction materials need quite a bit of heat before they generate friction. Heat that typical street driving may never achieve.

elquiosc

An impressive project while expensive ... pay attention to this post!
Thanks!

Robert Linton

Chris:

Disks look like the carbon ceramic material produced by Surface Transforms in UK as opposed to the SGL material used by Porsche, Ferrari, Bugatti, McLaren, etc.

chris walrod

Hey Bob, hope you're well! -- the reason I asked. However, by the photos they do strongly resemble c-c construction. Could be wrong though.