GT500 Track Performance

[NipSC4328]

Try an IMSA race weekend and see drivers push a car (seriously prepped at that) as far as it can go.

Not to change the subject, the pace car at today's IMSA race appeared to be a GT 500, was it?

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[SCCA Racer #75]

On Billy Johnson's IG someone asked why it (GT mk II) didn't have carbon wheels. He answered that the "car has slicks and Michelin does not make 20" slicks to fit on the carbon wheels"

Yet the GT350 uses the same tire on both the Carbon and Aluminum wheels.

And even it was true its just another reason you DON'T want carbon wheels for REAL track use, since they would require a bespoke tire and only that tire.

The reason the GT mk II is not on Carbon wheels is because Michelin (nor any other manufacturer that I'm aware of) makes a 20" slick. Most are 18's, and a few 19" sizes. It has nothing to do with needing a 'unique tire' for the CF rim vs. Alum wheel.

Best Regards,
Dave

 

[BillyJRacing]

EVERY race team would use carbon wheels if they were allowed to by the rules. The competitive advantage of the stiffer wheel (and a little lighter) is so significant that you can't compete against it with an aluminum wheel. It's about 1 second faster for most tracks:

https://motoiq.com/tested-carbon-revolution-carbon-fiber-wheels/

Read the article. You don't need to go "10/10ths" on a track to yield or notice a benefit. You can feel the difference at 40mph.

I've seen numerous Al wheels get grooves worn in the barrel from rocks. That's not a uniquely CF problem. CF wheels will also take hits far better and will not yield, crack, or break for a given load that yields and damages an Al wheel. And no, CF wheels don't "explode" or "shatter".

Now if you're an aluminum wheel manufacturer, you wouldn't want this to be well known or accepted because it would affect your own sales. Some might even lobby against allowing them in competition because of it, out of unjust and irrational fears.

Carbon monocoque cars are becoming more prevalent in lower levels of pro racing. Who knows if carbon will get past these false stereotypes in racing or if the big aluminum wheel guys successfully keep them out... Food for thought.

 

[nametoshowothers]

I laid out why cost is a big factor in the choice to either use or shelve a set of high dollar CF wheels. No hidden agenda there or attempt to shift the crux of the discussion.

Delicate? Sure they are. Their advantage over that of an aluminum wheel besides weight reduction is tensile strength where they do very well. Yet they are very poor when it comes to toughness (or hardness). They don't perform very well when it comes to abrasion - witness the circumferential grooves cut into the barrel of a given CF wheel when a rock is trapped under the caliper. You don't have to cut very deep before cutting through any number of layers which can also lead to delamination.

What's up with fractions and my understand as to how they work? Lol, son you are apparently out of the loop as to how the 10/10ths fraction is used with respect to how an automobile can be driven, typically in an on-track environment. Plenty of drivers have pushed a given car to as far as it can be pushed for more than "split second." I'd suggest you need a refresher in this case. Try an IMSA race weekend and see drivers push a car (seriously prepped at that) as far as it can go.

Hack - I get it, you're a contrarian. Spend some time embedded with a team in a serious race environment. Acquire a sense as to cost for a given race weekend. You'll see why teams don't use fiber when it comes to rolling stock. They sure do look pretty on a street car though!

Carbon fibre is not as delicate as you make it. The structure of multiple layers with resin means that the failure is more gradual than one would suspect.

There is a reason that all drivers in serious racing trust there life to monocoque carbon fibre tubs. I have seen fernando alonso barrel role into wall and get out and walk away. The tub was all intact

I would trust cf wheels

 

[Hack]

Delicate? Sure they are. Their advantage over that of an aluminum wheel besides weight reduction is tensile strength where they do very well. Yet they are very poor when it comes to toughness (or hardness). They don't perform very well when it comes to abrasion - witness the circumferential grooves cut into the barrel of a given CF wheel when a rock is trapped under the caliper. You don't have to cut very deep before cutting through any number of layers which can also lead to delamination.

I just wanted to talk about this part of your post. Aluminum is not very tough or hard. Aluminum doesn't have an endurance limit - meaning it will always fail if it goes through enough load cycles. And aluminum is notoriously soft compared to steel. Yet aluminum is commonly used in wheels.

So while I agree that carbon fiber is not hard (I don't really know about its toughness), I'm not sure how important hardness is to wheels. I don't typically see wheels made from hard materials.

My assumption is that carbon fiber is light enough that the wheel can be "over built" to be much stronger than it needs to be and still gain a significant benefit in weight reduction. AFAIK this is why people have raved about the performance of cars with CF wheels. The stiffness and light weight translates to amazing/impressive feel for the road. Feel seems to be one of the key things that drivers want - especially for driving on a road course.

You said I'm a contrarian and maybe I am. I mostly want evidence of things. Sometimes a statement will trigger me because it doesn't jive with the evidence I'm aware of. And in that case I tend to ask questions - and maybe argue a bit too much.

 

[JT1]

I think this post is off the rails. Point is for most of us that are paying to drive fast, not being paid to race, the cost is prohibitive considering that things can go wrong, either on track or during the tire mounting process.

I was at a track event where a bunch of fairly well heeled Porsche guys were discussing Carbon brakes (yes I knoiw a slightly different subject), but the consensus was it was cheaper to go faster to buy a whole dedicated track car, than to track a street car with Carbon brakes. I think we are getting to that point here. If you really want to go quicker (in your meaningless DE event), there are easier cheaper ways to do it.

 

[Hack]

I think this post is off the rails. Point is for most of us that are paying to drive fast, not being paid to race, the cost is prohibitive considering that things can go wrong, either on track or during the tire mounting process.

I was at a track event where a bunch of fairly well heeled Porsche guys were discussing Carbon brakes (yes I knoiw a slightly different subject), but the consensus was it was cheaper to go faster to buy a whole dedicated track car, than to track a street car with Carbon brakes. I think we are getting to that point here. If you really want to go quicker (in your meaningless DE event), there are easier cheaper ways to do it.

I think the difference is that wheels aren't normally a wear item like brakes are. I've never had more than cosmetic damage to any wheel I've ever owned, but I've replaced brakes lots of times. I would much rather see CF wheels than carbon ceramic brakes - if I were making that choice.

The cost for CF wheels is prohibitive for me (and maybe for you), but not for others. The GT500 track performance and feel will be significantly better with the CF wheels than with aluminum, so to me talk about the CF wheels is on topic for a GT500 track performance thread. CF wheels to me are like any other high performance option/item - it's a personal decision whether it's worth it or not. Most reviewers of the GT350R said the car was amazing and significantly better than the GT350. And we all know wheels and tires were the biggest difference between them.

 

[JT1]

I think the difference is that wheels aren't normally a wear item like brakes are. I've never had more than cosmetic damage to any wheel I've ever owned, but I've replaced brakes lots of times. I would much rather see CF wheels than carbon ceramic brakes - if I were making that choice.

The cost for CF wheels is prohibitive for me (and maybe for you), but not for others. The GT500 track performance and feel will be significantly better with the CF wheels than with aluminum, so to me talk about the CF wheels is on topic for a GT500 track performance thread. CF wheels to me are like any other high performance option/item - it's a personal decision whether it's worth it or not. Most reviewers of the GT350R said the car was amazing and significantly better than the GT350. And we all know wheels and tires were the biggest difference between them.

The cost of ONE SET of wheels isn't that cost prohibitive [edit for clarity, by that I mean the initial cost of the CF track pack]. I submit that anyone that can afford multiple sets, or to throw away CF wheels when they get damaged, are not driving GT500s at DEs.
If GT500s haven't stolen all the driving enthusiast press, it will be interesting to see if anyone compares back to back same day the 2019 GT350 with Cup2s with the GT350 R with the cup2s and CF wheels.

I guess we will probably see a GT500 comparison, with and without the CF package, those results will be interesting too.

 

[Epiphany]

Carbon fibre is not as delicate as you make it. The structure of multiple layers with resin means that the failure is more gradual than one would suspect.

There is a reason that all drivers in serious racing trust there life to monocoque carbon fibre tubs. I have seen fernando alonso barrel role into wall and get out and walk away. The tub was all intact

A carbon fiber wheel used in service in a racing environment is indeed delicate and needs some very special attention. And CF failure isn't gradual it is imminent and rather spectacular. Cracks, etc, may be easy to see in other materials but not so much in a fiber weave and even more so when painted such as on the GT350R. You are likely not to see fissures beneath the surface of CF. It is widely understood that CF has a high strength to weight ratio - hence the performance advantage over that of a heavier wheel. But once the matrix is compromised (inadvertent high impact from curbing at a poor angle at speed, large pothole, etc) the wheel needs to be repaired if possible or replaced - at fairly high cost. That said, CR makes the wheels to Ford specification and I hold that in high regard. The wheels have no doubt passed every durability test Ford deemed necessary. From a theoretical standpoint they make sense and they absolutely have the potential to increase suspension module performance. Sorry (Hack), the issue that trumps the tech here, and its a big one, is cost and it cannot be avoided.

And we are talking about wheels here, not monocoque carbon fiber tubs. They are designed for certain aspects and in that regard the material performs very well. And in that environment we are talking uber expensive.

So while I agree that carbon fiber is not hard (I don't really know about its toughness), I'm not sure how important hardness is to wheels. I don't typically see wheels made from hard materials.

My assumption is that carbon fiber is light enough that the wheel can be "over built" to be much stronger than it needs to be and still gain a significant benefit in weight reduction. AFAIK this is why people have raved about the performance of cars with CF wheels. The stiffness and light weight translates to amazing/impressive feel for the road. Feel seems to be one of the key things that drivers want - especially for driving on a road course.

Again - I'm not here to argue that a lighter wheel doesn't perform better or at least have the potential to do so. Nobody is arguing that a lighter wheel couldn't "feel" better either as I'm quite sure they do.

My point about hardness had to do with impact resistance on the wheel face, typical lip damage, or barrel damage from an object trapped underneath the caliper. This is the type of damage that GT350R owners will or have witnessed. And it is cost, sorry but you can't look the other way here, that erases the benefit for many that are likely never to even track their car and thus utilize the performance benefit.

I think this post is off the rails. Point is for most of us that are paying to drive fast, not being paid to race, the cost is prohibitive considering that things can go wrong, either on track or during the tire mounting process.

I was at a track event where a bunch of fairly well heeled Porsche guys were discussing Carbon brakes (yes I knoiw a slightly different subject), but the consensus was it was cheaper to go faster to buy a whole dedicated track car, than to track a street car with Carbon brakes. I think we are getting to that point here. If you really want to go quicker (in your meaningless DE event), there are easier cheaper ways to do it.

And there you have it. This is back to my initial point that was then challenged with the statement that "You are changing the discussion to cost, serviceability and cosmetic damage rather than talk about the strength of the rims." I agree and have agreed, the CF wheels are fantastic in terms of a potential performance increase or improvement. My point is that for the typical road going car owner, the cost to benefit ratio shows them to be rather weak. Until the price drastically decreases this will remain the norm.

to me talk about the CF wheels is on topic for a GT500 track performance thread.

In the context of a performance-only discussion on the merits, I agree with you completely. Outside of that constraint, real world use exposes them as an exorbitantly high priced component that can be replaced by less expensive materials/construction with a loss in potential performance that most will never see.

]EVERY race team would use carbon wheels if they were allowed to by the rules. The competitive advantage of the stiffer wheel (and a little lighter) is so significant that you can't compete against it with an aluminum wheel. It's about 1 second faster for most tracks:

https://motoiq.com/tested-carbon-revolution-carbon-fiber-wheels/

Read the article. You don't need to go "10/10ths" on a track to yield or notice a benefit. You can feel the difference at 40mph.

I've seen numerous Al wheels get grooves worn in the barrel from rocks. That's not a uniquely CF problem. CF wheels will also take hits far better and will not yield, crack, or break for a given load that yields and damages an Al wheel. And no, CF wheels don't "explode" or "shatter".

Now if you're an aluminum wheel manufacturer, you wouldn't want this to be well known or accepted because it would affect your own sales. Some might even lobby against allowing them in competition because of it, out of unjust and irrational fears.

Carbon monocoque cars are becoming more prevalent in lower levels of pro racing. Who knows if carbon will get past these false stereotypes in racing or if the big aluminum wheel guys successfully keep them out... Food for thought.

Read the post. Nobody said anything about a 10/10ths benefit at any speed. It was worded that "the cost to benefit for someone not running them 10/10ths is rather high." Of course the improvement they can provide runs across the spectrum. Point was, the are an extremely expensive item for those that never exploit the delta between them and a typical aluminum wheel.

Nobody said that only CF wheels can suffer from barrel grooves. CF does "take hits far better and will not yield, crack, or break for a given load that yields and damages an Al wheel" in general and assuming they were designed to perform this way. And since cabon monocoque keeps getting mentioned...

https://jalopnik.com/heres-how-carbon-fiber-absorbs-crash-energy-in-slow-mot-1578920092



CF is very strong when designed for a specific purpose and takes certain loads very well with respect to deformity or failure.

https://i.kinja-img.com/gawker-medi...ogressive,q_80,w_800/qumrdno5nqlspmwvuats.mp4

Step outside the intended window and CF doesn't perform so well.

https://i.kinja-img.com/gawker-medi...ogressive,q_80,w_800/o1oxmtbzkxdrr7f4giqc.mp4


And since everyone else has included areas of use beyond the GT350/GT500 wheel and with respect to the statement that "CF wheels don't explode or shatter - tell these guys that. CF "wheels" can and have both exploded and shattered. All inclusive statements opened the door here...




Ouch.

 

[Eritas]

If GT500s haven't stolen all the driving enthusiast press, it will be interesting to see if anyone compares back to back same day the 2019 GT350 with Cup2s with the GT350 R with the cup2s and CF wheels.

I guess we will probably see a GT500 comparison, with and without the CF package, those results will be interesting too.

How? The GT350 & 350R have different size wheels and tires. The GT350R & GT500 Carbon have way more Downforce than the base GT350 & 500.

 

[JT1]

How? The GT350 & 350R have different size wheels and tires. The GT350R & GT500 Carbon have way more Downforce than the base GT350 & 500.

That even with those differences the difference will still be negligible.

 

[V00D00]

Cant say something is negligible if you can feel a difference immediately

 

[JT1]

Cant say something is negligible if you can feel a difference immediately

I was trying to avoid the wrath of the GT350 R religion, but to me the difference was negligible. On track, NJMP Lightning. Maybe there's some magic track somewhere that has a much bigger difference.

 

[the5]

The reason the GT mk II is not on Carbon wheels is because Michelin (nor any other manufacturer that I'm aware of) makes a 20" slick. Most are 18's, and a few 19" sizes. It has nothing to do with needing a 'unique tire' for the CF rim vs. Alum wheel.

Best Regards,
Dave

Correct me if Im wrong here.

But it looks like in the Photos the car comes with Michelin Slicks on the wheels, Why not Make those wheels out of carbon and Mount the slicks to those?

 

[the5]

EVERY race team would use carbon wheels if they were allowed to by the rules. The competitive advantage of the stiffer wheel (and a little lighter) is so significant that you can't compete against it with an aluminum wheel. It's about 1 second faster for most tracks:

https://motoiq.com/tested-carbon-revolution-carbon-fiber-wheels/

Read the article. You don't need to go "10/10ths" on a track to yield or notice a benefit. You can feel the difference at 40mph.

I've seen numerous Al wheels get grooves worn in the barrel from rocks. That's not a uniquely CF problem. CF wheels will also take hits far better and will not yield, crack, or break for a given load that yields and damages an Al wheel. And no, CF wheels don't "explode" or "shatter".

Now if you're an aluminum wheel manufacturer, you wouldn't want this to be well known or accepted because it would affect your own sales. Some might even lobby against allowing them in competition because of it, out of unjust and irrational fears.

Carbon monocoque cars are becoming more prevalent in lower levels of pro racing. Who knows if carbon will get past these false stereotypes in racing or if the big aluminum wheel guys successfully keep them out... Food for thought.

Now the advantage you talk about (1 second). Is that able to be felt by the above average driver or only one of your caliber?
It seems that if we are really talking about flexing of wheels that only a true Pro could feel and use the difference.

My original jab at carbon wheels was meant to be as someone that tracks their car regularly will not want carbon wheels as they are too prohibitive and when you track cars you need lots of wheels and tires. It was NOT against their performance gain.

Before this thread became a Carbon wheel debate, it was meant to be about actual track performance. As you would know best about the track performance of these cars, I would love to hear anything you are allowed to say

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