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Do you experience vibration and rumbling between 50 and 70 mph?


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15Pony

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they finally did notice the vibration after I took one of the techs out onto the turnpike and got it up to 62 miles an hour and he could really feel it,
That's completely normal. The vibration when you get it up to 62mph is the Flux Capacitor kicking in, preparing to send you back to 1965. :lol::lol:
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cbrookre

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Many times over ... along with a half dozen other possible fixes. Hope they find the cause, keep us posted.
Figured so, but I was on my phone which completely fails to let me do any searches...thanks! Seems like a way to hide the symptoms as opposed to understanding the root cause. What caused it (after 27k miles) to suddenly get out of balance? That is what I would want to know.
 

cbrookre

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That's completely normal. The vibration when you get it up to 62mph is the Flux Capacitor kicking in, preparing to send you back to 1965. :lol::lol:
It is building up the 1.21 Gigawatts needed to make the transition! 1.21 GIGAWATTS!
 

GT Pony

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What caused it (after 27k miles) to suddenly get out of balance? That is what I would want to know.
That's an even bigger mystery than the root cause is. I've always suspected the rubber mounted center bearing carrier, which could degrade with time.

I wonder if any aftermarket company makes a beefier center bearing carrier?
 

ScottsGT

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Somewhere in this thread I posted I was experiencing the vibration but thought it was tires. New tires and still on occasion get the cyclic vibration around 70. Weird thing is, it's not always there. Some days I notice it, other days nothing. When it is there it is ever so slight. My luck it won't be acting up when I take it in.
It's not constant, kind of like a bad pinion angle. A womp......womp.....womp.....womp.....
 

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lugz

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That's an even bigger mystery than the root cause is. I've always suspected the rubber mounted center bearing carrier, which could degrade with time.

I wonder if any aftermarket company makes a beefier center bearing carrier?
I'd guess the center bearing and massive guibo are the engineering band-aids to work around the vibration, not the cause.
 

ScottsGT

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I just can't figure out why Ford went with this two piece DS to begin with? I'd like to know if anyone that has these issues replace the DS and had the problem go away.
 

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I just can't figure out why Ford went with this two piece DS to begin with?
Because a 2 piece driveshaft has a higher critical rotating speed than a 1 piece made of the same material and length. You can watch tons of S197 II V6 mustangs (which had a 1 piece driveshaft unlike the GT's) with the speed limiter removed blowing the driveshafts apart on the dyno or on the road.

I know I cite the panther platform a lot when talking about Ford's flaws but history tends to repeat itself. The panther platform has a long 1 piece driveshaft and back in 1999, a lot of police departments were complaining about driveline vibrations during high speed pursuits while driving 3.55 geared P71's. Ford contacted Alcoa and made what is called the "Alcoa Metal Matrix Composite" or AMMX/AMMC driveshaft to cure these woes. It's a popular upgrade for panther owners with gears to grab a 99-00 AMMX driveshaft as it has a higher critical speed than factory aluminum or steel shafts. (03-04 Marauders, like V6 S197II's, were limited to 117mph due to driveline vibes).

I'd like to know if anyone that has these issues replace the DS and had the problem go away.
I've read plenty of posts on here saying a 1 piece driveshaft didn't fix or even amplified the driveline vibrations. The solution to a vibration isn't to replace it with a less NVH complaint part.

If this was a driveline vibration at 130mph+ coming from the bowing of the driveshaft, than upgrading to something like a carbon fiber one piece would work. Less rotating mass = higher critical driveline speed. But for a 55-70mph vibe, this isn't the problem. After seeing some videos of how much the S550 pinion moves up and down I wouldn't at all be surprised if bad driveline angles from the factory are the root cause. Haven't had time to look at my car though.
 

smokinzx14r

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Because a 2 piece driveshaft has a higher critical rotating speed than a 1 piece made of the same material and length. You can watch tons of S197 II V6 mustangs (which had a 1 piece driveshaft unlike the GT's) with the speed limiter removed blowing the driveshafts apart on the dyno or on the road.

I know I cite the panther platform a lot when talking about Ford's flaws but history tends to repeat itself. The panther platform has a long 1 piece driveshaft and back in 1999, a lot of police departments were complaining about driveline vibrations during high speed pursuits while driving 3.55 geared P71's. Ford contacted Alcoa and made what is called the "Alcoa Metal Matrix Composite" or AMMX/AMMC driveshaft to cure these woes. It's a popular upgrade for panther owners with gears to grab a 99-00 AMMX driveshaft as it has a higher critical speed than factory aluminum or steel shafts. (03-04 Marauders, like V6 S197II's, were limited to 117mph due to driveline vibes).



I've read plenty of posts on here saying a 1 piece driveshaft didn't fix or even amplified the driveline vibrations. The solution to a vibration isn't to replace it with a less NVH complaint part.

If this was a driveline vibration at 130mph+ coming from the bowing of the driveshaft, than upgrading to something like a carbon fiber one piece would work. Less rotating mass = higher critical driveline speed. But for a 55-70mph vibe, this isn't the problem. After seeing some videos of how much the S550 pinion moves up and down I wouldn't at all be surprised if bad driveline angles from the factory are the root cause. Haven't had time to look at my car though.
I agree with the bad driveline angles , but why did mine work fine for 5k and then out of the blue it has a problem ..? Seems strange that some guys replaced the stock shaft with a new stock shaft just to have the problem come after a few 100+ miles .. In all the cases I have read in this thread no one replaced the carrier bearing and support rubber bushing . I'm thinking that because of so much movement in the rear pinion angles it's taking its toll on the carrier bearing and the rubber support in the carrier .. I'm not sure but I think when the dealer replaces the drive shaft it's a complete unit ( carrier bearing included ) .. some have had it fix the problem for a short time just to have it come back with more miles .. So maybe we have two problems ( carrier rubber support breaking down because of the bad pinion angles )...
 

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The Chevy Camaro has a carrier bearing ds on their cars 0 vibrations, Dodge Challenger has the same set up no vibes. I changed my pinion angles by shimming my trans down with 1/4 inch shims between the body and the x member and the vibes went a away i have a 1 piece dynotech ds as well! Also there are zero vibrations reported from gt-350 owners but then again ford made sure the car was balanced correctly because of tendencies of plane engines being prone to vibrations. The driveline angles in these are fubar from the factory, this is the root cause of the issue!
 

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ScottsGT

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The driveline angle does seem to ring a bell in my memory. When I was setting up the 4 link coil over in my '66 GT Fastback I had a terrible vibration at 50 MPH that was about 100X worse than the occasional vibration I'm experiencing. It was the same oscillating vibration. I got out my magnetized angle gauge and went to work and solved the problem.
Since mine is so intermittent, maybe I should try some 1/8" shims. Trying to avoid pulling the DS to check angles.
 

cbrookre

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Dealer sent my car to a driveline balancing shop (did not know there was such a thing), after a week they came back and said that my car does not have a balance-able drive shaft so they are replacing it. Will try the shim method if it is not magically fixed...
 

cbrookre

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Update: Got my car back yesterday after they replaced the driveline. Vibration is certainly much better, barely perceptible now. Will look to possibly do the shim fix at some point to see if it eliminates the rest.
 

ScottsGT

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Sounds great. I'm thinking the out of spec angles is causing the DS to prematurely wear out. Just a WAG though on my part.
 

shelbywannabe

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A 1/4" shim will make that much difference ? Mine is at the dealer now going through the testing process
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