135 MPH driveshaft failure

No comment on the driver but this is relevant

http://www.tccoa.com/articles/tranny/transmission/page17.shtml

My '94 Crown Vic (civvy not PI) is speed limited to 106 mph due to the length of the one piece steel driveshaft. If memory serves, the PI models had a factory speed limiter of ~140 mph and either an aluminum or MMC (metal matrix composite) driveshaft to raise the critical speed of the driveline.

I never bothered with changing the speed limiter (or much else) on my car since it is/was a DD.

thestig99 wrote: Do we have any pics of the aftermath?

There don't seem to be any pics floating around. There is a YouTube vid of a V6 driveshaft letting go on the dyno: http://www.youtube.com/watch?v=1_AjKt-KSNU I can't find the exact conversation, but at some point the guy alleges it was showing 145 MPH when it let go, and a heavy duty aftermarket shaft went to 160 with no problems. There's also some talk about one failing at parking lot speeds.

So you guys are saying it's OK because the manufacturer put parts on the car that weren't up to the performance standards of the car? A simpler method would have been just to detune the horsepower of the car, but wait that would have made it slow. We want bragging rights AND WE WANT MORE MONEY.

What they did was the equivalent of putting a LS3 in a base Miata and then since they would be leaving the brakes and suspension stock they simply put a speed limiter of 70mph on the car.

carguy123 wrote: So you guys are saying it's OK because the manufacturer put parts on the car that weren't up to the performance standards of the car?

The parts WERE up to the performance standard of the car. The mfg installed a speed limiter to enforce the upper limit of that standard.

The owner removed the limit and excceded the factory rating.

It's E36 M3ty what happened but it's hardly Fords fault.

It's a v6 Mustang. Look at the target market for those. How many middle-aged female hairdressers are going to put the car through what he did?

Why are so many people defending E36 M3ty engineering? Honda makes hairdresser cars that don't explode. So do lots of companies.

I guess really it is forced E36 M3ty engineering by management. I suspect the engineers are not proud of this.

Because everyone wants HP and economy, there are compromises that have to be made to achieve that.

There is no need for a street driven car to need to exceed 112 mph but that aside, they designed the car for an intended purpose, it was just not the owners intended purpose. The car is not under designed or E36 M3ty engineering, it functions fine when operated within the specifications for which it was designed.

I'm interested in the question previously posed regarding the "track pack" for these cars. Does anyone know if the driveshaft is different on such equipped cars?

JThw8 wrote: Because everyone wants HP and economy, there are compromises that have to be made to achieve that. There is no need for a street driven car to need to exceed 112 mph but that aside, they designed the car for an intended purpose, it was just not the owners intended purpose. The car is not under designed or E36 M3ty engineering, it functions fine when operated within the specifications for which it was designed.

What if someone wants to drive it on the autobahn? What if somebody wants to take it to a track day?

I suspect that on the Autobahn or Track the car will safely top out at 112 mph. I too suspect that the Track Pack handles curves better right up to the same 112 mph limit.

112 an arbitrary limit put on the car to protect it from it's substandard parts.

So when they limit the Miata to 100 mph you won't be upset? I mean after all it's a girlie car.

jrw1621 wrote: I suspect that on the Autobahn or Track the car will safely top out at 112 mph. I too suspect that the Track Pack handles curves better right up to the same 112 mph limit.

Well, that just sucks then.

Part of engineering is the art of finding the right (or an acceptable) compromise between resources and constraints to meet a list of requirements.
Speed limitations (whether enforced or not) are inherent of every vehicle.
Aircraft speed and G limitations are very explicit, exceed those and you will have a very bad day.
It's good engineering to do the research to design a product which will meet those limitations, to test and verify that it will repeatably and reliably meet them, and that such design can be manufactured in required quantities at the required price point.
Why is it that we can accept that a tire built and rated for 118 MPH at a particular price is good engineering, but that a car built and rated for 113 MPH is not?

Carter

erohslc wrote: Part of engineering is the art of finding the right (or an acceptable) compromise between resources and constraints to meet a list of requirements. Speed limitations (whether enforced or not) are inherent of every vehicle. Aircraft speed and G limitations are very explicit, exceed those and you will have a very bad day. It's *good engineering* to do the research to design a product which will meet those limitations, to test and verify that it will repeatably and reliably meet them, and that such design can be manufactured in required quantities at the required price point. Why is it that we can accept that a tire built and rated for 118 MPH at a particular price is good engineering, but that a car built and rated for 113 MPH is not? Carter

Why then it's obvious the car is overbuilt and we ought to be applauding Ford for giving us soo much more for our money.

carguy123 wrote: 112 an arbitrary limit put on the car to protect it from it's substandard parts. So when they limit the Miata to 100 mph you won't be upset? I mean after all it's a girlie car.

They are not substandard if they do the job they were meant to do. You're not usually this silly. Think about it. The manufacturer places limits on the car to protect it mechanically. If you remove the rev limiter on the engine, is it Ford's fault that it threw a rod at 8 grand?

carguy123 wrote: So you guys are saying it's OK because the manufacturer put parts on the car that weren't up to the performance standards of the car? A simpler method would have been just to detune the horsepower of the car, but wait that would have made it slow. We want bragging rights AND WE WANT MORE MONEY. What they did was the equivalent of putting a LS3 in a base Miata and then since they would be leaving the brakes and suspension stock they simply put a speed limiter of 70mph on the car.

Point by point

Parts did clearly meet the "Performance standards of the car"

The car is detuned by the use of a speed limiter.

The car is slower as a result, hence your illogical complaint.

What "bragging rights" are there for a low cost, V6, auto, secretary's fastback?

This is the cheapest Mustang, how does that equal "We want more money"?

How is a V6 the same as a LS3 in any way?

How is a Miata and a Mustang comparable?

How is 70mph the same as 113mph?

In summary, you just exaggerated you way out of any relevance in this topic, seriously man.

The car is limited to the speed of the tires and the driveshaft was built down to this standard to make the car more economical to buy and to run.

Ford has built the secretary version of the Mustang since day 1 in 1964, this is nothing new.

If you want a fast Mustang, buy a fast Mustang.

Car and Driver article

http://www.caranddriver.com/news/2011-ford-mustang-v6-official-photos-and-info

http://www.youtube.com/watch?v=VLmXeUflf4I&feature=player_embedded#!

I hate to do this, but lets bring some math into this argument: (WARNING: kind of long and engineering related)

Centripital Force is the force than a rotating object experiences that keeps it zinging around the center of rotation instead of going straight off in a tangent.

This force is calulated by: F= m * r * w^2, where F= force, m=mass of the object, r= distance from the center of rotation to the center of mass of the object and w= rotation speed.

As you can see, the rotation speed is squared, which means that it makes the force increase really quickly when it spins faster.

Lets take and example: F(@112) = m * r * w(@112)^2 = Fx

Now at 135: w(@135) = 135-112/112 + 100% = 1.205 * w(@112), and this means that F(@135) = m * r * [1.205 * w(@112)]^2 which results in:

F(@135) = 1.453 * F(@112), so this driveshaft was subjected to over 45% more force than it was designed for at 112mph.

To put this in perspective, if you had a vehicle hoist that was rated for 4000lbs, would you get under it if someone parked a 5,800lb vehicle on it?

The driver exceeded the design specs and a part failed. I don't think this is Ford's problem. If the driver wanted to go over 112mph, he should have bought the GT with the strengthened driveshaft.

Sorry about bringing math's into this, I just had to say something.

I agree with Aussie and Tuna. You guys are logically correct.

But I think "Ford built a E36 M3ty car precisely to their E36 M3ty specs" does not make for good advertisement fodder.

People like to get more than what is promised.

MrJoshua wrote: It does seem really odd that a driveshaft would be designed with less than a 20% safety margin. I wonder if that is the reason they set the speed limiter. One piece shaft developed nasty harmonics above 120mph or so?

Quite a bit less than that when you realize you can get the V6 with a 3.31 rear end.

I am speaking hypothetically of the Mustang being E36 M3ty, at this point anyway. One moron blasting his driveshaft doesn't make it a Mustang problem.

In reply to Enggboy:

My favorite post in this thread yet. Well done sir. I tip my hat to you.

This all does boil down to the rev limiter analogy. Someone wringing the motor 2000rpm past redline wouldn't be met with this "substandard" vitriol yet it is an electronic limiter just like the speed limiter.

2012 Mustang. All legend. Zero compromise. 31 MPG, 305 HP V6.

That is the Mustang homepage. Nice tagline. Now what's all this about acceptable engineering compromise in the driveshaft?

Otto Maddox wrote: 2012 Mustang. All legend. Zero compromise. 31 MPG, 305 HP V6. That is the Mustang homepage. Nice tagline. Now what's all this about acceptable engineering compromise in the driveshaft?

Braggin' rights.

Upon further (albeit quick) review, the Ford's Mustang V6 page has tons of information about it being an all-out high performance car, but no mention of the speed limiter.

tr8todd wrote: They don't know the difference between 3K rpm in first gear and 3K rpm in 5th.

Um, no... driveshaft is after the transmisison. It's spinning much faster at 3k rpm in 5th gear.

Again though... single data point. Has anyone heard of any other issues with these driveshafts? I mean, with the MT82 shift issues, you at least knew somebody who knew somebody who was experiencing it... this is one jackass on youtube who thinks trying to do a max speed run on a public road is a good idea.