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The CF material cost, is a fraction of the total cost, really, for something complex like a wheel.
Simple panel, non structural things...they'll be a few bucks cheaper, sure.
Lots of experienced labor, and lots of it, will still be involved.
Far from melt it pour it, heat treat it, machine it, polish it in 6hrs...and 98% requiring nothing more than a hand to move it from machine to machine cheaply.
The wheels were the result of applied research by SPEEDLINE in collaboration with the racing department of Fiat- Abarth, Enichem and IDC.
The objective of this research was to propose and to evaluate the construction of a wheel-rim made from carbon fiber for rally-use on "gravel surfaces", this being the most extreme use condition, with the aim of achieving a significant weight saving compared to the typical magnesium-alloy rims, which were normally used for rally-events.
The composite rims were made from :
Carbon-fabric sheets impregnated with epoxy resin;
A honeycomb and aluminum centre flange with an additional adhesive protective film to withstand the high temperatures generated by the brakes;
Special resin formulas at the wheel rim edge to reinforce this critical area.
Due to these innovative materials and processing methods, weight savings of 40% and a total weight of 6 kg per wheel were achieved for a gravel rim measuring 8x16 ", capable of withstanding the stresses imposed by a rally-car with a power of 600 hp.
The reality of racing is that wheels hit things, a lot.
Besides, losing unsprung weight is a good thing, but dramatically decreases in benefits every time you upshift..making it nearly pointless above 2nd gear.
No, that is not true at all... you are confusing losing weight of the flywheel, with losing weight on the wheel. if the weight is lost equally , as it would be vs a regular wheel, its barely worth 20% more as if it was sitting in the car. so, ignoring the unsprung weight , (which is good for handling on bumpy tracks, or very tight transitional tracks), this weight loss is an expensive way to loose 32lbs plus 20%, or 40lbs overall effectiveness on acceleration at ANY vehicle speed or ANY gear!
The reality of racing is that wheels hit things, a lot.
Besides, losing unsprung weight is a good thing, but dramatically decreases in benefits every time you upshift..making it nearly pointless above 2nd gear.
Leno seems a little unimpressed after a test drive. Wasn't there another carbon fiber rim manufacturer (Dymag?) that had a few breakages and then became defunct?
Different design though
What about just getting some BBS E85's?
It is intriguing though.
nice demo with the gyros, but look at the movement they are making! doesn't anyone understand that when you are on the track, that wheel is only moving a few degrees.... the feel , or stiffness is the car sticking to the road, attaching the entire mass of the car to the road, ever notice how light steering is on a rainy day?
folks, its 5 lbs a wheel in this instance..... 20 vs 15lbs. that's 5lbs.... its like 6 If it was sitting in the car as far as acceleration. Everyone seems to forget that this is the WHEEL ONLY!! the tire is still spinning at a much greater diameter. 25" or so. the wheel is lighter , yes, but the weight is reduced overall. most of the weight comes from the center actually, so its effects are muted...... if it was all coming from the edge (barrel) of the wheel, it would be like 40% more sitting in the car (translational, or "linear" weight")..... if its over the wheel evenly, its half that (20%).... and if that weight is naturally more weighted In the center, which it is... its less than 20% for its acceleration effects.
5lbs =6lbs which is 1lbs more net effect as if it was sitting in the car.
that's 4lbs in the car..... that's like a big dinner sitting in your stomach...... don't think that you are going to feel that folks as far as performance as far as it rotational effects........ but the 5 or (6lbs effectively) per wheel is something to save, for sure, and that's 25lbs overall..... but, I can think of other cheaper ways to save 25lbs on a car!
Sorry, not correct. Take a bicycle tire and hold the axle. Then spin the tire and try to move the tire in any direction. The faster the tire spins the harder it is to change direction. Reducing this mass by that much makes turning easier and under steer is reduced.
Braking that rotational mass is in addition to the weight of the car as well, so stopping distance is reduced.
Many benefits to this. I want a set!
braking is the same as acceleration. its all part of the inertial mass of the vehicle... both the rotating plus the linear mass. basically , this is a very very small part of the entire 3000lb+ car and the benefit has very lttle effect. (following the physics.... following the hype? well, then its a great improvement )
yes, the gyro effects are something to consider, but it wont effect "understeer" that is a condition of weight transfer and grip , not gryo effects for the most part. remember, movements of the wheel are very very tiny.... watch my hard turns at the track, like turn 4 at laguna. my hands move 90 degrees.. the tires move only a small fraction of that, almost hard to see the tires actually turn its so small. we are not drifting here folks, at full lock!
Originally Posted by UpFixenDerPorsche
Noooooooooooooooooooooooo ... !
You're looking (validly) at only the rotational inertia issue. But the real benefit is the road-holding benefit: lighter wheels track the road surface more closely: = better traction all round: braking, accelerating and cornering.
You're looking only at the rotational inertia aspect ie that the reflected rear wheel rotational inertia (to the crankshaft) is the inverse function of the square of the overall gear ratio.
Got that?
Thought so.
Yes, the lighter weight will follow the road more closely and easier to control for the suspension. but, on a smooth surface, this is not going to be an issue. plus, there is some added stability for a lighter wheel , fighting lockup. not that I would want a heavier wheel for that purpose, but it is a side benefit.
the reflected inertia to the engine on the flywheel would have different effects in different gears. ..... this is not the case in the rear wheel, as the speed is increased proportionally with the higher gear ratio, for a given RPM, which is reduction the multiplication effect.
get that?
bottomline, the 5lbs you save with this light wheel is rotationally less than if 6lbs was siting in the car. big deal!! gyroscopically, its more effective and that's gong to depend on how fast you are driving and the type of track you are on. (bumps, tight transitional turns, lots of hard fast steering imputs, etc))
Just a thought......
And correct me if I'm wrong...but..
CF Wheels will not assist in dissipating heat...might be an issue in high performance applications..
Just sayin'
Michelin made composite wheels 1970-75 for the SM - 9.5lbs in 400mm dia. Article in Hemmings from 2007. I actually know a guy with an SM, and the wheels look just like alloys in silver finish. Carbon reinforced resin, with some steel plates around the bolt holes. One major disadvantage was where do you get 400mm tyres? Many people apparently tried fitting 16" tyres (400mm=15.74") with bad results! Hemmings reported a sale of a set at $7000 in Europe in 2006.
jp 83 Euro S AT 56k
Michelin made composite wheels 1970-75 for the SM - 9.5lbs in 400mm dia. Article in Hemmings from 2007. I actually know a guy with an SM, and the wheels look just like alloys in silver finish. Carbon reinforced resin, with some steel plates around the bolt holes. One major disadvantage was where do you get 400mm tyres? Many people apparently tried fitting 16" tyres (400mm=15.74") with bad results! Hemmings reported a sale of a set at $7000 in Europe in 2006.
jp 83 Euro S AT 56k
you kind of defeat the purpose of lightening the rotating weight, when you go too small on the rim, AND the lower profile tires have better handling characteristics on street racers.
Originally Posted by 928 at last
Just a thought......
And correct me if I'm wrong...but..
CF Wheels will not assist in dissipating heat...might be an issue in high performance applications..
Just sayin'
. Yep, I would be worried about that as well. that's a HUGE heat sink that is suddenly gone. however, many high performance brakes systems have very loosely connected 2 piece brake rotors. they actually rattle around... don't know how much heat can pass the little connectors to the rotor centers. However, those type of systems usually have good cooling ducting
Dont forget the time of the michelins - 16" rims were not at all common on street cars then - nearly 10 years later the 928 came out with 16" rims.
jp 83 Euro S AT 56k
10-18-2014, 02:39 PM
