125 MPH Vibration

[tbone]

I was on the backroads in downstate I$@&*%*s this morning and had a chance to open her up on a long straightaway to 125, with plenty more left, when a small vibration started, so I shut her down.
Is this the driveshaft issue I've heard about? Is this the typical speed it starts at? Is the only fix a special (expensive) aluminum/hybrid driveshaft?

(Yes, I did it in a remote area with no side streets, traffic, hills, etc.)

[MM03MOK]

The fix is not to go that fast. ;) That's cheaper than replacing or balancing your drive shaft.

[FormulaMarauder]

Anything can create a little vibration at those speeds such as tire pressure, loose suspension, and driveshaft wobble. If you're not traveling at that speed often, which I hope you are not, then I wouldn't worry.
Also check your flux capacitor, muffler bearings, and headlight fluid to make sure they are all in working order.

[tbone]

Ok, I was in Utah on the salt flats this morning.............

[tbone]

It's not that I want to travel at that speed often, not the point.

A lot of cars are designed to travel at high rates of speed, for instance on the autobahn. They make the cars perform at these speeds. Maybe I want to go to Montana and go as fast as I want. Maybe I want to ship my car to Europe. I'm just curious about the technical aspects of what is going on here.

[Joe Walsh]

If it didn't start until you hit @ 125.....driveshaft.

Too much of that and your rear transmission seal will give up the ghost.

[ChiTownMaraud3r]

Never felt it on my '04 at even faster than that..not a pleasant feeling I bet.

[FordNut]

True, but that is the driveshaft symptom. The solution is not just an aluminum driveshaft, as the Marauder came from the factory with one. The solution is a metal matrix driveshaft, or a 4" aluminum one. Metal matrix has a different metallic structure from regular aluminum. The problem is they're hard to find. Dynotech used to sell one but they no longer have it, they sell a 4" regular aluminum one. The diameter, material, length all figure in to determine the critical speed of the driveshaft.

Interesting factoid, the critical speed applies to any rotating cylinder, it was a big problem with gas centrifuge development. Lots of the early models ran at sub-critical speeds (like putting the speed limiter in the stock MM program), it took years for the scientists to figure out how to get them to rotate at supercritical speeds. It's sort of like harmonic frequency in RF electronics. First critical speed is like a bow, second critical speed is like a S, 3rd critical speed has 3 bows, etc...

[DOOM]

I have had my marauder at 150+ MPH several times and have never felt any types of vibration at all.

Also my 01 CVPI I have had at 140MPH on more than one occasion with no issues.

Now I have a 05 CVPI without any vibration issues at all.

[tbone]

I'll peak at the seal tomorrow and see. I shut it down right away, so probably not an issue.
No, not a good feeling.

[tbone]

True, but that is the driveshaft symptom. The solution is not just an aluminum driveshaft, as the Marauder came from the factory with one. The solution is a metal matrix driveshaft, or a 4" aluminum one. Metal matrix has a different metallic structure from regular aluminum. The problem is they're hard to find. Dynotech used to sell one but they no longer have it, they sell a 4" regular aluminum one. The diameter, material, length all figure in to determine the critical speed of the driveshaft.

Interesting factoid, the critical speed applies to any rotating cylinder, it was a big problem with gas centrifuge development. Lots of the early models ran at sub-critical speeds (like putting the speed limiter in the stock MM program), it took years for the scientists to figure out how to get them to rotate at supercritical speeds. It's sort of like harmonic frequency in RF electronics. First critical speed is like a bow, second critical speed is like a S, 3rd critical speed has 3 bows, etc...

What do they do with driveshafts designed for the autobahn?

[FordNut]

My car never vibrated that I could feel, but it did cause trans seal leakage. This was after 4.10 gears were installed. Upgraded driveshaft fixed it.

[Joe Walsh]

I have had my marauder at 150+ MPH several times and have never felt any types of vibration at all.

Also my 01 CVPI I have had at 140MPH on more than one occasion with no issues.

Now I have a 05 CVPI without any vibration issues at all.

Jake, your CVPI's came with the high speed/metal matrix driveshaft.
You can't feel the vibration in your Marauder because once you punch it the rear wheels never touch the pavement again!....:bows:

[FordNut]

High speed driveshafts can be made of carbon fiber, metal matrix aluminum, or have a carrier bearing in the middle of the shaft.

[tbone]

I have had my marauder at 150+ MPH several times and have never felt any types of vibration at all.

Also my 01 CVPI I have had at 140MPH on more than one occasion with no issues.

Now I have a 05 CVPI without any vibration issues at all.

Did you have your driveshafts balanced or are you just lucky?

[Joe Walsh]

What do they do with driveshafts designed for the autobahn?

The Germans design and manufacture them the correct way....stiff and sometimes they make them 2 piece...
which makes the critical speed much higher for the 2 shorter shafts.

(waiting for the "TWSS!")

[tbone]

My car never vibrated that I could feel, but it did cause trans seal leakage. This was after 4.10 gears were installed. Upgraded driveshaft fixed it.

I did the 4.10's not long ago. I've noticed some driveline lash since they were installed. I figure this is normal(??) Possibly a contributing factor to the vibration?

[tbone]

The Germans design and manufacture them the correct way....stiff and sometimes they make them 2 piece...
which makes the critical speed much higher for the 2 shorter shafts.

(waiting for the "TWSS!")

I know Corvettes have the drive tube. Not sure how that thing works.

[DOOM]

Did you have your driveshafts balanced or are you just lucky?

Lucky I guess.

Also my marauder doesn't have 4:10 gears!

Seems like most of the guys with the 4:10's are the ones having the vibration issues.

[tbone]

Lucky I guess.

Also my marauder doesn't have 4:10 gears!

Seems like most of the guys with the 4:10's are the ones having the vibration issues.

Worth it though!:burnout:

[tbone]

I just remembered that new Vettes have the tranny in the rear that helps with vibration. Still not sure how it all works.

[Motorhead350]

The fix is not to go that fast. ;) That's cheaper than replacing or balancing your drive shaft.


Ok, I was in Utah on the salt flats this morning.............

:lol:

I'm glad I am not the only one that admits to having Fun Fun Fun.

[4play]

At 150mph you must be hitting the red line.

[LSCR351]

Jake, your CVPI's came with the high speed/metal matrix driveshaft.
You can't feel the vibration in your Marauder because once you punch it the rear wheels never touch the pavement again!....:bows:

ONLY the 2000 P71's have the MMX driveshaft.

[LSCR351]

I know Corvettes have the drive tube. Not sure how that thing works.

One thing about that is the drive tube rotates at engine RPM, not RPM X OD ratio.

[Speed]

ONLY the 2000 P71's have the MMX driveshaft.

Actually 1999 and 2000

http://www.crownvic.biz/ubbthreads/ubbthreads.php?ubb=showflat&Number=1406997&fpart=2

[Dennis Reinhart]

I was on the backroads in downstate I$@&*%*s this morning and had a chance to open her up on a long straightaway to 125, with plenty more left, when a small vibration started, so I shut her down.
Is this the driveshaft issue I've heard about? Is this the typical speed it starts at? Is the only fix a special (expensive) aluminum/hybrid driveshaft?

(Yes, I did it in a remote area with no side streets, traffic, hills, etc.)

Well most senior members here know, that these cars are speed limited to 128 MPH because the OEM drive shaft reaches critical drive line vibration at speeds close to this, that is why Dynotech made the MMDS back in 2003, this is why every FHP Marauder had a MMDS these cars ran about 150 MPH, if you have 4:10 gears the critical drive line point is even lower, so you are taking the chance of walking out the rear tail shaft bushing or fracturing the rear tail shaft or killing your self and bystanders at this speed.

[LANDY]

i cracked my tailshaft housing with the stock driveshaft, it came out in three pieces be carefull out there and upgrade yours.

[tbone]

Well most senior members here know, that these cars are speed limited to 128 MPH because the OEM drive shaft reaches critical drive line vibration at speeds close to this, that is why Dynotech made the MMDS back in 2003, this is why every FHP Marauder had a MMDS these cars ran about 150 MPH, if you have 4:10 gears the critical drive line point is even lower, so you are taking the chance of walking out the rear tail shaft bushing or fracturing the rear tail shaft or killing your self and bystanders at this speed.

Thanks Dennis!
That's just the kind of input I was trying to find out by posting this. I'm glad that my "seat of the pants" feel at that speed told me to shut it down immediately. The car will always "talk" to you if you are listening, as you well know.
I don't make a habit of speeding like this. Evidence is seen as I have had this car for over three years and I have never wondered about this phenomenon. Obviously I don't recommend or condone this speed. I was in, what I consider, an extraordinarily safe situation, at least for any innocents. I was literally in the middle of nowhere.

It has made for interesting conversation, which we all like.
I hope the input continues.........

[tbone]

Well most senior members here know, that these cars are speed limited to 128 MPH because the OEM drive shaft reaches critical drive line vibration at speeds close to this, that is why Dynotech made the MMDS back in 2003, this is why every FHP Marauder had a MMDS these cars ran about 150 MPH, if you have 4:10 gears the critical drive line point is even lower, so you are taking the chance of walking out the rear tail shaft bushing or fracturing the rear tail shaft or killing your self and bystanders at this speed.

Dennis,
Does the installation of 4.10 gears cause a little driveline lash? I've noticed this on my car.

[napolitano]

I had same issue. After a couple times, I noticed fanny fluid from tailshaft leaking. Had to replace rear seal and upgraded to new dive shaft. All fixed now. No ned to speed here. I go to a road course track. Right?

[DOOM]

After a couple times, I noticed fanny fluid from tailshaft leaking.


THATS WHAT SHE SAID!!!! :puke:

[FordNut]

At 150mph you must be hitting the red line.

No. At 145 with 4.10's there's still plenty more...

[hotford]

well when i got into it with a AMG 6.3 on the hwy my GPS showed 241 klms which equalls out to 150 mph and thats at 6700 rpm with 4:10 and a 305/45/18= 29 inchs tall.

Yes I do have a metal matrix drive shaft.

Not that I'm at that speed alot but it's good to know she can handle it.

[LANDY]

well when i got into it with a AMG 6.3 on the hwy my GPS showed 241 klms which equalls out to 150 mph and thats at 6700 rpm with 4:10 and a 305/45/18= 29 inchs tall.

Yes I do have a metal matrix drive shaft.

Not that I'm at that speed alot but it's good to know she can handle it.I assume that's on 3rd gear. I also have 29" tires and at 6500 rpms I'm T 135mph. That doesn't add up.

[babbage]

True, but that is the driveshaft symptom. The solution is not just an aluminum driveshaft, as the Marauder came from the factory with one. The solution is a metal matrix driveshaft, or a 4" aluminum one. Metal matrix has a different metallic structure from regular aluminum. The problem is they're hard to find. Dynotech used to sell one but they no longer have it, they sell a 4" regular aluminum one. The diameter, material, length all figure in to determine the critical speed of the driveshaft.

Interesting factoid, the critical speed applies to any rotating cylinder, it was a big problem with gas centrifuge development. Lots of the early models ran at sub-critical speeds (like putting the speed limiter in the stock MM program), it took years for the scientists to figure out how to get them to rotate at supercritical speeds. It's sort of like harmonic frequency in RF electronics. First critical speed is like a bow, second critical speed is like a S, 3rd critical speed has 3 bows, etc...


Agree, with all of that. Here is some more info on the MMC Shaft.


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 vics. 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.
Joe walsh has a carbon fiber shaft from PST. Carbon fiber is the best type of driveshaft to get, 2nd best would be the Alcoa MMC shaft.

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

With my 3.73's and MMC shaft I'm safe at 160+ :burnout:

[CBT]

THATS WHAT SHE SAID!!!! :puke:
Hello!!!!!!!!

[DOOM]

At 150mph you must be hitting the red line.

Nope! I didnt red line until 160mph!

Car felt fine!

[Seneca]

I can feel the slight viberation in my car anywhere over 110. Had to replace the tail shaft seal already. Only time my car see's that speed is at the track. :D.. A new shaft is on my to do list.

[hotford]

I assume that's on 3rd gear. I also have 29" tires and at 6500 rpms I'm T 135mph. That doesn't add up.

Well my tach may be off or I wasn't tryin to look at it for look at that speed but this what I came up with.
So either the GPS is faulty or the tach is off.236klm= 147 mph? @6700
Maybe I was closer to 6800-7000 thats the limiter is set to.

Now the 1 gear and 2 gear show high becuase it thinks it shifting the 6700 rpm, which its not I'm just strining out thrid gear.
It could be wrong and you could be right?

Wheel Size: InchTyre Width: mmTyre Height: %Engine Max RPM:Differential Ratio:1st Gear Ratio:2nd Gear Ratio:3rd Gear Ratio:4th Gear Ratio:5th Gear Ratio:6th Gear Ratio:Results:Tyre Diameter = 2410.58 mm
1st Gear = 83.22 km/h
2nd Gear = 152.49 km/h
3rd Gear = 236.35 km/h
4th Gear = 337.65 km/h
5th Gear = Infinity km/h
6th Gear = Infinity km/h

[tbone]

Who speaks metric? Anyone? lol