Video: Jamal Hameedi Interview

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[Tob]

Finally!:thumbsup:

Some interesting commentary for sure. Especially when Jamal stated that they never even thought about putting in a TR6060 just because "they are way too heavy." So ultimate torque capacity was sacrificed due to weight considerations. No built-in over capacity beyond typical safety factoring. With that compromise in mind one thing is for certain...this new gearbox better shift well at the very least. Hopefully the shifter was given more attention than even that of the regular Mustang GT.

The use of a two-piece steel driveshaft is a bit of a letdown. I hope we can get more detail as time passes because to be quite honest, I'm struggling with Jamal's comment that the engineers couldn't get a CF shaft that was "stiff enough." From Tom Wilson's article of a couple of years ago we learned that the 662 hp, 200+ mph car, was using a CF shaft. Why?

It is lighter, stiffer, and transmits torque better than the two-piece aluminum (Note - this was an error as the GT500 was using steel and not aluminum) shaft it replaces. The carbon fiber is not so much for lightness as stiffness. It was the only way to get the bending frequency of the shaft above the rotational speed driven by the 200-mph vehicle speed, according to its lead engineer, Brian Zorman.

Another interesting tidbit from that article.

The '13 one-piece carbon-fiber driveshaft was the only way to accommodate the new GT500's higher torque and road speed. This saves nearly 15 pounds, can transmit 36 percent more torque, and eliminates the friction of the center support bearing used in earlier GT500s.

Saves weight, has the ability to transmit more torque, and has the potential to eliminate friction when in comparison to a two-piece steel shaft with a center support bearing. In other words, a CF shaft represents everything Ford was looking to accomplish with the GT350. Yet we now have commentary that Ford couldn't get one "stiff enough" for use behind a similar wheel base vehicle that has less horsepower/torque, and undoubtedly a lower top speed.

Suddenly, cost rears its head (but not openly). Especially given the context Jamal provided in that same article.

All told the steel inserts cost more than the tube, leading Jamal to joke, "We managed to design steel that's more expensive than carbon fiber!"

What is most ironic is that the pre-production GT350 used for the reveal in Las Vegas, looked to be sporting a CF shaft. Hopefully, Ford "found" a way to get one stiff enough for the "R" model so that it can be retrofitted back and onto a standard GT350. Arrgh...

 

[2L8IWON]

Good points Tob. Thanks for your insight and time!

 

[ponyboyisaac]

Good stuff. I would have asked about the 5.2s official red line!

 

[01SVTSnake]

I wonder if it was for more NVH reasons from the 5.2L and costs. CF shafts are plenty strong. Ford has been saying people will be surprised how affordable this car will be. I would tend to guess the R version will have a CF shaft and hopefully it can be retrofitted to the base 350

 

[08KR525]

Jamal's comments about cutting weight wherever they can only to reintroduce the two piece ds in the car didn't add up to me either. I have a hard time believing that cf isn't "stiff enough". It appears the bean counters got ahold of this. The aftermarket will correct it, but it should have come from the factory with it already.

 

[Devious_Snake]

I watched it twice, and he danced around some of those answers. I know he was BS'ing some of that, so let's wait and see.

 

[5 DOT 0]

Nice job on the interview.

A couple of more hard ball questions I would have asked:
1. Carbon Rev has announced that they have inked a deal with a MAJOR manufacturer to supply CF wheels on a production car. Are they going on the GT350 as on option?
2. It would seem obvious that a Laguna Seca type version of the GT350 is in order. Any plans for a GT350R?
3. Were CCB's considered?
4. What consideration was given to rear brake ducting?

I also agree about the CF driveshaft explanation. I'm sure he's telling the truth but maybe only half of it. ;-)

 

[Tob]

A driveshaft is a rotating shaft that transmits power from the engine to the differential gear of a rear wheel drive vehicles. Driveshaft must operate through constantly changing angles between the transmission and axle. High quality steel (Steel SM45) is a common material for construction. Steel drive shafts are usually manufactured in two pieces to increase the fundamental bending natural frequency because the bending natural frequency of a shaft is inversely proportional to the square of beam length and proportional to the square root of specific modulus. The two piece steel drive shaft consists of three universal joints, a center supporting bearing and a bracket, which increase the total weight of a vehicle. Power transmission can be improved through the reduction of inertial mass and light weight. Substituting composite structures for conventional metallic structures has many advantages because of higher specific stiffness and higher specific strength of composite materials.

Composite materials can be tailored to efficiently meet the design requirements of strength, stiffness and composite drive shafts weight less than steel or aluminum of similar strength. It is possible to manufacture one piece of composite drive shaft to eliminate all of the assembly connecting two piece steel drive shaft. Also, composite materials typically have a lower modulus of elasticity. As a result, when torque peaks occur in the driveline, the driveshaft can act as a shock absorber and decrease stress on part of the drive train extending life.

Merits of Composite Drive Shaft
1. They have high specific modulus and strength.
2. Reduced weight.
3. Due to the weight reduction, fuel consumption will be reduced.
4. They have high damping capacity hence they produce less vibration and noise.
5. They have good corrosion resistance.
6. Greater torque capacity than steel or aluminum shaft.
7. Longer fatigue life than steel or aluminum shaft

From here.

When the length of a steel drive shaft goes beyond 1500 mm, it is manufactured in two pieces to increase the fundamental natural frequency, which is inversely proportional to the square of the length and proportional to the square root of the specific modulus. The nature of composites, with their higher specific elastic modulus, which in carbon/epoxy exceeds four times that of aluminum, enables the replacement of the two-piece metal shaft with a single-component composite shaft which resonates at a higher rotational speed, and ultimately maintains a higher margin of safety. A composite drive shaft offers excellent vibration damping, cabin comfort, reduction of wear on drivetrain components and increases tire traction. In addition, the use of single torque tubes reduces assembly time, inventory cost, maintenance, and part complexity

Since carbon fiber epoxy composite materials have more than four times specific stiffness of steel or aluminum materials, it is possible to manufacture composite drive shaft s in one-piece. The composite drive shaft has many benefits such as reduced weight and less noise and vibration

From here.

Graphite composites (graphite fibers/composites are sometimes called carbon fibers) are ideally suited for applications where high stiffness and low weight is required. Most metals used for structural applications have very similar specific stiffness, which is around 100 x 10^6 psi. If an application demands high stiffness and lightweight, graphite composites are the only material of choice.

Examples are:

Spacecraft structure
Aircraft structure
Drive shaft for trucks and high performance vehicles
Machinery rollers
Sail boat mast and boom
Bicycle frame
Machinery components that experience high acceleration & require stiffness & precision

From here.


[video=youtube;hjErH4_1fks]https://www.youtube.com/watch?v=hjErH4_1fks[/video]



In the video below, fast forward to 11:02...
[video=youtube_share;kaoq8Mc4xxw]http://youtu.be/kaoq8Mc4xxw?t=11m2s[/video]

Just an example of what BMW is using CF for, here.



I'll stop. So Ford couldn't get a CF shaft that was "stiff enough?" Come on. I would have been less disappointed with a response like "when we weighed the overall benefit of using a CF shaft in this specific application we found that a two-piece steel shaft was able to meet our performance goals and come in at a much lower cost which is in keeping with our philosophy about producing a vehicle that provided the best bang for the buck."


Thinking through the '15 transmission/driveshaft philosophy (which may or may not have influence on the GT350 in this case), I wondered about the use of a "Guibo" joint and what role it played in conjunction with a CF shaft. I wrote Kelly at BMR this morning looking for a photo of his joint as I knew had added an aluminum driveshaft to his 2015. Of note, and as Kelly put it "that guibo is only on the Performance Pack Manual trans car.....the auto GT does not have that joint." Here's a photo of the joint which Ford is using between the front of the driveshaft and the fixed flange at the rear of the transmission. Many aftermarket shaft manufacturers are eliminating this joint when adding their shafts. It is assumed there would be an NVH increase.

Any, I'm thinking that the use of a CF shaft in this application would indeed negate the use of a guibo joint as the material properties in the CF shaft have an inherent damping capacity as well. A CF shaft with a guibo may have been counterproductive. So what could be the issue? The rear subframe is isolated (and hence the axle gear case) from the body via bushings (which are presumably stiffer on the GT350). The transmission has been reworked for this application. But the engine needed a lot of attention due to the FPC design. I'm just not seeing a "stiffness" issue that couldn't have been overcome (putting cost aside for the moment which may not be entirely fair). Was Jamal hinting at some sort of "delay" at high rpm when shifting due to the CF's ability to twist and recover? Was the "feel" of it just not right?

I hope he can elaborate.


ON EDIT:

I see that BMW's CF shaft maintains use of a guibo.