I found an MMX driveshaft for $50, so they are still out there

[Stranger in the Black Sedan]

I found one of the factory TSB police MMX driveshafts for 50 bucks plus shipping, and I verified w/ the seller that it is indeed the pink/green/blue striped shaft which indicates MMX vs. the regular aluminum/police shaft.

Better than $800 for the same thing from a new driveshaft manufacturer!

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=370203093460

On its way to me, yeay!

[babbage]

I got mine for $12 - I had to pull it myself. 19 sided 19mm socket - in the rain - on broken glass under a 99 CVPI. YEccchk!

I got it out though. Yes that's a HELL of a deal. Bonus: you didn't have to pull it.


Now you can still "safely" do 140mph with the 3.73's :D

(Just like me)

[SILVERSURFER03]

Wow great find ...... 373's who runs those and why ..

[offroadkarter]

Wow great find ...... 373's who runs those and why ..



they were free, thats why :P

[Stranger in the Black Sedan]

I run 373s and ^ is correct. I can install gears myself and the gears were free

and


19 sided 19mm socket

its a 12 point 12mm socket.

[Phrog_gunner]

So the MMX driveshaft is just rated for higher RPMs?

I had never heard of a 19pt socket until just now. Not even for any of our crazy aircraft stuff.

[Stranger in the Black Sedan]

the mmx shaft, by virtue of its material properties, has a higher critical speed so yes can be run to higher rpms. This will also move the 1/2 critical speed, which with the stock gears and stock shaft is in the high 60's mph range and around 70 mph for me, high enough that I won't be cruising in that range anymore. So generally the car should be smoother overall even at highway cruise.

There is no such thing as a 19 point socket. Ford uses 12 point bolt heads for the rear d/s flange

[Phrog_gunner]

There is no such thing as a 19 point socket. Ford uses 12 point bolt heads for the rear d/s flange

I was being facetious.;)

Material properties? What material do they use thats different than our shaft? I would have guessed it was just balanced to higher standards.

[Stranger in the Black Sedan]

No, its a different alloy, balancing is not the difference. I am not a metallurgist so I don't know how the alloy is different. I do know that critical speed is improved by decreasing weight and increasing stiffness (also increasing diameter). The diameter of the 3.5 MMC shaft is the same as the 3.5 aluminum shaft. So the MMC shaft must be either lighter or stiffer, or both.

http://www.markwilliams.com/Images/critspeed.jpg


Look at how much higher the critical speed is for a 3.5" MMC shaft of the same length as a 3.5 aluminum shaft. Like look at 52". The MMC shaft has a 1,000 rpm higher critical speed. That is a HUGE difference

[Phrog_gunner]

No, its a different alloy, balancing is not the difference. I am not a metallurgist so I don't know how the alloy is different. I do know that critical speed is improved by decreasing weight and increasing stiffness (also increasing diameter).

Sweet info. I learned something new today, thanks. The metallurgy stuff really is simple. Engineers use materials books that show graphs (which in this case would be mass vs stiffness) and you would just follow the curve until you find a material that meets your needs. There is never a PERFECT fit, so you will always have to use a judgment call on the critical parameter.

[Stranger in the Black Sedan]

Heh, my degree is in mechanical engineering, but I don't work in the engineering field (I deal with intellectual properties law). Materials classes were not my strong point in school

[Phrog_gunner]

I also have a BSME. We had to take 2 semesters of Materials.

[babbage]

I run 373s and ^ is correct. I can install gears myself and the gears were free

and



its a 12 point 12mm socket.

Yeah, my mistake. I didn't have one of those and had to borrow it. It was an odd size as I didn't have it in my tool set.

MMX basically is as strong as steel yet weighs the same as aluminum. About 17 pounds.

[babbage]

the mmx shaft, by virtue of its material properties, has a higher critical speed so yes can be run to higher rpms. This will also move the 1/2 critical speed, which with the stock gears and stock shaft is in the high 60's mph range and around 70 mph for me, high enough that I won't be cruising in that range anymore. So generally the car should be smoother overall even at highway cruise.


huh?! Highway crusing at 60 or 70mph, you can't tell the difference between stock and MMC. There is something wrong if you can tell that it's "smoother" I seriously doubt you can feel any difference, except at very high speed.

[Stranger in the Black Sedan]

I read that when designing a driveshaft, not only do you not want to approach critical speed, so the shaft doesn't start bending, but also you wanted to avoid placing a constant cruise speed at 1/2 critical speed, because a driveshaft running near 1/2 critical speed can experience a vibration that can not be balanced out.

There is a very minor driveline vibe through the chassis, in the high 60 mph range on my Marauder, that most people would not notice but I am finicky and I notice it. This coincides with half critical speed of the driveshaft. I swapped in another stock aluminum shaft and it did not affect the vibe. Is it a coincidence that I have a driveline vibe and that it happens to be at half critical speed of the shaft? I can't tell you, but I will be able to tell you if the MMC shaft eliminates the slight vibe, and then maybe my theory is correct.

[babbage]

Sweet info. I learned something new today, thanks. The metallurgy stuff really is simple. Engineers use materials books that show graphs (which in this case would be mass vs stiffness) and you would just follow the curve until you find a material that meets your needs. There is never a PERFECT fit, so you will always have to use a judgment call on the critical parameter.


MMC = Metal Matrix Composite. The Composite is a special blend of Aluminum and Steel that Alcoa manufactured into driveshafts for Ford PI's in 99 and 1/2 of 2000. The MMX shaft made by Alcoa was a BLEND of metals which was 30% STRONGER than aluminum, yet it weighed the same as an all aluminum shaft. This is why those AMMX shafts are so sought after -- this is what I remember from my research about this.

MMC police shaft is about 1/4 lb lighter than the aluminum police shaft, and a few pounds lighter than the longer aluminum shaft. MMC is only slightly lighter than 6061 aluminum. Mild steel is about twice as heavy as the MMC.

My MMC feels feather light, especially after I removed the steel yolk and universals, it's only about 6 lbs.

MMC's elasticity is nearly 1.5 times that of 6061 aluminum, this allows the MMC shaft to absorb more drive-line vibrations. The issue with shafts is that they create ultra high frequency vibrations at high rpms, and they will eventually self-destruct. It also absorbs shaft "twist" much better.

The 53" police MMC shaft's critical speed is 9093 rpm, and the aluminum shaft is 7930 rpms.

I have no idea about the high speed extended run testing of the MMC? It will out run 6061 aluminum in every aspect, and is the best alternative aside from carbon fiber for our cars. Carbon fiber is as good an improvement over the MMC as the MMC is over the 6061, and it brings the rpms up to about 12-13000 rpms at critical speed.

Note: critical speed is a max, if you reach it, your shaft can become a deadly projectile.

For those who would like to tell whether a driveshaft is MMC or not:

MMC - found on most (not all) 1999 and 2000 P71's - has pink and green stripes running around the shaft, and if you look carefully in small black print you will see the letters "MMC"

Aluminum - on all other P71's - markings vary by year but 1999/2000 ones have pink/blue/orange stripes


VICEvilBrother: does your's have the small MMC black lettering on it?

[Stranger in the Black Sedan]

It has the pink/green/blue stripes on it per the seller when I emailed him, so it has to be the MMC shaft, he had some others there that had the orange stripe that indicated regular aluminum . I had him look for lettering and he didn't see it. I don't have the shaft in my hands yet. But as long as he isn't color blind I'm good

[Georges93LX]

In found one of these in a '07PI. It had the Green and Pink stripe but I couldn't find any other (AMMX or MMX) markings on it. Is it possible they are being used in newer models again?

[babbage]

It has the pink/green/blue stripes on it per the seller when I emailed him, so it has to be the MMC shaft, he had some others there that had the orange stripe that indicated regular aluminum . I had him look for lettering and he didn't see it. I don't have the shaft in my hands yet. But as long as he isn't color blind I'm good


Just go to a yard and pull one. Don't forget your 19 sided (err 12 sided) 12mm socket.

XW7Z-4602-AA MMC Driveshaft

MMC = found on most (not all) 1999 and 2000 P71's - has pink and green stripes running around the shaft.

Aluminum = on all other P71's - markings vary by year but 1999/2000 ones have pink/blue/orange stripes.

[babbage]

In found one of these in a '07PI. It had the Green and Pink stripe but I couldn't find any other (AMMX or MMX) markings on it. Is it possible they are being used in newer models again?


Ford did offer them as an upgrade (about $1200!) so YES those colors are correct. That's a rare find George.

The shaft I pulled out of a 99 myself had those colors (stripes are green and pink/redish) and had the small black letters MMC on it.

[babbage]

I read that when designing a driveshaft, not only do you not want to approach critical speed, so the shaft doesn't start bending, but also you wanted to avoid placing a constant cruise speed at 1/2 critical speed, because a driveshaft running near 1/2 critical speed can experience a vibration that can not be balanced out.

There is a very minor driveline vibe through the chassis, in the high 60 mph range on my Marauder, that most people would not notice but I am finicky and I notice it. This coincides with half critical speed of the driveshaft. I swapped in another stock aluminum shaft and it did not affect the vibe. Is it a coincidence that I have a driveline vibe and that it happens to be at half critical speed of the shaft? I can't tell you, but I will be able to tell you if the MMC shaft eliminates the slight vibe, and then maybe my theory is correct.


That's interesting. Let me/us know how it goes. So based on your calculations what is 1/2 the driveline critical speed with 3.73's and the MMC shaft with factory wheels??

[UncleLar]

"There is a very minor driveline vibe through the chassis, in the high 60 mph range on my Marauder, that most people would not notice but I am finicky and I notice it. This coincides with half critical speed of the driveshaft. I swapped in another stock aluminum shaft and it did not affect the vibe. Is it a coincidence that I have a driveline vibe and that it happens to be at half critical speed of the shaft? I can't tell you, but I will be able to tell you if the MMC shaft eliminates the slight vibe, and then maybe my theory is correct."
A harmonic?
Let me know how the scratch from the wire looks when you get it.

[CBT]

MMC = Metal Matrix Composite. The Composite is a special blend of Aluminum and Steel that Alcoa manufactured into driveshafts for Ford PI's in 99 and 1/2 of 2000. The MMX shaft made by Alcoa was a BLEND of metals which was 30% STRONGER than aluminum, yet it weighed the same as an all aluminum shaft. This is why those AMMX shafts are so sought after -- this is what I remember from my research about this.

MMC police shaft is about 1/4 lb lighter than the aluminum police shaft, and a few pounds lighter than the longer aluminum shaft. MMC is only slightly lighter than 6061 aluminum. Mild steel is about twice as heavy as the MMC.

My MMC feels feather light, especially after I removed the steel yolk and universals, it's only about 6 lbs.

MMC's elasticity is nearly 1.5 times that of 6061 aluminum, this allows the MMC shaft to absorb more drive-line vibrations. The issue with shafts is that they create ultra high frequency vibrations at high rpms, and they will eventually self-destruct. It also absorbs shaft "twist" much better.

The 53" police MMC shaft's critical speed is 9093 rpm, and the aluminum shaft is 7930 rpms.

I have no idea about the high speed extended run testing of the MMC? It will out run 6061 aluminum in every aspect, and is the best alternative aside from carbon fiber for our cars. Carbon fiber is as good an improvement over the MMC as the MMC is over the 6061, and it brings the rpms up to about 12-13000 rpms at critical speed.

Note: critical speed is a max, if you reach it, your shaft can become a deadly projectile.

For those who would like to tell whether a driveshaft is MMC or not:

MMC - found on most (not all) 1999 and 2000 P71's - has pink and green stripes running around the shaft, and if you look carefully in small black print you will see the letters "MMC"

Aluminum - on all other P71's - markings vary by year but 1999/2000 ones have pink/blue/orange stripes


VICEvilBrother: does your's have the small MMC black lettering on it?

My head just exploded.

[Phrog_gunner]

My head just exploded.

And they say Marines are supposed to be the dumb ones.

[babbage]

My head just exploded.

Just a note on MMC: The modulus of elasticity is 14.1 million pounds per inch2. The density is .106 pounds an inch3. Aluminum elasticity is 10 million pounds/inch2 and .098 density.

:D

maximum Critical Speed (16 inch wheels)
--------------------------------------
CVPI Amuminum Driveshaft 4.10 = 116mph
CVPI Amuminum Driveshaft 3.55 = 132mph
CVPI Amuminum Driveshaft 3.27 = 145mph
CVPI Amuminum Driveshaft 3.08 = 154mph
CVPI Metal/Matrix Driveshaft 4.10 = 133mph
CVPI Metal/Matrix Driveshaft 3.55 = 154mph
CVPI Metal/Matrix Driveshaft 3.27 = 167mph
CVPI Metal/Matrix Driveshaft 3.08 = 177mph


MMC = found on most (not all) 1999 and 2000 P71's - has pink and green stripes running around the shaft. Mine from a 99 had POLICE and a small MMC printed on the shaft itself from "door to door"

Aluminum = on all other P71's - markings vary by year but 1999/2000 ones have pink/blue/orange stripes.

[Stranger in the Black Sedan]

Update, the joke's on me. I received the driveshaft and it is indeed the correct pink, green, blue striped MMC shaft. But there is a HUGE groove cut in the shaft from where a screw must have been touching the shaft, from a police floor mount somethin-or-other. It scribed its way pretty deep into the shaft and there is no way in hell I would run it. It's a stress riser waiting to happen. Friekin great. These stupid shafts are not easy to find because most junkyards are not willing to look at the paint code and ensure it is the MMC shaft.

[UncleLar]

Bummer,sorry to hear it.

[Phrog_gunner]

So are they going to give you your money back since the part can't be used. I'm pretty sure you would have noticed if the AD said "Has groove worn into it", so you rate a refund.

[Stranger in the Black Sedan]

The junkyard said there was a cosmetic blemish from something "slightly rubbing it". I don't equate a nice clean near-break in the shaft as a cosmetic blemish. It's like 1/3 way through the wall thickness. You might be able to break this shaft over the end of a table, on the line.

I'm sure they are going to try to send me a regular aluminum P71 shaft now as a replacement, we'll find out.